The temporal bone, os temporale, is a paired bone, complex in shape and structure, which participates in the formation of the base of the skull, being placed between the occipital and sphenoid bones, and also complements the lateral walls of the cranial roof. It has three parts located around the external auditory opening: scaly, tympanic and stony.
The scaly part, pars squamosa, is a vertically located bone plate. With a free, uneven, obliquely cut edge, it is connected through a scaly suture to the lower edge of the parietal bone and to the greater wing sphenoid bone. Below, the scaly part is adjacent to the petrous and tympanic parts and is separated from it by a petrosquamous fissure, fissura petrosquamosa (visible only on the bones of young subjects), and from the tympanic part by a tympanic-squamous fissure, fissura tympanosquamosa.
The outer temporal surface, facies temporalis, of the scaly part is smooth, participates in the formation of the temporal fossa. Near the lower edge, the zygomatic process, processus zygomaticus, departs from it, directed anteriorly, where it connects with temporal process zygomatic bone and forms the zygomatic arch, arcus zygomaticus. The zygomatic process extends with two roots, between which the mandibular fossa, fossa mandibularis, is formed. It is covered with cartilage and articulates with the articular process of the lower jaw. Anterior root The zygomatic process, thickening anterior to the mandibular fossa, forms an articular tubercle, tuberculum articulare. On the posterior root of the zygomatic process there is a similar retroarticular tubercle, tuberculum retroarticulare, less pronounced. Posteriorly it passes into the temporal line, linea temporalis.
The inner cerebral surface, facies cerebralis, of the scaly part is equipped with cerebral elevations, digital impressions, as well as grooves for the vessels of the meninges.

Figure: Temporal bone, right, external view.
1 - zygomatic process; 2 - articular tubercle; 3 - mandibular fossa; 4 - petrotympanic fissure; 5 - styloid process; 6 - drum part; 7 - external auditory opening; 8 - edge of the drum part; 9 - mastoid process; 10 - mastoid foramen; 11 - temporal line; 12 - scaly part.

The tympanic part, pars tympanica, is centered around the external auditory canal, meatus acusticus externus. In newborns, it is expressed in the form of a ring, anulus tympanicus, open upward and surrounding the external auditory canal. Subsequently, it grows and merges with neighboring parts. In adults, the tympanic part limits below and behind the external auditory opening, porus acusticus externus, and the tympanic cavity, cavum tympani, merging with the free edge with the scales and the mastoid part. It is separated from the scales by a tympanic-squamous fissure, into which a process of the tympanic roof enters from the front surface of the pyramid, due to which the said fissure is divided into two parallel fissures: the stony-squamous one, fissura petrosquamosa, and the stony-tympanic one, fissura petrotympanica, through which tympanic cavity goes through a branch facial nerve- drum string, chorda tympani. The cartilaginous part of the auditory canal is attached to the free rough and curved edge of the tympanic part, limiting the external auditory opening.
Above the external auditory opening rises the supra-ductal spine, spina supra meatum.
The petrous part, pars petrosa, or pyramid, is shaped like a three-sided pyramid, the base of which faces posteriorly and laterally, the apex facing anteriorly and medially. There are three surfaces on the pyramid, of which the anterior, facies anterior, and posterior, facies posterior, face the cranial cavity, and the lower, facies inferior, is part of the outer surface of the base of the skull. The surfaces are separated by three edges: top, back and front. The base of the pyramid is fused with the scaly part. A small portion of the base of the pyramid, facing outward, remains uncovered and contains the external auditory opening. The pyramid of the temporal bone contains most of the elements of the hearing organs: the bony part of the external auditory canal, the middle and inner ear.
On the anterior surface of the pyramid there is an arcuate eminence, eminentia arcuata, corresponding to the anterior semicircular canal of the labyrinth inner ear. In front of this elevation there are two thin grooves: the greater and lesser petrosal nerves, sulcin. retrosi majoris et n. petrosi minoris, ending in front with clefts of the same name, hiatus canalis n. petrosi majoris et hiatus canalis n. petrosi minoris. Nerves exit through these holes. The lateral part of this surface of the bone, lying between the arcuate eminence and the squamous-stony fissure, constitutes the upper wall of the tympanic cavity and is therefore called the tympanic roof, tegmen tympani. Near the apex of the pyramid there is a trigeminal impression, impressio trigemini. Along the upper edge of the pyramid there is a groove of the superior petrosal sinus, sulcus sinus petrosi superioris. On the posterior surface of the pyramid there is an internal auditory opening, porus acusticus internus, leading to the internal auditory canal, meatus acusticus internus. Posterior to the internal auditory opening is the external opening of the aqueduct of the vestibule, apertura externa aqueductus vestibuli, through which the ductus endolymphaticus passes. At the upper edge of the pyramid, between the internal auditory opening and the external opening of the aqueduct of the vestibule, there is a subarc fossa, fossa subarcuata, which in children reaches large sizes, and in adults it decreases significantly. At the lower edge at the level of porus acusticus internus there is an opening of the cochlear canaliculus, apertura externa canaliculi cochleae. Along the posterior edge of the pyramid there is a groove of the inferior petrosal sinus, sulcus sinus petrosi inferioris. The bottom surface of the pyramid is uneven. From it the styloid process descends down and forward, the processus styloideus - the place of muscle attachment. The process reaches its full development in older people. It is composed of several segments that ossify separately and merge with each other quite late. Between the styloid and mastoid processes, under the external auditory foramen, there is a stylomastoid foramen, foramen stylomastoideum, which serves as the exit point for the facial nerve. Anterior and medial to the styloid process is the jugular fossa, fossa jugularis. At the bottom of this fossa, the opening of the mastoid tubule, canaliculus mastoideus, is visible. Anterior to the jugular fossa is the external opening of the carotid artery canal, foramen caroticum externum, leading into the carotid artery canal, canalis caroticus, which opens at the apex of the pyramid with an internal exit opening, foramen caroticum internum. On back wall of the carotid artery canal, near the external opening, there are several small openings of the carotid-tympanic tubules, canaliculi caroticotympanici, opening into the tympanic cavity and conducting vessels and nerves. In the ridge between the external opening of the carotid canal and the jugular fossa, a stony fossa, fossula petrosa, is identified, at the bottom of which the tympanic canaliculus for the nerve of the same name begins. Laterally from the foramen caroticum internum, in the depth of the angle formed by the scales and the anterior edge of the pyramid, the entrance opening of the muscular-tubal canal, canalis musculotubarius, is determined, divided by an incomplete bone septum into two half-canals: for the tensor muscle eardrum, semicanalis m. tensoris tympani, auditory tube, semicanalis tubae auditivae.

