Sphenoid and occipital bones on the right and above. Sphenoid bone of the skull. Description. What is the sphenoid bone

• The presphenoidal part, or presphenoid, is located in front of the tubercle of the sella turcica and includes the lesser wings and the anterior part of the body.

• The postsphenoidal part, or postsphenoid, consists of the sella turcica, dorsum sellae, greater wings and pterygoid processes.

Rice. Parts of the sphenoid bone: PrSph - presphenoid, BSph - postsphenoid, OrbSph - orbital part of the lesser wing of the sphenoid, AliSph - greater wing of the sphenoid. In addition, the diagram shows: BOc – body of the occipital bone, Petr – petrous part of the temporal bone, Sq – squama of the temporal bone. II, IX, X, XI, XII - cranial nerves.

During embryogenesis, 12 ossification nuclei are formed in the sphenoid bone:
1 core in each large wing,
1 core in each small wing,
1 nucleus in each lateral plate of the pterygoid processes,
1 nucleus in each medial plate of the pterygoid processes,
2 nuclei in presphenoid,
2 nuclei in postsphenoid.

Division into cartilaginous and membranous ossification of the sphenoid bone:

Large wings and pterygoid processes are formed as a result of membranous ossification. In the remaining parts of the sphenoid bone, ossification occurs according to the cartilaginous type.

At the moment of birth, the sphenoid bone consists of three independent parts:

1. Body of the sphenoid bone and lesser wings
2. The right greater wing together with the right pterygoid process in one complex
3. The left greater wing together with the left pterygoid process in one complex

Anatomy of the sphenoid bone

Body of the sphenoid bone

The sella turcica, or sella turcica, is located on the upper surface of the body. .

The small wings of the sphenoid bone extend from the body by two roots - upper and lower. There remains a hole between the roots - visual channel ( canalis opticus), through which the optic nerve (n. opticus) and the ophthalmic artery (a. ophthalmica) pass.

The small wings of the sphenoid bone participate in the construction of the posterior (dorsal) wall of the orbit.

Rice. Wings of the sphenoid bone in the construction of the dorsal wall of the orbit.

The small wings are projected onto the lateral surface of the cranial vault in the area of ​​the frontozygomatic suture of the outer wall of the orbit. The projection of the lesser wing corresponds to an almost horizontal segment between the frontozygomatic suture ventrally and the pterion dorsally.

In addition, the lesser wings are a “step” between the anterior cranial fossa with the frontal lobe of the brain, and the middle cranial fossa with the temporal lobe.

Large wings of the sphenoid bone

A round opening (for. rotundum) is formed between the anterior and middle roots, through which the maxillary branch of the trigeminal nerve (V2 - cranial nerve) passes.
Between the middle and posterior roots, an oval foramen (for. ovale) is formed through which the mandibular branch of the trigeminal nerve (V3 - cranial nerve) passes.
At the level of the posterior root (either in it or at the junction of the greater wing with the temporal bone), a spinous foramen (for. spinosum) is formed, through which the middle meningeal artery (a. meningea media) passes.

The large wings of the sphenoid bone have three surfaces:

1. Endocranial surface involved in the base of the middle cranial fossa.
2. The orbital surface forms the dorsolateral wall of the orbit.
3. Extracranial surface of the pterion region.

Rice. Endocranial surface of the greater wings of the sphenoid bone.

Rice. Orbital surfacegreater wings of the sphenoid bone – posterolateral wall of the orbit.

The infratemporal crest divides the large wing into two parts:
1) Vertical, or temporal part.
2) Horizontal, or infratemporal part.

At the very back of the great wing is the spine of the sphenoid bone, or spina ossis sphenoidalis.

Sutures of the sphenoid bone

Connection of the sphenoid bone with the temporal bone.
Presented in the form of sutures with the petrous pyramid and with the scales of the temporal bone.

Wedge-squamous suture, or sutura spheno-squamosa:
The sphenosquamosal suture is the connection of the greater wing of the sphenoid bone with the squama of the temporal bone. The suture, like the large wing, begins on the vault of the skull and then passes from the lateral surface of the vault of the skull to its base. In the area of ​​this transition there is a reference point, or pivot - punctum spheno-sqamosum (PSS). Thus, two parts can be distinguished in the wedge-squamoid suture.

1. The vertical part of the suture is from the pterion to the supporting point, punctum sphenosquamosum (PSS), where the suture has an external cut: the temporal bone covers the sphenoid;
2. The horizontal part of the suture is from the support point (PSS) to the spine of the sphenoid bone, where the suture has an internal cut: the sphenoid bone covers the temporal bone.

