Os occipitale - odd, participates in the formation of the base and roof of the skull. Upper part The scales of the occipital bone ossify on the basis of connective tissue, the remaining parts (main and lateral) - on the basis of cartilage. The outer surface of the occipital bone is convex, the inner surface is concave. The anterior inferior section contains the foramen magnum, foramen magnum. The occipital bone has four parts: the main one, pars basilaris, two lateral parts, partes lateralis, and the occipital scales, squama occipitalis. Until 3-6 years of a child’s life, these parts are separate bones, and then, fused, they form one bone.
Main part, pars basilaris - short, thick, quadrangular. It limits the large (occipital) foramen, foramen magnum, of oval or round shape (Yu. V. Zadvornov, 1972). The upper surface of the main part is concave in the form of a groove and faces the cranial cavity; it forms a slope, clivus, to which the medulla oblongata is adjacent. In the middle of the lower outer surface there is a small pharyngeal tubercle, tuberculum pharyngeum. The outer, slightly uneven edges of the main part, together with the stony parts, form the petrooccipital fissures, which in childhood filled with cartilage, and ossify with age.
Side parts, partes lateralis - form the lateral sides of the foramen magnum and connect the main part with the scales. On the inner, cerebral surface, at the outer edge there is a narrow groove of the petrous sinus, which, together with the same groove of the temporal bone, forms something like a canal where the inferior petrosal sinus, sul, lies. sinus petrosi inferioris.
On the lower outer surface of each lateral part is the occipital process, condylus occipitalis, for connection with the upper articular surface of the atlas. Behind the occipital condyle there is a condylar fossa, fossa condylaris, with an opening in the bottom, which leads into the unstable condylar canal, canalis condylaris. The outer edge of the lateral part contains a jugular notch, incisura jugularis, on which a small internal jugular process, processus jugularis, protrudes. The jugular notch with the notch of the same name on the temporal bone forms the jugular foramen, foramen jugularis, which is divided by the intrajugular process into anterior and posterior sections. The jugular vein originates in the anterior one, and the cranial nerves (IX-XI pair) pass through the posterior one. Along the jugular processes from the side inner surface on the lateral part there is a deep groove of the transverse sinus, sul. sinus transversus. The anterior section of the lateral part contains the jugular tubercle, tuberculum jugulare, back and down from which, between the jugular and occipital processes, lies the canal of the hypoglossal nerve, canalis nervi hypoglossi.
Occipital scales, squama occipitalis - has a triangular shape, curved, limiting the foramen magnum at the back. The lateral edge of the scales is divided into two sections: the upper (lambda-like margo lambdoideus) and the lower (mastoid, margo mastoideus). In the middle of the outer surface of the scales there is an external occipital protrusion, protuberantia occipitale externa. The upper cervical lines, linea nuchalis supreior, diverge from it. Above them are additional high cervical lines, linea nuchalis suprema. From the external occipital protrusion down to the foramen magnum, the external nuchal crest, crista occipitalis externa, is directed. In the middle of the segment connecting the foramen magnum and the external occipital protrusion, the lower cervical lines, linea nuchalis inferior, diverge in different directions. Muscles are attached to these lines. On the inner surface of the scales there is a cruciform eminence, eminentia cruciformis, in which the internal occipital protrusion, protuberantia occipitalis interna, is located. A cruciform eminence divides the inner surface of the scales into four fossae; the two lower ones contain the cerebellar hemispheres, and the upper ones contain the occipital lobes of the brain. From the cruciform eminence, grooves of the transverse sinus, sul. sinus transversa - the groove of the superior sagittal sinus goes upward, sul. sinus sagittalis superior, and downwards - the internal occipital crest, crista occipitalis interna.
Ossification. The first points of ossification in the occipital bone appear at the beginning of the 3rd month of the intrauterine period of development in the connective tissue and cartilaginous parts. In the cartilaginous part there are five points of ossification: one in the main part, two in the lateral parts and two in the cartilaginous part of the scales. In the connective tissue part of the scales there are two points of ossification. At the end of 3 months, the upper and lower sections of the scales grow together, and the main part, scales and side parts grow together at 3-6 years of life. The main part fuses with the body
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1st temporal bone
2-parietal bone
3-crown (toothed) suture
4-frontal bone
5-frontal tubercle ( tuber frontale)
6-greater wing of the sphenoid bone ( ala major ossis sphenoidalis)
7-socket
8-tear bone ( os lacrimale)
9-nose bone ( os nasale)
10-frontal process of the maxilla ( processus frontalis maxillae)
11-upper jaw
12-alveolar eminences of the maxilla
13-zygomatic bone
14-mental foramen
15-tuberosity of the lower jaw
16-coronoid process of the mandible ( processus coronoideus mandibulae)
17-zygomatic arch ( arcus zygomaticus)
18-styloid process ( processus styloideus)
19-articular process of the mandible
20 mastoid process of the temporal bone ( processus mastoideus ossis temporalis)
21-external auditory canal ( meatus acusticus externus)
22 scales of the temporal bone
23-occipital bone
24-inferior temporal line
25-superior temporal line.
1st frontal bone
2-coronal stitch ( sutura coronalis)
3-parietal bone
4-socket
5-scales of the temporal bone
6-zygomatic bone
7-upper jaw
8-hole hole
9-lower jaw
10-mental puffiness
11 teeth of the lower jaw
12-intermaxillary suture
13-nasal bone ( os nasale)
14-zygomatic arch ( arcus zygomaticus)
15-tear bone ( os lacrimale)
16th large wing of the sphenoid bone ( ala major ossis sphenoidalis)
17-brow ridge
18-glabella (glabella)
19-frontal tubercle.
1-frontal scales ( squama frontalis)
2-frontal tubercle ( tuber frontale)
3-glabella (glabella)
4-zygomatic process ( processus zygomaticus)
5-supraorbital margin ( margo supraorbitalis)
6-nasal part (frontal bone)
7-nasal spine ( spina nasalis)
8-frontal notch
9-brow ridge
10-supraorbital foramen ( foramen supraorbitalis)
11-temporal line
1-parietal edge
2-sulcus of the superior sagittal sinus ( )
3-frontal ridge ( crista frontalis)
4-zygomatic process ( processus zygomaticus)
5-finger-shaped impressions ( impressions digitales)
6-blind hole ( foramen caecum)
7-nose ( pars nasalis)
8-orbital part ( pars orbitalis)
9-cerebral eminences
10-arterial grooves ( sulci arteriosi)
11-frontal scales.
1-visual channel ( canalis opticus)
2-back saddle
3-posterior oblique process
4-anterior oblique process
5-small wing ( ala minor)
6-superior orbital fissure ( fissura orbitalis superior)
7-parietal angle
8-large wing (cerebral surface)
9-round hole ( foramen rotundum)
10-pterygoid canal ( canalis pterygoideus)
11-scaphoid fossa
12-lateral plate (pterygoid process)
13-pterygoid notch ( incisura pterygoidea)
14-groove of the pterygoid hook
15-vaginal process
16-wedge ridge
17-body of the sphenoid bone ( corpus ossis sphenoidalis)
18-medial plate (pterygoid process)
19-wing hook ( Hamulus pterygoideas)
20-pterygoid fossa ( fossa pterygoidea)
21-sulcus of the internal carotid artery
1-aperture of the sphenoid sinus ( aperture sinus sphenoidalis)
2-back saddle
3-wedge shell ( conchae sphenoidalis)
4-small wing ( ala minor)
5-superior orbital fissure ( fissura orbitalis superior)
6-zygomatic margin
7-infratemporal surface, 8-sphenoid bone ( spina ossis sphenoidalis)
9-pterygopalatine groove
10-lateral plate ( lamina lateralis)
11-wing hook ( Hamulus pterygoideas)
12-medial plate of the pterygoid process
13-vaginal process
14-wedge comb
15-pterygoid notch ( incisura pterygoidea)
16-pterygoid canal ( canalis pterygoideus)
17-round hole ( foramen rotundum)
18-temporal crest ( crista infratemporalis)
19-orbital surface of the greater wing
20-temporal surface of the greater wing
1-sulcus of the superior sagittal sinus ( sulcus sinus sagittalis superioris)
2-squama of occipital bone
3-internal occipital protuberance ( )
4-internal nuchal crest ( crista occipitalis inferna)
5-foramen magnum ( foramen occipitale magnum)
6-sulcus of the sigmoid sinus ( sulcus sinus sigmoidei)
7-mouse channel
8-groove of the inferior petrosal sinus ( )
9-slope ( clivus)
10-basilar (main) part
11-lateral part ( pars lateralis)
12-Jegment Tenderloin
13th jugular tubercle
14-jugular process
15-inferior occipital fossa
16-sulcus of the transverse sinus ( sulcus sinus transversi)
17-superior occipital fossa
1-highest nuchal line
2-external occipital protuberance ( )
3-superior nuchal line ( linea nachalis superior)
4-inferior nuchal line ( linea nuchalis inferior)
5-condylar canal ( canalis condylaris)
6-occipital condyle ( condylus occipitalis)
7-intraspinal process
8-pharyngeal tubercle ( tuberculum phanryngeum)
9-basilar (main) part
10-lateral part ( pars lateralis)
11-jugular notch
12-jugular process
13th condylar fossa ( fossa condylaris)
14-foramen magnum ( foramen occipitale magnum)
15-neck surface (platform)
16-external nuchal crest ( crista occipitalis externa)
17-occipital scales
1-frontal angle ( angulus frontalis)
2-superior temporal line
3-frontal edge ( margo frontalis)
4-inferior temporal line
5-wedge angle ( angulus sphenoidalis)
6-scale edge
7-mastoid angle ( angulus mastoideum)
8-occipital edge ( margo occipitalis)
9-parietal tubercle ( tuber parietale)
10-sagittal edge
1-occipital angle ( angulus occipitalis)
2-occipital edge ( margo occipitalis)
3-arterial grooves ( sulci arteriosi)
4-sulcus of the sigmoid sinus ( sulcus sinus sigmoidei)
5-mastoid angle ( angulus mastoideum)
6-scale edge
7-wedge angle ( angulus sphenoidalis)
8-frontal edge ( margo frontalis)
9-frontal angle ( angulus frontalis)
10-pit granulations
11-sagittal edge
12-sulcus of the superior sagittal sinus.
1-cockscomb ( crista galli)
2-orbital plate ( lamina orbitalis)
3-perpendicular plate ( lamina perpendicularis)
4-uncinate process ( processus uncinatus)
5-middle turbinate ( concha nasalis media)
6-superior turbinate ( concha nasalis superior)
7-lattice cells.
1-perpendicular plate ( lamina perpendicularis)
2-middle turbinate ( concha nasalis media)
3-cockscomb ( crista galli)
4-lattice cells
5-grid plate
6-orbital plate ( lamina orbitalis)
7-anterior ethmoidal groove
8-uncinate process
1-squamous part (scales) of the temporal bone
2-zygomatic process ( processus zygomaticus)
3-articular tubercle ( tuberculum articulare)
4-mandibular fossa ( fossa mandibularis)
5-stony-scaly fissure ( fissure petrosquamosa)
6-petrostympanic (Glaserian) fissure
7-styloid process ( processus styloideus)
8-tympanic part of the temporal bone
9-external auditory opening ( porus acusticus externus)
10-mastoid process ( processus mamillaris)
11-mastoid notch ( incisura mastoidea)
12-tympanomastoid fissure ( fissura tympanomastoidea)
13-supragastric spine (above the auditory canal)
14-mastoid foramen ( foramen mastoideus)
15-parietal notch ( incisura parietalis)
16-temporal line.
