Cavum nasi is a space that lies in the sagittal direction from the pyriform aperture to the choanae and is divided into two halves by a septum. The nasal cavity is limited by five walls: upper, lower, lateral and medial.
Top wall formed by the frontal bone, the inner surface of the nasal bones, the lamina cribrosa of the ethmoid bone and the body of the sphenoid bone.
Bottom wall formed by the bony palate, palatinum osseum, which includes the palatine process of the upper jaw and the horizontal plate of the palatine bone.
Lateral wall formed by the body of the maxilla, the nasal bone, the frontal process of the maxilla, the lacrimal bone, the labyrinth of the ethmoid bone, the inferior nasal concha, the perpendicular plate of the palatine bone and the medial plate of the pterygoid process.
Medial wall, or nasal septum, septum nasi osseum, divides the nasal cavity into two halves. It is formed by the perpendicular plate of the ethmoid bone and the ploughshare, above by the nasal spine of the frontal bone, spina nasalis, behind by the sphenoid crest, crista sphenoidalis, sphenoid bone, below by the nasal crest, crista nasales, the upper jaw and palatine bone. The nasal cavity opens in front with a pear-shaped aperture, apertura piriformis, and in the back with choanae. Choanae, choanae - paired internal openings of the nasal cavity that connect it with the nasal part of the pharynx.
On the lateral wall of the nasal cavity there are three nasal conchas: superior, middle and inferior, concha nasalis superior, media et inferior. The superior and middle turbinates belong to the labyrinth of the ethmoid bone, the inferior is an independent bone. The listed shells limit three nasal passages: upper, middle and lower, meatus nasalis superior, medius et inferior.
Superior nasal passage, meatus nasalis superior, lies between the superior and middle nasal conchae. The posterior cells of the ethmoid bone open into it. At the posterior end of the superior turbinate there is a sphenopalatine opening, foramen sphenopalatinum, leading into the fossa pterygopalatina, and above the superior turbinate there is a sphenoethmoidal recess, recessus spheno-ethmoidalis, in the area of ​​which the sinus of the sphenoid bone, sinus sphenoidalis, opens.
Middle nasal passage, meatus nasalis medius, located between the middle and inferior nasal concha. Within its boundaries, after removal of the middle shell, the semilunar foramen, hiatus semilunaris, opens. The posteroinferior part of the semilunar foramen expands, at the bottom of which there is an opening, hiatus maxillaris, leading into the maxillary sinus, sinus maxillaris. In the anterior-superior part of the nasal cavity, the semilunar foramen expands and forms a ethmoidal funnel, infundibulum ethmoidale, into which the frontal sinus, sinus frontalis, opens. In addition, the anterior and some middle ethmoidal cells open into the middle meatus and the semilunar foramen.
Lower nasal passage, meatus nasalis inferior, located between the bony palate and the inferior nasal concha. The nasolacrimal duct, canalis nasolacrimal, opens in it. In clinical (otolaryngological) practice, a puncture of the maxillary sinus is performed through the lower nasal passage for diagnostic and therapeutic purposes.
The slit-like space between the posterior portions of the turbinates and the bony nasal septum is called the common nasal meatus, meatus nasi communis. The section of the nasal cavity, located behind the nasal turbinates and the bony nasal septum, forms the nasopharyngeal passage, meatus nasopharyngeus, which opens into the posterior nasal openings - choanae.
Buttresses- these are bone thickenings in certain areas of the skull, interconnected by transverse crossbars, along which the force of pressure is transmitted to the cranial vault during chewing. Buttresses balance the amount of pressure that occurs during chewing, pushing and jumping. Between these thickenings are thin bone formations called weak spots. It is here that fractures most often occur during physical activity, which does not coincide with the physiological acts of chewing, swallowing and speech. In clinical practice, fractures are most often observed in the neck of the lower jaw, the angle and upper jaw, as well as the zygomatic bone and its arch. The presence of holes, crevices and weak spots in the bones of the skull determine the direction of these fractures, which is important to consider in oral surgery. In the upper jaw, the following buttresses are distinguished: frontonasal, collar-zygomatic, palatine and pterygopalatine; at the bottom - cellular and ascending.

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The nasal cavity (cavum nasi) is a canal passing in the sagittal direction through the facial skeleton.

It is located between the anterior cranial fossa, the oral cavity, and the paired maxillary and ethmoid bones.

The nasal cavity opens outwards with the nostrils (anterior nasal openings), and backwards with the choanae (posterior nasal openings).

Along its entire length, it is divided in the middle by the nasal septum (septum nasi), consisting of bone and cartilaginous parts (Fig. 32).