Sphenoid-stony synchondrosis. Or, as people say, wedge-petrous. Aka synchondrosis spheno-petrosus.

Synchondrosis connects the posterointernal part of the greater wing of the sphenoid bone with the pyramid of the temporal bone.
The sphenopetrosal suture runs dorsolaterally from the foramen lacerum (for. lacerum) between the greater wing and the petrosal. Lies above the cartilage of the auditory tube.

Gruber, or petrosphenoidal syndesmosis, or ligamentum sphenopetrosus superior ( syndesmosis).

It goes from the apex of the pyramid to the posterior sphenoid processes (to the back of the sella turcica).

Connection of the sphenoid bone with the ethmoid bone, or wedge-ethmoidal suture, or sutura spheno-ethmoidalis.
In the extensive connection of the anterior surface of the body of the sphenoid bone with the posterior part of the ethmoid bone, three independent sections are distinguished:

1. The ethmoid process of the sphenoid bone connects to the posterior part of the horizontal (perforated) plate of the ethmoid bone (in green in the figure).
2. The anterior sphenoid crest is connected to the posterior part by the perpendicular plate of the ethmoid bone (in red in the figure).
3. The hemi-sinuses of the sphenoid bone are combined with the hemi-sinuses of the ethmoid bone (in the picture in yellow and weaving).

Connection of the sphenoid bone with the parietal bone occurs through sutura spheno-temporalis.
The connection lies in the region of the pterion, where the posterosuperior edge of the greater wing of the sphenoid bone connects with the anteroinferior angle of the parietal bone. In this case, the sphenoid bone covers the parietal bone on top.

Connection of the sphenoid bone with the palatine bone.
The connection occurs in three independent areas, which is why there are three seams:

1. The sphenoid process of the palatine bone is connected to the lower surface of the body of the sphenoid bone by a harmonious suture.
2. The orbital process is connected to the anterior inferior edge of the body of the sphenoid bone by a harmonious suture.
3. The pyramidal process with its posterior edge enters the pterygoid fissure. Shuttle movement.

The connection between the anterior surface of the lesser wing of the sphenoid bone and the posterior edge of the orbital plates of the frontal bone is a harmonious suture (green in the figure). This deep suture is projected onto the lateral surface of the skull in the area of ​​the frontozygomatic suture.

The suture between the L-shaped articular surface of the greater wing of the sphenoid bone and the outer columns of the frontal bone (in red in the figure). The L-shaped suture is more complex, and consists of a small shoulder (directed towards the sella turcica) and a large shoulder (directed towards the tip of the nose). Part of the L-shaped suture is accessible to direct palpation on the lateral surface of the cranial vault in the area of ​​the pterion: ventral to the greater wing of the sphenoid bone.

Rice. Connection of the sphenoid bone with the frontal bone.

Connection of the sphenoid bone with the zygomatic bone, or to
In the outer wall of the orbit, the anterior edge of the greater wing of the sphenoid bone connects with the posterior edge of the zygomatic bone.

Connection of the sphenoid bone with the vomer, or sutura sphenovomeralis.
On the lower surface of the body of the sphenoid bone there is a lower wedge-shaped ridge that connects to the upper edge of the vomer. In this case, a compound is formed: schindelosis. It allows longitudinal sliding movements.

Craniosacral mobility of the sphenoid bone.

Axis of motion of the sphenoid bone.
The axis of craniosacral mobility of the sphenoid bone passes transversely through the lower edge of the anterior wall of the sella turcica. We can also say that the axis lies at the intersection of two planes: the horizontal plane at the level of the bottom of the sella turcica and the frontal plane at the level of the anterior wall of the sella turcica.

Rice. Movement of the sphenoid bone during the flexion phase of the primary respiratory mechanism.

The transverse axis of the sphenoid bone emerges onto the surface of the cranial vault, crossing the sphenosquamous pivots (PSS – punctum sphenosquamous pivot).
Continuing further, the axis of movement of the sphenoid bone crosses the middle of the zygomatic arch.

Rice. The crosshair corresponds to the projection of the axis of movement of the sphenoid bone. The arrow is the direction of movement of the large wings during the flexion phase of the primary respiratory mechanism.

During the flexion phase of the primary respiratory mechanism:
The body of the sphenoid bone rises;
The large wings extend ventro-caudo-laterally towards the mouth.
The pterygoid processes diverge and descend;

During the extension phase of the primary respiratory mechanism:
The body of the sphenoid bone descends;
Large wings extend upward, posteriorly and inwardly;
The pterygoid processes converge and rise.