1-squamosal part of the temporal bone
2-arc-shaped elevation ( eminentia arcuata)
3-parietal notch ( incisura parietalis)
4-roof tympanic cavity
5-sulcus of the superior petrosal sinus
6-boroeda of the sigmoid sinus
7-mastoid foramen ( foramen mastoideus)
8-occipital edge ( margo occipitalis)
9-external opening (aperture) of the vestibule water supply
10-subarc fossa ( fossa subarcuata)
11-vagina of the styloid process ( vagina processus styloidei)
12-styloid process ( processus styloideus)
13-external opening (aperture) of the cochlear canaliculus
14-internal auditory opening ( porus acusticus internus)
15-groove of the inferior petrosal sinus ( )
16-posterior surface of the pyramid of the temporal bone
17-top of the pyramid
18 zygomatic process ( processus zygomaticus)
19-arterial grooves
1-external auditory canal ( meatus acusticus externus)
2-styloid process ( processus styloideus)
3-pose-disarticular tubercle
4-mandibular fossa ( fossa mandibularis)
5-articular tubercle ( tuberculum articulare)
6-zygomatic process ( processus zygomaticus)
7-stony-scaly shel
8-lower process of the pyramid of the temporal bone (roof of the tympanic cavity)
9-petrostympanic (Glaser's) fissure
10-musculotubal canal ( canalis muculotubarius)
11-internal opening of the carotid canal ( foramen caroticum internum)
12-external opening of the carotid canal ( foramen caroticum externum)
13-petalled dimple ( fossula petrosa)
14-external opening (aperture) of the cochlear canaliculus
15 mastoid tubule
16-jugular fossa
17-stylomastoid foramen ( foramen mastoideus)
18-occipital edge ( margo occipitalis)
19-sulcus of the occipital artery ( sulcus arteriae occipitalis)
20-mastoid notch ( incisura mastoidea)
21st mastoid process ( processus mamillaris)
1-temporal bone scales
2-mastoid cave ( antrum mastoideum)
3-prominence of the lateral semicircular canal
4-protrusion of the facial nerve canal
5-window vestibule
6-probe in the facial nerve canal
7-cleft canal of the greater petrosal nerve ( hiatus canalis nervi petrosi majoris)
8-cleft canal of the lesser petrosal nerve ( hiatus canalis nervi petrosi minoris)
9-sulcus of the greater petrosal nerve ( sulcus nervi petrosi majoris)
10-sulcus of the lesser petrosal nerve ( sulcus nervi petrosi minoris)
11-hemicanal of the tensor tympani muscle
12-half-channel auditory tube
13-internal opening of the carotid canal
14-external opening of the carotid canal ( foramen caroticum externum)
15-Cape
16-tympanic cavity
17-pyramid elevation
18-stylomastoid foramen ( foramen mastoideus)
19 mastoid cells
1-frontal process
2-anterior lacrimal ridge
3-infraorbital margin
4-front surface
5-infraorbital foramen
6-nose tenderloin
7-anterior nasal spine
8-body of the upper jaw ( corpus maxillae)
9-alveolar eminences
10-zygomatic process ( processus zygomaticus)
11-alveolar foramina
12-tubercle of the upper jaw ( tuber maxillae)
13-infraorbital groove
14-orbital surface
1-frontal process
2-tear edge
3-tear groove
4-maxillary (Maxillary) sinus
5-nasal surface of the body of the maxilla
6-greater palatine sulcus
7-alveolar process
8-palatine process
9-incisal canal ( canalis incisivus)
10-anterior nasal spine
11-shell comb
12 lattice comb.
1-frontal process
2-orbital surface ( facies orbitalis)
3-zygomatic-orbital foramen
4-lateral surface
5-temporal process
1-grid edge
2nd left wing of the opener
3-free edge
4-palatal margin
1-internasal suture
2-hole of the nasal bone
3-free edge
1-lacrimal process
2-ethmoid process
3-bottom (free) edge
1-tear groove
2-posterior lacrimal ridge
3-tear hook
1st orbital process
2-latticed comb
3-sphenopalatine notch
4-sphenoid process
5-perpendicular plate (nasal surface)
6-shell comb
7-horizontal plate
8-pyramidal process
9-greater palatine sulcus
10-posterior nasal spine
11-nasal comb
12-maxillary process
1-coronoid process ( processus coronoideus)
2-condylar process
3-hole of the lower jaw ( foramen mandibulae)
4-notch of the lower jaw ( incisura mandibulae)
5-head of the lower jaw ( caput mandibulae)
6th branch of the lower jaw ( ramus mandibulae)
7-chewing bulkiness
8-angle of the lower jaw ( angulus mandibulae)
9-oblique line
10-base of the lower jaw
11-body of the lower jaw ( corpus mandibulae)
12-mental foramen
13-mental protuberance
14-alveolar eminences
1-body of the hyoid bone ( corpus ossis hyoidei)
2-big horn
3-small horn
1-palatine process of the maxilla ( processus palatinus maxillae)
2-incisal hole
3-median palatal suture
4-transverse palatal suture
5-choana
6-inferior orbital fissure ( fissura orbitalis inferior)
7-zygomatic arch ( arcus zygomaticus)
8-wing opener
9-pterygoid fossa ( fossa pterygoidea)
10-lateral plate of the pterygoid process
11-pterygoid process ( processus pterygoideus)
12-oval hole ( foramen ovale)
13-mandibular fossa
14-styloid process ( processus styloideus)
15-external auditory canal ( meatus acusticus externus)
16 mastoid process ( processus mamillaris)
17-mastoid notch ( incisura mastoidea)
18-occipital condyle ( condylus occipitalis)
19th condylar fossa ( fossa condylaris)
20-major (occipital) foramen
21-inferior nuchal line ( linea nuchalis inferior)
22-external occipital protuberance ( protuberantia occipitalis externa)
23-pharyngeal tubercle ( tuberculum phanryngeum)
24-muscular channel
25 jugular hole
26-occipitalomastoid suture
27-external carotid foramen
28-stylomastoid foramen ( foramen mastoideus)
29-ragged hole
30-petrostympanic fissure ( fissura petrotympanica)
31st spinous foramen ( foramen spinosum)
32-articular tubercle ( tuberculum articulare)
33-wedge-squamous suture
34-wing hook ( Hamulus pterygoideas)
35-greater palatine foramen
36-zygomatic-maxillary suture
1st orbital part of the frontal bone
2-cock feb
3-grid plate
4-view channel ( canalis opticus)
5-pituitary fossa
6-back saddle. 7-round hole ( foramen rotundum)
8-oval hole ( foramen ovale)
9-ragged hole
foramen tenspinalis ( foramen spinosum)
11-internal auditory opening ( porus acusticus internus)
12 jugular foramen
13-hyoid canal
14-lambdoid suture ( sutura lamboidea)
15-slope ( clivus)
16-beard of the transverse sinus
17-internal occipital protrusion
18-major (occipital) foramen
19-occipital scales ( squama occipitalis)
20-sulcus of the sigmoid sinus ( sulcus sinus sigmoidei)
21-pyramid (petrous part) of the temporal bone
22-squamosal part of the temporal bone
23-greater wing of the sphenoid bone ( ala major ossis sphenoidalis)
24-lesser wing of the sphenoid bone
1st zygomatic process of the frontal bone ( processus zygomaticus ossis frontalis)
2nd large wing of the sphenoid bone (orbital surface)
3-orbital surface of the zygomatic bone
4-frontal process of the zygomatic bone
5-inferior orbital fissure ( fissura orbitalis inferior)
6-zygomatico-facial deviation
7-zygomatic bone
8-infraorbital groove
9-upper jaw (maxillary bone, infraorbital surface)
10-infraorbital foramen
11-orbital surface of the maxilla ( facies orbitalis maxillae)
12-nasal cavity
13-orbital process of the palatine bone
14-tear bone ( os lacrimale)
15-orbital plate of the ethmoid bone
16-nasal bone ( os nasale)
17-tear groove (tear bone)
18-posterior lacrimal fene (lacrimal bone)
19-frontal process of the maxilla ( processus frontalis maxillae)
20-anterior ethmoidal opening
21-posterior ethmoidal foramen
22 frontal notch
23-orbital part (orbital surface) of the frontal bone
24-supraorbital foramen ( foramen supraorbitalis)
25-view channel ( canalis opticus)
26-lesser wing of the sphenoid bone ( ala minor ossis sphenoidalis)
27-superior orbital fissure
1-frontal bone (scales of the frontal bone)
2-frontal sinus
3-cockscomb ( crista galli)
4-ethmoid plate of ethmoid bone
5-superior turbinate ( concha nasalis superior)
6-middle turbinate ( concha nasalis media)
7-sphenoid sinus ( sinus sphenoidalis)
8-sphenopalatine foramen
9-inferior nasal concha ( concha nasalis inferior)
10-vertical plate of the palatine bone
11-medial plate of the pterygoid process
12-horizontal plate of the palatine bone
13-palatine process of the maxilla ( processus palatinus maxillae)
14-incisal canal ( canalis incisivus)
15-inferior nasal passage ( meatus nasi inferior)
16-medium nasal passage ( meatus nasi medius)
17-superior nasal passage ( meatus nasi superior)
18-nose bone.
1-coronal suture ( sutura coronalis)
2-sagittal suture ( sutura sagittalis)
3-lambdoid suture ( sutura lamboidea)
4-occipital bone (squama)
5-parietal bone
6-frontal bone
1st frontal bone
2-frontal ridge ( crista frontalis)
3-pit granulations
4-crown stitch ( sutura coronalis)
5-arterial grooves ( sulci arteriosi)
6-parietal bone
7-sulcus of the superior sagittal sinus ( sulcus sinus sagittalis superioris)
8-occipital bone
1-frontal seam
2-frontal tubercle ( tuber frontale)
3-anterior (frontal) fontanel
4-crown stitch ( sutura coronalis)
5-parietal tubercle ( tuber parietale)
6-sagittal suture
7-posterior occipital) fontanelle
8-occipital bone
9-lambdoid suture
1st frontal bone
2-anterior (frontal) fontanel
3-crown seam ( sutura coronalis)
4-parietal tubercle ( tuber parietale)
5-posterior (occipital) fontanel
6-occipital bone (squama)
7-mastoid fontanelle
8-petallous part (pyramid) of the temporal bone
9-temporal bone scales
10-tympanic bone (tympanic ring)
11-wedge-shaped (anterolateral) fontanel
12-mandible
13-zygomatic bone
14-upper jaw
15-socket
1-roof (vault) of the skull
2-frontal bone
3-frontal sinus
4-cells of the ethmoid bone
5-bone septum of the nasal cavity
6-anterior nasal spine
7-intermaxillary suture
8-lower jaw
9-mental protuberance
10-nasal cavity
11-maxillary sinus
12 mastoid process ( processus mamillaris)
13-socket
Scull, cranium, - consists of two sections - the bones of the skull, ossa cranium, and facial bones, ossa faciei.
The skeleton of the head is the skull, cranium, the individual bones of which are subdivided into the bones of the medulla of the skull, which form the cranial cavity, cavitas cranii, receptacle for the brain and facial bones, ossa faciei. The skull serves as a container for the brain (cerebral cranium) and some sensory organs (sight, hearing and smell).
The bones of the face (facial part of the skull) make up the skeleton of the face, the initial parts of the digestive and respiratory systems.
Both sections of the skull are formed from separate bones, fixedly connected to each other using sutures, suturae, and cartilaginous joints, synchondroses, with the exception of the lower jaw, which is movably connected to the skull through the temporomandibular joint, .
Based on data on its development, the bones of the brain skull include unpaired bones: occipital, sphenoid, frontal, ethmoid, vomer - and paired bones: temporal, parietal, inferior turbinate, lacrimal, nasal.
The bones of the face include paired bones: the upper jaw, palatine bone, zygomatic bone - and unpaired bones: the lower jaw and hyoid bone. The latter, although located in the neck, develops as a bone of the facial part of the skull and is described together with it.
Topographically, the inferior turbinate, vomer, lacrimal and nasal bones belong to the facial skeleton.
Occipital bone
occipital bone, os occipitale, unpaired, forms the posteroinferior part of the skull. Its outer surface is convex, and its inner, cerebral, concave surface. In its anterior-inferior section there is a large (occipital) foramen, foramen magnum, connecting the cranial cavity with the spinal canal. This opening is surrounded by a shallow groove of the occipital sinus, sulcus sinus occipitalis. Based on data on the process of development of the occipital bone, four parts are distinguished in it surrounding the large (occipital) foramen: the basilar part - in front of the large (occipital) foramen, paired lateral parts - on the sides of it, and the occipital scales, located behind.basilar part, pars basilaris, short, thick, quadrangular; its posterior edge is free, smooth and slightly pointed, limiting the foramen magnum (occipital) in front; the anterior edge is thickened and rough, connected to the body of the sphenoid bone through cartilage, forming sphenoid-occipital synchondrosis, synchondrosis sphenooccipitalis.
IN teenage years The cartilage is replaced by bone tissue and both bones merge into one. The upper surface of the basilar part, facing the cranial cavity, is smooth and slightly concave. It forms a slope with the part of the body of the sphenoid bone located in front of it, clivus, directed to the large (occipital) foramen (on it lie the medulla oblongata, the bridge and the basilar artery of the brain with branches). In the middle of the lower, outer, slightly convex surface of the basilar part there is a small pharyngeal tubercle, tuberculum pharyngeum, (the place of attachment of the anterior longitudinal ligament and the fibrous membrane of the pharynx), and rough lines (traces of attachment of the rectus anterior and long muscles of the head).
The outer, slightly irregular edge of the basilar part and lateral parts of the occipital bone is adjacent to the posterior edge of the petrous part of the temporal bone. A petrosoccipital fissure is formed between them, fissura petrooccipitalis, on a non-macerated skull it is made of cartilage, forming the petrooccipital synchondrosis, synchondrosis petrooccipitalis, which, as a remnant of the cartilaginous skull, ossifies with age.
Lateral parts paries laterales, somewhat elongated, thickened in the posterior sections, and somewhat narrowed in the anterior; they form the lateral sides of the large (occipital) foramen, fused in front with the basilar part, and behind with the occipital scales.
On the cerebral surface of the lateral part, at its outer edge, there is a narrow groove of the inferior petrosal sinus, sulcus sinus petrosi inferioris, which is adjacent to the posterior edge of the petrous part of the temporal bone, forming, with the groove of the same name in the temporal bone, a canal where the venous inferior petrosal sinus lies, sinus petrosus inferior.
On the lower, outer surface of each lateral part there is an oblong-oval convex articular process - the occipital condyle, condylus occipitalis. Their articular surfaces come closer in front and diverge behind; they articulate with the superior articular fossa of the atlas. Behind the occipital condyle there is a condylar fossa, fossa condylaris, and at its bottom there is a hole leading into the unstable condylar canal, canalis condylaris, which is the location of the condylar emissary vein, v. emissaria condylaris.
