What passes through the foramen ovale of the skull. The base of the skull and its openings in the diagrams. Facial part of the skull

The middle cranial fossa is located between the small wings of the sphenoid bone, the upper edges of the pyramids (margo petrosus superior) and the back of the sella turcica. It is formed by the sella turcica, the large wings of the sphenoid bone and the anterior surface of the pyramid of the temporal bone. The temporal lobes of the brain are located in the lateral sections of the fossa, and the pituitary gland is located in the sella turcica. The sella turcica is surrounded on both sides by a system of venous cavities that make up the cavernous sinus. These venous cavities are located between the bone of the base of the skull and the dura mater, which hangs over the sella turcica and forms the sella diaphragm (diaphragma sellae) with an opening for the funnel connecting the pituitary gland to the brain. The sinuses of the right and left sides communicate with each other using the anterior and posterior intercavernous sinuses (sinus intercavernosus anterior et posterior). The ophthalmic veins (v. ophthalmica) of the corresponding side flow into the sinuses. Blood from the sinuses flows through the sinus petrosus superior into the sigmoid sinus. The cavernous sinuses anastomose with the veins of the face through the vessels that follow the anterior laceration and foramen ovale.

The topography of the cavernous sinuses is complex, since the internal carotid arteries and abducens nerves pass through them. In the outer wall of the sinuses between the layers of the dura mater are the oculomotor, trochlear and orbital nerves (nn. oculomotorius, trochlearis, ophthalmicus). Anterior to the sella turcica and the pituitary gland is the optic chiasm (hiasma optici). Pathological enlargement of the pituitary gland leads to compression of the visual pathways and visual impairment.

The middle cranial fossa has a number of openings through which blood vessels and nerves pass. The superior orbital fissure (fissura orbitalis superior) is located between the small and large wings of the sphenoid bone. It leads into the cavity of the orbit. The oculomotor, trochlear and abducens nerves, branches of the orbital nerve (frontal, lacrimal and nasociliary) and the ophthalmic vein pass through the gap. Posterior and outward from the superior orbital fissure there is a round opening (foramen rotundum), which passes the second branch of the trigeminal nerve (n. maxillaris) into the pterygopalatine fossa. Next is the oval foramen (foramen ovale), through which the third branch of the trigeminal nerve (n. mandibularis) passes. In the spinous foramen (foramen spinosum) there are the middle artery of the meninges (a. meningea media) and the meningeal branch of the mandibular nerve (n. spinosus) passing into the cranial cavity. The torn hole (foramen lacerum) is located between the large wing of the sphenoid bone and the pyramid of the temporal bone. Through the fibrous membrane covering the opening pass the petrosal nerves (nn. petrosus major et minor), the tensor tympani muscle, the nerve innervating it (m. et n. tensor tympani) and small veins connecting the inferior petrosal sinus with
veins of the outer surface of the base of the skull. The internal carotid foramen (foramen caroticum internum) is located next to the foramen lacerum. The internal carotid artery, surrounded by the nerve plexus of the same name, passes through it into the cranial cavity.

Current page: 4 (book has 25 pages total) [available reading passage: 6 pages]

Font:

100% +

Table 2

Openings of the external base of the skull and their contents

The anterior cranial fossa communicates with the orbit through the optic canal, which contains the optic nerve and ophthalmic artery. In some cases a. ophthalmica passes in a separate bone canal. A crescent-shaped fold of the dura mater is attached to the optic canal (bone), forming the membranous part canalis opticus, the length of which is about 3 mm. The openings of the optic canals are connected by a transversely located precross fissure, sulcus prechiasmaticus. In addition, the anterior cranial fossa communicates with the orbit through the anterior ethmoidal foramen, foramen ethmoidae anterius. Information about the contents of messages in the anterior cranial fossa is given in Table. 3. It should be noted that the ophthalmic artery, when entering the canal, is located below and medial to the optic nerve, and when the canal exits into the orbit, it is below and lateral to the nerve.

Table 3

Foramina of the anterior cranial fossa and their contents

On the lateral surface of the body of the sphenoid bone there is a well-defined carotid groove, sulcus caroticus, around which the dura mater forms the cavernous sinus. Near the top of the pyramid of the temporal bone, a torn hole is visible, covered with cartilage. Between the greater and lesser wings of the sphenoid bone, as well as its body, there is the superior orbital fissure, fissura orbitalis superior, through which the following nerves pass into the orbital cavity: oculomotor, trochlear, ophthalmic (the first branch of the trigeminal nerve) and abducens. Behind and just below the superior orbital fissure is a round foramen, foramen rotundum, through which the maxillary nerve passes (the second branch of the trigeminal nerve).

The foramen ovale, located next to the previous one, contains the mandibular nerve (the third branch of the trigeminal nerve). The foramen spinosum at the posterior edge of the greater wing of the sphenoid bone serves to pass into the skull the middle meningeal artery. In some cases, there may be an asymmetrical venous opening within the middle cranial fossa, foramen venosum, which is located posterior to the foramen rotundum and medial to the foramen spinosum. It contains an emissary vein connecting the cavernous sinus with the pterygoid venous plexus.

On the anterior surface of the pyramid of the temporal bone at the very apex there is a trigeminal depression, behind and lateral to which are located the clefts of the canals of the greater and lesser petrosal nerves, as well as their grooves, the arcuate eminence and the roof of the tympanic cavity. The arcuate eminence corresponds to the anterior semicircular canal of the labyrinth. It is a landmark for the extradural approach to the internal auditory foramen from the middle cranial fossa. In this case, the distance from the trepanation site above the root of the zygomatic process of the temporal bone to the arcuate eminence is 18–28 mm.

Information about the foramina of the middle cranial fossa and their contents is presented in Table. 4.

Table 4

Foramina of the middle cranial fossa and their contents

Note: contents of the lacerated, oval and spinous foramen - see table. 2.

Posterior cranial fossa, fossa cranii posterior, has greater depth compared to the middle and especially the anterior cranial fossae. Its basis is the occipital bone. In addition, the posterior cranial fossa includes the posterior surfaces of the pyramids and the mastoid parts of the temporal bones, the posterior part of the body of the sphenoid bone, and the mastoid angle of the parietal bone.