Sphenoid bone

The occipital bone (os occipitale) (Fig. 59) is unpaired, located in the posterior part of the cranium and consists of four parts located around the large foramen (foramen magnum) (Fig. 60, 61, 62) in the antero-inferior part of the outer surface.

The main, or basilar, part (pars basilaris) (Fig. 60, 61) lies anterior to the external opening. In childhood, it connects to the sphenoid bone with the help of cartilage and sphenoid-occipital synchondrosis (synchondrosis sphenooccipitalis) is formed, and in adolescence (after 18-20 years) the cartilage is replaced by bone tissue and the bones grow together. The upper inner surface of the basilar part, facing the cranial cavity, is slightly concave and smooth. It contains part of the brain stem. At the outer edge there is a groove of the inferior petrosal sinus (sulcus sinus petrosi inferior) (Fig. 61), adjacent to the posterior surface of the petrous part of the temporal bone. The lower outer surface is convex and rough. In its center is the pharyngeal tubercle (tuberculum pharyngeum) (Fig. 60).

The lateral, or lateral, part (pars lateralis) (Fig. 60, 61) is paired and has an elongated shape. On its lower outer surface there is an ellipsoidal articular process - the occipital condyle (condylus occipitalis) (Fig. 60). Each condyle has an articular surface through which it articulates with the first cervical vertebra. Behind the articular process there is a condylar fossa (fossa condylaris) (Fig. 60) with a non-permanent condylar canal (canalis condylaris) located in it (Fig. 60, 61). At the base, the condyle is pierced by the hypoglossal canal (canalis hypoglossi). On the lateral edge there is a jugular notch (incisura jugularis) (Fig. 60), which, combining with the same notch of the temporal bone, forms the jugular foramen (foramen jugulare). The jugular vein, glossopharyngeal, accessory and vagus nerves pass through this opening. At the posterior edge of the jugular notch there is a small protrusion called the jugular process (processus intrajugularis) (Fig. 60). Behind it, along the inner surface of the skull runs a wide groove of the sigmoid sinus (sulcus sinus sigmoidei) (Fig. 61, 65), which has an arched shape and is a continuation of the groove of the same name in the temporal bone. Anterior to it, on the upper surface of the lateral part, there is a smooth, gently sloping jugular tubercle (tuberculum jugulare) (Fig. 61).

The most massive part of the occipital bone is the occipital scales (squama occipitalis) (Fig. 60, 61, 62), located behind the foramen magnum and taking part in the formation of the base and vault of the skull. In the center on the outer surface of the occipital scales there is an external occipital protuberance (protuberantia occipittalis externa) (Fig. 60), which is easily palpable through the skin. From the external occipital protrusion to the foramen magnum the external occipital crest (crista occipitalis externa) is directed (Fig. 60). Paired upper and lower nuchal lines (linea nuchae superiores et inferiores) (Fig. 60), which represent a trace of muscle attachment, extend to both sides of the external occipital crest. The upper nuchal lines are at the level of the outer protrusion, and the lower ones are at the level of the middle of the outer ridge. On the inner surface, in the center of the cruciform eminence (eminentia cruciformis), there is an internal occipital protuberance (protuberantia occipittalis interna) (Fig. 61). Down from it, down to the foramen magnum, the internal occipital crest (crista occipitalis interna) descends (Fig. 61). A wide, gentle groove of the transverse sinus (sulcus sinus transversi) runs to both sides of the cruciform eminence (Fig. 61); The groove of the superior sagittal sinus (sulcus sinus sagittalis superioris) runs vertically upward (Fig. 61).

The occipital bone is connected to the sphenoid, temporal and parietal bones.

The sphenoid bone (os sphenoidale) (Fig. 59) is unpaired and is located in the center of the base of the skull. The sphenoid bone, which has a complex shape, is divided into a body, small wings, large wings and pterygoid processes.

The body of the sphenoid bone (corpus ossis sphenoidalis) has a cubic shape, with six surfaces. The upper surface of the body faces the cranial cavity and has a depression called the sella turcica (sella turcica), in the center of which is the pituitary fossa (fossa hypophysialis) with the lower appendage of the brain lying in it - the pituitary gland. In front, the sella turcica is limited by the tubercle of the sella (tuberculum sellae) (Fig. 62), and behind by the dorsum of the sellae (dorsum sellae). The posterior surface of the body of the sphenoid bone is connected to the basilar part of the occipital bone. On the anterior surface there are two openings leading into the air-bearing sphenoid sinus (sinus sphenoidalis) and called the aperture of the sphenoid sinus (apertura sinus sphenoidalis) (Fig. 63). The sinus is finally formed after 7 years inside the body of the sphenoid bone and is a paired cavity separated by the septum of the sphenoid sinuses (septum sinuum sphenoidalium), emerging onto the anterior surface in the form of a wedge-shaped crest (crista sphenoidalis) (Fig. 63). The lower part of the crest is pointed and represents a wedge-shaped beak (rostrum sphenoidale) (Fig. 63), wedged between the wings of the vomer (alae vomeris), attached to the lower surface of the body of the sphenoid bone.