Figure: Right temporal bone, internal and posterior view.
1 - arcuate elevation; 2 - parietal edge; 3 - roof of the tympanic cavity; 4 - groove of the superior petrosal sinus; 5 - groove of the sigmoid sinus; 6 - mastoid foramen; 7 - occipital edge; 8 - styloid process; 9 - groove of the inferior petrosal sinus; 10 - top of the pyramid; 11 - rocky part, or pyramid; 12 - zygomatic process; 13 - wedge-shaped edge; 14 - arterial groove; 15 - rear surface of the pyramid; 16 - internal auditory opening.

The base of the pyramid is extended downward into the mastoid process, processus mastoideus, the outer surface of which is rough due to the attachment of the sternocleidomastoid muscle to it. Inside the mastoid process there are cells, cellulae mastoidei, various shapes and sizes lined with mucous membrane. The largest cell is the mastoid cave, antrum mastoideum, which communicates with the cavity of the middle ear. Inward from the apex of the mastoid process there are two parallel grooves. The groove of the occipital artery, sulcus a, runs medially. occipitalis, and laterally - the mastoid notch, incisura mastoidea, which is the origin of the digastric muscle. The mastoid process is separated from the tympanic part by the tympanomastoid fissure, fissura tympanomastoidea, through which the auricular branch of the vagus nerve passes. In the suture between the mastoid part and the occipital bone there is a mastoid foramen, foramen mastoideum. On the outer surface of the mastoid process, a practically important area is distinguished - the mastoid triangle, which is limited in front by a line drawn from the spina supra meatum (see the chapter “Temporal bone”) to the apex of the mastoid process, behind - by the line of attachment of the sternocleidomastoid muscle and above - a line that is a continuation of the lower edge of the zygomatic process. The triangle serves as a trepanation site for inflammatory processes middle ear.
On the inner surface of the mastoid process there is an S-shaped curved groove of the sigmoid sinus, sulcus sinus sigmoidei. Approximately halfway along its length, the mastoid opening opens.
Canals of the temporal bone. 1. The canal of the facial nerve, canalis facialis, begins at the bottom of the internal auditory canal and goes forward and laterally to the level of the clefts of the petrosal nerve canals. From here, at a right angle, it goes laterally and backwards, forming a bend - the geniculum canalis facialis, changes direction from horizontal to vertical and ends with the stylomastoid foramen.
2. Canal of the carotid artery, canalis caroticus (described in the text).
3. Musculotubal canal, canalis musculotubarius.
4. The canaliculus chordae tympani, starts from the facial canal slightly above the stylomastoid foramen and ends in the fissura petrotympanica region. A branch of the facial nerve passes through it - the chorda tympani.
5. The mastoid tubule, canaliculus mastoideus, originates at the bottom of the jugular fossa and ends in the tympanomastoid fissure. A branch of the vagus nerve passes through this canaliculus.
6. The tympanic canaliculus, canaliculus tympanicus, arises in the fossula petrosa with the opening apertura inferior canaliculi tympanici, through which the branch of the glossopharyngeal nerve enters, n. tympanicus. After passing through the tympanic cavity, this nerve called n. petrosus superficialis minor exits through the upper opening of the canal, located on the front surface of the pyramid.

Figure: Right temporal bone, ventral view.
1 - articular tubercle; 2 - mandibular fossa; 3 - petrotympanic fissure; 4 - drum part; 5 - mastoid process; 6 - mastoid notch; 7 - muscular-tubal canal; 8 - internal carotid foramen; 9 - external carotid foramen; 10 - jugular fossa; 11 - stylomastoid foramen; 12 - groove of the occipital artery.