Rice. 32. Nasal septum: 1 - nasal bone; 2 - cartilaginous part of the nasal septum; 3 - alveolar process; 4 - perpendicular plate of the ethmoid bone; 5 - opener; 6 - palatine bone; 7 - frontal sinus; 8 - sphenoid sinus

The first is represented by the perpendicular plate of the ethmoid bone (lamina perpendicularis as ethmoidalis) and the vomer (vomer), the second by the quadrangular cartilage (cartilago guadrangularis septi nasi). In newborns, the perpendicular plate of the ethmoid bone is represented by a membranous formation and ossifies until the 6th year of life. In the places where it connects to the cartilage and vomer, there is a growth zone. The uneven growth of the nasal septum is due to the presence of tissues of different structures in it, which leads to the development of deformations that can interfere with nasal breathing. A perfectly straight nasal septum is very rare.

The upper wall of the nasal cavity is formed in front by the nasal and frontal bones, in the middle sections by the cribriform plate (lamina cribrosd) of the ethmoid bone, and behind by the anterior wall of the main sinus. The cribriform plate is thin and may have dehiscence, which predetermines the possibility of infection spreading into the cranial cavity. Fibers of the olfactory nerve (fila olfactoria) pass through its numerous small openings (25-30 on both sides of the cock's comb).

The lower wall of the nasal cavity is formed in front by the palatine processes of the upper jaw (processus palatimis maxillae), and in the back by the horizontal plate of the palatine bone (lamina horizontalis ossis palatini). In the anterior part of the bottom of the nasal cavity near the nasal septum there is an incisive canal (canalis incisivus), through which the nerve and artery of the same name pass, anastomosing in the canal with the great palatine artery.

The lateral wall of the nasal cavity is formed in front by the nasal bone and the frontal process of the upper jaw, to which the lacrimal bone is adjacent, then by the medial surface of the body of the upper jaw, the ethmoid bone, the vertical plate of the palatine and the medial plate of the pterygoid process of the main bone. On the lateral wall there are three nasal conchae (conchae nasales): lower, middle and upper (Fig. 33).

Rice. 33. Lateral wall of the nasal cavity: 1 - frontal sinus; 2 - superior nasal concha; 3 - sphenoid sinus; 4—upper nasal passage; 5 - middle turbinate; 6 - middle nasal passage; 7 - inferior nasal concha; 8 - lower nasal passage

The inferior nasal concha is an independent bone, and the other conchae are processes extending from the medial wall of the ethmoid labyrinth. Under each nasal concha there is a corresponding nasal passage - lower, middle and upper (meatus nasi inferior, medius, superior). The space between the turbinates and the septum is the common nasal passage (meatus nasi communis).

The anterior third of the lower nasal meatus contains the opening of the nasolacrimal duct. On the lateral wall of the middle nasal meatus there is a semilunar-shaped fissure (hiatus semilunaris), leading to a depression - the funnel (infundibulum). The edges of the fissure are bounded behind and above by the ethmoidal bladder (bulla ethmoidalis), in front and below by the uncinate process (processus uncinatus).

The outlet of the frontal sinus (ductus nasofrontalis) opens into the funnel in front and above, and near its posterior end there is the opening of the maxillary sinus (ostium maxillare). Sometimes this sinus has an additional opening (ostium accessorium), which also opens into the middle meatus. Here, in the space between the ethmoidal bladder and the place of attachment of the middle turbinate, the anterior and middle cells of the ethmoidal labyrinth open. The shortest upper nasal meatus opens the opening of the sphenoid sinus and the posterior cells of the ethmoid bone.

The entire nasal cavity is covered with mucous membrane, which through the corresponding openings passes into the mucous membrane of the paranasal sinuses, so inflammatory processes developing in the nasal cavity can spread to the sinuses.

The mucous membrane of the nasal cavity is divided into two sections: respiratory (regio respiratoria) and olfactory (regio olfactoria). The respiratory area occupies the space from the bottom of the nasal cavity to the middle of the middle turbinate. The mucous membrane in this area is covered with multirow cylindrical ciliated epithelium with a large number of goblet cells that secrete mucus. The vibration of the cilia of the ciliated epithelium is directed towards the choanae.

Under the epithelium there is a thin subepithelial membrane, and under it is the own tissue of the mucous membrane. Mainly in the middle section of the native tissue there is a large number of tubular-alveolar branched glands with serous or serous-mucosal secretion and excretory ducts that open on the surface of the mucous membrane. In some places, the mucous membrane of the respiratory zone is very thick: in the area of ​​​​the anterior and posterior ends of the lower and middle turbinates, on the nasal septum at the level of the anterior end of the middle turbinate, near the inner edge of the choanae. The vascular network here is represented by varicose venous plexuses (cavernous tissue), as a result of which the mucous membrane in this area can easily swell.