On the outer edge of the lateral part there is a large, smooth-edged jugular notch, incisura jugularis, on which a small intrajugular process protrudes, processus intrajugularis.
The jugular notch with the same fossa of the petrous part of the temporal bone forms the jugular foramen, foramen jugulare.
The intrajugular processes of both bones divide this opening into two parts: the large posterior one, in which the superior bulb of the internal jugular vein lies, bulbus v. jugularis superior, and the smaller anterior one, through which the cranial nerves pass: glossopharyngeal ( n. glossopharyngeus), wandering ( n. vagus) and additional ( n. accessorius).
Posteriorly and externally, the jugular notch is limited by the jugular process, processus jugularis. On the outer surface of its base there is a small paramastoid process, processus paramastoideus, (place of attachment of the rectus lateral capitis muscle, m. rectus capitis lateralis).
Behind the jugular process, on the side of the inner surface of the skull, there is a wide groove of the sigmoid sinus, sulcus sinus sigmoidei, which is a continuation of the groove of the same name in the temporal bone. Anterior and medial lies the smooth jugular tubercle, tuberculum jugular. Posteriorly and downward from the jugular tubercle, between the jugular process and the occipital condyle, the hypoglossal canal passes through the bone, canalis hypoglossalis, (it contains the hypoglossal nerve, n. hypoglossus).
occipital scales, squama occipitalis, limits the posterior foramen magnum (occipital) and makes up most of the occipital bone. This is a wide, curved, triangular plate with a concave inner (cerebral) surface and a convex outer surface.
The lateral edge of the scale is divided into two sections: a larger upper, highly serrated lambdoid edge, margo lamboideus, which, joining the occipital edge of the parietal bones, forms a lambdoid suture, sutura lamboidea, and a smaller lower, slightly serrated mastoid margin, margo mastoideus, which, adjacent to the edge of the mastoid process of the temporal bone, forms the occipital-mastoid suture, sutura occipitomastoidea.
In the middle of the outer surface of the scales, in the area of its greatest convexity, there is an external occipital protrusion, protuberantia occipitalis externa, easily palpable through the skin. Paired convex upper nuchal lines diverge from it, lineae nuchae superiores, above which and parallel to them there are additional highest nuchal lines, lineae nuchae supremae.
The external occipital crest descends from the external occipital protuberance to the foramen magnum (foramen magnum), crista occipitalis externa. At the middle of the distance between the large (occipital) foramen and the external occipital protrusion, the lower nuchal lines diverge from the middle of this ridge to the edges of the occipital scales, lineae nuchae inferiores, running parallel to the top. All these lines are places of muscle attachment. On the surface of the occipital scales below the upper nuchal lines, muscles ending on the occipital bone are attached.
On the surface of the brain facies cerebralis, the occipital scales have a cruciform eminence, eminentia cruciformis, in the middle of which the internal occipital protuberance rises ( protuberantia occipitalis interna). On the outer surface of the scales it corresponds to the external occipital protrusion.
The groove of the transverse sinus extends from the cruciate eminence in both directions, sulcus sinus transversi, upward – groove of the superior sagittal sinus, sulcus sinus sagittalis superioris, downwards – internal occipital crest, crista occipitalis interna, going to the posterior semicircle of the large (occipital) foramen. The dura mater with the venous sinuses located in it is attached to the edges of the grooves and to the internal occipital crest; in the region of the cruciate eminence there is a confluence of these sinuses.
Sphenoid bone
sphenoid bone, os sphenoidale, unpaired, forms the central section of the base of the skull.The middle part of the sphenoid bone is the body, corpus, cubic in shape, has six surfaces. On the upper surface, facing the cranial cavity, there is a depression - the sella turcica, sella turcica, in the center of which is the pituitary fossa, fossa hypophysialis. It contains the pituitary gland, hypophysis. The size of the pit depends on the size of the pituitary gland. The border of the sella turcica in front is the tubercle of the sella, tuberculum sellae. Posterior to it, on the lateral surface of the saddle, there is a non-constant middle inclined process, processus clinoideus medius.
Anterior to the tubercle sella there runs a shallow transverse precross groove, sulcus prechiasmatis. Behind it lies the optic chiasm, chiasma opticum. Laterally, the groove passes into the optic canal, canalis opticus. In front of the furrow there is a smooth surface - a wedge-shaped eminence, jugum sphenoidale, connecting the small wings of the sphenoid bone. The anterior crane of the upper surface of the body is serrated, protrudes slightly forward and connects with the posterior edge of the ethmoidal plate of the ethmoid bone, forming a sphenoethmoidal suture, sutura spheno-ethmoidalis. The posterior border of the sella turcica is the dorsum of the sella, dorsum sellae, which ends on the right and left with a small posterior inclined process, processus clinoideus posterior.
A carotid groove runs along the sides of the saddle from back to front, sulcus caroticus, (trace of the internal carotid artery and the accompanying nerve plexus). At the posterior edge of the groove, on its outer side, a pointed process protrudes - a wedge-shaped tongue, lingula sphenoidalis.
The posterior surface of the dorsum sella passes into the upper surface of the basilar part of the occipital bone, forming a slope, clivus, (on it lie the bridge, medulla oblongata, basilar artery and its branches). The posterior surface of the body is rough; through a cartilaginous layer it connects to the anterior surface of the basilar part of the occipital bone and forms sphenoid-occipital synchondrosis, synchondrosis spheno-occipitalis. As we age, the cartilage is replaced by bone tissue and the two bones fuse together.
The front surface of the body and part of the bottom face the nasal cavity. A wedge-shaped ridge protrudes in the middle of the anterior surface, crista sphenoidalis, its anterior edge is adjacent to the perpendicular plate of the ethmoid bone. The lower process of the crest is pointed, extended downwards and forms a wedge-shaped beak, rostrum sphenoidale. The latter is connected to the wings of the opener, alae vomeris, forming the vomerococoid canal, canalis vomerorostratis, lying along the midline between the upper edge of the vomer and the wedge-shaped beak. Lateral to the ridge lie thin curved plates - wedge-shaped shells, conchae sphenoidales. The shells form the anterior and partly the lower walls of the sphenoid sinus, sinus sphenoidalis. Each shell has a small opening - the aperture of the sphenoid sinus, apertura sinus sphenoidalis. Outside the aperture there are small depressions that cover the cells of the posterior part of the labyrinth of the ethmoid bone. The outer edges of these recesses are partially connected to the orbital plate of the ethmoid bone, forming a sphenoethmoidal suture, sutura spheno-ethmoidalis, a lower - with orbital processes, processus orbitalis, palatine bone.
sphenoid sinus, sinus sphenoidalis– a paired cavity that occupies most of the body of the sphenoid bone; it belongs to the air-bearing paranasal sinuses. The right and left sinuses are separated from one another by the septum of the sphenoid sinuses, septum sinuum sphenoidalium, which anteriorly continues into the wedge-shaped ridge. As in the frontal sinuses, the septum is often asymmetrical, as a result of which the size of the sinuses may not be the same. Through the aperture of the sphenoid sinus, each sphenoid sinus communicates with the nasal cavity. The cavity of the sphenoid sinus is lined with mucous membrane.
Small wings, alae minores, the sphenoid bones extend in both directions from the anterosuperior corners of the body in the form of two horizontal plates, at the base of which there is a rounded hole. From this hole begins a bone canal up to 5-6 mm long - the optic canal, canalis opticus. It contains optic nerve, n. opticus, and ophthalmic artery, a. ophthalmica. The small wings have an upper surface facing the cranial cavity and a lower surface directed into the orbital cavity and closing the superior orbital fissure on top, fissura orbitalis superior.
The anterior edge of the lesser wing, thickened and jagged, connects to the orbital part of the frontal bone. The posterior edge, concave and smooth, protrudes freely into the cranial cavity and is the boundary between the anterior and middle cranial fossae, fossae cranii anterior et media. The medial posterior edge ends in a prominent, well-defined anterior inclined process, processus clinoideus anterior, (a part of the dura mater is attached to it - the diaphragm of the sella turcica, diaphragma sellae).
Big wings alae majores, extend from the lateral surfaces of the body of the sphenoid bone and are directed outward.
The large wing has five surfaces and three edges.
facies cerebralis, concave, facing the cranial cavity. It forms the anterior section of the middle cranial fossa. There are finger-shaped impressions on it, impressiones digitatae, [gyrorum]), and arterial grooves, sulci arteriosi, (relief imprints of the adjacent surface of the brain and middle meningeal arteries).
At the base of the wing there are three permanent openings: a round opening is located inwardly and anteriorly, foramen rotundum, (the maxillary nerve exits through it, n maxillaris), outward and posterior to the round is the foramen ovale, foramen ovale, (it passes the mandibular nerve, n. mandibularis), and outward and posterior to the oval - the spinous foramen, foramen spinosum, (the middle meningeal artery, vein and nerve come through it). In addition, in this area there are intermittent holes. One of them is the venous opening, foramen venosum, located slightly posterior to the foramen ovale. It passes the vein coming from the cavernous sinus into the pterygoid venous plexus. The second is a rocky hole, foramen petrosum, through which the lesser petrosal nerve passes, is located behind the spinous foramen, closer to the axis of the sphenoid bone.
Anterior superior orbital surface, facies orbitalis, smooth, diamond-shaped, facing the cavity of the orbit and forms most of its outer wall. The lower edge of the surface is spaced from the posterior edge of the orbital surface of the body of the upper jaw - the lower orbital fissure is formed here, fissura orbitalis inferior.
Anterior maxillary surface, facies maxillaris, - a small triangular area, limited above by the orbital surface, on the side and below by the root of the pterygoid process of the sphenoid bone. It is part of the posterior wall of the pterygopalatine fossa, fossa pterygopalatina, it has a round hole.
Superolateral temporal surface, facies temporalis, somewhat concave, takes part in the formation of the wall of the temporal fossa, fossa temporalis, (bundles of the temporal muscle begin from it). This surface is limited below by the infratemporal crest, crista infratemporal, below the ridge there is a surface on which the oval and spinous foramina open. It forms the superior wall of the infratemporal fossa ( fossa infratemporalis), (part of the lateral pterygoid muscle begins here ( m. pterygoideus lateralis).
superior frontal margin, margo frontalis, widely serrated, connects to the orbital part of the frontal bone, forming a sphenoid-frontal suture, sutura sphenofrontalis. The outer sections of the frontal edge end with a sharp parietal edge, margo parietalis, which with the wedge-shaped angle of the other bone forms the sphenoid-parietal suture, sutura sphenoparietalis. The internal sections of the frontal edge pass into a thin free edge, which is spaced from the lower surface of the lesser wing, limiting the superior orbital fissure from below.
Anterior zygomatic margin, margo zygomaticus, jagged frontal process, processus frontalis, the zygomatic bone and the zygomatic margin are connected to form the sphenoid-zygomatic suture, sutura sphenozygomatica.
Posterior scaly edge, margo squamosus, connects to the wedge-shaped edge, margo sphenoidalis, temporal bone and forms a sphenoid-squamous suture, sutura sphenosquamosa. Posteriorly and outwardly, the scaly edge ends with the spine of the sphenoid bone (the place of attachment of the sphenomandibular ligament, lig sphenomandibularis, and fascicles of the tensor muscle curtain of palate, m. tensor veli palatini).
Inward to the spine of the sphenoid bone, the posterior edge of the greater wing lies in front of the petrous part, pars petrosa, temporal bone and limits the sphenoid-petrosal fissure, fissura sphenopetrosa, passing medially into the foramen lacerum, foramen la-lacerum, on a non-macerated skull this gap is filled with cartilaginous tissue and forms a wedge-shaped petrosal synchondrosis, synchondrosis sphenopetrosa.
Pterygoid processes ( processus pterygoidei, extend from the junction of the large wings with the body of the sphenoid bone and are directed downwards. They are formed by two plates - lateral and medial. Lateral plate, lamina lateralis, (processus pterygoidei), wider, thinner and shorter than the medial one (the lateral pterygoid muscle begins from its outer surface, ( m. pterygoideus lateralis). medial plate, lamina medialis, (processus pterygoidei), narrower, thicker and slightly longer than the lateral one. Both plates fuse with their anterior edges and, diverging posteriorly, limit the pterygoid fossa, fossa pterygoidea, (the medial pterygoid muscle begins here, m. pterygoideus medialis). In the lower parts, both plates do not fuse and limit the pterygoid notch, incisura pterygoidea. It contains a pyramidal process, processus pyramidalis, palatine bone. The free end of the medial plate ends with a wing-shaped hook directed downwards and outwards, hamulus pterygoideus, on the outer surface of which there is a groove of the pterygoid hook, sulcus hamuli pterygoidei, (the tendon of the muscle that strains the velum palatine is thrown through it, m. tensor veli palatini).
The posterosuperior edge of the medial plate at the base expands and forms a scaphoid fossa, fossa scaphoidea.
Outward from the navicular fossa there is a shallow groove of the auditory tube, sulcus tubae auditivae, which laterally passes to the lower surface of the posterior edge of the large wing and reaches the spine of the sphenoid bone (the cartilaginous part of the auditory tube is adjacent to this groove). Above the scaphoid fossa and medially there is an opening where the pterygoid canal begins, canalis pterygoideus, (vessels and nerves pass through it). The canal runs in the sagittal direction in the thickness of the base of the pterygoid process and opens on the maxillary surface of the greater wing, on the posterior wall of the pterygopalatine fossa.