In the center of the fossa there is a large hole, in front of which there is a slope, clivus, formed by the fusion of the occipital and sphenoid bones. On the clivus lie the medulla oblongata and the pons, the basilar artery and its branches, as well as the basilar venous plexus. From the posterior edge of the large foramen to the cruciform eminence, eminentia cruciformis, the internal occipital crest rises. The groove of the transverse sinus extends to the right and left of the cruciate eminence, sulcus sinus transversi, continues into the groove of the sigmoid sinus, sulcus sinus sigmoidei, which is located on the inner surface of the mastoid angle of the parietal bone and the mastoid part of the temporal bone. The groove of the sigmoid sinus reaches the jugular notch on the lateral part of the occipital bone and ends in the region of the jugular foramen. From the side of the posterior cranial fossa in foramen jugulare three parts can be distinguished: stony (anteromedial) - the groove of the inferior petrosal sinus is suitable, sigmoid (posterolateral) - the groove of the sigmoid sinus is suitable, and neural (intrajugular), where the IX - XI pairs of cranial nerves pass. The petrous and neural parts are separated by processus intrajugularis occipital and temporal bones.

Medial to the jugular foramen is the opening of the hypoglossal nerve canal, canalis nervi hypoglossi, through which the nerve of the same name exits. On each side, on the posterior surface of the pyramids, the internal auditory foramen opens into the posterior cranial fossa, porus acusticus internus, leading to the internal auditory canal, in the depths of which the facial nerve canal originates. The vestibulocochlear nerve exits from the internal auditory foramen into the posterior cranial fossa and enters the facial nerve. In depth, the internal auditory canal is divided by two ridges (vertical and horizontal) into four openings. The facial nerve enters through the anterosuperior foramen. They exit from the auditory portion (anteroinferior foramen), superior and inferior vestibular portions (posterior superior and inferior foramina) of the vestibulocochlear nerve.

Above porus acusticus internus there is a subarc fossa, fossa subarcuata, to which the process of the dura mater is fixed. Posterior from porus acusticus internus located at a distance of 10 mm apertura aqueductus vestibuli, through which one exits the labyrinth ductus endolymphaticus. Information about the messages of the posterior cranial fossa and their contents are presented in Table. 5.

Table 5

Foramina of the posterior cranial fossa and their contents

Note: contents of the large, jugular and mastoid foramina, condylar canal and hypoglossal nerve canal - see table. 2.

Temporal fossa, fossa temporalis, located on the lateral surface of the skull. This surface of the skull is within fossa temporalis is called the temporal plane, planum temporale. The temporal fossa has medial, anterior and lateral walls. The medial wall is formed by the parietal, frontal bones, squama of the temporal bone and the greater wing of the sphenoid bone. The anterior wall is represented by the temporal surface of the zygomatic bone. The lateral wall is formed by the zygomatic arch.

Inferiorly, the temporal fossa passes into the infratemporal fossa. The border between them is the infratemporal crest, crista infratemporalis. In the temporal fossa are located:

– temporalis muscle, m. temporalis;

– superficial temporal artery, a. temporalis superficialis, and some of its branches ( rr. auriculares anteriores, a. zygomaticoorbitalis, a. temporalis media);

– deep temporal artery, a. temporalis profunda(branch a. maxillaris);

– superficial temporal vein , v. temporalis superficialis(inflow v. retromandibularis);

– superficial middle and deep temporal veins, vv. temporales superficiales mediae et profundae(tributaries v. retromandibularis);

– auriculotemporal nerve, n. auriculotemporalis;

– deep temporal nerves, nn. temporales profundi(branches n. mandibularis from n. trigeminus);

– branches of the parotid plexus of the facial nerve, plexus parotideus nervi facialis.

Standard craniometric points

In neurosurgical practice, to perform access to certain formations of the cranial cavity, it is necessary to rely on standard points. These points are easily identified on the outer surface of the skull. The system adopted in craniometry for designating the most important points on the skull makes it possible to sharply reduce the description of the dimensions based on them and achieve their unification. We provide a description of the most important craniometric points from a practical point of view (Fig. 12).

Rice. 12. Standard craniometric points:

1 – nasion, nasion; 2 – glabella, glabella; 3 – sphenion, sphenion; 4 – stephanion, stephanion; 5 – bregma, bregma; 6 – lambda, lambda; 7 – asterion, asterion; 8 – inion, inion; 9 – auricular point, auriculare; 10 – porion, porion; 11 – mastoid point, mastoidale

Asterion, asterion, is the junction point of the parietal, temporal and occipital bones. It is located at the intersection of the lambdoid, occipital-mastoid and parieto-mastoid sutures. The point is located above the transition of the transverse sinus to the sigmoid sinus. This point is the “key” point when performing retrosigmoid access.

auricular point, auriculare, is located on the root of the zygomatic process of the temporal bone at its intersection with the perpendicular drawn from the middle of the external auditory canal.

Bazion, basion, is the lowest point of the anterior edge of the large hole in the median plane.

Bregma, bregma, is the junction point of the frontal bone and both parietal bones. Located at the intersection of the coronal and sagittal sutures. If they make a sharp bend in this place or there is a suture bone, the point is determined at the intersection of lines that continue the general direction of the seams.

Glabella, glabella, is the most anterior point of the frontal bone in the median plane.

Zigion, zygion, – the most protruding point in the lateral direction on the zygomatic arch. Almost always located on the zygomatic process of the temporal bone.

Inion, inion, is located at the intersection of the median plane with the superior nuchal line, slightly above the most prominent point of the external occipital protrusion.

Lambda, lambda, is the point of connection between the occipital bone and both parietal bones. Lies at the intersection of the sagittal and lambdoid sutures.

Mastoid point, mastoidale, lies at the top of the mastoid process.

Nazion, nasion, is located at the intersection of the median plane with the nasofrontal suture.

Opistion, opistion, lies at the intersection of the median plane with the posterior edge of the large foramen.

Porion, porion, is located on the upper edge of the external auditory canal. Stefanion, stephanion, – the point of intersection of the superior temporal line with the coronal suture.

supraorbital point, supraorbitale, located at the intersection of the median plane with the line connecting the upper edges of the orbits.

Sphenion, sphenion, – the point of intersection of the sphenoparietal, sphenoid-frontal and coronal sutures.

Sphenobazion, sphenobasion, – the point of intersection of the median plane with the line of fusion of the occipital and sphenoid bones.

Eurion, euryon, is the point farthest from the median plane on the lateral surface of the skull. It can be located on both the parietal and temporal bones.

In addition to standard craniometric points, neurosurgeons especially highlight the “key point”, located 1 cm superior to the frontozygomatic suture and 0.5 cm posterior to the temporal line - one of the main landmarks when performing pterional access.

Also in clinical terminology such a concept as pterion. This area is located at the junction of the sphenoid, frontal, temporal and parietal bones.