The small wings (alae minores) (Fig. 62, 63) of the sphenoid bone are directed in both directions from the anterosuperior corners of the body and represent two triangular plates. At the base, the small wings are pierced by the optic canal (canalis opticus) (Fig. 62), which contains the optic nerve and ophthalmic artery. The upper surface of the small wings faces the cranial cavity, and the lower one takes part in the formation of the upper wall of the orbit.

The large wings (alae majores) (Fig. 62, 63) of the sphenoid bone extend to the sides from the lateral surfaces of the body, heading outward. At the base of the large wings there is a round opening (foramen rotundum) (Fig. 62, 63), then an oval (foramen ovale) (Fig. 62), through which the branches of the trigeminal nerve pass, and outward and posteriorly (in the area of ​​the angle of the wing) ) there is a spinous foramen (foramen spinosum) (Fig. 62), which passes through the artery that supplies the dura mater of the brain. The inner, cerebral, surface (facies cerebralis) is concave, and the outer is convex and consists of two parts: the orbital surface (facies orbitalis) (Fig. 62), involved in the formation of the walls of the orbit, and the temporal surface (facies temporalis) (Fig. 63) , participating in the formation of the wall of the temporal fossa. The large and small wings limit the superior orbital fissure (fissura orbitalis superior) (Fig. 62, 63), through which vessels and nerves penetrate the orbit.

The pterygoid processes (processus pterygoidei) (Fig. 63) extend from the junction of the large wings with the body and are directed downward. Each process is formed by outer and inner plates, fused in front, and diverging behind and limiting the pterygoid fossa (fossa pterygoidea).

The internal medial plate of the pterygoid process (lamina medialis processus pterygoideus) (Fig. 63) takes part in the formation of the nasal cavity and ends in the pterygoid hook (hamulus pterygoideus) (Fig. 63). The outer lateral plate of the pterygoid process (lamina lateralis processus pterygoideus) (Fig. 63) is wider, but less long. Its outer surface faces the infratemporal fossa (fossa infratemporalis). At the base, each pterygoid process is pierced by a pterygoid canal (canalis pterygoideus) (Fig. 63), through which vessels and nerves pass.

The sphenoid bone connects to all the bones of the brain skull.

The temporal bone (os temporale) (Fig. 59) is paired and takes part in the formation of the base of the skull, the lateral wall and the vault. It contains the organ of hearing and balance (see section “Sense Organs”), the internal carotid artery, part of the sigmoid venous sinus, the vestibulocochlear and facial nerves, the trigeminal ganglion, branches of the vagus and glossopharyngeal nerves. In addition, connecting to the lower jaw, the temporal bone serves as a support for the masticatory apparatus. It is divided into three parts: stony, scaly and drum.

The stony part (pars petrosa) (Fig. 65) has the shape of a three-sided pyramid, the apex of which faces anteriorly and medially, and the base, which passes into the mastoid process (processus mastoideus), faces posteriorly and laterally. On the smooth anterior surface of the stony part (facies anterior partis petrosae), near the top of the pyramid, there is a wide depression, which is the site of the adjacent trigeminal nerve - trigeminal depression (impressio trigemini), and almost at the base of the pyramid there is an arcuate eminence (eminentia arcuata) (Fig. 65), formed by the underlying superior semicircular canal of the inner ear. The anterior surface is separated from the internal stony-scaly fissure (fissura petrosquamosa) (Fig. 64, 66). Between the gap and the arcuate elevation there is a vast area - the tympanic roof (tegmen tympani) (Fig. 65), under which lies the tympanic cavity of the middle ear. Almost in the center of the posterior surface of the stony part (facies posterior partis petrosae), the internal auditory opening (porus acusticus internus) is noticeable (Fig. 65), heading into the internal auditory canal. Vessels, facial and vestibulocochlear nerves pass through it. Above and lateral to the internal auditory opening is the subarcuate fossa (fossa subarcuata) (Fig. 65), into which the process of the dura mater penetrates. Even lateral to the opening is the external opening of the vestibular aqueduct (apertura externa aquaeductus vestibuli) (Fig. 65), through which the endolymphatic duct emerges from the cavity of the inner ear. In the center of the rough lower surface (facies inferior partis petrosae) there is an opening leading to the carotid canal (canalis caroticus), and behind it is the jugular fossa (fossa jugularis) (Fig. 66). Lateral to the jugular fossa, a long styloid process (processus styloideus) extends downwards and anteriorly (Fig. 64, 65, 66), which is the point of origin of muscles and ligaments. At the base of this process there is a stylomastoid foramen (foramen stylomastoideum) (Fig. 66, 67), through which the facial nerve exits the cranial cavity. The mastoid process (processus mastoideus) (Fig. 64, 66), which is a continuation of the base of the petrous part, serves as the attachment point for the sternocleidomastoid muscle.