The medial plate at its base passes into the inwardly directed flat, horizontally running vaginal process, processus vaginalis, which is located under the body of the sphenoid bone, covering the side of the vomer wing, ala vomeris. In this case, the groove of the vaginal process facing the wing of the vomer is the vomerovaginal groove, sulcus vomerovaginalis, turns into the vomerovaginal canal, canalis vomerovaginalis.
Outward from the process there is a small sagittal sulcus running sagittally, sulcus palatovaginalis. Adjacent below is the sphenoid process of the palatine bone, processus sphenoidalis ossis palatini, closes the groove into the canal of the same name, canalis palatovaginalis, (in the vomerovaginal and palatovaginal canals the nerve branches of the pterygopalatine ganglion pass, and in the palatovaginal canal, in addition, branches of the sphenopalatine artery).
Sometimes the pterygospinous process is directed from the posterior edge of the outer plate towards the spine of the sphenoid bone, processus pterygospinosus, which can reach the specified spine and form a hole.
The anterior surface of the pterygoid process connects with the posterior surface of the upper jaw in the region of the medial edge of the tubercle, forming a sphenoid-maxillary suture, sutura sphenomaxillaris, which lies deep in the pterygopalatine fossa.
Frontal bone
frontal bone, os frontale, in an adult, forms the anterior part of the cranial vault and partly its base. It consists of four parts: the frontal scales, two orbital parts and the nasal part.Frontal scales
Frontal scales, squama frontalis, convex anteriorly, has the following surfaces: the outer, or frontal, two temporal, or lateral, and the inner, or cerebral.
outer surface, facies externa, smooth, convex anteriorly. There is not always a noticeable elevation along the midline - the metopic suture, sutura metopica) - a trace of fusion of the halves of the frontal bone that existed in early childhood. In the anterior sections, the frontal surface of the scales passes into the orbital surface, facies orbitalis, forming a supraorbital edge on each side, margo supraorbitalis, which is top part orbital edge, margo orbitalis. Above and parallel to the supraorbital margin, an arched elevation protrudes more or less prominently - the brow ridge, arcus superciliaris. Above each brow ridge, a rounded elevation is visible - the frontal tubercle, tuber frontale. Between the convexities of the superciliary arches and slightly above them, the surface of the frontal scales in the region of the glabella looks like a somewhat recessed area - this is the glabella, glabella. At the inner third of the supraorbital margin there is a small supraorbital notch, incisura supraorbitalis. This notch is very variable and can be expressed in the form of a supraorbital foramen, foramen supraorbitale. Closer to the midline, i.e. more medially, lies an equally pronounced frontal notch, incisura frontalis, (the lateral branch of the supraorbital nerve and vessels pass through the supraorbital notch, and the medial branch of the same nerve and vessels pass through the frontal notch). A frontal opening may form at the site of this notch, foramen frontale.
Laterally, the supraorbital margin passes into a blunt, triangular-shaped zygomatic process, processus zygomaticus, its serrated edge connects with the frontal process of the zygomatic bone, forming the frontozygomatic suture, sutura frontozygomatica.
From the zygomatic process upward and backward, the temporal line is directed in an arcuate manner, linea temporalis, it separates the frontal surface of the scales from the temporal surface. Temporal surface, facies temporalis, is the anterior superior part of the temporal fossa, fossa temporalis, where the anterior bundles of the temporal muscle begin.
Inner surface facies interna, concave. It has faint finger-like impressions ( impressiones digitatae, and unstable arterial grooves, sulci arteriosi, (as an imprint of the relief of the brain and blood vessels adjacent here).
In the middle of the inner surface of the frontal scales there is a groove of the superior sagittal sinus, sulcus sinus sagittalis superioris. Its both edges, heading upward and backward, pass into the groove of the same name in the parietal bones, and below they connect into a sharp frontal ridge, crista frontalis, (a process of the dura mater is attached to it - the sickle big brain). The lowest part of the crest and wing of the cockscomb of the ethmoid bone, ala cristae galli ossis ethmoidalis, form a channel - a blind hole, foramen cecum, in which there is a vein that drains blood from the nasal cavity to the superior sagittal sinus.
The upper, or posterior, edge of the frontal scales is the parietal edge, margo parietalis, thickened; its serrated edge connects with the frontal edge of the parietal bones, forming the coronal suture, sutura coronalis. The lower parts of the scales are triangular in shape, connected to the frontal edge of the large wings of the sphenoid bone.
Each orbital part pars orbitalis, the frontal bone is part of the upper wall of the orbit. From the supraorbital edge of the frontal scales it is directed backward and horizontally. It distinguishes between the inferior orbital and superior cerebral surfaces.
orbital surface, facies orbitalis, facing the cavity of the orbit, smooth and concave. In its lateral section, at the base of the zygomatic process, lies a shallow fossa of the lacrimal gland, fossa glandulae lacrimalis, – location of the lacrimal gland.
In the medial part of the orbital surface there is a weakly defined trochlear fossa, fovea trochlearis, near which there is often a cartilaginous trochlear spine, spina trochlearis, (a cartilaginous ring is attached here, which is a block of the tendon of the superior oblique muscle of the eyeball).
Superior cerebral surface facies cerebratis, the orbital part has well-defined imprints of the adjacent surface of the frontal lobes of the brain in the form of finger-like impressions, impressiones digitatae, gyrorum).
Orbital parts
The orbital parts are separated from each other by the ethmoidal notch, incisura ethmoidalis, in which the cribriform plate is located, lamina cribrosa, ethmoid bone. The notch on the sides is limited by an edge, outward from which there are dimples covering the open cells of the upper part of the labyrinth of the ethmoid bone, forming their upper wall. Between the ethmoid dimples there are two grooves running in the transverse direction - anterior and posterior, which, together with the same grooves of the labyrinth of the ethmoid bone, form the tubules. The latter open on the inner wall of the orbit - two small openings: the anterior ethmoidal foramen, foramen ethmoidae anterius,(the anterior ethmoidal vessels and nerve pass through it), and the posterior ethmoidal foramen, foramen ethmoidae posterius, (the posterior ethmoidal vessels and nerve pass through it). The edge of the ethmoidal notch is connected to the upper edge of the orbital plate, lamina orbitalis, ethmoid bone, forming the frontoethmoidal suture, sutura frontoethmoidalis, and in front - with the lacrimal bone - the frontolacrimal suture, sutura frontolacrimalis.
The posterior edge of the orbital part, racemed and serrated, connects with the small wing of the sphenoid bone, forming the internal portion of the sphenoid-frontal suture, sutura sphenofrontalis.
The lateral edge of the orbital part is rough and triangular in shape. It connects to the frontal edge of the greater wing of the sphenoid bone and forms the outer portion of the sphenoid-frontal suture.
Bow
bow part, pars nasalis, the frontal bone in the form of an arch closes the ethmoid notch in front. In front, in the middle of the nasal part, the nasal spine protrudes (sometimes double) obliquely downward and forward ( spina nasalis, pointed at the end and flattened on the sides. It is surrounded in front and on the side by a jagged nasal edge, margo nasalis. It connects to the upper edge of the nasal bone, forming the frontonasal suture, sutura frontonasalis, and with the frontal process ( processus frontalis) of the upper jaw, forming the frontomaxillary suture, sutura frontomaxillaris. The lower surface of the posterior parts of the nasal part has shallow dimples, which, as noted, cover the cells of the labyrinths of the ethmoid bone, which are open to the top.
On each side of the nasal spine there is one aperture of the frontal sinus, apertura sinus frontalis; heading upward and anteriorly, it leads into the cavity of the corresponding frontal sinus.
Frontal sinus, sinus frontalis, is a paired cavity lying between both plates of the frontal bone in its antero-inferior sections. Frontal sinus Refers to the air-bearing bones of the sinuses. The right sinus is separated from the left by the vertical septum of the frontal sinuses, septum sinuum frontalium. By deviating to the side, the septum causes the unequal size of the cavities of both sinuses. The boundaries vary dramatically. Sometimes the frontal sinuses reach upward to the frontal tuberosities, downward to the supraorbital margins, posteriorly to the lesser wings of the sphenoid bone, and laterally to the zygomatic processes. The frontal sinus aperture connects the frontal sinus and the middle meatus, meatus nasi medius, nasal cavity. The sinus cavity is lined with mucous membrane.
Ethmoid bone
Ethmoid bone, os ethmoidae, unpaired. Most of it lies in the upper parts of the nasal cavity, the smaller part lies in the anterior parts of the base of the skull. It has the shape of an irregular cube, consists of air cells and belongs to the group of air bones, ossa pneumatica.In the ethmoid bone, there is a ethmoidal plate that runs horizontally, a perpendicular plate that lies vertically, and ethmoidal labyrinths located on both sides of the latter.
cribriform plate, lamina cribrosa, is the upper wall of the nasal cavity, located horizontally in the ethmoidal notch of the frontal bone, forming the frontoethmoidal suture, sutura frontoethmoidalis. It is perforated with 30-40 small holes, foramina fibrosae, through which nerves (olfactory nerve fibers) and vessels pass.
Perpendicular plate, lamina perpendicularis, is divided into two parts: a smaller upper one, lying above the cribriform plate, and a larger lower one, located under this plate. The upper part forms the cock's comb, crista galli, and is directed into the cranial cavity (the falx cerebri, a process of the dura mater, is attached to the crest).
The border of the anterior-inferior edge of the cockscomb on each lateral side is a non-permanent formation - the wing of the cockscomb, ala cristae galli. Both processes delimit the foramen cecum posteriorly and superiorly, foramen cecum, frontal bone. The lower part of the perpendicular plate is irregularly quadrangular in shape, directed vertically down into the nasal cavity, and forms the anterosuperior part of the bony septum. From above it adjoins the nasal spine of the frontal bone, in front - to the nasal bones, behind - to the sphenoid crest, below - to the vomer, and in front and below - to the cartilaginous part of the nasal septum. Often there is a deviation of all or part of the perpendicular plate to the side.
lattice labyrinth, labyrinthus ethmoidalis, – a paired formation, located on both sides of the perpendicular plate, adjacent to the lower surface of the cribriform plate. Consists of numerous air-carrying lattice cells, cellulae ethmoidales, communicating both with each other and through a series of openings with the nasal cavity. The ethmoid cells are lined with mucous membrane, which is a direct continuation of the nasal mucosa.
The cells located in front open into the middle nasal meatus, the middle and posterior ones communicate with the upper nasal meatus.
The lateral wall is a thin, smooth orbital plate, lamina orbitalis, forming most of the inner wall of the orbit. The plate connects at the top with the frontal bone, forming the frontoethmoidal suture, sutura fronto-ethmoidalis, below – with the upper jaw – ethmoidomaxillary suture, sutura ethmoidomaxillaris, and with the orbital process of the palatine bone - the palatoethmoidal suture, sutura palato-ethmoidalis, in front - with the lacrimal bone - the lacrimal-ethmoidal suture and behind - with the sphenoid bone - the sphenoethmoidal suture, sutura spheno-ethmoidalis. Along the upper edge of the labyrinth there are two small grooves - the anterior and posterior ethmoidal grooves, which, together with the grooves of the same name in the frontal bone, form tubules that open into the anterior and posterior ethmoidal openings, foramina ethmoidales anterius et posterius, (vessels and nerves of the same name pass through these openings).
The medial wall of the labyrinth is a rough, grooved plate that forms most of the lateral wall of the nasal cavity. On its surface, facing the perpendicular plate, there are two thin processes, slightly curved at the edges and turned outward: the upper one is the superior nasal concha, concha nasalis superior, and the lower one is the middle turbinate, concha nasalis media. Sometimes above the superior nasal concha there is a rudimentary process in the form of a thin bone ridge - the highest nasal concha, concha nasalis suprema. In the superoposterior section of the medial wall of the labyrinth, between the superior and middle nasal conchae, a slit-shaped space is formed - the superior nasal meatus, meatus nasi superior. The gap under the middle turbinate is the middle meatus, meatus nasi medius.
From the inferoanterior surface of each labyrinth, anterior and inferior to the middle turbinate, a hook-shaped process, curved posteriorly and inferiorly, extends processus uncinatus. On the whole skull it connects with the ethmoid process, processus ethmoidalis, inferior nasal concha.
Posterior and superior to the uncinate process is located one of the largest cells, which has the appearance of a swelling - the ethmoidal vesicle, bulla ethmoidalis.
Between the uncinate process below and in front and the large ethmoidal vesicle behind and above there is a gap - the ethmoidal funnel, infundibulum ethmoidae, the upper end of which communicates with the opening of the sinus of the frontal bone. The posterior edge of the uncinate process and the lower surface of the greater ethmoidal vesicle form the cleft semilunaris, hiatus semilunaris, through which the sinus of the maxillary bone communicates with the middle nasal meatus.
Opener
opener, vomer, is an unpaired, diamond-shaped plate that forms the posterior part of the nasal septum.The vomer, excluding its rear edge, is usually slightly curved to the side,
The upper edge of the opener is thicker than the others. It is separated by a furrow of the vomer, sulcus vomeris, on two processes bent outward - the wings of the vomer, alae vomeris. They are adjacent to the lower surface of the body of the sphenoid bone and cover its beak, forming the sphenoid-vomer suture, sutura sphenomeriana. Such stitches are associated with schindylosis, schyndilesis. This section is the wedge-shaped part of the opener, pars cuneiformis vomeris.