2.3. Descriptive anatomy of the brain

Brain, encephalon, is the highest department of the central nervous system. It contains the brain stem, truncus encephali, cerebellum, cerebellum, and a big brain, cerebrum.

Classification of brain regions

The brain stem (Fig. 13, 14) is a phylogenetically ancient part in which structures related to the segmental apparatus of the brain and the subcortical centers of hearing, vision, smell and tactile sensitivity are located. The brain stem consists of the medulla oblongata, pons, and midbrain. 10 pairs of cranial nerves are anatomically and functionally connected to them - from III to XII. The first pair of cranial nerves - the olfactory nerves, is associated with the telencephalon, the second pair of cranial nerves - the optic nerve - with the intermediate brain.

The cerebellum is the integration center of the rhombencephalon. It ensures coordination of movements, regulation of muscle tone, balance.

The diencephalon, which developed from the posterior part of the forebrain, is functionally and morphologically connected with the organ of vision. Communication centers of all types of sensitivity and an integration center of vegetative functions are formed in it. The telencephalon, also developed from the forebrain, constitutes the new brain. This is a phylogenetically new formation, in which the highest integration centers are located. They carry out a conscious analysis of incoming information and voluntary movements in response.

Medulla, medulla oblongata (bulbus, myelencephalon), is a direct continuation of the spinal cord. It has the shape of a truncated cone, with the base facing upward. Its average length in men is 29 mm, in women it is slightly less - 27 mm. The width of the medulla oblongata at the junction with the pons is 17 - 18 mm, the thickness at the border with the spinal cord is 10 mm, and at the border with the pons - 14 mm. The average weight is about 6 g. With its ventral surface, the medulla oblongata is adjacent to the lower part of the clivus of the occipital bone and to the tooth of the II cervical vertebra. To understand the structure of the medulla oblongata, it is necessary to remember that in terms of development in ontogenesis, it is a segment of the neural tube. However, during the process of organogenesis, the lateral walls of the original neural tube become much thicker, and the dorsal wall becomes thinner and remains only in the form of a thin plate. It is an ependymal epithelium, to which the choroid of the fourth ventricle is adjacent externally.

The medulla oblongata has ventral, dorsal And side surfaces.

On the ventral surface of the medulla oblongata there is an anterior median fissure, which is a direct continuation of the same fissure of the spinal cord.

On both sides of the slot there are two longitudinal rollers. These are the pyramids pyramides, formed by nerve fibers of the descending direction. At the border of the medulla oblongata with the spinal cord, most of the fibers of each pyramid pass to the opposite side, resulting in the formation of a decussation of the pyramids, decussatio pyramidum. The lower border of the medulla oblongata is determined by the decussation of the pyramids. According to our data, regardless of the shape of the skull, in 90% of cases this border is projected onto the anterior arch of the first cervical vertebra. Lateral to the pyramids is the anterior lateral groove, which is a continuation of the spinal cord groove of the same name. This groove is clearly visible in the upper part of the organ, where the roots of the XII pair - the hypoglossal nerve - emerge from it. In the lower part, the groove is interrupted by transversely running anterior outer arcuate fibers, fibrae arcuatae externae anteriores.

Rice. 13. Brain stem (front view):

1 – fissura longitudinalis cerebri; 2 – gyrus subcallosus; 3 – chiasma opticum; 4 – infundibulum;5 – tuber cinereum; 6 – corpus mamilare; 7 – fossa interpeduncularis; 8 – tractus opticus; 9 – n. trochlearis; 10 – ganglion trigeminale; 11 – radix motoria n. trigemini; 12 – radix sensoria n. trigemini; 13– n. facialis; 14 – n. vestibulocochlearis; 15 – n. glossopharyngeus; 16 – n. vagus; 17 – n. accessorius;18 – n. hypoglossus; 19 – radix anterior n. cervicalis;20 – fissura mediana anterior; 21 – funiculus lateralis;22 – medulla spinalis; 23 – sulcus anterolateralis; 24 – funiculus anterior; 25 – decussatio pyramidum; 26 – fibrae arcuatae externae; 27 – olive; 28 – pyramis medullae oblongatae; 29 – pedunculus cerebellaris inferior; 30 – n. abducens; 31 – pedunculus cerebellaris medius; 32 – sulcus basilaris; 33 – n. oculomotorius;34 – sulcus n. oculomotorii; 35 – substantia perforata posterior; 36 – pedunculus cerebri; 37 – tractus opticus;38 – uncus; 39 – substantia perforata anterior; 40 – tractus olfactorius; 41 – gyrus rectus

Rice. 14. Brain stem (posterior view, cerebellum removed):

1 – glandula pinealis; 2 – colliculus superior; 3 – colliculus inferior; 4 – n. trochlearis; 5 – pedunculus cerebellaris superior; 6 – colliculus facialis; 7 – pedunculus cerebellaris inferior; 8 – striae medullares ventriculi quarti; 9 – trigonum n. hypoglossi; 10 – sulcus medianus; 11 – tuberculum gracile; 12 – tuberculum cuneatum; 13 – fasciculus cuneatus; 14 – fasciculus gracilis; 15 – sulcus medianus posterior; 16 – trigonum n. vagi; 17 – area vestibulocochlearis; 18 – pedunculus cerebellaris medius; 19 – trigonum lemnisci; 20 – thalamus

From the upper part of the anterior lateral sulcus protrudes an oval-shaped elevation called the olive. Olive, Oliva, has a length of about 16 mm and a width of 6 mm. Its upper end is located near the bridge. Lateral to the olive is the posterior lateral sulcus of the medulla oblongata, which does not correspond to the posterior lateral sulcus of the spinal cord. From this groove emerge the cranial roots of the XI pair - the accessory nerve, the roots of the X pair - the vagus nerve and the IX pair - the glossopharyngeal nerve.

The dorsal surface of the medulla oblongata forms the lower part of the floor of the fourth ventricle (the rhomboid fossa). It has a different structure in the lower and upper parts. On the sides of the median sulcus in the lower part are the right and left posterior cords. Approximately halfway along the length of the medulla oblongata, they diverge laterally and upward, and then continue in the form of thick ridges called the inferior cerebellar peduncles. . These rollers are immersed in the substance of the cerebellum. Between the right and left inferior cerebellar peduncles a triangular-shaped platform is formed, which represents the lower half of the rhomboid fossa. At the point where the posterior cords originate from the midline there are small thickenings called the thin and wedge-shaped tubercles, tuberculum gracile et tuberculum cuneatum.