On the medial side, the mastoid process is limited by the mastoid notch (incisura mastoidea) (Fig. 66), and along its inner, cerebral, side there is an S-shaped groove of the sigmoid sinus (sulcus sinus sigmoidei) (Fig. 65), from which to the outer surface of the skull leads to the mastoid foramen (foramen mastoideum) (Fig. 65), which belongs to the non-permanent venous outlets. Inside the mastoid process there are air cavities - mastoid cells (cellulae mastoideae) (Fig. 67), communicating with the cavity of the middle ear through the mastoid cave (antrium mastoideum) (Fig. 67).

The scaly part (pars squamosa) (Fig. 64, 65) has the shape of an oval plate, which is located almost vertically. The outer temporal surface (facies temporalis) is slightly rough and slightly convex, participates in the formation of the temporal fossa (fossa temporalis), which is the origin of the temporal muscle. The inner cerebral surface (facies cerebralis) is concave, with traces of adjacent convolutions and arteries: digital indentations, cerebral eminences and arterial sulcus. Anterior to the external auditory canal, the zygomatic process (processus zygomaticus) rises sideways and forward (Fig. 64, 65, 66), which, connecting with the temporal process, forms the zygomatic arch (arcus zygomaticus). At the base of the process, on the outer surface of the scaly part, there is a mandibular fossa (fossa mandibularis) (Fig. 64, 66), which provides a connection with the lower jaw, which is limited in front by the articular tubercle (tuberculum articularae) (Fig. 64, 66).

The tympanic part (pars tympanica) (Fig. 64) is fused with the mastoid process and the scaly part, and is a thin plate that bounds the external auditory opening and the external auditory canal in front, behind and below.

The temporal bone contains several canals:

- carotid canal (canalis caroticus) (Fig. 67), in which the internal carotid artery lies. It starts from the outer hole on the lower surface of the rocky part, goes vertically upward, then, bending smoothly, passes horizontally and comes out at the top of the pyramid;

- facial canal (canalis facialis) (Fig. 67), in which the facial nerve is located. It begins in the internal auditory canal, goes horizontally forward to the middle of the anterior surface of the petrous part, where, turning at a right angle to the side and passing into the posterior section of the medial wall of the tympanic cavity, it goes vertically down and opens with the stylomastoid foramen;

- the muscular-tubal canal (canalis musculotubarius) (Fig. 66) is divided by a septum into two parts: the semi-canal of the tensor tympani muscle (semicanalis m. tensoris tympani) (Fig. 67), and the semi-canal of the auditory tube (semicanalis tubae auditivae) (Fig. 67), connecting the tympanic cavity with the pharyngeal cavity. The canal opens with an external opening located between the anterior end of the petrous part and the squama of the occipital bone, and ends in the tympanic cavity.

The temporal bone connects to the occipital, parietal and sphenoid bones.

The parietal bone (os parietale) (Fig. 59) is paired, flat, has a quadrangular shape and takes part in the formation of the upper and lateral parts of the cranial vault.

The outer surface (facies externa) of the parietal bone is smooth and convex. The place of its greatest convexity is called the parietal tubercle (tuber parietale) (Fig. 68). Below the tubercle are the superior temporal line (linea temporalis superior) (Fig. 68), which is the attachment point of the temporal fascia, and the inferior temporal line (linea temporalis inferior) (Fig. 68), which serves as the attachment point of the temporal muscle.

The internal, cerebral, surface (facies interna) is concave, with a characteristic relief of the adjacent brain, the so-called digital impressions (impressiones digitatae) (Fig. 71) and tree-like branching arterial grooves (sulci arteriosi) (Fig. 69, 71).

The bone has four edges. The anterior frontal edge (margo frontalis) (Fig. 68, 69) connects to the frontal bone. Posterior occipital margin (margo occipitalis) (Fig. 68, 69) - with the occipital bone. The upper sagittal, or sagittal, edge (margo sagittalis) (Fig. 68, 69) is connected to the edge of the same name of the other parietal bone. The lower scaly edge (margo squamosus) (Fig. 68, 69) is covered in front by the large wing of the sphenoid bone, a little further - by the scales of the temporal bone, and in the back it connects with the teeth and mastoid process of the temporal bone.