The posterior edge of the bone is the choanal crest, crista choanalis vomeris, slightly pointed, separates the posterior openings of the nasal cavity - choanae, choanae.
The anterior and lower edges are rough. The lower edge connects with the nasal ridge of the upper jaw and palatine bone, and the anterior (oblique) edge connects at the top with the perpendicular plate of the ethmoid bone, and at the bottom with the cartilage of the nasal septum.
Temporal bone
Temporal bone, os temporale, steam room, participates in the formation of the base of the skull and the side wall of its vault. It contains the organ of hearing and balance. It articulates with the lower jaw and is the support of the masticatory apparatus.On the outer surface of the bone there is an external auditory opening, porus acusticus externus, around which three parts of the temporal bone are located; on top is the scaly part, inwardly and behind is the stony part, or pyramid, in front and below is the tympanic part.
Squamosal part of the temporal bone
scaly part, pars squamosa, has the shape of a plate and is located almost in the sagittal direction. Outer temporal surface facies temporalis, The scaly part is slightly rough and slightly convex. In the posterior section, the groove of the middle temporal artery runs in the vertical direction, sulcus arteriae temporalis mediae
In the posteroinferior part of the scaly part there is an arcuate line, which continues into the lower temporal line, linea temporalis inferior, parietal bone.
From the scaly part, above and slightly anterior to the external auditory opening, the zygomatic process extends horizontally, processus zygomaticus. It is like a continuation of the supramastoid crest, crista supramastoidea, located horizontally along the lower edge of the outer surface of the scaly part. Beginning with a wide root, the zygomatic process then narrows. It has an inner and outer surface and two edges - a longer upper one and a shorter lower one. The anterior end of the zygomatic process is serrated. Zygomatic process of the temporal bone and temporal process, processus temporalis, the zygomatic bones are connected using the temporomygomatic suture, sutura temporozygomatica, forming the zygomatic arch, arcus zygomaticus.
On the lower surface of the root of the zygomatic process there is a transverse oval-shaped mandibular fossa, fossa mandibularis. The anterior half of the fossa, up to the petrosquamosal fissure, is the articular surface, facies articularis, temporomandibular joint. Anteriorly, the mandibular fossa is limited by the articular tubercle, tuberculum articulare.
The outer surface of the scaly part is involved in the formation of the temporal fossa, fossa temporalis, (the bundles of the temporal muscle begin here, m. temporalis).
Inner brain surface facies cerebralis, slightly concave. It has finger-like indentations, impressiones digitatae, as well as the arterial groove, sulcus arteriosus, (it contains the middle meningeal artery, a. meningea media).
The squamous part of the temporal bone has two free edges - the sphenoid and the parietal.
Anteroinferior wedge-shaped edge, margo sphenoidalis, wide, serrated, connects with the scaly edge of the large wing of the sphenoid bone and forms a sphenoid-squamous suture, sutura sphenosquamosa. Superior posterior parietal edge, margo parietalis, pointed, longer than the previous one, connected to the scaly edge of the parietal bone.
Pyramid of temporal bone
Pyramid, rocky part - pars petrosa, the temporal bone consists of posterolateral and anteromedial sections.
The posterolateral portion of the petrous part of the temporal bone is the mastoid process, processus mastoideus, which is located posterior to the external auditory opening. It distinguishes between outer and inner surfaces. The outer surface is convex, rough and is the site of muscle attachment. Inferiorly, the mastoid process passes into a cone-shaped protrusion, which can be easily felt through the skin,
On the inner side, the process is limited by the deep mastoid notch, incisura mastoidea, (the posterior belly of the digastric muscle originates from it, venter posterior m. digastrici). Parallel to the notch and somewhat posteriorly is the groove of the occipital artery, sulcus arteriae occipitalis, (trace of the junction of the artery of the same name).
On the inner, cerebral, surface of the mastoid process there is a wide S-shaped groove of the sigmoid sinus, sulcus sinus sigmoidei, passing at the top into the groove of the same name of the parietal bone and further into the groove of the transverse sinus of the occipital bone (it contains the venous sinus, sinus transversa). Downwards, the groove of the sigmoid sinus continues as the groove of the same name of the occipital bone.
The posterior border of the mastoid process is the serrated occipital margin, margo occipitalis, which, connecting with the mastoid edge of the occipital bone, forms the occipital-mastoid suture, sutura occipitomastoidea. In the middle of the length of the suture or in the occipital edge there is a mastoid foramen, foramen mastoideum, (sometimes there are several of them), which is the location of the mastoid veins, vv. emissariae mastoidea connecting the saphenous veins of the head with the sigmoid venous sinus, as well as the mastoid branch of the occipital artery, ramus mastoideus a. occipitalis.
From above, the mastoid process is limited by the parietal edge, which, at the border with the same edge of the squamous part of the temporal bone, forms the parietal notch, incisura parietalis; the mastoid angle of the parietal bone enters it, forming the parietal-mastoid suture, sutura parietomastoidea.
At the point of transition of the outer surface of the mastoid process into the outer surface of the squamous part, one can notice the remains of the squamous-mastoid suture, sutura squamosomastoidea, which is well expressed on the skull of children.
On the cut of the mastoid process, the bony air cavities located inside it are visible - mastoid cells, cellulae mastoideae. These cells are separated from one another by the bony mastoid walls ( paries mastoideus). The permanent cavity is the mastoid cave, antrum mastoideum, in the central part of the process; mastoid cells open into it, it connects with the tympanic cavity, cavitas tympanica. The mastoid cells and mastoid cave are lined with mucous membrane.
The anteromedial part of the petrous part lies medial to the squamosal part and the mastoid process. It has the shape of a triangular pyramid, the long axis of which is directed from the outside and from behind to the front and medially. The base of the stony part is directed outward and posteriorly; top of the pyramid apex partis petrosae, directed inward and anteriorly.
In the stony part there are three surfaces: anterior, posterior and lower, and three edges: upper, posterior and anterior.
The front surface of the pyramid facies anterior partis petrosae, smooth and wide, facing the cranial cavity, is directed obliquely from top to bottom and forward and passes into the cerebral surface of the scaly part. It is sometimes separated from the latter by a stony-scaly gap, fissura petrosquamosa. Almost in the middle of the front surface there is an arched elevation, eminentia arcuata, which is formed by the anterior semicircular canal of the labyrinth underlying it. Between the elevation and the stony-scaly fissure there is a small platform - the roof of the tympanic cavity, tegmen tympani, under which is the tympanic cavity, cavum tympani. On the anterior surface, near the apex of the petrous part, there is a small trigeminal depression, impressio trigemini, (place of contact of the trigeminal ganglion, ganglion trigeminale).
Lateral to the depression is the cleft of the greater petrosal nerve canal, hiatus canalis n. petrosi majoris, from which the narrow groove of the greater petrosal nerve extends medially, sulcus n. petrosi majoris. Anterior and somewhat lateral to this opening there is a small cleft of the canal of the lesser petrosal nerve, hiatus canalis n. petrosi minoris, from which the groove of the lesser petrosal nerve is directed, sulcus n. petrosi minoris.
Back surface of the pyramid facies posterior partis petrosae, like the anterior one, faces the cranial cavity, but is directed upward and posteriorly, where it passes into the mastoid process. Almost in the middle of it there is a round internal auditory opening, porus acusticus internus which leads to the internal auditory canal, meatus acusticus internus(facial, intermediate, vestibulocochlear nerves pass through it, nn. facialis, intermedius, vestibulocochlearis, as well as the artery and vein of the labyrinth, a. et v. labirinthi). Slightly above and lateral to the internal auditory opening there is a well-defined subarcicular fossa of small depth in newborns, fossa subarcuata, (it includes a process of the dura mater of the brain). Even more lateral lies the slit-like external aperture of the vestibule aqueduct, apertura externa aqueductus vestibuli, opening into the aqueduct of the vestibule, aqueductus vestibuli. The endolymphatic duct emerges from the cavity of the inner ear through the aperture.
The bottom surface of the pyramid facies inferior partis petrosae, rough and uneven, forms part of the lower surface of the base of the skull. On it there is a round or oval jugular fossa, fossa jugularis, (place of contact of the superior bulb of the internal jugular vein).
A small groove is noticeable at the bottom of the fossa (the auricular branch of the vagus nerve passes through it). The groove leads into the opening of the mastoid tubule, canaliculus mastoideus which opens in the tympanomastoid fissure, fissura tympanomastoidea.
The posterior edge of the jugular fossa is limited by the jugular notch, incisura jugularis, which is a small intrajugular process, processus intrajugularis, divides into two parts - anteromedial and posterolateral. Anterior to the jugular fossa lies a rounded opening; it leads to the sleepy canal, nalis caroticus, opening at the top of the rocky part.
Between the anterior circumference of the jugular fossa and the external opening of the carotid canal there is a small stony dimple, fossula petrosa, (place of contact of the inferior ganglion of the glossopharyngeal nerve). In the depths of the dimple there is a hole - a passage into the tympanic canaliculus, canaliculus tympanies, (the tympanic nerve and the inferior tympanic artery pass through it). The tympanic canaliculus leads to the middle ear, auris media, or tympanic cavity, cavum lympani), cavitas tympanis).
Laterally from the jugular fossa, the styloid process, directed downwards and somewhat anteriorly, protrudes, processus styloideus, from which muscles and ligaments begin. In front of the outside of the base of the process, the bony protrusion of the tympanic part descends - the sheath of the styloid process, vagina processus styloidei. Behind the base of the process there is a stylomastoid foramen, foramen stytomastoideum, which is the outlet of the facial canal, canalis facialis.
The top edge of the pyramid marge superior partis petrosae, separates its front surface from the back. A groove of the superior petrosal sinus runs along the edge, sulcus sinus petrosi superioris, - an imprint of the superior petrosal venous sinus lying here and the attachment of the tentorium cerebellum - part of the dura mater of the brain. This groove passes posteriorly into the groove of the sigmoid sinus of the mastoid process of the temporal bone.
Rear edge of the pyramid margo posterior partis petrosae, separates its back surface from the bottom. Along it, on the brain surface, runs the groove of the inferior petrosal sinus, sulcus sinus petrosi inferioris, (trace of contact of the inferior petrosal venous sinus). Almost in the middle of the posterior edge, near the jugular notch, there is a triangular funnel-shaped depression in which the external aperture of the cochlear tubule lies, apertura externa canaliculi cochleae, the cochlear tubule ends in it, canaliculus cochleae.
The anterior edge of the petrous part, located on the lateral side of its anterior surface, is shorter than the upper and posterior ones; it is separated from the scaly part of the temporal bone by a stony-squamosal fissure, fissura petrosquamosa. On it, lateral to the internal opening of the carotid canal, there is an opening of the muscular-tubal canal leading to the tympanic cavity.
Canals and cavities of the petrous part of the temporal bone:
Sleepy channel, canalis caroticus, begins in the middle sections of the lower surface of the stony part with an external opening. Initially, the canal is directed upward, located here in front of the middle ear cavity, then, bending, it follows anteriorly and medially and opens at the apex of the pyramid with an internal opening (the internal carotid artery, accompanying veins and a plexus of sympathetic nerve fibers pass through the carotid canal).
Carotid-tympanic tubules, canaliculi caroticotympanici, are two small tubules that branch from the carotid canal and lead into the tympanic cavity (the carotid-tympanic nerves pass through them).
Facial canal, canalis facialis, begins at the bottom of the internal auditory canal, meatus acusticus internus, (in the field of the facial nerve, area n. facialis). The canal runs horizontally and almost at right angles to the axis of the petrous part, and is directed to its anterior surface, to the cleft of the canal of the greater petrosal nerve, hiatus canalis n. petrosi majoris. Here, turning at a right angle, it forms the elbow of the facial canal, geniculum canalis facialis, and passes to the posterior section of the medial wall of the tympanic cavity (accordingly, on this wall of the tympanic cavity there is a protrusion of the facial canal, prominentia canalis facialis). Next, the canal, heading posteriorly, follows along the axis of the stony part to the pyramidal eminence, eminentia pyramidalis; from here it goes vertically down and opens with a stylomastoid foramen, foramen stylomastoideum, (the facial and intermediate nerves, arteries and veins pass through the canal).
Drum string channel, canaliculus chordae tympani, begins on the outer wall of the facial canal, a few millimeters above the stylomastoid foramen. Heading forward and upward, the canaliculus enters the tympanic cavity and opens on its posterior wall (a branch of the intermediate nerve passes through the canaliculus - the chorda tympani, chorda tympani, which, having entered the tympanic cavity through the canaliculus, leaves it through the petrotympanic fissure, fissura petrotympanica).
tympanic canaliculus, canaliculus tympanicus, begins on the lower surface of the stony part, in the depths of the stony dimple. Then it goes to the lower wall of the tympanic cavity and, perforating it, enters the tympanic cavity, passes along its medial wall and is located in the promontory groove, sulcus promontorii. Then it follows to the upper wall of the tympanic cavity, where it opens with the cleft of the canal of the lesser petrosal nerve ( hiatus canalis n. petrosi minoris).