Bridge, pons, represents the anterior part of the rhombencephalon. It has the appearance of a transversely located roller, gradually narrowing in the lateral direction. Its average length is 27 mm in men and 25 mm in women, width 36 mm, thickness 23 mm, weight 16–18 g. The pons has a ventral surface facing the clivus of the occipital bone and a dorsal surface facing the cerebellum. On the ventral surface along the midline there is a shallow basilar groove, sulcus basilaris, in which the artery of the same name is located. It should be noted that in many cases, especially in patients of older age groups, the course of the basilar artery deviates from the midline and is not projected onto the above-mentioned groove. On the sides of the basilar groove, small elevations are visible, caused by bundles of corticospinal tracts passing through the thickness of the bridge. A distinct transverse striation is detected on the surface of these elevations. It is formed by nerve fibers traveling to the middle cerebellar peduncles. The conditional lateral border of the bridge is considered to be a longitudinal line passing through the exit site of the trigeminal nerve roots, n. trigeminus. This nerve is the largest of all cranial nerves. The diameter of its trunk reaches 5 – 6 mm.

In addition to the roots of the trigeminal nerve, the roots of the abducens, facial and vestibulocochlear nerves also emerge from the substance of the bridge. Abducens nerve (VI pair of cranial nerves), n. abducens, has one root, which is located in a horizontal groove on the border between the pons and the pyramid of the medulla oblongata. Facial nerve (VII pair of cranial nerves), n. facialis, and the vestibulocochlear nerve (VIII pair of cranial nerves), n. vestibulocochlearis, exit at the cerebellopontine angle. The dorsal surface of the bridge faces the cavity of the fourth ventricle and forms the superior triangle of the rhomboid fossa.

On the lateral sides, the upper half of the rhomboid fossa is limited by the superior cerebellar peduncles, . Its base is formed by the medullary stripes of the fourth ventricle, striae medullares ventriculi quarti. The median groove runs along the midline, sulcus medianus. On the sides of the median sulcus a paired medial eminence is visible, eminentia medialis, limited laterally by the border groove, sulcus limitans. Above the medullary stripes of the fourth ventricle on the medial eminence is the tubercle of the facial nerve, colliculus facialis, formed by the motor fibers of the facial nerve, which arc around the nucleus of the abducens nerve.

Midbrain, mesencephalon, develops from the middle cerebral vesicle. Functionally, it is the subcortical motor center of the extrapyramidal system and is responsible for the unconditioned reflex regulation of muscle tone and unconditioned reflex movements. Compared to other parts of the central nervous system, the midbrain is small in size. Its ventral surface is represented by the cerebral peduncles, pedunculi cerebri, and the posterior perforated substance located between them, . The dorsal surface is formed by the roof of the midbrain, tectum mesencephali, the cavity is the midbrain aqueduct, aqueductus mesencephali(Sylvian aqueduct).

In most cases (57%), the border of the midbrain and diencephalon is projected in the plane of the tentorium cerebellum notch. In 37%, the tentorium notch is located at the border of the upper and middle thirds of the midbrain, and only in 6%, the projection of the tentorium notch is located in the middle of its length.

On the ventral side, the cerebral peduncles look like two thick, flattened ridges that appear from under the upper edge of the pons. From here they are directed upward and to the sides at an angle of 70 - 80° and are immersed in the substance of the diencephalon. The average length of the cerebral peduncle is 14 mm. One leg is the same size in width. The anteroposterior size of the cerebral peduncle is 13 mm. The anterior border of the cerebral peduncles is the optic tract, tractus opticus, which belongs to the diencephalon. The cerebral peduncles are white in color and have a fibrous structure due to the longitudinal arrangement of nerve fibers. The cerebral peduncles have a base and a tegmentum.

The groove of the oculomotor nerve runs along the medial edge of the base of the cerebral peduncles. sulcus nervi oculomotorii, from which the third pair of cranial nerves emerges with one root - the oculomotor nerve, n. oculomotorius. The lateral fissure of the midbrain runs along the lateral edge of the cerebral peduncle. sulcus lateralis mesencephali, which is a continuation of the rhombencephalon groove separating the superior and middle cerebellar peduncles.

On the ventral side between the two cerebral peduncles there is a depression called the interpeduncular fossa, fossa interpeduncularis. It is narrower at the upper edge of the bridge, widens anteriorly and ends near the two mastoid bodies, corpora mamillaria related to the diencephalon. The surface of the interpeduncular fossa has a grayish color and is dotted with holes through which numerous perforating arteries pass - branches of the basilar and posterior cerebral arteries. This area of ​​the brain is called the posterior perforated substance. substantia perforata posterior.

On the dorsal surface of the midbrain, represented by the roof plate (quadrigeminal plate), lamina tecti(lamina quadrigemina), there are four rounded elevations - two upper mounds, colliculi superiores, and two lower mounds, colliculi inferiores. The mounds are separated by grooves intersecting at right angles. The lower hillocks are smaller than the upper ones.

The handles of the hillocks extend from each hillock on the lateral side, brachia colliculi. They move forward to the diencephalon. The handles of the superior colliculi, narrower and longer, end in the lateral geniculate bodies. The handles of the inferior colliculi, thicker and shorter, end in the medial geniculate bodies.

Posterior to the inferior colliculus in the midline is the frenulum of the superior medullary velum, frenulum veli medullaris superioris, having a triangular shape. On each side of the frenulum of the superior medullary velum, one root of the fourth pair of cranial nerves emerges. trochlear nerve, n. trochlearis, IV pair of cranial nerves, is the thinnest of all cranial nerves and the only one emerging from the substance of the brain on its dorsal surface. The nerve bends around the cerebral peduncles and goes to their ventral surface.

On the lateral surface of the midbrain, in the interval between the lateral sulcus of the midbrain and the handles of the inferior colliculi, a triangular-shaped area is distinguished - the triangle of the lateral lemniscus, trigonum lemnisci lateralis. The third side of the triangle is the lateral edge of the superior cerebellar peduncle. In the projection of the triangle, in the thickness of the cerebral peduncles, nerve fibers pass that make up the lateral, medial, trigeminal and spinal lemniscus. Thus, in this place, in a small area near the surface of the brain, almost all the pathways of general sensitivity (conducting impulses to the diencephalon) and the auditory pathway are concentrated.