7. Carotid-tympanic tubules, canaliculi caroticotympanici, pass in the wall of the carotid artery canal near its external opening and open into the tympanic cavity. They serve for the passage of blood vessels and nerves.
Ossification. The temporal bone has 6 ossification points. At the end of the 1st month of intrauterine development, ossification points appear in the scales, and at the 3rd month - in the tympanic part. At the 5th month, several points of ossification appear in the cartilaginous anlage of the pyramid. By the time of birth, the temporal bone consists of three parts: the squamous with the rudiment of the zygomatic process, the petrous with the rudiment of the mastoid part and the tympanic, which are basically already connected, but in the newborn there are still gaps between them filled with connective tissue. The styloid process develops from two centers. The superior centrum appears before birth and fuses with the petrosal portion during the 1st year of life. The lower center appears after birth and merges with the upper only after the onset of puberty. During the 1st year of life, the three parts of the bone fuse together.

Carotid canal: short and curved, has an external opening on the lower surface of the pyramid and an internal opening opening into the cranial cavity (middle cranial fossa), passing the internal carotid artery with its petrosal flexure and the internal carotid sympathetic nerve.

Musculo-tubal canal:

· has a common wall with the carotid canal;

· consists of two semicircular canals: the upper one for the tensor tympani muscle and the lower one for the auditory tube.

Both semicircular canals open into the tympanic cavity, and the auditory tube, with its opposite end, also opens into the nasopharynx.

The facial canal has an inlet at the bottom of the internal auditory canal, and the exit from the canal is the stylomastoid foramen. There is a complex, loop-like passage in the channel, and inside the rocky part and closer to the base of the pyramid a bend in the form of an elbow is formed.

The canal contains the facial nerve with the genu ganglion; inside the pyramid it has openings for the branches of the nerve to exit into the tympanic cavity.

Drum string channel:

· departs from the facial canal and opens into the tympanic cavity;

· a branch of the facial nerve passes through the canaliculus - the chorda tympani, which leaves the skull through the petrotympanic fissure.

Tympanic canaliculus:

· the lower hole lies in a stony dimple;

· the canal passes through the tympanic cavity and the septum of the muscular-tubal canal;

· the superior opening opens into the cleft of the lesser petrosal nerve on the anterior surface of the pyramid;

· in the tubule, the tympanic nerve, a branch of the glossopharyngeal nerve (IX pair), passes into the tympanic cavity, and the lesser petrosal nerve exits.

Carotid tympanic tubules (two):

· origin in the wall of the carotid canal near the external carotid foramen;

end in the tympanic cavity;

· contents - carotid-tympanic sympathetic nerves and vessels.

Mastoid tubule:

· the beginning in the jugular fossa, along its course crosses the facial canal, opens into the tympanomastoid fissure;

· contents - auricular branch of the vagus nerve (X pair).

10(II) Sphenoid bone

In the development of bones, the following are important:

· endochondral ossification of 5 pairs of primary nuclei, formed at the 9th week of the fetal period in the body and wings;

· endodesmal ossification of the pterygoid processes and the tips of the greater wings, beginning at 8 weeks;

· fusion of the body, small and large wings, and pterygoid processes occurs at the age of 3-8 years.

The sphenoid sinus appears at the 3rd year of life, its formation ends at 30-40 years.

During development, at the initial stage, a pharyngeal-cranial canal is formed in the body of the bone, through which the anterior rudiment of the pituitary gland passes from the primary oral cavity. After the movement of the rudiment, the canal becomes overgrown, and in case of developmental disorders, a cranial hernia occurs.

The sphenoid bone - pneumatic - consists of a body, small and large wings and pterygoid processes.

Body - contains the pneumatic sinus inside and has six surfaces:

· upper (cerebral);

· lower - with openings of the sphenoid sinus for communication with the nasal cavity;

· anterior, adjacent to the ethmoid bone and forms a sphenoid-ethmoid synchondrosis;

Posterior connects to the basilar part occipital bone, participating in the formation of the clivus and sphenoid-occipital synchondrosis;

· lateral: right and left go into the wings.

On the upper surface of the body there is a sella turcica, and in it:

· pituitary fossa - for the pituitary gland - the central neuroendocrine gland;

· tubercle sella - anterior to the fossa;

· back of the saddle with posterior inclined processes - posterior to the fossa;

· carotid grooves: right and left with wedge-shaped tongues, lie on the lateral surfaces of the saddle, intended for the internal carotid artery and internal carotid sympathetic nerve, venous cavernous sinus.

On the front surface of the body:

· wedge-shaped ridge, passing downwards into the keel.

On the lower surface of the body:

· wedge-shaped keel (beak);

· on the sides of the beak and crest there are wedge-shaped shells that limit the wedge-shaped openings leading to the sinus.

The lateral (lateral) surfaces continue into the lesser and greater wings.

Small wings: right and left - lie in front and on the sides of the body. They have:

· anterior edge connecting to the frontal bone with a flat suture;

· the posterior edge is free, facing the middle cranial fossa along with the medially located anterior inclined processes;

· the optic canal under the inclined processes - for the optic nerve (II pair) and the central artery and vein of the retina;

· the groove of the optic chiasm, connecting the internal openings of the optic canals.

Large wings: right and left.