Musculo-tubal canal, canalis muculotubarius, is a continuation of the anterosuperior part of the tympanic cavity. The external opening of the canal is located at the notch between the petrous and squamosal parts of the temporal bone, at the anterior end of the petrosquamosal fissure. The canal is located lateral and slightly posterior to the horizontal part of the carotid canal, almost along the longitudinal axis of the petrous part. Horizontally located septum of the muscular-tubal canal, septum canalis musculotubarii, divides the canal into an upper, smaller hemicap of the tensor tympani muscle, semicanals m. tensoris tympani, and the lower larger palucanal of the auditory tube, semicanals lubae auditivae, (in the first lies the muscle that strains the tympanic membrane, the second connects the tympanic cavity with the pharyngeal cavity.
mastoid tubule, canaliculus mastoideus, begins in the depths of the jugular fossa, runs across the lower part of the facial canal and opens in the tympanomastoid fissure (the auricular branch of the vagus nerve passes through the canaliculus).
tympanic cavity, cavum tympani. - an elongated, laterally compressed cavity lined with mucous membrane. Inside the cavity lie three auditory ossicles: the malleus, malleus, anvil, incus, and stirrup ( stages), which, articulated with each other, form a chain auditory ossicles(more about the structure of these canals, the tympanic cavity, the auditory ossicles and the labyrinth.
Tympanic part of the temporal bone
drum part, pars tympanlca, is the smallest section of the temporal bone. It is a slightly curved ring-shaped plate and forms the anterior, lower walls and part of the posterior wall of the external auditory canal, meatus acusticus extenus. The border tympanic-squamosal fissure is also visible here, fissura tympanosquamosa, which, together with the stony-squamosal fissure, separates the tympanic part from the mandibular fossa of the squamosal part. The outer edge of the tympanic part, closed on top by the scales of the temporal bone, limits the external auditory opening, porus acusticus externus. At the posterosuperior outer edge of this opening there is a supraductal spine, spina suprameatica. Below it is the supraductal fossa, foveola suprameatica. On the border of the larger, internal, and smaller, external, parts of the external auditory canal there is a tympanic groove, sulcus tympanicus, (place of attachment eardrum). At the top it is limited by two curved projections: in front - the greater tympanic spine, spina tympanica major, and behind is the small tympanic spine, spina tympanica minor. Between these projections there is a tympanic notch ( incisura tympanica) opening into the supratympanic recess, recessus epitympanicus.
The lower process of the roof of the tympanic cavity is wedged between the medial part of the tympanic part and the squamosal part of the temporal bone. In front of this process there is a stony-scaly fissure, fissura petrosquamosa, and behind - the petrotympanic fissure, fissura petrotympanica, (from the latter the nerve emerges - the chorda tympani and small vessels). Both grooves continue outward into the tympani-squamosal fissure, fissura tympanosquamosa.
The lateral section of the tympanic part passes into the stony ridge, the elongated part of which forms the sheath of the styloid process, vagina processus styloidei. In a newborn, the external auditory canal is still absent and the tympanic part is represented by the tympanic ring, anulus tympanicus, which then grows to form a significant part of the external auditory canal.
On the inner surface of the greater tympanic spine, the spinous crest is clearly visible, at the ends of which there are anterior and posterior tympanic processes, and the malleus groove runs along it.
Parietal bone
parietal bone, os parietale, steam room, forms the upper and lateral parts of the cranial vault. It has the shape of a quadrangular, convex plate on the outside, in which two surfaces are distinguished: outer and inner - four edges: upper, lower, anterior and posterior.outer surface, facies externa, smooth and convex. The place of greatest convexity of the bone is the parietal tubercle, tuber parietale. Below the parietal tubercle, an arched, rough superior temporal line runs horizontally, linea temporalis superior, which starts from the anterior edge of the bone and, being a continuation of the line of the same name of the frontal bone, stretches across the entire surface of the parietal bone to its posterior-inferior corner. Below this line, parallel to the lower edge of the parietal bone, runs another, more pronounced inferior temporal line, linea temporalis inferior, (the first is the site of attachment of the temporal fascia, fascia temporalis, the second - the temporal muscle, m. temporalis).
Inner surface facies interna, concave; it has faint relief imprints of the adjacent brain in the form of finger-like impressions, impressiones digitatae, and tree-like branching arterial grooves, sulci arteriosi, (traces of the adjacent branches of the middle meningeal artery, a. meningea media).
An incomplete groove of the superior sagittal sinus runs along the upper edge of the inner surface of the bone, sulcus sinus sagittalis superioris. With the groove of the same name on the other parietal bone, it forms a complete groove (a process of the dura mater, the falx cerebri, is attached to the edges of the groove, falx cerebri).
At the back of the same upper edge of the bone there is a small parietal foramen, foramen parietale, through which the branch of the occipital artery passes to the dura mater and the parietal emissary vein. In the depths of the groove of the sagittal sinus and in the vicinity of it (especially on the parietal bones in old age) there are many small pits of granulation, foveolae granulares, (outgrowths come here - granulations of the arachnoid membrane of the brain)).
On the inner surface, at the posteroinferior angle, of the parietal bone lies a deep groove of the sigmoid sinus, sulcus sinus sigmoidei, (imprint of the sigmoid venous sinus of the dura mater). Anteriorly, this groove passes into the groove of the same name of the temporal bone, and posteriorly into the groove of the transverse sinus of the occipital bone.
Superior, sagittal, edge, margosagittalis, straight, strongly serrated, longer than the others, connected to the edge of the other parietal bone of the same name in a sagittal suture, sutura sagittalis. Lower scaly edge, margo squamosus, pointed, arched; its anterior section is covered by the posterior section of the upper edge of the large wing of the sphenoid bone; further posteriorly the scales of the temporal bone are superimposed with their parietal edge; the most posterior portion is connected by teeth to the mastoid process of the temporal bone. According to these three sections, three seams are formed: a scaly seam, sutura squamosa, parietomastoid suture, sutura parietomastoidea, and sphenoid parietal suture, sutura sphenoparietalis.
Anterior, frontal, edge, margo frontalis, toothed; it connects to the parietal edge of the squama of the frontal bone, forming the coronal suture, sutura coronalis.
Posterior, occipital, edge, margo occipitalis, serrated, connects to the lambdoid edge of the occipital bone and forms a lambdoid suture, sutura lamboidea.
Corresponding to the four edges, the parietal bone has four corners:
Anterosuperior frontal angle, angulus frontalis, approaches straight (limited by coronal and sagittal sutures);
anteroinferior wedge-shaped angle, angulus sphenoidalis, acute (limited by the coronal and sphenoparietal sutures);
posterosuperior occipital angle, angulus occipitalis, blunt (limited by the lambdoid and sagittal sutures).
posteroinferior mastoid angle, angulus mastoideus, more obtuse than the posterosuperior one (limited by the lambdoid and parietomastoid sutures); its anterior section fills the parietal notch, incisura parietalis, temporal bone.
Inferior turbinate
inferior nasal concha, concha nasalis inferior, steam room, is a curved bone plate and has three processes: the lacrimal and the ethmoid.maxillary process, processus maxillaris, forms an acute angle with the bone; the lower edge of the maxillary cleft enters this angle. The process is clearly visible from the side of the maxillary sinus after its opening.
lacrimal process, processus lacrimalis, connects the inferior nasal concha with the lacrimal bone.
ethmoid process, processus ethmoidalis, extends from the junction of the maxillary process with the body of the bone and protrudes into the maxillary sinus. It often fuses with the uncinate process of the ethmoid bone.
The lower shell is strengthened by the anterior section of the upper edge on the conchal ridge of the upper jaw, crista conchalis maxillae, and the posterior section - on the conchal ridge of the perpendicular plate of the palatine bone, crista conchalis lamini perpendicularis os palatini. Under the lower concha there is a longitudinal fissure - the lower nasal meatus, meatus nasi inferior.
Lacrimal bone
lacrimal bone, os lacrimale, steam room, is located in the anterior section of the medial wall of the orbit and has the shape of an oblong quadrangular plate. Its upper edge connects with the orbital part of the frontal bone, forming the frontolacrimal suture, sutura frontolacrimalis, posterior - with the anterior edge of the orbital plate of the ethmoid bone and forms the ethmoidolacrimal suture, sutura ethmoidolacrimalis. The lower edge of the lacrimal bone at the border with the orbital surface of the upper jaw forms the lacrimal-maxillary suture, sutura lacrimomaxillaris, and with the lacrimal process of the inferior concha - the lacrimal-conchaal suture, sutura lacrimoconchalis. In front, the bone connects with the frontal process of the maxilla, forming the lacrimal-maxillary suture, sutura lacrimomaxillaris.The bone covers the anterior cells of the ethmoid bone and bears on its lateral surface the posterior lacrimal crest, crista lacrimalis posterior, which divides it into the posterior section, the larger one, and the anterior one, the smaller one. The ridge ends with a protrusion - a lacrimal hook, hamulus lacrimalis. The latter is directed to the lacrimal groove on the frontal process of the upper jaw. Posterior flattened, the anterior one is concave and forms a tear trough, sulcus lacrimalis. This groove, together with the lacrimal groove of the upper jaw, sulcus lacrimalis maxillae, forms the fossa of the lacrimal sac, fossa sacci lacrimalis which continues into the nasolacrimal duct, canalis nasolacrimalis. The canal opens into the lower nasal passage, meatus nasalis inferior.
Nasal bone
nasal bone, os nasale, steam room, has the shape of a quadrangle, slightly elongated and somewhat convex anteriorly. Its upper edge is connected to the nasal part of the frontal bone, the lateral edge is connected to the anterior edge of the frontal process of the upper jaw.The anterior surface of the bone is smooth and perforated by one or more holes (a trace of the passage of blood vessels and nerves). The posterior surface is slightly concave and has a ethmoid groove, sulcus ethmoidalis, – trace of the anterior ethmoidal nerve. With their inner, slightly jagged edges, both nasal bones form the internasal suture, sutura intensalis, on which the longitudinal groove is located.
Both bones with their internal surfaces are adjacent to the nasal spine of the frontal bone and the perpendicular plate of the ethmoid bone.
Upper jaw
Upper jaw, maxilla, steam room, is located in the upper anterior part of the facial skull. It is one of the air-bearing bones, since it contains a large cavity lined with mucous membrane - the maxillary sinus, sinus maxillaris.The bone has a body and four processes.
Body of the maxilla corpus maxillae, has four surfaces: orbital, anterior, nasal and infratemporal.
The following bone processes are distinguished: frontal, zygomatic, alveolar and palatine.
orbital surface, facies orbitalis, smooth, triangular in shape, slightly inclined anteriorly, outward and downward, forms the lower wall of the orbit, orbita.
Its medial edge connects in front with the lacrimal bone, forming the lacrimal-maxillary suture, posteriorly with the lacrimal bone - with the orbital plate of the ethmoid bone in the ethmoid-maxillary suture, and further posteriorly - with the orbital process of the palatine bone in the palatine-maxillary suture.
The anterior margin of the orbital surface is smooth and forms a free infraorbital margin, margo infraorbitalis, being the lower part of the orbital margin of the orbit, margo orbitalis. On the outside it is serrated and passes into the zygomatic process. Medially, the infraorbital margin forms an upward bend, sharpens and passes into the frontal process, along which the longitudinal anterior lacrimal crest stretches, crista lacrimalis anterior. At the junction with the frontal process, the inner edge of the orbital surface forms the lacrimal notch ( incisura lacrimalis), which, together with the lacrimal hook of the lacrimal bone, limits the upper opening of the nasolacrimal canal.
The posterior edge of the orbital surface, together with the lower edge of the orbital surface of the large wings of the sphenoid bone running parallel to it, forms the inferior orbital fissure, fissura orbitalis inferior. In the middle part of the lower wall of the fissure there is a groove - the infraorbital groove, sulcus infraorbitalis, which, moving anteriorly, becomes deeper and gradually passes into the infraorbital canal, canalis infraorbitalis, (in the groove and to the pala lie the infraorbital nerve, artery and veins). The canal describes an arch and opens on the anterior surface of the body of the upper jaw. In the lower wall of the canal there are many small openings of the dental tubules - the so-called alveolar foramina, foramina alveolaria, nerves pass through them to the group of anterior teeth of the upper jaw.
infratemporal surface, facies infratemporalis, facing the infratemporal fossa, fossa infratemporalis, and pterygopalatine fossa, fossa pterygopalatina, uneven, often convex, forms a tubercle of the upper jaw, tuber maxillae. There are two or three small alveolar openings leading to the alveolar canals, canales alveolares, through which nerves pass to the posterior teeth of the upper jaw.
Front surface fades anterior, slightly curved. Below the infraorbital margin, a rather large infraorbital foramen opens on it, foramen infraorbitale, below which there is a small depression - the canine fossa, fossa canina, (the levator anguli oris muscle originates here, m. levator anguli oris).
Below, the anterior surface, without a noticeable border, passes into the anterior (buccal) surface of the alveolar process, processus alveolaris, on which there is a series of convexities - alveolar elevations, juga alveolaria.