The cavity of the midbrain is the aqueduct of the midbrain (aqueduct of the brain, aqueduct of Sylvius), aqueductus mesencephali. It is a remnant of the cavity of the middle cerebral bladder, oriented along the axis of the brain, connecting the third and fourth ventricles. Its length is about 15 mm, the average diameter is 1 – 2 mm. There is a slight expansion in the middle part of the cerebral aqueduct.

The hole through which the aqueduct begins from the third ventricle is located under the posterior commissure of the brain. The hole through which the aqueduct opens into the fourth ventricle is located under the superior medullary velum in the upper corner of the ventricle.

Cerebellum, cerebellum, develops from the dorsal wall of the hindbrain and is the largest part of the brain after the cerebral hemispheres (Fig. 15). Functionally, the cerebellum is the integration center of the rhomboid brain - the center of statokinetic and vestibular functions. It has a diamond shape with a predominance of transverse size. Its width is on average 10 cm, its length along the midline is 3–4 cm, and its thickness is 4–5 cm.

Rice. 15. Cerebellum:

A- view from above: 1 – incisura cerebelli anterior; 2 – folia cerebelli; 3 – fissura horizontalis; 4 – incisura cerebelli posterior; 5 – fissurae cerebelli; 6 – vermis;

b- front view: 1 – vermis; 2 – pedunculus cerebellaris superior; 3 – pedunculus cerebellaris medius; 4– flocculus; 5 – pedunculus flocculi; 6 – nodulus; 7– incisura cerebelli posterior; 8 – fissura horizontalis; 9 – tela choroidea ventriculi IV; 10 – velum medullare superius

In the cerebellum there is a middle part - the vermis, vermis cerebelli, and two lateral volumetric parts - hemispheres, hemispheria cerebelli. Based on the development of the cerebellum in phylogenesis, it is necessary to distinguish a small formation adjacent to the hemisphere on the ventral side - a flocculus, flocculus. In the vermis and cerebellar hemispheres, two surfaces are distinguished: superior and inferior.

The superior surface of the cerebellum faces upward and backward. It is convex and has a longitudinal elevation in the middle, called the superior vermis, vermis superior. The worm passes into the hemispheres from the lateral sides. The inferior surface of the cerebellum is directed downward and forward. It is adjacent to the occipital bone. On the lower surface of the cerebellum there is a longitudinal depression called the valley, vallecula cerebelli. In this recess is the lower worm, vermis inferior, separated from each hemisphere by a fissure.

The surface of the cerebellum is striated with a large number of parallel transverse grooves, which have varying depths. Small grooves divide the surface of the cerebellum into plates, lamellae(convolutions, gyri). Deeper grooves separate groups of platelets into plates, laminae, which are called the cerebellar sheets, folia cerebelli. Finally, the deepest grooves divide the surface of the cerebellum into lobules, lobuli. The furrows of the cerebellum, without interruption, pass from the vermis to the hemispheres. The shred also has plates, but no segments are distinguished in it.

Among the grooves separating the cerebellar lobules, the deepest (up to 2 cm) is the horizontal fissure, fissura horizontalis. It runs along the entire circumference of the cerebellum and separates the superior and inferior surfaces of the hemispheres.

There are eight lobules in the worm, four lobules each in the upper and lower worm. The most anterior lobule of the superior vermis is the uvula, lingula. The tongue is formed by several plates. The next one is the central lobule, lobulus centralis, which corresponds to the upper, most protruding part of the worm. The apex is located posterior to the central lobule, culmen, followed by a slope, declive. The most posterior lobule of the upper worm is the leaf of the worm, folium vermis, which limits the horizontal furrow from above.

In the lower worm, below the leaf of the worm, there is a tubercle, tuber. In front of it is a pyramid, pyramids, protruding at the bottom of the cerebellar valley. Further anteriorly lies the narrowest part of the lower vermis - the uvula, uvula, which is, as it were, compressed by the adjacent parts of the hemispheres. Finally, the most anterior lobule of the inferior vermis is the node, nodulus.

In each hemisphere, the lobules of the worm correspond to the lobes of the hemispheres. On the upper surface of the hemisphere, the anterior quadrangular lobe is determined, lobulus quadrangularis anterior, simple slice, lobulus simplex, superior semilunar lobule, lobulus semilunaris superior.

On the lower surface of the hemisphere in the direction from back to front are the inferior semilunar lobule, lobulus semilunaris inferior, thin slice, lobulus gracilis, digastric lobule, lobulus biventer, and the cerebellar amygdala, tonsilla cerebelli.

Shred, flocculus, is a small group of cerebellar plates adjacent to its middle peduncle.

Through three pairs of peduncles, the cerebellum is connected to various parts of the brain. superior cerebellar peduncles, pedunculi cerebellares superiores, connect it with the midbrain, middle cerebellar peduncles, pedunculi cerebellares medii, - with the bridge, and the inferior cerebellar peduncles, pedunculi cerebellares inferiores, – with the medulla oblongata. The superior and inferior cerebellar peduncles are visible from the dorsal surface of the brainstem, and the middle peduncles are visible from its ventral surface.

Diencephalon, diencephalon, develops from the caudal part of the forebrain, prosencephalon. During the process of ontogenesis, it undergoes significant changes. The ventral and dorsal walls become thinner and the lateral walls become significantly thicker. The cavity of this segment of the neural tube expands significantly and takes the form of a slit located in the median plane - the third ventricle.

It should be noted that the dorsal (upper) wall of the third ventricle is represented only by ependymal epithelium. Above the ependymal epithelium is a process of the choroid, which delimits the diencephalon and the structures of the telencephalon (fornix and corpus callosum). The lateral parts of the diencephalon on the lateral side are directly fused with the structures of the telencephalon.

We all remember how we learned about the openings of the skull in anatomy class - once you learn a couple of holes, all the rest are forgotten. And this feeling that they are scattered like stars in the anatomical sky. But just as the stars in the sky are connected into constellations, the cunning French combined the holes on the inner base of the skull into several “constellations”. In this case, you can try to remember them.

Rice. base of skull.

F – (yellow);
lce – perforated plate of the ethmoid bone. Makes up the roof of the nasal cavity;
ga – greater wing of the sphenoid bone;
pa – lesser wing of the sphenoid bone;
S – body of the sphenoid bone;
fm – foramen magnum, which opens the entrance to the spinal canal;
T – ;
o – (green color).

Superior orbital fissure

Rice. base of skull

pa – lesser wing of the sphenoid bone (pink)
ga – greater wing of the sphenoid bone (yellow)

fos – superior orbital fissure.

On both sides of the body of the sphenoid bone there are its large wings (ga), pierced with holes. Anterior and lateral to the body lie the small wings (pa) of the sphenoid bone.