The olfactory zone is located in the upper parts of the nasal mucosa - from the lower edge of the middle turbinate to the vault of the nasal cavity, including the adjacent part of the nasal septum. The mucous membrane here is covered with a specific epithelium consisting of supporting, basal and olfactory neurosensory cells. The surface of the olfactory epithelium is covered with the secretion of simple and branched tubular (Bowman's) glands, which dissolve aromatic substances.

The supporting cells contain granular yellowish pigment, which gives the corresponding color to the mucous membrane of this area. Olfactory cells are shaped like a flask. They are the 1st neuron of the olfactory tract. The peripheral process of the olfactory cells (dendrite) ends in a club-shaped thickening.

The central processes of olfactory cells (axons) form olfactory filaments (fila olfactoria), which enter the anterior cranial fossa through the cribriform plate and end in the olfactory bulb (bulbus olfactorius), which contains the 2nd neuron. The axons of the 2nd neuron form the olfactory tract (tractus olfactorius). The third neuron is contained in the olfactory triangle (trigonum olfactorium), perforated substance (substantia perforate). From the 3rd neuron, impulses go to the olfactory cortical center of its own and the opposite side, located in the temporal lobe in the region of the seahorse gyrus (gyrus hippocampi).

Blood supply to the nasal cavity is provided by the terminal branch of the internal carotid artery (a. ophthalmica), which in the orbit is divided into ethmoidal arteries (a.a. ethmoidalis anterior etposterior), and a large branch from the external carotid artery system (a. sphenopalatina), which enters into the nose near the posterior edge of the middle turbinate through the opening of the same name and gives off branches to the lateral wall of the nasal cavity and the nasal septum.

A feature of the vascularization of the nasal septum is the formation of a dense vascular network in the mucous membrane of its anterior inferior section - the bleeding zone of the nasal septum (the so-called Kisselbach site), where there is a network of superficially located vessels, capillaries and precapillaries. Most nosebleeds originate from this area.

The veins of the nasal cavity are accompanied by their corresponding arteries. A feature of the venous outflow from the nasal cavity is the formation of plexuses connecting these veins with the veins of the skull, orbit, pharynx, and face, which makes it likely that the infection will spread through these routes with the development of complications. With the help of the orbital veins, with which the veins of the nasal cavity anastomose through the anterior and posterior ethmoidal veins, communication is made with the sinuses of the dura mater of the brain (cavernous, sagittal), and the venous plexus of the soft shell of the brain.

From the nasal cavity and nasal pharynx, blood also flows into the venous plexus of the pterygopalatine fossa, from where the infection can spread into the middle cranial fossa through the oval and rotund openings and the inferior orbital fissure.

The outflow of lymph from the anterior sections of the nasal cavity is carried out mainly into the submandibular nodes, from the middle and posterior sections - into the deep cervical ones. The lymphatic vessels of both halves of the nose anastomose with each other along the posterior free edge of the nasal septum and in front - through its cartilaginous part. Of no small importance is the connection between the lymphatic network of the olfactory membrane and the intershell spaces along the perineural tracts of the olfactory nerves, through which infection can spread (after surgery on the ethmoid labyrinth, nasal septum) with the development of intracranial complications (meningitis, etc.).

Specific innervation of the nose is carried out using the olfactory nerve (n. olfactorius). Sensitive innervation of the nasal cavity is carried out by the first (n. ophthalmicus) and second (n. maxillaris) branches of the trigeminal nerve.

The anterior and posterior ethmoidal nerves depart from the first branch, penetrating the nasal cavity together with the vessels of the same name and innervating the lateral sections and vaults of the nasal cavity. The pterygopalatine and inferior orbital nerves depart from the second branch of the trigeminal nerve.

The pterygopalatine nerve enters part of its fibers into the pterygopalatine ganglion, and most of its fibers pass further, bypassing the ganglion. Nasal branches depart from the pterygopalatine ganglion and enter the nasal cavity through the pterygopalatine opening. These branches are distributed in the posterosuperior part of the lateral wall of the nasal cavity, in the superior meatus, in the superior and middle turbinates, ethmoid cells and the main sinus. A number of branches innervate the inferior turbinate, maxillary sinus, and mucous membrane of the hard palate.

The inferior orbital nerve gives off the superior alveolar nerves to the mucous membrane of the floor of the nasal cavity and the maxillary sinus. The branches of the trigeminal nerve anastomose with each other, which explains the irradiation of pain from the nose and paranasal sinuses to the area of ​​the teeth, eyes, dura mater (headache), etc. The sympathetic and parasympathetic innervation of the nose and paranasal sinuses is represented by the nerve of the pterygoid canal, or vidian nerve (n. ccmalispterygoidei), which originates from the plexus on the internal carotid artery (superior cervical sympathetic ganglion) and from the geniculate ganglion of the facial nerve (parasympathetic portion). The collector of the sympathetic innervation of the nose is the superior cervical sympathetic ganglion, and the parasympathetic innervation is the pterygoid ganglion.