· At the base of the wing, closer to the sella turcica, there are three holes sequentially from front to back: round - for the second branch trigeminal nerve(Y pair), oval - for the third branch of the trigeminal nerve, spinous - for the middle meningeal artery.

· The sphenoid spine is located behind and below the opening for the meningeal artery.

· Surfaces of the wings: cerebral - with cerebral projections, digital depressions, arterial grooves, orbital - for the lateral wall of the orbit, maxillary - facing the pterygopalatine fossa, has a round opening, temporal - divided by the infratemporal crest into two parts - temporal and infratemporal.

Between the lesser and greater wings there is the superior orbital fissure, through which pass: the oculomotor (III pair), trochlear (IY pair), abducens (YI pair) cranial nerves and the first branch (ophthalmic, orbital nerve) of the trigeminal nerve (Y pair), as well as the orbital artery and vein.

The right and left pterygoid processes extend from the lower surface of the body and contain:

· medial and lateral plates, fused in front, where the pterygopalatine groove passes;

· between the plates behind and downwards there is a pterygoid fossa, which passes downwards into the pterygoid notch;

· the medial plate is longer and ends with a hook;

· at the base of the pterygoid processes there is a canal of the same name for vessels and nerves.

11(II) Pterygopalatine fossa

It is part of the facial skull, but is located on the border with the outer base of the cranium. The fossa is adjacent to and has connections with the temporal and infratemporal fossa. The upper jaw with its tubercle and posterior surface, the sphenoid bone with its greater wing and pterygoid process, and the palatine bone with its perpendicular plate participate in its formation. The shape of the fossa is a narrow gap limited by the three bones listed above; it borders and communicates with the cranial cavity (middle cranial fossa), the cavities of the nose and mouth, the orbit, the temporal and infratemporal fossae.

The pterygopalatine fossa has the following walls:

· The anterior wall includes the tubercle of the maxilla with the posterior alveolar foramina, through which the superior posterior alveolar vessels and nerves pass from the fossa to supply the maxilla, its alveoli, teeth and gums.

· The posterior wall is the maxillary surface of the greater wing and the base of the pterygoid process of the sphenoid bone with the canal of the same name, which passes into the fossa from the area torn hole autonomic pterygoid nerve and vessels of the same name.

· The medial wall is a perpendicular plate of the palatine bone and a small section of the sphenoid bone adjacent to it; vessels and nerves for the nasal mucosa pass through the sphenopalatine foramen of the wall from the fossa.

The pterygopalatine fossa communicates:

· with the oral cavity through the greater and lesser palatine canals with the vessels and nerves of the same name that supply the hard and soft palate and the palatine tonsils;

· with the nasal cavity through the sphenopalatine foramen with the same vessels and nerves for the mucous membrane of the turbinates and nasal passages;

· with the middle cranial fossa through the foramen rotundum, through which the maxillary branch of the trigeminal nerve passes;

· with the area of ​​the lacerated foramen through the pterygoid canal, containing the autonomic nerve and vessels of the same name;

· with the orbit through the inferior orbital fissure for the passage of the infraorbital branches of the maxillary vessels and nerves;

· with the infratemporal fossa through the pterygomaxillary fissure, where the connection is made by connective tissue and fatty tissue.

The fossa is filled with fiber, part of the pterygoid venous plexus, the terminal sections of the maxillary vessels, the maxillary branch of the Y pair and the parasympathetic pterygopalatine ganglion of the head with postganglionic branches extending from it: orbital, medial and lateral nasal, greater and lesser palatine, inferior posterior nasal. The maxillary branch of the trigeminal nerve, the terminal section of the maxillary artery, and the maxillary vein, which flows into the pterygopalatine plexus, pass through the fossa.

The infraorbital and zygomatic nerves and nodal branches to the pterygopalatine ganglion depart from the maxillary nerve in the fossa. Through the inferior orbital fissure, the infraorbital nerve enters the orbit, where it lies in the infraorbital groove and canal and gives off the superior alveolar nerves (anterior, middle and posterior) to the teeth, gums and alveoli. From the orbit through the same gap, the vegetative orbital branches come into the fossa and enter the node. From hard and soft palate The greater and lesser palatine nerves enter the fossa using the canals of the same name. From the mucous membrane of the nasal cavity, vegetative posterior nasal branches are directed through the sphenopalatine foramen into the node.

In the pterygopalatine fossa there is the final section of the maxillary artery with the following branches: infraorbital, sphenopalatine and palatine arteries, pharyngeal branches and branches to the auditory tube. The infraorbital artery leaves the fossa through the inferior orbital fissure and supplies blood upper jaw, teeth and gums, lower eyelid, lacrimal sac and eye muscles, cheek and upper lip, forming anastomoses with the facial artery. The sphenopalatine artery leaves through the homonymous foramen to supply blood to the mucosa lateral wall and nasal septum. The veins of the parotid salivary gland, middle meningeal, tympanic, inferior ophthalmic and deep facial veins flow into the pterygoid venous plexus.

Loose connective tissue fills the pterygopalatine fossa and serves as a support (soft skeleton) for the vessels and nerves located here. It is associated with the fiber of the temporopterygoid, suprapterygoid, interpterygoid and pterygomaxillary space. Through the pterygomaxillary fissure, fiber penetrates into the infratemporal fossa, and from it into the temporal fossa.