Between the greater wing (ga) and the lesser wing (pa) there remains a gap - the superior orbital fissure (fos), which has the shape of a drop, wider in the medial part. Superior orbital

Rice. base of skull
pa – lesser wing of the sphenoid bone,
ga – greater wing of the sphenoid bone,
S – body of the sphenoid bone,
fc – carotid foramen,
co – optic nerve canal,
R – rocky pyramid,
The temporal bone is marked in purple.

Two more holes at the base of the skull are in contact with the lateral angles of the body of the sphenoid bone (S). The optic nerve canal (co) opens into the upper part of the orbit. The optic nerve passes through it. The carotid foramen (fc) is located at the junction of the body of the sphenoid wing with the apex of the petrous pyramid (R) and encloses the carotid artery.

Foramina of the greater wing of the sphenoid bone

On the horizontal section of the greater wing (a") of the sphenoid bone there are 6 holes. They are located approximately on the line of a conventional triangle. This is triangle ABC, the base of which (bc) lies on the border (suture) of the greater wing and the petrous pyramid of the temporal bone. Then in the area of ​​the vertices This triangle will have 3 holes:
a – round foramen (foramen rond), b – foramen spinosum (foramen épineux), c – internal carotid foramen.

a’ – vertical portion of the large wing of the sphenoid bone,

a’’ – horizontal portion of the greater wing of the sphenoid bone.

Rice. Foramina of the greater wing of the sphenoid bone.
a – round hole (foramen rond),
b – foramen spinosum (foramen épineux),
c – internal carotid foramen,

There is also a hole on each side of our triangle ABC:

d – oval foramen, foramen ovale,

e – torn hole, foramen lacerum,

F – Vidian canal opening.

Posterior cranial fossa

Rice. openings of the posterior cranial fossa.
r’ – front surface of the cairn,
r’’ – back surface of the cairn,
pai – internal auditory opening (pore acoustique interne)
dp – jugular foramen
h – canal of the hypoglossal nerve

Three pairs of holes are located approximately on a straight line AA":
dp - jugular foramen
c – anterior condylar foramen (anterior condyloid foramen)
h – canal of the hypoglossal nerve

A’ – vertical portion of the large wing of the sphenoid bone,
a’’ – horizontal portion of the large wing of the sphenoid bone,
e – ethmoid bone (perforated plate),

The skeleton of the skull (Fig. 32, 33) is conventionally divided into a vault, or roof, and a base.

Rice. 32.

(front view, according to R. D. Sinelnikov):

1 - coronal suture; 2 - parietal bone; 3 - orbital part of the frontal bone; 4 - orbital surface of the greater wing, sphenoid bone; 5- zygomatic bone; 6- inferior nasal concha; 7- upper jaw; 8 - chin protuberance of the lower jaw; 9 - nasal cavity; 10- opener; 11 - perpendicular plate of the ethmoid bone; 12- orbital surface of the upper jaw; 13 - inferior orbital fissure; 14 - lacrimal bone; 15 - orbital plate of the ethmoid bone; 16 - superior orbital fissure; 17 - scaly part of the temporal bone; 18-zygomatic process of the frontal bone; 19- visual channel; 20- nasal bone; 21 - frontal tubercle

The cranial vault is formed by the scaly parts of the frontal, temporal, occipital bones and parietal bones. The base of the skull consists of the frontal, ethmoid, sphenoid, temporal and occipital bones. There are internal and external bases of the skull.

Rice. 33.

(side view, according to R. D. Sinelnikov):

1 - parietal bone; 2- coronal suture; 3 - frontal tubercle; 4 - temporal surface of the large wing of the sphenoid bone; 5 - orbital plate of the ethmoid bone; b - lacrimal bone; 7- nasal bone; 8- temporal fossa; 9- anterior nasal spine; 10 - body of the upper jaw; 11 - lower jaw; 12 -- zygomatic bone; 13 - zygomatic arch; 14 - styloid process; 15 - condyle process of the lower jaw; 16-mastoid process; 17- external auditory canal; 18- lambdoid suture; 19 - scales of the occipital bone; 20 - superior temporal line; 21 - scaly part of the temporal bone

The internal base of the skull (basis cranii interna) has three cranial fossae: anterior, middle and posterior (Fig. 34). In the anterior cranial fossa there are the lobes of the cerebral hemispheres, in the middle - the temporal lobes of the cerebral hemispheres, and in the posterior - the cerebellum and parts of the brain stem: the cerebral peduncles and the medulla oblongata.

The anterior cranial fossa is formed by the orbital part of the frontal bone, the ethmoid bone (ethmoid plate) and the lesser wings of the sphenoid bone and communicates with the nasal cavity through the holes in the cribriform plate. These openings serve as the passage for the olfactory nerves (1st pair).

The walls of the middle cranial fossa are formed by the body and large wings of the sphenoid bone, the anterior surface of the pyramids, and the squamous part of the temporal bones. The middle cranial fossa communicates with the orbit and the pterygopalatine fossa. From this fossa, the optic nerve (II pair), the orbital artery and vein pass into the cavity of the orbit through the optic canal. Through the superior orbital fissure, the oculomotor (III pair), trochlear (IV pair), abducens (VI pair) and ophthalmic (first branch of the trigeminal nerve (V pair)) nerves pass into the orbit. Somewhat posterior to the superior orbital fissure there is a round foramen through which the the maxillary nerve (the second branch of the V pair), and the mandibular nerve (the third branch of the V pair) emerges from the skull through the foramen ovale.In the pituitary fossa of the sella turcica there is an endocrine gland - the pituitary gland.

1 - orbital part of the frontal bone; 2 - cockscomb; 3 - cribriform plate; 4- visual channel; 5 - pituitary fossa;. 6- back of the saddle; 7 - round hole; 8 - oval hole; 9 - torn hole; 10 - foramen spinosum; 11 - internal auditory opening; 12 - jugular foramen; 13 - sublingual canal; 14 - lambdoid seam; 75 - slope; 16 - groove of the transverse sinus; 77-internal occipital protuberance; 18 - large (occipital) foramen; 19 - occipital scales; 20 - groove of the sigmoid sinus; 21 - pyramid (stony part) of the temporal bone; 22 - scaly part of the temporal bone; 23 - large wing of the sphenoid bone; 24 - lesser wing of the sphenoid bone

The occipital bone, posterior surfaces of the pyramids, and temporal bones take part in the formation of the posterior cranial fossa.

Between the back of the sella turcica and the foramen magnum there is a clivus.