DI. Zabolotny, Yu.V. Mitin, S.B. Bezshapochny, Yu.V. Deeva

The anatomy of the nose and paranasal sinuses is of great clinical importance, since in close proximity to them there is not only the brain, but also many great vessels that contribute to the rapid spread of pathogenic processes.

It is important to understand exactly how the nasal structures communicate with each other and with the surrounding space in order to understand the mechanism of development of inflammatory and infectious processes and effectively prevent them.

The nose, as an anatomical formation, includes several structures:

• external nose;
• nasal cavity;
• paranasal sinuses.

External nose

This anatomical structure is an irregular pyramid with three sides. The external nose is very individual in appearance and has a wide variety of shapes and sizes in nature.

The dorsum delimits the nose from the upper side, it ends between the eyebrows. The top of the nasal pyramid is the tip. The lateral surfaces are called wings and are clearly separated from the rest of the face by nasolabial folds. Thanks to the wings and the nasal septum, such a clinical structure as the nasal passages or nostrils is formed.

The structure of the external nose

The outer nose includes three parts

Bone frame

Its formation occurs due to the participation of the frontal and two nasal bones. The nasal bones on both sides are limited by processes extending from the upper jaw. The lower part of the nasal bones is involved in the formation of the pyriform opening, which is necessary for attaching the external nose.

Cartilaginous part

Lateral cartilages are necessary for the formation of the lateral nasal walls. If you go from top to bottom, you will notice the junction of the lateral cartilages with the large cartilages. The variability of small cartilages is very high, since they are located next to the nasolabial fold and can vary from person to person in number and shape.

The nasal septum is formed by quadrangular cartilage. The clinical significance of cartilage is not only in hiding the inside of the nose, that is, organizing a cosmetic effect, but also in the fact that due to changes in the quadrangular cartilage, a diagnosis of deviated nasal septum may appear.

Soft tissues of the nose

A person does not experience a strong need for the functioning of the muscles surrounding the nose. Basically, muscles of this type perform facial functions, helping the process of identifying odors or expressing an emotional state.

The skin is closely adjacent to the tissues surrounding it, and also contains many different functional elements: glands that secrete sebum, sweat, hair follicles.

The hair that blocks the entrance to the nasal cavities performs a hygienic function, serving as additional air filters. Hair growth causes the formation of a nasal threshold.

After the nasal threshold there is a formation called the intermediate belt. It is tightly connected to the perichondral part of the nasal septum, and when deepened into the nasal cavity it transforms into the mucous membrane.

To correct a deviated nasal septum, an incision is made exactly in the place where the intermediate belt is tightly connected to the perichondrium.

Circulation

The facial and orbital arteries provide blood flow to the nose. The veins follow the course of the arterial vessels and are represented by the external and nasofrontal veins. The veins of the nasofrontal region merge in an anastomosis with the veins that provide blood flow to the cranial cavity. This happens due to the angular veins.

Because of this anastomosis, infection can easily penetrate from the nasal area into the cranial cavities.

The flow of lymph is ensured through the nasal lymphatic vessels, which flow into the facial vessels, and those, in turn, into the submandibular vessels.

The anterior ethmoidal and infraorbital nerves provide sensation to the nose, while the facial nerve controls muscle movement.

The nasal cavity is limited by three formations. This:

• anterior third of the cranial base;
• eye sockets;
• oral cavity.

The nostrils and nasal passages anteriorly limit the nasal cavity, and posteriorly it extends into the upper part of the pharynx. The transition places are called choanae. The nasal cavity is divided by the nasal septum into two approximately equal components. Most often, the nasal septum may deviate slightly to one side, but these changes are not significant.

Structure of the nasal cavity

Each of the two components has 4 walls.

Inner wall

It is created through the participation of the nasal septum and is divided into two sections. The ethmoid bone, or rather its plate, forms the posterosuperior section, and the vomer forms the posteroinferior section.

Outer wall

One of the complex formations. Consists of the nasal bone, the medial surface of the maxillary bone and its frontal process, the lacrimal bone adjacent posteriorly, and the ethmoid bone. The main space of the posterior part of this wall is formed by the participation of the palate bone and the main bone (mainly the internal plate belonging to the pterygoid process).

The bony part of the outer wall serves as the attachment point for the three nasal conchae. The bottom, fornix and shells participate in the formation of a space called the common nasal passage. Thanks to the nasal conchae, three nasal passages are also formed - upper, middle and lower.

The nasopharyngeal passage is the end of the nasal cavity.

Superior and middle turbinates

Nasal turbinates

They are formed due to the participation of the ethmoid bone. The outgrowths of this bone also form the vesicular concha.