Inwardly and anteriorly, towards the nose, the anterior surface of the body of the upper jaw passes into the sharp edge of the nasal notch, incisura nasalis. Inferiorly, the notch ends in the anterior nasal spine, spina nasalis anterior. The nasal notches of both maxillary bones limit the pyriform aperture ( apertura piriformis) leading into the nasal cavity.
nasal surface, facies nasalis, the upper jaw is more complex. In its upper posterior corner there is an opening - the maxillary cleft, hiatus maxillaris, leading to the maxillary sinus. Posterior to the cleft, the rough nasal surface forms a suture with the perpendicular plate of the palatine bone. Here, a large palatine groove runs vertically along the nasal surface of the upper jaw, sulcus palatinus major. It forms one of the walls of the greater palatine canal, canalis palatinus major. Anterior to the maxillary cleft runs the lacrimal groove, sulcus lacrimalis, limited anteriorly by the posterior edge of the frontal process. Adjacent to the lacrimal groove is the lacrimal bone at the top and the lacrimal process of the inferior concha at the bottom. In this case, the tear trough closes into the nasolacrimal canal, canalis nasolacrimalis. Even more anteriorly on the nasal surface there is a horizontal protrusion - the conchal ridge, crista conchalis, to which the inferior turbinate is attached.
From the upper edge of the nasal surface, at the place of its transition to the anterior one, the frontal process straightens upward, processus frontalis. It has medial (nasal) and lateral (facial) surfaces. The lateral surface of the anterior lacrimal ridge, crista lacrimalis anterior, divides into two sections - front and rear. The posterior portion passes downwards into the lacrimal groove, sulcus lacrimalis. Its border from the inside is the tear edge, margo lacrimalis, to which the lacrimal bone is adjacent, forming with it the lacrimal-maxillary suture, sutura lacrimo-maxillaris. The ethmoidal ridge runs along the medial surface from front to back. crista ethmoidalis. The upper edge of the frontal process is serrated and connects to the nasal part of the frontal bone, forming the frontomaxillary suture, sutura frontomaxillaris. The anterior edge of the frontal process is connected to the nasal bone in the nasomaxillary suture, sutura nasomaxillaris.
Zygomatic process, processus zygomaticus, extends from the outer-superior corner of the body. The rough end of the zygomatic process and the zygomatic bone, os zygomaticum, form the zygomaticomaxillary suture, sutura zygomaticomaxillaris.
palatine process, processus palatinus, is a horizontally located bone plate that extends internally from the lower edge of the nasal surface of the body of the upper jaw and, together with the horizontal plate of the palatine bone, forms a bony septum between the nasal cavity and the oral cavity. The internal rough edges of the palatine processes connect both maxillary bones, forming the median palatine suture, sutura palatina mediana. To the right and left of the suture there is a longitudinal palatine ridge, torus palatinus.
In the median palatal suture, the palatine processes form a sharp marginal projection directed towards the nasal cavity - the so-called nasal ridge, crista nosalis, which is adjacent to the lower edge of the vomer and the cartilaginous septum of the nose. The posterior edge of the palatine process is in contact with the anterior edge of the horizontal part of the palatine bone, forming a transverse palatal suture with it, sutura palatina transversa. The upper surface of the palatine processes is smooth and slightly concave. The lower surface is rough, near its posterior end there are two palatine grooves, sulci palatini, which are separated from one another by small palatine spines, spinae palatinae, (vessels and nerves lie in the grooves). The right and left palatine processes at their anterior edge form an oval incisive fossa, fossa incisiva. At the bottom of the fossa there are incisive holes, foramina incisiva, (there are two of them), with which the incisive canal opens, canalis incisivus, also ending with incisive openings on the nasal surface of the palatine processes. The canal may be located on one of the processes; in this case, the incisive groove is located on the opposite process. The area of the incisive fossa is sometimes separated from the palatine processes by the incisive suture, sutura incisiva), in such cases the incisive bone is formed, os incisivum.
Alveolar process ( processus alveolaris), the development of which is associated with the development of teeth, extends downward from the lower edge of the body of the upper jaw and describes an arc directed convexly forward and outward. The lower surface of this area is the alveolar arch, arcus alveolaris. There are holes on it - dental alveoli, alveoli dentales, in which the roots of the teeth are located - 8 on each side. The alveoli are separated from one another by interalveolar septa, septa interalveolaria. Some of the alveoli are in turn divided by interradicular septa, septa interradicularia, into smaller cells according to the number of tooth roots.
The anterior surface of the alveolar process, corresponding to the five anterior alveoli, has longitudinal alveolar elevations, juga alveolaria. The part of the alveolar process with the alveoli of the two anterior incisors represents a separate incisor bone in the embryo, os incisivum, which early merges with the alveolar process of the upper jaw. Both alveolar processes connect and form the intermaxillary suture, sutura intermaxillaris.
Palatine bone
palatine bone, os palatinum- paired bone. It is a curved plate lying in the posterior part of the nasal cavity, forming part of the bottom of this cavity - the bony palate, palatum osseum, and the side wall. It distinguishes between horizontal and perpendicular plates.horizontal plate, lamina horizon-talis, each of the palatine bones, joining together along the midline of the bony palate, participates in the formation of the posterior part of the median palatal suture, and connecting with the two anterior palatine processes of the maxillary bones, forms a transverse palatine suture, sutura palatina transversa.
Upper, nasal, surface, facies nasa-lis, the horizontal plate faces the nasal cavity, and the lower one is the palatal surface ( facies palatina) is part of the bony palate, palatum osseum, the upper wall of the oral cavity itself, cavitas oris propria.
At the posteromedial end of the horizontal plate there is a posterior nasal spine ( spina nasalis posterior, along the medial edge - the nasal ridge, crista nasalis. The upper surface of each horizontal plate is slightly concave and smooth, the lower surface is rough.
A thick pyramidal process extends backward from the outer part of the base of the perpendicular plate, processus ru- ramidalis. It wedges into the notch between the plates of the pterygoid process of the sphenoid bone and limits the pterygoid fossa below, fossa pterygoidea.
On the lower surface of the pyramidal process there are 1-2 openings - the small palatine foramina, foramina palatina mi-By r a, entrances to the lesser palatine canals, canales palatini minores, in which the nerves of the same name pass. Anterior to them, along the lateral edge of the horizontal plate, on its lower side, the lower edge of the greater palatine groove forms a large palatine foramen with the same edge of the groove on the upper jaw, foramen palatinum majus, which is located in the palatal-maxillary suture.
Perpendicular plate, lamina re r-pendicularis, the palatine bone forms a right angle with the horizontal plate. This thin bony plate is adjacent to the anterior edge of the medial surface of the pterygoid process and to the posterior part of the nasal surface of the body of the maxilla. On the maxillary surface, facies ma-xillaris, there is a large palatine sulcus, sul-cus palatinus major, which, with the groove of the same name in the upper jaw and the pterygoid process, forms the large palatine canal, canalis palatinus major opening on the bony palate with the large palatine foramen, foramen palatinum majus.
On the nasal surface, facies nasalis, perpendicular to the plate of the palatine bone there is a conchal crest, crista concha lis, - a trace of fusion with the posterior part of the nasal concha on it.
Slightly higher is the ethmoid ridge ( crista ethmoidalis), where the middle concha of the ethmoid bone has grown.
The upper edge of the perpendicular wall ends in two processes, the orbital process, processus orbitalis, and wedge-shaped otro c tcom, processus sphenoidalis, which are separated from one another by the sphenopalatine notch, cisura sphenopalatina. The latter, with the body of the sphenoid bone adhering here, forms the sphenopalatine foramen, men sphenopalatinum.
orbital process, processus orbitalis, adjacent to the orbital surface of the jaw; there is often a cell on it that connects to the posterior pits of the ethmoid bone.
sphenoid process, processus sphenoidalis, approaches the lower surface of the sphenoid bone, its shell and the wings of the vomer.
Zygomatic bone
Zygomatic bone, os zygomaticum, steam room, enters from the lateral sections of the facial skull. There are three surfaces. The lateral surface faces outwards, facies lateralis, irregularly quadrangular shape is convex, especially in the area of the protruding tubercle.Inwardly and anteriorly directed concave orbital surface, facies orbitalis, is part of the outer and lower walls of the orbit and meets the lateral surface with a sharp arcuate edge, complementing the infraorbital edge below, margo infraorbitalis.
Temporal surface, facies temporalis, facing the temporal fossa.
The frontal process extends from the upper corner of the body of the bone, processus frontalis. It connects with the zygomatic process of the frontal bone, forming the frontozygomatic suture, sutura frontozygomatica, and with the greater wing of the sphenoid bone, forming the sphenoid-zygomatic suture, sutura sphenozygomatica. Along the posterior edge of the upper third of the frontal process of the zygomatic bone there is a marginal tubercle, tuberculum marginale. On the orbital surface of the frontal process there is often a well-defined orbital eminence, eminentia orbitalis.
Connecting with the upper jaw, the zygomatic bone forms the zygomatic maxillary suture, sutura zygomaticomaxillaris.
On the orbital surface of the bone there is a zygomatic orbital foramen, foramen zygomaticoorbitale, which leads into a canaliculus that bifurcates inside the bone. One branch of this tubule opens on the anterior surface of the bone in the form of the zygomaticofacial foramen, foramen zygomaticofaciale, the other - on the temporal surface in the form of the zygomaticotemporal foramen (nerves pass through these tubules). The orbital eminence is often pronounced on this same surface, eminentia orbitalis.
The temporal process extends from the posterior angle of the zygomatic bone, processus temporalis. It connects to the zygomatic process of the temporal bone through the temporomygomatic suture, sutura temporozygomatica, forming the zygomatic arch, arcus zygomaticus.
Lower jaw
lower jaw, mandibula, unpaired, forms the lower part of the facial skull. The bone is distinguished by a body and two processes called branches (running upward from the posterior end of the body).Body, corpus, is formed from two halves connecting along the midline (mental symphysis, symphysis mentalis), which fuse into one bone in the first year of life. Each half is curved with a convex outward. Its height is greater than its thickness. On the body there is a lower edge - the base of the lower jaw, basis man-dibulae, and the upper one - the alveolar part, pars alveolaris.
On the outer surface of the body, in its middle sections, there is a small chin protuberance ( protuberantia mentalis) outward from which the mental tubercle immediately protrudes, tuberculum mentale. Above and outward from this tubercle lies the mental foramen, foramen mentale, (place of exit of blood vessels and nerve). This hole corresponds to the position of the root of the second small molar. An oblique line extends upward from the mental foramen, linea obliqua, which passes into the anterior edge of the ramus of the lower jaw.
The development of the alveolar part depends on the teeth it contains.
This part is thinned and contains alveolar eminences, juga alveolaria. At the top it is limited by an arched free edge - the alveolar arch, arcus alveolaris. There are 16 (8 on each side) dental alveoli in the alveolar arch, alveoli dentales, separated from one another by interalveolar septa, septa interalveolaria.
On the inner surface of the body of the lower jaw, near the midline, there is a single or bifurcated mental spine, spina mentalis, (place of origin of the geniohyoid and genioglossus muscles). At its lower edge there is a depression - the digastric fossa, fossa digastrica, trace of the attachment of the digastric muscle. On the lateral sections of the inner surface, on each side, the mylohyoid line runs obliquely towards the branch of the lower jaw, linea mylohyoidea, (the mylohyoid muscle and the maxillopharyngeal part of the superior pharyngeal constrictor begin here).
Above the maxillary-hyoid line, closer to the hyoid spine, there is a hypoglossal fossa, fovea sublingualis, - trace of the adjacent sublingual gland, and below and posterior to this line there is often a weakly defined submandibular fossa, fovea submandibularis, trace of the attachment of the submandibular gland.
Branch of the lower jaw, ramus mandibulae, is a wide bone plate that rises from the posterior end of the body of the lower jaw upward and obliquely backward, forming an angle of the lower jaw with the lower edge of the body, angulus mandibulae.
On the outer surface of the branch, in the area of the corner, there is a rough surface - a chewing tuberosity ( tuberositas masseterica) trace of attachment of the muscle of the same name. On the inner side, corresponding to the chewing tuberosity, there is a smaller roughness - the pterygoid tuberosity, tuberositas pterygoidea, trace of the insertion of the medial pterygoid muscle.
In the middle of the inner surface of the branch there is a hole in the lower jaw ( foramen mandibulae) limited from the inside and front by a small bony prominence- tongue of the lower jaw ( lingula mandibulae). This hole leads into the mandibular canal, canalis mandibulae, in which blood vessels and nerves pass. The canal lies in the thickness of the spongy bone. On the anterior surface of the body of the lower jaw it has an exit - the mental foramen, foramen mentale.
From the opening of the lower jaw down and forward, along the upper border of the pterygoid tuberosity, the mylohyoid groove runs, sulcus mylohyoideus, (trace of occurrence of vessels and nerves of the same name). Sometimes this groove or part of it is covered with a bone plate, turning into a canal. The mandibular ridge is located slightly above and anterior to the opening of the lower jaw. torus mandibularis.
At the upper end of the ramus of the mandible there are two processes that are separated by the notch of the mandible, incisura mandibulae. Anterior, coronoid, process, processes-sus coronoideus, on the inner surface often has a roughness caused by the attachment of the temporal muscle. Posterior, condylar, process, processus condylaris, ends with the head of the lower jaw, caput mandibulae. The latter has an ellipsoidal articular surface, which participates together with the temporal bone of the skull in the formation of the temporomandibular joint, articulatio temporomandibularis.