The internal auditory (right and left) foramen opens into the posterior cranial fossa, from which the vestibulocochlear nerve (VIII pair) emerges, and from the facial nerve canal - the facial nerve (VII pair). The lingual pharyngeal (IX pair), vagus (X pair) and accessory (XI pair) nerves exit through the jugular foramen of the base of the skull. The nerve of the same name, the XII pair, passes through the canal of the hypoglossal nerve. In addition to the nerves, the internal jugular vein emerges from the cranial cavity through the jugular foramen, which passes into the sigmoid sinus. The formed foramen magnum connects the cavity of the posterior cranial fossa with the spinal canal, at the level of which the medulla oblongata passes into the spinal cord.

The outer base of the skull (basis cranii extema) in its anterior section is closed by the facial bones (it contains a bony palate, limited in front by the alveolar process of the upper jaw and teeth), and the posterior section is formed by the outer surfaces of the sphenoid, occipital and temporal bones (Fig. 35).

1 - palatine process of the upper jaw; 2- incisive hole; 3 - median palatal suture; 4 - transverse palatal suture; 5-choana; b- inferior orbital fissure; 7- zygomatic arch; 8 - opener wing; 9- pterygoid fossa; 10 - lateral plate of the pterygoid process; 77 - pterygoid process; 12 - oval hole; 13 - mandibular fossa; 14- styloid process; 15 - external auditory canal; 16- mastoid process; 77 - mastoid notch; 18- occipital condyle; 19 - condylar fossa; 20- large (occipital) foramen; 27 - lower nuchal line; 22 - external occipital protuberance; 23 - pharyngeal tubercle; 24 - condylar canal; 25- jugular foramen; 26 - occipital-mastoid suture; 27 - external carotid foramen; 28 - stylomastoid foramen; 29- torn hole; 30 - petrotympanic fissure; 31 - spinous foramen; 32 - articular tubercle; 33 - wedge-squamous suture; 34 - wing-shaped hook; 35 - greater palatine foramen; 36-zygomaticomaxillary suture

This area has a large number of openings through which vessels and nerves pass, providing blood supply to the brain. The central part of the external base of the skull is occupied by the foramen magnum, on the sides of which are the occipital condyles. The latter connect to the first vertebra of the cervical spine. The exit from the nasal cavity is represented by paired openings (choanae), which pass into the nasal cavity. In addition, on the outer surface of the base of the skull there are the pterygoid processes of the sphenoid bone, the external opening of the carotid canal, the styloid process, the stylomastoid foramen, the mastoid process, the myotubal canal, the jugular foramen and other formations.

In the skeleton of the facial skull, the central place is occupied by the nasal cavity, orbits, oral cavity, infratemporal and pterygopalatine fossa.

The nasal cavity (cavitas nasi) is the initial section of the respiratory tract and contains the organ of smell. It has one entrance pyriform opening and two exit openings - choanae.

The nasal cavity is divided into two halves by a bone plate. The nasal cavity is divided into upper, lower and lateral (lateral) walls. The upper wall is formed by the nasal bones, the ethmoid bone, the nasal part of the frontal and the body of the sphenoid bones. The lower wall is represented by the upper palatine processes of the upper jaw and the horizontal plates of the bones of the palate. The lateral wall consists of the frontal process of the maxilla, the lacrimal bone, the ethmoid labyrinth, the perpendicular plate of the palatine bone, the middle (medial) plate of the pterygoid process of the sphenoid bone.

The turbinates divide the lateral part of the cavity into three nasal passages: upper, middle and lower. The sinuses of the sphenoid bone and the posterior cells of the ethmoid bone open into the upper nasal passage; in the middle nasal passage - the sinuses of the upper jaw and frontal bone, as well as the cells of the ethmoid bone; in the lower nasal passage - the nasolacrimal canal, which begins in the orbit.

The orbit (orbita) is a paired cavity, has the shape of a tetrahedral pyramid with rounded edges, the apex of which is directed backward and medially. The optic canal passes through this area. The orbital cavity contains the eyeball with muscles, the lacrimal gland and other formations. It has an entrance and four walls: upper, lower, medial and lateral. The upper wall is formed by the orbital part of the frontal bone and the lesser wings of the sphenoid bone; lower - zygomatic bone and upper jaw; medial - by the frontal process of the maxilla, the lacrimal bone, the orbital plate of the ethmoid bone, the body of the sphenoid bone and part of the frontal bone; lateral - the zygomatic bone and the greater wing of the sphenoid bone. Between the lateral and inferior walls there is the inferior orbital fissure, which opens into the pterygopalatine and infratemporal fossa. The superior orbital fissure and optic foramen open into the middle cranial fossa; The nasolacrimal duct connects to the nasal cavity.

The oral cavity (cavitas oris) is formed by the bony (hard) palate, the palatine processes of the right and left upper jaws and the horizontal plates of the palatine bones; the lateral and anterior walls are formed by the alveolar processes of the upper jaws, which together make up the upper alveolar arch. The bony palate serves as the hard (bone) basis of the upper wall of the oral cavity. The upper and lower alveolar arches, together with the teeth and the body of the lower jaw, make up the skeleton of the anterior and lateral walls of the oral cavity.

The infratemporal fossa is located behind the upper jaw, inward from the zygomatic bone and zygomatic arch and externally from the pterygoid process of the sphenoid bone, and forms part of the outer base of the skull.

The pterygopalatine fossa is located between the bones of the brain and facial skull and has four walls: anterior, superior, posterior and medial. The anterior wall is formed by the tubercle of the upper jaw, the upper - by the part of the body and the base of the greater wing of the sphenoid bone, the posterior - by the base of the pterygoid process of the sphenoid bone, the medial - by the perpendicular plate of the palatine bone. Canals and openings open into the pterygopalatine fossa, through which it communicates with neighboring cavities.

* pairs of cranial nerves.

FACIAL REGION OF THE SKULL

Eye socket, orbita , has the shape of a tetrahedral pyramid.

The base of the pyramid is the entrance to the orbit, aditus orbitae.

The tip of the pyramid passes into the optic canal, canalis opticus.

Walls of the orbit: superior, medial, inferior, lateral.

1. Top wall , paries superior , educated:

1) orbital part of the frontal bone,

2) the small wing of the sphenoid bone.

Top wall structures:

Fossa of the lacrimal gland, fossa glandulae lacrimalis,

trochlear fossa, fovea trochlearis.

2. medial wall, paries medialis , educated:

1) frontal process of the maxilla,

2) lacrimal bone,

3) orbital plate of the ethmoid bone.