, vestibulocochlear and facial nerves, trigeminal ganglion, branches of the vagus and glossopharyngeal nerves.

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✪ Skull #3: Temporal bone; temporal bone canals

✪ Temporal bone (Os Temporale)

✪ Temporal bone, its parts, purpose of holes, canals, cracks

✪ Temporal bone

✪ Anatomy of the temporal bone. Part 1

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Anatomy

On the surface of the brain, traces of the brain are visible in the form of impressions (impressiones digitatae). The zygomatic process (processus zygomaticus) departs from it, which is directed forward to connect with the zygomatic bone. In the lower part there is an articular fossa for articulation with the lower jaw (fossa mandibularis).

The tympanic part (pars tympanica) is fused with the mastoid process (processus mastoideus) and the scaly part (pars squamosa), is a thin plate that bounds the external auditory opening (porus acusticus externus) and the external auditory canal (meatus acusticus externus) in front, behind and below. .

The stony part (pars petrosa) has the shape of a three-sided pyramid, the apex of which faces anteriorly and medially, and the base, which passes into the mastoid process (processus mastoideus), faces posteriorly and laterally.

There are three surfaces: anterior, posterior and lower, as well as three edges: anterior, posterior and upper.

The anterior surface (facies anterior) is part of the bottom of the middle cranial fossa; posterior (facies posterior) faces backward and medially, forms part of the anterior wall of the posterior cranial fossa; the lower one (facies inferior) faces down and is visible only on the outer surface of the base of the skull.

The external relief of the pyramid is due to its structure as a container for the middle and inner ear, as well as for the passage of blood vessels and nerves.

A thin pointed styloid process (processus styloideus) extends from the lower surface of the pyramid, serving as a site of muscle attachment. The relief of the outer surface of the pyramid is the site of muscle attachment; downward it extends into the mastoid process, to which the sternocleidomastoid muscle is attached.

On the mastoid process (on its anterior smooth surface) of the temporal bone, a triangle Spike is distinguished, which is the site of operational access to the cells of the mastoid process. On the X-ray of the temporal bones, the so-called sinodural angle (Citelli angle) is distinguished. Inside, the mastoid process contains cells (cellulae mastoideae), which are air cavities communicating with the tympanic cavity (middle ear) through the mastoid cave (antrum mastoideum).

The temporal bone is connected to the occipital, parietal and sphenoid bones. Participates in the formation of the jugular foramen.

Temporal bone canals

• sleepy channel, canalis caroticus, in which the internal carotid artery lies. It begins on the lower surface of the pyramid, with the external carotid foramen (foramen caroticum externum), directed vertically upward, bending at a right angle, directed forward and medially. The canal opens into the cranial cavity through the internal carotid foramen (foramen caroticum internum).
• drum string channel, canaliculus chordae tympani, starts from the canal of the facial nerve, slightly above the stylomastoid foramen (foramen stylomastoideum), goes forward and opens into the tympanic cavity. A branch of the facial nerve, the chorda tympani, passes through this canaliculus, which then exits the tympanic cavity through the petrotympanic fissure (fissura petrotympanica).
• facial canal, canalis facialis, in which the facial nerve passes, it begins at the bottom of the internal auditory canal, then runs horizontally from back to front. Having reached the level of the cleft of the canal of the greater petrosal nerve, the canal goes back and laterally, at a right angle, forming a bend, or elbow, of the facial canal. Next, the channel is directed back, following horizontally along the axis of the pyramid. Then it turns vertically downwards, bending around the tympanic cavity, and on the lower surface of the pyramid it ends with a stylomastoid opening.
• myotubal canal, canalis musculotubaris, has a common wall with the carotid canal. It begins in the angle formed by the anterior edge of the pyramid and the squama of the temporal bone, running posteriorly and laterally, parallel to the anterior edge of the pyramid. The muscular-tubal canal is divided into two semi-canals by a longitudinal horizontal septum. The upper hemicanal is occupied by the tensor tympani muscle, and the lower is the bony part of the auditory tube. Both canals open into the tympanic cavity on its anterior wall.
• mastoid tubule, canaliculus mastoideus, originates at the bottom of the jugular fossa and ends in the tympanomastoid fissure. A branch of the vagus nerve passes through this canaliculus.
• tympanic canaliculus, canaliculus tympanicus, arises in the stony fossa (fossula petrosa) with an opening through which a branch of the glossopharyngeal nerve, the tympanic nerve, enters. After passing through the tympanic cavity, this nerve, called the lesser petrosal nerve, exits through the cleft of the same name on the anterior surface of the pyramid.
• carotid tympanic tubules, canaliculi caroticotympanici, pass in the wall of the canal of the internal carotid artery near its external opening and open into the tympanic cavity. They serve for the passage of the vessels and nerves of the same name.
• vestibule water supply, aqueductus vestibuli, a canal in the pyramid of the temporal bone that connects the vestibule of the bony labyrinth (the expanded part of the bony labyrinth between the cochlea of ​​the inner ear and the bony semicircular canals) with the cranial cavity (posterior cranial fossa). It opens with a gap on the posterior surface of the pyramid of the temporal bone, behind the opening of the internal auditory canal. The canal contains the vein of the aqueduct of the vestibule and the ductus endolymphaticus, which ends in the blind sac (saccus endolymphaticus), on the posterior surface of the pyramid of the temporal bone, between the opening of the internal auditory canal and the sigmoid sinus.
• snail plumbing, aqueductus cochleae, about 10 mm long, connects the vestibule of the inner ear and the posterior surface of the pyramid of the temporal bone, opening at its lower edge, below the opening of the internal auditory canal. Its internal opening is located at the beginning of the staircase of the drum of the bony cochlea. The vein of the cochlear canaliculus passes through the canal.