The clinical significance of this shell is explained by the fact that its large size can interfere with the normal process of breathing through the nose. Naturally, breathing becomes difficult on the side where the concha is too large. Its infection must also be taken into account when inflammation develops in the cells of the ethmoid bone.

Lower sink

This is an independent bone that is attached to the crest of the maxillary bone and the palate bone.
The lower nasal passage has in its anterior third the mouth of a canal intended for the outflow of tear fluid.

The turbinates are covered with soft tissues that are very sensitive not only to the atmosphere, but also to inflammation.

The median passage of the nose has passages into most of the paranasal sinuses. The exception is the main sinus. There is also a semilunar fissure, the function of which is to provide communication between the middle meatus and the maxillary sinus.

Top wall

The perforated plate of the ethmoid bone provides the formation of the nasal arch. The holes in the plate give passage to the olfactory nerves into the cavity.

Bottom wall

Blood supply to the nose

The bottom is formed due to the participation of the processes of the maxillary bone and the horizontal process of the palate bone.

The nasal cavity is supplied with blood by the sphenopalatine artery. The same artery gives off several branches to supply blood to the wall located behind. The anterior ethmoidal artery supplies the lateral wall of the nose with blood. The veins of the nasal cavity merge with the facial and ophthalmic veins. The ophthalmic branch has branches going to the brain, which is important in the development of infections.

The deep and superficial network of lymphatic vessels ensure the outflow of lymph from the cavity. The vessels here communicate well with the spaces of the brain, which is important for accounting for infectious diseases and the spread of inflammation.

The mucosa is innervated by the second and third branches of the trigeminal nerve.

Paranasal sinuses

The clinical significance and functional properties of the paranasal sinuses are enormous. They work in close contact with the nasal cavity. If the sinuses are exposed to an infectious disease or inflammation, this leads to complications on important organs located in close proximity to them.

The sinuses are literally dotted with various openings and passages, the presence of which contributes to the rapid development of pathogenic factors and aggravation of the situation in diseases.

Paranasal sinuses

Each sinus can cause infection to spread into the cranial cavity, eye damage and other complications.

Maxillary sinus

It has a pair and is located deep in the bone of the upper jaw. The sizes vary greatly, but the average is 10-12 cm.

The wall inside the sinus is the lateral wall of the nasal cavity. The sinus has an entrance to the cavity, located in the last part of the semilunar fossa. This wall is endowed with a relatively small thickness, and therefore it is often pierced in order to clarify the diagnosis or carry out therapy.

The wall of the upper part of the sinus has the smallest thickness. The posterior sections of this wall may not have a bone base at all, making do with cartilage tissue and many crevices of bone tissue. The thickness of this wall is penetrated by the canal of the inferior orbital nerve. The infraorbital foramen opens this canal.

The canal does not always exist, but this does not play any role, since if it is absent, then the nerve passes through the sinus mucosa. The clinical significance of this structure is that the risk of developing complications inside the skull or inside the orbit increases if a pathogenic factor affects this sinus.

From below, the wall represents the sockets of the most posterior teeth. Most often, the roots of the tooth are separated from the sinus by only a small layer of soft tissue, which is a common cause of inflammation if the condition of the teeth is not monitored.

Frontal sinus

It has a pair, is located deep in the forehead bone, in the center between the scales and the plates of part of the eye sockets. The sinuses can be delimited using a thin bone plate, and not always equally. It is possible that the plate may shift to one side. There may be holes in the plate that provide communication between the two sinuses.

The size of these sinuses is variable - they may be absent altogether, or they may have a huge distribution throughout the frontal scales and the base of the skull.

The wall in front is where the nerve of the eye exits. The exit is provided by the presence of a notch above the orbit. The notch cuts the entire upper part of the orbit of the eye. In this place, it is customary to perform a sinus opening and trephine puncture.

Frontal sinuses

The wall below is the smallest in thickness, which is why infection can quickly spread from the sinus to the eye orbit.

The brain wall provides separation of the brain itself, namely the lobes of the forehead from the sinuses. It also represents a point of entry for infection.

The canal passing in the frontonasal region provides interaction between the frontal sinus and the nasal cavity. The anterior cells of the ethmoidal labyrinth, which have close contact with this sinus, often intercept inflammation or infection through it. Also, through this connection, tumor processes spread in both directions.

Lattice Maze

It is cells separated by thin partitions. The average number is 6-8, but it can be more or less. The cells are located in the ethmoid bone, which is symmetrical and unpaired.

The clinical significance of the ethmoidal labyrinth is explained by its close location to important organs. Also, the labyrinth may be adjacent to the deep parts that form the facial skeleton. The cells located in the back of the labyrinth are in close contact with the canal in which the nerve of the visual analyzer runs. Clinical diversity appears to be an option when the cells serve as the direct path of the canal.