4) body of the sphenoid bone,

Structures of the medial wall:

Fossa of the lacrimal sac, fossa sacci lacrimalis,

Nasolacrimal duct, canalis nasolacrimalis,

Anterior ethmoidal opening, foramen ethmoidae anterius,

Posterior ethmoidal foramen, foramen ethmoidae posterius.

3.Bottom wall, paries inferior , educated:

1) orbital surface of the upper jaw,

2) orbital surface of the zygomatic bone,

3) orbital process of the palatine bone.

Bottom wall structures:

Infraorbital groove, sulcus infraorbitalis,

infraorbital canal, canalis infraorbitalis.

4. lateral wall,paries lateralis , educated:

1) orbital surface of the greater wing of the sphenoid bone,

2) the orbital surface of the zygomatic process of the frontal bone,

3) the orbital surface of the frontal process of the zygomatic bone.

Lateral wall structures:

Zygomaticoorbital foramen, foramen zygomaticoorbitale.

Between the superior and lateral walls is the superior orbital fissure, fissura orbitalis superior, leading into the middle cranial fossa.

Between the lateral and inferior walls there is an inferior orbital fissure, fissura orbitalis inferior, which communicates the orbit with the pterygopalatine and infratemporal fossae.

nasal cavity, cavitas nasi, front opens pear-shaped aperture, apertura piriformis, which is limited:

1) from the sides - nasal notches of the upper jaws,

2) from above - the lower edges of the nasal bones,

3) from below - the anterior nasal spine.

Posteriorly, the nasal cavity communicates with the pharynx through joan, choanae, limited:

1) lateral - medial plates of the pterygoid processes of the sphenoid bone,

2) from below – horizontal plates of the palatine bone,

3) from above - the body of the sphenoid bone,

4) medially – by the vomer.

Bone septum of the nose, septum nasi osseum, educated:

1) perpendicular plate of the ethmoid bone,

2) opener,

3) nasal crest of the upper jaws and palatine bones.

Walls of the nasal cavity: upper, lower, lateral.

1. Upper wall,paries superior , educated:

1) nasal bones,

2) the nasal part of the frontal bone,

3) cribriform plate of the ethmoid bone,

4) the body of the sphenoid bone.

2. Bottom wall , paries inferior , educated:

1) palatine processes of the upper jaws,

3. lateral wall,paries lateralis , educated:

1) nasal bone,

2) the nasal surface of the body and the frontal process of the maxilla,

3) lacrimal bone,

4) ethmoid labyrinth of the ethmoid bone,

5) perpendicular plate of the palatine bone,

6) medial plate of the pterygoid process of the sphenoid bone.

On the lateral wall there are three nasal conchae: superior, middle and inferior. The superior and middle turbinates are part of the ethmoid labyrinth. The inferior nasal concha is a separate (independent) bone.

Below the nasal turbinates are located nasal passages: upper, middle and lower.

1. Upper nasal passage,meatus nasi superior , limited by the superior and middle turbinates. Located in the posterior part of the nasal cavity and its posterior end reaches the sphenopalatine foramen, foramen sphenopalatinum.

The upper nasal passage opens:

Posterior cells of the ethmoid bone.

Above the superior nasal concha there is a sphenoethmoidal recess, recessus sphenoethmoidalis, into which the aperture of the sphenoid sinus opens , apertura sinus sphenoidalis.

2. Middle nasal passagemeatus nasi medius , located between the middle and inferior turbinates.

The middle nasal meatus opens:

Anterior and middle cells of the ethmoid bone,

Frontal sinus through the ethmoidal infundibulum, infundibulum ethmoidae,

Maxillary sinus through the cleft semilunaris, hiatus semilunaris.

3.Lower nasal passage , meatus nasi inferior , located between the inferior turbinate and the lower wall of the nasal cavity.

The lower nasal meatus opens:

Nasolacrimal duct.

Between the nasal septum and the nasal turbinates is located common nasal passage, meatus nasi communis .

Bone palate palatum osseum, limited by the alveolar processes of the upper jaws and formed by:

1) palatine processes of the upper jaws,

2) horizontal plates of the palatine bones.

Structures of the bony palate:

Median palatal suture sutura palatina mediana,

Transverse palatal suture, sutura palatina transversa,

incisal hole, foramen incisivum, leading into the incisive canal, canalis incisivus,

Greater palatine foramen ,foramen palatinum majus,

Small palatine foramina, foramina palatina minora.

temporal fossa, fossa temporalis, It is limited from above by the superior temporal line, from below by the infratemporal crest of the sphenoid bone.

Walls of the temporal fossa: anterior, medial and lateral.

1. Front wall,paries anterior , educated:

1) zygomatic process of the frontal bone,

2) the temporal surface of the zygomatic bone.

2. medial wall,paries medialis , educated:

1) the temporal surface of the squamous part of the temporal bone,

2) the outer surface of the parietal bone in the region of the sphenoid angle,

3) the temporal surface of the greater wing of the sphenoid bone.

3. lateral wall,paries lateralis , represented by the zygomatic arch.

infratemporal fossa, fossa infratemporalis, delimited from the temporal fossa by the infratemporal crest of the greater wing of the sphenoid bone.

Walls of the infratemporal fossa: anterior, superior, medial.

1. Front wall,paries anterior , educated:

1) tubercle of the upper jaw,

2) zygomatic bone.

2. Upper wall,paries superior , presented:

1) temporal bone,

2) the temporal surface of the greater wing of the sphenoid bone below the infratemporal crest.

3. medial wall,paries medialis , educated:

1) lateral plate of the pterygoid process of the sphenoid bone.

On the lateral side, the infratemporal fossa is covered by the ramus of the mandible. In front, through the inferior orbital fissure, it communicates with the orbit. From the medial side through the pterygomaxillary fissure, fissura pterygomaxillaris, communicates with the pterygopalatine fossa. The hole is open below.

Pterygopalatine fossa, fossa pterygopalatina, has four walls: anterior, superior, posterior and medial.

1. Front wall,paries anterior , presented:

1) tubercle of the upper jaw.

2. Upper wall,paries superior , educated:

1) the maxillary surface of the greater wing of the sphenoid bone.

3. Back wall,paries posterior , educated:

1) the base of the pterygoid process of the sphenoid bone.

4. Medial wall , paries medialis , presented:

1) perpendicular plate of the palatine bone.

The pterygopalatine fossa narrows downwards and passes into the greater palatine canal, canalis palatinus major.