Each bone of the human body is an important “cog” in a huge mechanism. The head bone elements perform protective function. These elements include the temporal bone.

Temporal bone: description

An important part of the skull is the temporal bone, which is located on both sides of the skull, and therefore is a pair. More precisely, it belongs to one of the components of the skull that covers the brain. It is surrounded by the sphenoid, parietal and occipital bones.

This bone element, in combination with the lower jaw, forms a movable joint. And in tandem they form the zygomatic arch.

The temporal element itself is not a single bone: it is represented by a number of parts that form it.

The temporal bone develops by ossification from six points. At the end of the 8th week of embryonic development, the scaly parts are the first to ossify. In the 3rd month, hardening occurs in the tympanic part. With the arrival of the 5th month of fetal development, several areas of ossification appear in the cartilaginous portion of the pyramid.

By the period preceding birth, the temporal bone already consists of a scaly part, a tympanic and a petrous part, and in between these parts there are clefts with connective tissue.

Bone structure

Anatomy of the temporal bone looks like as follows. It consists of a pyramid, a drum part and scales.

The pyramid is also called the rocky part. And for good reason, because this element consists of a very hard bone element. In its shape, the rocky part is very similar to a triangular pyramid (hence the name). The base of the pyramid extends into the mastoid process.

The pyramid consists of the following parts: the top; front, back and bottom surfaces; apical, posterior and inferior margins.

The frontal has an orientation expressed forward and upward. On the lateral side, the pyramid passes into the scales of the temporal bone. Between these two elements of the temporal bone is the petrosquamosal foramen. In its central part, the front surface of the pyramid has a small arc-shaped elevation. At a distance through these elevations, in the form of a scaly opening, there is a flat section that serves as the roof of the tympanic cavity.

The back surface of the pyramid is adjacent to the center. Almost in the central part of this surface of the pyramid there is a small auditory opening, which flows into the internal auditory canal. On the lateral side of the auditory opening is the subarcular fossa. And on the lower side there is a hole for the vestibule water supply.

The lower surface of the pyramid is equipped with a difficult surface relief. The lower surface flows into the mastoid process.

The upper edge of the pyramid is the boundary line connecting the front and back surfaces. At its base there is a groove for the petrosal sinus.

The posterior edge of the pyramid separates the posterior and inferior surfaces. Along its surface lies the groove of the inferior petrosal sinus. Near the lateral side of the furrow there is a dimple with the external opening of the cochlear canaliculus.

WITH inside the pyramid houses the organs of hearing and balancing.

The diagram shows:

Functions

The temporal bone has three functions:

1. Protective. The temporal bone, together with the rest of the bones of the skull, protects the brain from various kinds damage.
2. Support. The cranial bone supports the brain, being its support.
3. The temporal bone is the attachment point for the head muscles.

In addition, this bone contains organs and canals hearing aid, equilibrium, and also contains various tubules and vessels.

The functions performed depend entirely on the anatomy of the temporal bone. Additionally, the location of nearby bones also affects functionality.

Temporal bone canals

The temporal bone is completely striated with various notches, depressions and canaliculi. The canals and cavities of the temporal bone serve to conduct blood vessels, nerve branches, and arteries. The canals are hollow tubular cords that intertwine parts of the temporal bone.

Below is a table of the temporal bone canals.

Temporal bone canals

Bone canals	What cavities connect	What crosses the channels
Facial canal	Dorsal wall of the pyramid and stylomastoid foramen	7th petrosal artery and stylomastoid vessels
Sleepy channel	Apex of the pyramid and outer base of the skull	Carotid artery and carotid plexus
Musculo-tubal canal	and the upper wall of the pyramid	Superior tympanic artery, auditory tube
Drum string channel	Facial canal, tympanic cavity and tympanic fissure	7th facial nerve and posterior tympanic artery
Mastoid tubule	Jugular recess and mastoid fissure	auricular process of the 10th pulmonary gastric nerve
Tympanic canaliculus	Petrosal fossa, inferior wall of the pyramid and tympanic cavity	Lesser petrosal nerve vessel, tympanic artery, lying inferiorly
Carotid-tympanic tubules	The edge of the carotid cord and the tympanic cavity	Carotid-tympanic nerve fibers and arteries
Snail tubule	The beginning of the internal auditory organ and the lower base of the pyramid	Cochlear tubule vein
Internal auditory canal	Inner ear and posterior cranial fossa	7th facial nerve, 8th cochlear nerve and artery of the inner ear
Plumbing vestibule	The beginning of the inner ear and the cranial fossa located on the back side	Venous vessel of the aqueduct

Facial nerve canal

Let's look at the facial canal of the temporal bone. It originates on the underside of the hearing aid, located inside the ear. Its direction is expressed laterally - forward to the cleft of the petrosal nerve fiber canal. In this area it forms a turn, which is called the elbow of the facial canal. The facial canal of the temporal bone continues its path from the knee in the direction of the side and back, along the trajectory of a right angle parallel to the axis of the pyramid. Then the direction becomes vertical and ends with the mastoid opening at the rear wall of the tympanic cavity.