Diseases affecting the labyrinth are accompanied by a variety of pains, varying in location and intensity. This is explained by the peculiarities of the innervation of the labyrinth, which is provided by a branch of the orbital nerve, called the nasociliary. The cribriform plate also provides passage for the nerves necessary for the functioning of the sense of smell. That is why, if there is swelling or inflammation in this area, olfactory disturbances are possible.

Lattice Maze

Main sinus

The sphenoid bone, with its body, provides the location of this sinus directly behind the ethmoid labyrinth. The choanae and the nasopharynx will be located on top.

In this sinus there is a septum that has a sagittal (vertical, dividing the object into right and left parts) location. It most often divides the sinus into two unequal lobes and does not allow them to communicate with each other.

The wall in front consists of a pair of formations: the ethmoidal and nasal. The first occurs in the region of the labyrinth cells located posteriorly. The wall is characterized by a very small thickness and, thanks to its smooth transition, almost merges with the wall below. In both parts of the sinus there are small round passages that allow the sphenoid sinus to communicate with the nasopharynx.

The wall at the back has a frontal position. The larger the size of the sinus, the thinner this septum, which increases the likelihood of injury during surgical interventions in this area.

The wall on top is the bottom region of the sella turcica, which is the location of the pituitary gland and the chiasm of the nerve that provides vision. Often, if the inflammatory process affects the main sinus, it spreads to the optic chiasm.

The wall below is the vault of the nasopharynx.

The walls on the sides of the sinus are close to the bundles of nerves and vessels that are located on the side of the sella turcica.

In general, infection of the main sinus can be called one of the most dangerous. The sinus is closely adjacent to many brain structures, for example, the pituitary gland, subarachnoid and arachnoid membranes, which simplifies the spread of the process to the brain and can be fatal.

Pterygopalatine fossa

Located behind the tubercle of the mandibular bone. A large number of nerve fibers pass through it, so the significance of this fossa in a clinical sense is difficult to exaggerate. Inflammation of the nerves passing through this fossa is associated with a large number of symptoms in neurology.

It turns out that the nose and the formations that are closely connected with it are a very complex anatomical structure. Treatment of diseases affecting the nasal systems requires maximum care and caution from the doctor due to the close location of the brain. The main task of the patient is not to let the disease progress, bringing it to a dangerous limit, and to promptly seek help from a doctor.

Translation into Russian of the article "Illustrated essay: anatomical variations of the paranasal sinuses on computed tomography. How does this help surgeons during endoscopic surgery?"

The lateral wall of the nasal cavity contains protrusions, which are called the superior, middle and inferior turbinates; they divide the nasal cavity into the upper, middle and lower nasal passages. The superior meatus drains into the posterior ethmoidal cells, and the sphenoid sinuses drain into it through the sphenoethmoidal recess. The middle meatus drains the frontal sinuses through the frontal recesses and the maxillary sinuses through the sinus openings, as well as the anterior ethmoidal cells through their openings. The nasolacrimal duct drains into the inferior nasal meatus.

Ostiomeatal complex

Ostiomeatal complex(hereinafter referred to as the OMC) includes the opening of the maxillary sinus, the ethmoidal infundibulum, the anterior ethmoidal cells and the frontal recess (Fig. 1A). These structures are called anterior sinuses. OMC is a key structure in the pathogenesis of chronic sinusitis. Ethmoid cells are key in the drainage of the anterior sinuses. They are susceptible to injury during surgery due to their close relationship with the orbit and the anterior skull base.

Nasal tubercle cell

Nasal tubercle cell- the most anterior ethmoidal cell, which projects anteriorly into the lacrimal bone. It is located anteriorly, inferior to the frontal recess and borders the opening of the frontal sinus (Fig. 1B). A good examination of the frontal recess is possible when the nasal tubercle cell is opened. Its size can directly affect the patency of the frontal recess and the anterior sections of the middle nasal meatus.

Forehead pocket

Forehead pocket is a narrow air-containing canal that communicates with the frontal sinus. The frontal pocket is a common place for various kinds of inflammatory processes. The walls of the canal are formed by the cells of the nasal tubercle in front, the paper plate laterally, and the middle turbinate medially (Fig. 1B). The pocket opens into the middle meatus in 62%, and into the ethmoidal funnel in 38%. On coronal scans, the pocket is identified above the nasal tubercle cell.

Lattice funnel

Lattice funnel bounded anteriorly by the uncinate process, posteriorly by the anterior wall of the ethmoidal bulla, and laterally by the lamina paper (Fig. 1A). It opens into the middle meatus medially through the semilunar fissure. On coronal scans, the bulla is located above the ethmoidal infundibulum. The orifice of the maxillary sinus opens at the bottom of the funnel.