The head passes into the neck of the lower jaw, collum mandibulae, on the inner half of the circumference of which a pterygoid fossa is noticeable, fovea pterygoidea, - place of attachment of the lateral pterygoid muscle.
Hyoid bone
Hyoid bone, os hyoideum) lies under the body of the tongue, has the shape of a horseshoe and in thin people can be felt through the skin. It is connected to other bones through ligaments. The hyoid bone consists of a body corpus, and large and small horns, cornua majora et cornua minora.The body of the bone has the shape of a plate, convex anteriorly; it bears transverse and vertical ridges. The upper edge of the plate is pointed, the lower edge is thickened. The lateral edges of the body are connected to the large horns using articular surfaces or fibrous or hyaline cartilage.
Large horns extend from the body of the bone in a posterior and outward direction. They are thinner and longer than the body and have small thickenings at the ends.
The lesser horns extend from the junction of the body of the bone with the greater horns. Sometimes they remain cartilaginous. The small horns are connected to the body of the hyoid bone either through a joint with a weakly stretched capsule, or with the help of connective tissue. Their ends are enclosed in the stylohyoid ligament, lig. stylohyoideum. This ligament sometimes contains one or more small bones.
Occipital bone, os occipitale - odd, participates in the formation of the base and roof of the skull. The upper part of the scales of the occipital bone ossifies on the basis of connective tissue, the remaining parts (main and lateral) - on the basis of cartilage. The outer surface of the occipital bone is convex, the inner surface is concave. The anterior inferior section contains the foramen magnum, foramen magnum. The occipital bone has four parts: the main one, pars basilaris, two lateral parts, partes lateralis, and the occipital scales, squama occipitalis. Until 3-6 years of a child’s life, these parts are separate bones, and then, fused, they form one bone.
Main part, pars basilaris - short, thick, quadrangular. It limits the large (occipital) foramen, foramen magnum, of oval or round shape (Yu. V. Zadvornov, 1972). The upper surface of the main part is concave in the form of a groove and faces the cranial cavity; it forms a slope, clivus, to which the medulla oblongata is adjacent. In the middle of the lower outer surface there is a small pharyngeal tubercle, tuberculum pharyngeum. The outer, slightly uneven edges of the main part, together with the stony parts of the temporal bones, form the petrooccipital fissures, which are filled with cartilage in childhood and ossify with age.
Side parts, partes lateralis - form the lateral sides of the foramen magnum and connect the main part with the scales. On the inner, cerebral surface, at the outer edge there is a narrow groove of the petrous sinus, which, together with the same groove of the temporal bone, forms something like a canal where the inferior petrosal sinus, sul, lies. sinus petrosi inferioris.
On the lower outer surface of each lateral part is the occipital process, condylus occipitalis, for connection with the upper articular surface of the atlas. Behind the occipital condyle there is a condylar fossa, fossa condylaris, with an opening in the bottom, which leads into the unstable condylar canal, canalis condylaris. The outer edge of the lateral part contains a jugular notch, incisura jugularis, on which a small internal jugular process, processus jugularis, protrudes. The jugular notch with the notch of the same name on the temporal bone forms the jugular foramen, foramen jugularis, which is divided by the intrajugular process into anterior and posterior sections. The jugular vein originates in the anterior one, and the cranial nerves (IX-XI pair) pass through the posterior one. Along the jugular processes from the inner surface of the lateral part there is a deep groove of the transverse sinus, sul. sinus transversus. The anterior section of the lateral part contains the jugular tubercle, tuberculum jugulare, back and down from which, between the jugular and occipital processes, lies the canal of the hypoglossal nerve, canalis nervi hypoglossi.
Occipital scales, squama occipitalis - has a triangular shape, curved, limiting the foramen magnum at the back. The lateral edge of the scales is divided into two sections: the upper (lambda-like margo lambdoideus) and the lower (mastoid, margo mastoideus). In the middle of the outer surface of the scales there is an external occipital protrusion, protuberantia occipitale externa. The upper cervical lines, linea nuchalis supreior, diverge from it. Above them are additional high cervical lines, linea nuchalis suprema. From the external occipital protrusion down to the foramen magnum, the external nuchal crest, crista occipitalis externa, is directed. In the middle of the segment connecting the foramen magnum and the external occipital protrusion, the lower cervical lines, linea nuchalis inferior, diverge in different directions. Muscles are attached to these lines. On the inner surface of the scales there is a cruciform eminence, eminentia cruciformis, in which the internal occipital protrusion, protuberantia occipitalis interna, is located. A cruciform eminence divides the inner surface of the scales into four fossae; the two lower ones contain the cerebellar hemispheres, and the upper ones contain the occipital lobes of the brain. From the cruciform eminence, grooves of the transverse sinus, sul. sinus transversa - the groove of the superior sagittal sinus goes upward, sul. sinus sagittalis superior, and downwards - the internal occipital crest, crista occipitalis interna.
Ossification. The first points of ossification in the occipital bone appear at the beginning of the 3rd month of the intrauterine period of development in the connective tissue and cartilaginous parts. In the cartilaginous part there are five points of ossification: one in the main part, two in the lateral parts and two in the cartilaginous part of the scales. In the connective tissue part of the scales there are two points of ossification. At the end of 3 months, the upper and lower sections of the scales grow together, and the main part, scales and side parts grow together at 3-6 years of life. The main part fuses with the body of the sphenoid bone mainly at the age of twenty.
Occipital bone, os occipitdle, forms the posterior and lower walls of the cranium, participating simultaneously in both the cranial vault and its base. Accordingly, it (being a mixed bone) ossifies both as a covering bone on the basis of connective tissue (the upper part of the occipital scales), as well as on the basis of cartilage (the remaining parts of the bone).
In humans, it is the result of the fusion of several bones, existing independently in some animals. Therefore, it consists of 4 separately laid parts that grow together into a single bone only at the age of 3 - 6 years.
These parts, closing the foramen magnum, foramen magnum(the place of transition of the spinal cord into the medulla oblongata from the spinal canal into the cranial cavity), the following: in front - the basilar part, pars basilaris, on the sides - the lateral parts, partes laterales, and behind - the occipital scales, squama occipitalis.
The upper part of the scales, wedged between parietal bones, ossifies separately and often remains separated for life by a transverse suture, which is also a reflection of the existence in some animals of independent interparietal bone, os interparietale, as they call it in humans.
Occipital scale, squama occipitalis, as the integumentary bone has the appearance of a plate, convex on the outside and concave on the inside. Its external relief is due to the attachment of muscles and ligaments. Thus, in the center of the outer surface there is the external occipital protuberance, protuberantia occipitalis externa (the place where the ossification point appears). From the protrusion, it runs laterally on each side along a curved line - the superior nuchal line, linea nuchae superior.
A little higher there is a less noticeable one - linea nuchae suprema(highest). From the occipital protuberance down to the posterior edge of the foramen magnum, the external nuchal crest runs along the midline, crista occipitalis externa.
The lower nuchal lines extend from the middle of the ridge to the sides, liniea nuchae inferiores. The relief of the internal surface is determined by the shape of the brain and the attachment of its membranes, as a result of which this surface is divided by two ridges intersecting at right angles into four pits; both of these ridges together form a cruciform elevation, eminentia cruciformis, and at the place of their intersection - internal occipital protuberance, protuberantia occipitalis interna.
Lower half of longitudinal ridge more acute and is called crista occipitalis interna, the upper and both halves (usually the right) of the transverse are equipped with well-defined grooves: sagittal, sulcus sinus sagittalis superioris, and transverse, sulcus sinus transversi(traces of adjacency of the venous sinuses of the same name).
Each of lateral parts, partes laterales, participates in the connection of the skull with the spinal column, therefore it bears the occipital condyle on its lower surface, condylus occipitalis- place of articulation with the atlas.
Approximately about middle of condylus occipitalis goes through the bone sublingual canal canalis hypoglossalis.
On the upper surface of the pars lateralis there is sulcus sinus sigmoidei (trace of the homonymous venous sinus).
Basilar part, pars basilaris, by the age of 18 fuses with the sphenoid bone, forming a single bone in the center skull base os basilare.
On the upper surface of this bone is a fused two-piece stingray, clivus, on which the medulla oblongata and the pons lie. Protrudes on the bottom surface pharyngeal tubercle, tuberculum pharyngeum, to which the fibrous membrane of the pharynx is attached.
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(os occipitale), unpaired, participates in the formation of the posterior part of the base and vault of the skull (Fig. 1). It consists of a basilar part, 2 lateral parts and scales. All these parts, connecting, limit large hole (foramen magnum).
Rice. 1.
a — topography of the occipital bone;
6 — external view: 1 — external occipital protrusion; 2 - highest nuchal line; 3 - upper nuchal line; 4 - lower nuchal line; 5 - condylar canal; 6 - occipital condyle; 7 - intrajugular process; 8 - basilar part of the occipital bone; 9 - pharyngeal tubercle; 10 - lateral part of the occipital bone; 11 - jugular notch; 12 - jugular process; 13 - condylar fossa; 14 - large hole; 15 - external occipital crest; 16 - occipital scales;
c — internal view: 1 — groove of the superior sagittal sinus; 2 - internal occipital protrusion; 3 - internal occipital crest; 4 - large hole; 5 - groove of the sigmoid sinus; 6 - groove of the inferior petrosal sinus; 7 - slope; 8 - basilar part of the occipital bone; 9 - lateral part of the occipital bone; 10 - jugular tubercle; 11 - jugular process; 12 - cruciform elevation; 13 - groove of the transverse sinus; 14 - scales of the occipital bone;
d — side view: 1 — lateral part of the occipital bone; 2 - slope; 3 - basilar part of the occipital bone; 4 - groove of the inferior petrosal sinus; 5 - pharyngeal tubercle; 6 - canal of the hypoglossal nerve; 7 - jugular process; 8 - occipital condyle; 9 - condylar canal; 10 - condylar fossa; 11 - large hole; 12 - occipital scales; 13 - lambdoid edge of the occipital scales; 14 - mastoid edge of the occipital scales
Basilar part(pars basilaris) in front fuses with the body of the sphenoid bone (until 18-20 years of age they are connected by cartilage, which subsequently ossifies). On the middle of the lower surface of the basilar part there is pharyngeal tubercle (tuberculum pharyngeum), to which the initial part of the pharynx is attached. The upper surface of the basilar part faces the cranial cavity, is concave in the form of a groove, and together with the body of the sphenoid bone forms a slope (clivus). The medulla oblongata, pons, vessels and nerves are adjacent to the clivus. On the lateral edges of the basilar part there is groove of the inferior petrosal sinus (sulcus sinus petrosi inferioris)- the place of contact of the venous sinus of the dura mater of the brain.
Lateral part(pars lateralis) connects the basilar part with the scales and limits the large opening on the lateral side. On the lateral edge there is jugular notch (incisura jugularis), which, with the corresponding notch of the temporal bone, limits the jugular foramen. Located along the edge of the tenderloin intrajugular process (processus intrajugularis); it divides the jugular foramen into anterior and posterior sections. The internal jugular vein runs in the anterior section, and the IX-XI pairs in the posterior section. cranial nerves. The posterior part of the jugular notch is limited by the base jugular process (processus jugularis), which faces the cranial cavity. On the inner surface of the lateral part, posterior and medial to the jugular process, there is a deep groove of the sigmoid sinus (sulcus sinus sigmoidei). In the anterior section of the lateral part, on the border with the basilar part, is located jugular tubercle, tuberculum jugulare, and on the lower surface - occipital condyle (condylus occipitalis), which connects the skull to the first cervical vertebra. Behind each condyle is condylar fossa (fossa condylaris), at its bottom there is an opening of the emissary vein (condylar canal). The base of the condyle is pierced canal of the hypoglossal nerve (canalis nervi hypo-glossi), through which the corresponding nerve passes.
Occipital scales(squama occipitalis) has an upper lambdoid (margo lambdoideus) and lower mastoid margin (margo mastoideus). Outer surface scales are convex, in its middle there is external occipital protuberance (protuberantia occipitalis externa). Down towards the large hole, it continues into external nuchal crest (crista occipitalis externa). Perpendicular to the ridge are the upper and lower nuchal lines (lineae nuchalis superior et inferior). Sometimes the highest nuchal line (linea nuchalis suprema) is also noted. Muscles and ligaments are attached to these lines.
Inner surface occipital scales concave, has in the center an internal occipital protuberance (protuberantia occipitalis interna), which is the center cruciform eminence (eminentia cruciformis). extends upward from the internal occipital protrusion groove of the superior sagittal sinus (sulcus sinus sagittalis superioris), down - internal occipital crest (crista occipitalis interna), and to the right and left - grooves of the transverse sinus (sulci sinui transversi).
Ossification: at the beginning of the 3rd month of intrauterine development, 5 ossification points appear: in the upper (membranous) and lower (cartilaginous) parts of the scales, one in the basilar, two in the lateral parts. By the end of this month, the upper and lower sections of the scales grow together; in the 3-6th year, the basilar, lateral parts and scales grow together.
Human anatomy S.S. Mikhailov, A.V. Chukbar, A.G. Tsybulkin
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