Sleepy channel

The carotid canal of the temporal bone begins its journey on the lower side of the pyramid in the form of a hole (aperture). Its direction is straight and upward, but closer to the surface of the pyramid. The canal bends at an angle of 90 and exits through the external opening at the apex of the pyramid. The carotid artery passes through the canal.

Musculo-tubal canal

The myotubal canal of the temporal bone is a fragment of the auditory tube of the inner ear. The canal begins at the apex of the pyramid, namely, located between its frontal edge and the scales of the temporal bone.

Drum string channel

This canaliculus starts from the facial nerve canal, but its beginning is located slightly higher from the stylomastoid foramen, and ends in the petrotympanic fissure. The contents of this temporal bone canal have been discussed in more detail in the table.

Mastoid tubule

The canaliculus originates in the jugular fossa, crosses the lower part of the facial canal and ends in the mastoid-tympanic fissure. The mastoid canal carries the process of the vagus nerve through its cavity.

Tympanic canaliculus

The tympanic tubule originates from the bottom of the stony fossa. It continues its path in an upward and straight direction. It crosses the section of the tympanic cavity located below and rushes to the top of the promontory, but in the form of a groove. Its end exits through the cleft of the petrosal nerve, located on the anterior side of the pyramid of the temporal bone.

The tympanic canal contains the tympanic nerve in its cavity.

Carotid-tympanic tubules

There are two carotid tympanic tubules in total. They start from the wall of the carotid canal, from where they are further discharged into the tympanic cavity. The function of these channels is conduction.

The canals of the temporal bone are shown schematically above. They show the complexity of the processes occurring in the bones.

The temporal bone, the anatomy of which will be discussed further, is a pair. It contains organs of balance and hearing. The temporal bone of the skull takes part in the formation of its base and lateral wall of the vault. Articulating with the lower jaw, it provides support for the masticatory apparatus. Next, let's take a closer look at what the temporal bone is.

Anatomy

There is an auditory opening on the outer surface of the element. There are three parts around it: scaly (above), petrous (or pyramid of the temporal bone) - behind and inward, tympanic - below and in front. The rocky area, in turn, has 3 surfaces and the same number of edges. The left and right temporal bones are the same. The segments contain channels and cavities.

Scaly part

It is presented in the form of a plate. The outer surface of this part is slightly rough and has a slightly convex shape. In the posterior section, the groove of the temporal (middle) artery runs in a vertical direction. An arcuate line runs along the posterior lower section. From the scaly part, the zygomatic process extends slightly anteriorly and from above in a horizontal direction. It seems to be a continuation of the ridge located on the outer surface along the lower edge. Its beginning is presented in the form broad root. Then the process narrows. It has an outer and inner surface and 2 edges. One, the top one, is longer, and the second, the bottom one, is correspondingly shorter. The front end of the element is jagged. The processes of the temporal bone in this area are connected using a suture. As a result, the zygomatic arch is formed. The mandibular fossa is located on the lower surface of the root. It has a transverse oval shape. The anterior part of the fossa - half up to the stony-squamous fissure - is articular surface temporomandibular joint. In front, the fossa is limited by a tubercle. The outer plane of the scaly part takes part in the formation of the temporal fossa. This is where the muscle bundles originate. On the inner surface there are finger-like impressions and an arterial groove. The latter contains the meningeal (middle) artery.

The edges of the scaly part

There are two of them: parietal and sphenoid. The latter - jagged and wide - articulates with the squamosal edge in the large wing of the sphenoid bone. As a result, a seam is formed. The upper posterior parietal edge is longer than the previous one, pointed and articulates with the squamosal in the parietal bone.

Rocky part

The structure of the temporal bone in this area is quite complex. The petrous part includes the anteromedial and posterolateral sections. The latter is the mastoid process of the temporal bone. It is located posterior to the auditory (external) opening. It distinguishes between internal and outer surface. The outer one is rough and has a convex shape. Muscles are attached to it. Inferiorly the process becomes a protrusion. It has a cone-shaped shape and can be felt quite well through the skin. There is a deep notch on the inside. Parallel to it and slightly posteriorly there is a groove of the occipital artery. The posterior border of the process is the occipital jagged edge. Connecting, the edges in this area form a seam. In the middle of its length or at the occipital end there is a mastoid foramen. In some cases there may be several. The emissary mastoid veins lie here. From above the process is limited by the parietal edge. At the border with the area of ​​the scaly part of the same name, it forms a notch. The angle from the parietal bone enters it and forms a suture.