Also, according to the edges, four angles are distinguished: frontal (angulus frontalis) (Fig. 68, 69), occipital (angulus occipitalis) (Fig. 68, 69), wedge-shaped (angulus sphenoidalis) (Fig. 68, 69) and mastoid (angulus mastoideus ) (Fig. 68, 69).

The frontal bone (os frontale) (Fig. 59) is unpaired and participates in the formation of the anterior part of the vault and base of the skull, eye sockets, temporal fossa and nasal cavity. It has three parts: the frontal scales, the orbital part and the nasal part.

The frontal scales (squama frontalis) (Fig. 70) are directed vertically and posteriorly. The outer surface (facies externa) is convex and smooth. From below, the frontal scales end with a pointed supraorbital edge (margo supraorbitalis) (Fig. 70, 72), in the medial section of which there is a supraorbital notch (incisura supraorbitalis) (Fig. 70), containing the vessels and nerves of the same name. The lateral section of the supraorbital margin ends with a triangular zygomatic process (processus zygomaticus) (Fig. 70, 71), which connects to the frontal process of the zygomatic bone. An arcuate temporal line (linea temporalis) runs posteriorly and upward from the zygomatic process (Fig. 70), separating the outer surface of the frontal scales from its temporal surface. The temporal surface (facies temporalis) (Fig. 70) is involved in the formation of the temporal fossa. Above the supraorbital margin on each side is the brow ridge (arcus superciliaris) (Fig. 70), which is an arched elevation. Between and just above the brow ridges there is a flat, smooth area - the glabella (glabella) (Fig. 70). Above each arch there is a rounded elevation - the frontal tubercle (tuber frontale) (Fig. 70). The inner surface (facies interna) of the frontal scales is concave, with characteristic indentations from the convolutions of the brain and arteries. In the center of the inner surface there is a groove of the superior sagittal sinus (sulcus sinus sagittalis superioris) (Fig. 71), the edges of which in the lower section unite into the frontal ridge (crista frontalis) (Fig. 71).

The orbital part (pars orbitalis) (Fig. 71) is paired, takes part in the formation of the upper wall of the orbit and has the appearance of a horizontally located triangular plate. The lower orbital surface (facies orbitalis) (Fig. 72) is smooth and convex, facing the orbital cavity. At the base of the zygomatic process in its lateral section there is a fossa of the lacrimal gland (fossa glandulae lacrimalis) (Fig. 72). The medial section of the orbital surface contains the trochlear fossa (fovea trochlearis) (Fig. 72), in which the trochlear spine (spina trochlearis) lies (Fig. 72). The upper cerebral surface is convex, with a characteristic relief.

The nasal part (pars nasalis) (Fig. 70) of the frontal bone in an arc surrounds the ethmoid notch (incisura ethmoidalis) (Fig. 72) and contains pits that articulate with the cells of the labyrinths of the ethmoid bone. In the anterior section there is a descending nasal spine (spina nasalis) (Fig. 70, 71, 72). In the thickness of the nasal part lies the frontal sinus (sinus frontalis), which is a paired cavity separated by a septum, belonging to the air-bearing paranasal sinuses.

The frontal bone connects to the sphenoid, ethmoid and parietal bones.

The ethmoid bone (os ethmoidae) is unpaired and participates in the formation of the base of the skull, the orbit and the nasal cavity. It consists of two parts: a lattice, or horizontal, plate and a perpendicular, or vertical, plate.

The cribriform plate (lamina cribosa) (Fig. 73, 74, 75) is located in the ethmoidal notch of the frontal bone. On both sides of it there is a lattice labyrinth (labyrinthus ethmoidalis) (Fig. 73), consisting of air-bearing lattice cells (cellulae ethmoidales) (Fig. 73, 74, 75). On the inner surface of the ethmoid labyrinth there are two curved processes: the superior (concha nasalis superior) (Fig. 74) and the middle (concha nasalis media) (Fig. 74, 75) nasal turbinates.

The perpendicular plate (lamina perpendicularis) (Fig. 73, 74, 75) is involved in the formation of the septum of the nasal cavity. Its upper part ends with the cock's crest (crista galli) (Fig. 73, 75), to which the large falciform process of the dura mater is attached.