The fossa ethmoidalis is a critical element of the anatomy for two reasons. Firstly, it is most sensitive to iatrogenic damage, and, as a consequence, the formation of cerebrospinal fluid fistulas. Second, the anterior ethmoidal artery is at risk of injury, which can lead to uncontrolled orbital bleeding. In endoscopic surgery, intracranial injury may occur on the side where the fossa ethmoidalis is inferior (Figure 2).

The depth of the olfactory pit is determined by the height of the lateral lamella of the cribriform plate, which is part of the ethmoid bone. In 1962, Keros classified the depth of the olfactory pit into three types: Keros 1, when the pit is less than 3 mm deep (Fig. 3), Keros 2, when the pit is 4-7 mm deep (Fig. 4), Keros 3, when the pit is 8 -16 mm deep (Fig. 5). Keros type 3 is the most dangerous for iatrogenic damage.

Onodi cells

Onodi cells- These are the posterior ethmoid cells that project into the sphenoid sinuses (Fig. 6) and can even reach the optic nerve. When Onodi cells adhere to or surround the optic nerve, the nerve is at risk when these cells are surgically removed. This results in an incomplete sphenoidectomy.

According to radiopedia.org, Onodi cells are sphenoethmoidal air cells, also defined as the most posterior ethmoidal cells that project posteriorly, superiorly, and lateral to the sphenoid sinuses, located in close proximity to the optic nerve and internal carotid artery. They often extend to the anterior oblique processes; It is important that the airiness of the anterior inclined process may simply be due to this variant of the anatomy of the sphenoid sinus and does not necessarily indicate the presence of an Onodi cell.

Intersinus septum of sphenoid sinuses is attached to the wall containing the projection of the internal carotid artery, so damage to the artery may be due to the removal of this sinus septum (Fig. 7). The artery can prolapse into the sinus in 65-72% of cases. There may be dehiscence or absence of the bone wall between the artery and sinus in 4-8% of cases.

Sinus agenesis may also be observed (Fig. 8).

The pterygoid canal (Fig. 9) or the groove of the maxillary nerve (Fig. 10) can prolapse into the sphenoid sinus, which contributes to the appearance of trigeminal neuralgia due to sinusitis.

Pneumatization of the anterior oblique processes (Fig. 9) is associated with type 2 and 3 optic nerve positions and predisposes to nerve injury during endoscopic surgery.

Variants of the relationship between the optic nerve and the posterior paranasal sinuses

The optic nerve, carotid arteries and Vidian canal are formed before the appearance of the paranasal sinuses and contribute to congenital variations in the structure of the walls of the sphenoid sinuses. Delano, et al. divide the relationship between the optic nerve and the posterior paranasal sinuses into 4 groups:

• Type 1: The most common type, occurs in 76% of cases. In this case, the optic nerves are adjacent to the sphenoid sinus without forming depressions in its walls or contacting the posterior ethmoidal cells (Fig. 11).
• Type 2: The optic nerves are adjacent to the sphenoid sinus, with deepening of the sinus walls without contact with the posterior ethmoidal cells (Fig. 12).
• Type 3: Nerves pass through the sphenoid sinuses, with at least half the circumference of the nerve surrounded by air (Fig. 13)
• Type 4: The nerves are adjacent to the sphenoid sinus and posterior ethmoid cells (Fig. 14 and 15).

Delano, et al. found that in 85% of cases, pneumatized anterior oblique processes are associated with type 2 or 3 optic nerve position, while in 77% dehiscence of the nerve canal wall is detected (Fig. 16), which is associated with an increased risk of optic nerve injury when endoscopic surgery.

The sphenoid sinus septa may attach to the wall of the optic nerve canal, predisposing the nerve to injury during surgery (Figure 17).

Variants of the middle turbinate

The normal curvature of the middle turbinate is directed medially. When the bend is directed laterally, this situation is called a paradoxical bend of the middle turbinate (Fig. 18). Most authors agree that a paradoxically curved middle turbinate may be a contributing factor to sinusitis.

Сoncha bullosa is an aerated concha, more often the middle nasal concha. When pneumatization involves the middle turbinate bulb, the condition is called concha bullosa (Fig. 19). If pneumatization involves the attachment of the middle turbinate to the base of the skull, the condition is called lamellar concha (Fig. 20).

Variants of the uncinate process

Coronal scans show that the posterior section of the uncinate process is attached to the inferior turbinate inferiorly, leaving the posterior edge of the process free. The anterior section of the uncinate process is attached to the base of the skull from above, to the middle turbinate medially, to the paper plate or cell of the nasal tubercle laterally.