Rocky surfaces

There are three of them. The anterior surface is wide and smooth. It faces the cranial cavity, is directed obliquely forward and from top to bottom, and passes into the medullary plane of the scaly part. Almost in the center on the front surface there is an arched elevation. It is formed by the semicircular anterior canal of the labyrinth, which lies below. Between the gap and the elevation there is a roof of the drum part. The posterior surface of the stony part, like the anterior one, turns into the cranial cavity. However, it is directed posteriorly and upward. The posterior surface is continued by the mastoid process. Almost in the middle there is an auditory (internal) opening leading to the corresponding passage. The lower surface is uneven and rough. It forms part of the lower plane of the base of the skull. There is an oval or round jugular fossa. At its bottom there is a small groove leading to the opening of the mastoid canaliculus. The posterior edge of the fossa is limited by the notch. It is divided into two parts by a small process.

Edges of rocky area

IN top edge a groove runs through the pyramid. It represents the imprint of the venous sinus lying here and the fixation of the tentorium of the cerebellum. The posterior edge of the rocky area separates the posterior and inferior surfaces. The petrosal sinus groove runs along the brain surface along it. Almost in the middle of the posterior edge, near the jugular notch, there is a funnel-shaped triangular depression. The anterior edge is shorter than the posterior and upper edge. It is separated from the scaly part by a gap. At the anterior edge there is an opening of the muscular-tubal canal leading to the tympanic cavity.

Channels of the rocky part

There are several of them. The carotid canal originates in the middle sections on the lower surface in the stony part with an external opening. At first it is directed upward. Further, bending, the canal follows medially and anteriorly, opening at the apex of the pyramid with an opening. The carotid tympanic tubules are small branches. They lead into the tympanic cavity. The facial canal begins at the bottom of the internal auditory canal. It runs horizontally and almost at a right angle relative to the axis of the stony section. Next, the channel is directed to the front surface. In this place, turning at an angle of 90 degrees, it forms a knee. Next, the canal passes to the posterior part of the medial wall in the tympanic cavity. Then, heading posteriorly, it passes along the axis in the rocky part until it reaches an eminence. From this place it goes down vertically, opening with a stylomastoid foramen.

Drum string channel

It begins a few millimeters higher than the stylomastoid foramen. The channel goes up and forward, entering the tympanic cavity and opening on its back wall. The chorda tympani, a branch of the intermediate nerve, passes through the canaliculus. It exits the cavity through the petrotympanic fissure.

Musculo-tubal canal

It is a continuation of the anterior superior region of the tympanic cavity. Its external opening is located near the notch between the scaly and petrous parts of the bone. The canal runs laterally and somewhat posteriorly from the horizontal section of the carotid tract, almost along the longitudinal axis of the petrous section. There is a partition inside it. It is located horizontally. By means of this partition the canal is divided into two parts. The upper one is the semi-canal of the muscle that strains the eardrum. The large inferior section belongs to the auditory tube.

Tympanic canaliculus

It starts from the lower surface in the pyramidal part, in the depths of the rocky pit. Next, it is directed towards the lower cavity, perforating which, it passes along the medial wall, reaching the promontory groove. Then he goes to the top plane. There it opens into a cleft in the petrosal nerve canal.

Drum part

This is the smallest section that includes the temporal bone of the skull. It is presented in the form of a slightly curved ring-shaped plate. The tympanic part forms part of the posterior, inferior and anterior walls of the auditory canal (external meatus). Here you can see the border fissure, which, together with the stony fissure, delimits this area from the mandibular fossa. The outer edge is closed at the top by bone scales. It delimits the auditory (external) opening. There is a spine at its posterior upper outer edge. Below it is the supraductal fossa.

Damage

One of the most serious injuries is a fracture of the temporal bone. It can be either longitudinal or transverse. Both types of injury, unlike injuries to other bones, are characterized by the absence of movement of fragments. Due to this, the width of the gap is usually small. An exception is impression damage to the scales. In such cases, quite significant displacement of the fragments may be observed.

CT scan of the temporal bones

The study is used when there are suspected violations in the structure of an element. Computer diagnostics is a special method. With its help, the temporal bone is scanned layer by layer. This creates a series of images. The temporal bone is examined in cases of the presence of:

• Injuries on one or both sides.
• Otitis, especially of unknown nature.
• Balance and hearing disorders, signs of dysfunction of the formations next to which the temporal bone is located.
• Otosclerosis.
• Suspected tumor in structures located near or inside the temporal bone.
• Mastoiditis.
• Brain abscess in close proximity to the bone.
• Discharge from the ear.

Tomography of the temporal bones is also indicated in preparation for electrode implantation.

Contraindications for the study

Computed tomography allows specialists to obtain accurate information about the condition of the temporal bones and is considered one of the best diagnostic methods for various violations. However, in some cases it is necessary to refuse this procedure. This is due to the presence of contraindications in patients. Among them it should be noted:

• All stages of pregnancy. Impact ionizing radiation, generated by the tubes of the device, can provoke the development of fetal pathology.
• Overweight. Structurally, the tomograph is not intended for examining obese patients.
• Increased sensitivity to contrast agents. When a compound is introduced into the body, a severe allergic reaction may develop, including anaphylactic shock.
• Kidney failure. In this case, patients contrast agent is not excreted from the body, which can cause harm to health.

There are other limitations to diagnostics. They are quite rare.