Body of the sphenoid bone, corpus ossis sphenoidalis, the middle part of the bone, cubic in shape, has six surfaces. The upper surface of the body, facing the cranial cavity, has a depression in its middle sections - the sella turcica, sella turcica. in the center of which is the pituitary fossa. It contains the pituitary gland. The size of the fossa is determined by the size of the pituitary gland. The pituitary fossa is especially vulnerable in the case of premature birth. The fusion of the two ossification nuclei of the fossa occurs in the 8th month of intrauterine life. This raises the possibility of damage to the structure of the pituitary fossa with subsequent dysfunction of the pituitary gland. The sella turcica is limited in front by the tubercle of the sella, tuberculum sellae. Posterior to it, on the lateral surface of the saddle, there is a non-constant middle inclined process, processus clinoideus medius. Anterior to the tubercle sella there is a shallow transverse groove of the decussation, sulcus chiasmatis. It lies on the optic chiasm, chiasma opticum. On the sides the groove passes into the optic canal, canalis opticus. In front of the furrow there is a smooth surface - a wedge-shaped eminence, jugum sphenoidale, connecting the small wings of the sphenoid bone. The anterior edge of the upper surface of the body is serrated, protrudes slightly forward and connects with the posterior edge of the perforated plate, lamina cribrosa, ethmoid bone, forming a sphenoethmoidal suture, sutura sphenoethmoidalis. The perforated plate has a large number of holes (25-30), through which the branches of the anterior ethmoidal (olfactory) nerve and the vein accompanying the anterior ethmoidal artery go from the nasal cavity to the cranial cavity (there are olfactory grooves on the sides of the anterior edge of the sphenoid bone). If the sense of smell is impaired or absent, the kinetics of the anterior edge of the sphenoid bone should be checked. As a result of injury to the frontal bone, a violation of the relationship in the sphenoid-ethmoidal suture may occur with subsequent trauma to the olfactory bulbs.

The sella turcica is limited at the back by the back of the saddle, dorsum sellae, which ends on each side with a small posterior inclined process, processus clinoideus posterior. On the sides of the sella turcica, from back to front, runs the carotid groove, sulcus caroticus(imprint of the internal carotid artery located here and the accompanying nerve plexus).

Rice. Sphenoid bone (according to H. Feneis, 1994): 1 – body; 2 – wedge-shaped eminence; 3 – large wing, 4 – small wing; 5 – precross groove; 6 – sella turcica; 7 – pituitary fossa; 8 – anterior inclined process; 9 – posterior inclined process; 10 – back of the saddle; 11 – carotid groove; 12 – wedge-shaped ridge; 13 – wedge-shaped beak; 14 – aperture of the sphenoid sinus; 15 – visual channel; 16 – superior orbital fissure; 17 – brain surface; 18 – temporal surface; 19 – orbital surface; 20 – zygomatic edge; 21 – frontal edge; 22 – parietal edge; 23 – scaly edge; 24 – infratemporal crest; 25 – round hole; 26 – oval hole; 27 – foramen spinosum; 28 – spine of the sphenoid bone; 29 – pterygoid (vidian) canal; 30 – pterygoid process; 31 – lateral plate of the pterygoid process; 32 – medial plate of the pterygoid process; 33 – pterygoid hook; 34 – pterygoid notch; 35 – wedge-shaped surface of sphenobasilar synchondrosis.

The posterior surface of the dorsum sella passes into the upper surface of the basilar part of the occipital bone, forming a slope, clivus. On the slope there is a bridge, medulla oblongata, and basilar artery with its branches. The posterior surface of the body is rough. Through a cartilaginous layer, it connects to the anterior surface of the basilar part of the occipital bone, forming the sphenoid-occipital synchondrosis (SSO), synchondrosis sphenooccipitalis. More often in the osteopathic literature and among osteopaths, another term is found - sphenobasilar symphysis. Despite the existence of the International Nomenclature, the latter anatomical term has taken root and is most common among osteopaths. It is believed that by the age of 25, the cartilage is replaced by bone tissue and the two bones fuse together. However, there is still no consensus on this issue. It is likely that the bones are still not completely fused.

The front and part of the lower surface of the body are facing the nasal cavity. In the middle of the front surface of the body there is a vertically running wedge-shaped crest, crista sphenoidalis. Its anterior edge is adjacent to the posterior edge of the perpendicular plate, lamina perpendicularis, ethmoid bone. The lower segment of the crest is pointed, extended downwards, and forms a wedge-shaped beak, rostrum sphenoidale, which is wedged between the wings of the opener, alae vomeris. On the sides of the ridge lies a thin curved plate - a wedge-shaped shell, concha sphenoidalis. This shell, forming the anterior and partly lower walls of the sphenoid sinus, sinus sphenoidalis, has a small opening - the aperture of the sphenoid sinus, apertura sinus sphenoidalis. Outside the aperture there are small depressions that cover the cells of the posterior part of the labyrinth of the ethmoid bone. The outer edges of these recesses are partially connected to the orbital plate of the ethmoid bone, forming a sphenoethmoidal suture, sutura sphenoethmoidalis, and the lower ones - with the orbital process, processus orbitalis, palatine bone.