The uncinate process may be medialized, lateralized, pneumatized, or curved. Medialization occurs as a large ethmoidal bulla is present. Lateralization occurs when there is obstruction of the ethmoidal infundibulum. Pneumatization of the uncinate process (bulla process) (Fig. 21) occurs in 4% of the population and rarely leads to obstruction of the ethmoid funnel.

Haller cells

Haller cells, also known as infraorbial ethmoidal cells (Fig. 22), are located along the medial wall of the maxillary sinus and the lowest portion of the lamina paper, below the ethmoidal bulla, lateral to the uncinate process. These cells can narrow the ethmoidal infundibulum and the mouth of the maxillary sinus and contribute to the appearance of recurrent maxillary sinusitis.

According to radiopedia.org, Haller cells (infraorbital ethmoidal cells or maxilloethmoidal cells) are extramural ethmoidal cells that project toward the inferomedial rim of the orbit and are present in approximately 20% of patients (2-45%). Their significance increases when they are affected by the inflammatory process; inflammation from them can spread to the orbit; the cells can narrow the ethmoidal infundibulum or the mouth of the maxillary sinus if the cells are large, and contribute to sinus obstruction when it is inflamed; Resection of Haller's cell may damage the orbit.

Ethmoid bulla

The largest and most prominent anterior ethmoidal cell is called cribriform bulla. It is located lateral to the paper plate. The bulla may merge with the base of the skull superiorly and the basal plate of the middle turbinate posteriorly. On coronal scans it is located superior to the ethmoidal infundibulum (Fig. 23). The decrease in the degree of pneumatization of the bulla varies, and the absence of pneumatization of the bulla is called torus ethmoidalis. The giant bulla may fill the middle meatus and be located between the uncinate process and the middle turbinate.

Air cells of the posterior superior portion of the nasal septum

Air cells can be located in the posterior-superior portion of the nasal septum and connect to the sphenoid sinus (Fig. 24). Inflammatory processes that occur in the paranasal sinuses can also affect these cells. Such cells may resemble a cephalocele.

Cockscomb

Cockscomb may be pneumatized, and the ridge may communicate with the frontal recess, causing obstruction of the frontal sinus opening and leading to chronic sinusitis or mucocele formation. It is important to detect and differentiate this ethmoid cell variant preoperatively to avoid invasion of the anterior cranial fossa.

In the nasal cavity there are three nasal conchae: the upper and middle ethmoid bones and an independent bone - the inferior nasal concha. The nasal passages are located between the conchas.

Superior meatus: between the superior and middle turbinates.

Middle meatus: between the middle and inferior turbinates.

Inferior meatus: between the inferior turbinate and the floor of the nasal cavity.

Common nasal meatus: between the turbinates and the medial wall of the nasal cavity.

Messages.

To make it easier to remember the number of messages in the nasal passages, you need to remember the following formula: 4, 3, 2, i.e. the upper nasal passage has 4 messages, the middle one - 3, the lower one - 2.

Upper nasal passage:

Through the cribriform plate of the ethmoid bone with the anterior cranial fossa (the olfactory nerves go - the first pair of cranial nerves, as well as the nasal veins);

Through the aperture of the sphenoid sinus with the sphenoid sinus of the sphenoid bone;

Through the apertures of the ethmoid sinuses with the posterior cells of the ethmoid bone;

Through the pterygopalatine foramen with the pterygopalatine fossa (the posterior septal and lateral nasal arteries go from the 3rd section of the maxillary artery, postganglionic fibers from the pterygopalatine node to innervate the glands of the nasal mucosa).

Middle nasal passage:

With the anterior and middle cells of the ethmoid bone;

Through the semilunar cleft with the maxillary (maxillary) sinus;

Through a funnel-shaped depression with the frontal sinus.

Lower nasal passage:

Through the nasolacrimal duct with the orbit;

Through the incisive canal with the oral cavity (the nasopalatine nerves pass from the maxillary nerve).

The role of the cranial sinuses:

2. Lightening of the skull bones.

3. Protection of the skull bones from shocks during movement.

4. Warming the air.

5. Air humidification.

6. Air disinfection.

V. Hard palate.

Forms the upper wall of the oral cavity and the lower wall of the nasal cavity. It is formed by:

1. Palatine processes of the upper jaws and horizontal plates of the palatine bones. In front is the incisive opening, which leads into the incisive canal (communication of the lower nasal passage with the oral cavity).

2. Behind the hard palate (between the palatine processes of the upper jaws and the horizontal plates of the palatine bones) there are two openings: the large and small palatine foramina, which lead into the canals of the same name (communication of the oral cavity with the pterygopalatine fossa). The large and small palatine arteries pass through them - branches of the 3rd section of the maxillary artery, the veins of the same name lead to the pterygopalatine venous plexus. Postganglionic fibers from the pterygopalatine ganglion pass through these canals to innervate the oral glands.