sphenoid sinus, sinus sphenoidalis, a paired cavity, fills most of the body of the sphenoid bone and belongs to the air-bearing paranasal sinuses. Both, right and left, sinuses are separated from one another by the septum of the sphenoid sinuses, which anteriorly continues into the sphenoid crest. As in the frontal sinuses, the septum sometimes lies asymmetrically, as a result of which the size of both sinuses may not be the same. Through the aperture, the cavity of each sphenoid sinus opens into the nasal cavity. The cavity of the sphenoid sinus is lined with mucous membrane.

Small wings, alae minores, the sphenoid bone has two roots extending in both directions from the anterior-superior corners of the body in the form of two horizontally located plates, at the base of which there is a rounded hole. It represents the beginning of a bone canal up to 5-6 mm long - the optic canal, canalis opticus. It contains the optic nerve, n. opticus, and ophthalmic artery, a. ophthalmica. The small wings have an upper surface facing the cranial cavity and a lower surface directed into the orbital cavity and closing the superior orbital fissure from above, fissura orbitalis superior. The anterior edge of the lesser wing, thickened and jagged, connects to the orbital part of the frontal bone. The posterior concave and smooth edge protrudes freely into the cranial cavity and is the boundary between the anterior and middle cranial fossae, fossae cranii anterior et media. The medial posterior edge ends in a prominent, well-defined, anterior inclined process, processus clinoideus anterior(a part of the dura mater is attached to it, forming the diaphragm of the sella turcica, diaphragma sellae).

Large wings of the sphenoid bone, alae majores, extend from the lateral surfaces of the body of the sphenoid bone and are oriented outward. The large wing has five surfaces and three edges. Upper, medullary surface facies cerebralis, concave and facing the cranial cavity. It forms the anterior part of the middle cranial fossa and bears sulcal impressions, cerebral eminences and arterial grooves, sulci arteriosi(relief imprints of the adjacent surface of the brain and middle meningeal arteries). At the base of the large wing there are three openings: a round opening is located inwardly and anteriorly, foramen rotundum(the maxillary nerve exits through it, n. maxillaris). Outside and posterior to the round there is an oval foramen, foramen ovale (it passes the mandibular nerve, n. mandibularis, and the vascular network of the foramen ovale). Also lateral and posterior to the foramen ovale is the foramen spinosum, foramen spinosum(the middle meningeal artery, vein and nerve pass through it). Anterosuperior, orbital surface, facies orbitalis, smooth, diamond-shaped, facing the cavity of the orbit, where it forms most of its outer wall. The lower edge of this surface is distant from the posterior edge of the orbital surface of the body of the upper jaw; the inferior orbital fissure is formed here, fissura orbitalis inferior. Anterior, maxillary surface, facies maxillaris, a small triangular-shaped area, limited above by the orbital surface, and on the side and below by the root of the pterygoid process of the sphenoid bone. It is part of the posterior wall of the pterygopalatine fossa, fossa pterygopalatina. There is a round hole on the surface. Superolateral, temporal surface, facies temporalis, somewhat concave, takes part in the formation of the wall of the temporal fossa, fossa temporalis(the temporalis muscle is attached to it, m. temporalis). Below this surface is limited by the infratemporal crest, crista infratemporalis, below which is the surface where the foramen ovale opens, foramen ovale, and the foramen spinosum. It forms the superior wall of the infratemporal fossa, fossa infratemporalis. This is where part of the lateral pterygoid muscle begins, m. pterygoideus lateralis. The upper, frontal, edge is widely serrated, connected to the orbital part of the frontal bone in the sphenoid-frontal suture ( sutura sphenofrontalis). The outer sections of the frontal edge end with a sharp parietal edge, margo parietalis, which with the wedge-shaped angle of the parietal bone forms the sphenoid-parietal suture ( sutura sphenoparietalis). The internal sections of the frontal edge pass into a thin free edge, which is spaced from the lower surface of the lesser wing, limiting the superior orbital fissure from below fissura orbitalis superior. Anterior, zygomatic margin, margo zygomaticus, serrated, connected to the frontal process, processus frontalis, zygomatic bone, forming the sphenoid-zygomatic suture ( sutura sphenozygomatica). Posterior, scaly edge, margo squamosus, connects to the wedge-shaped edge, margo sphenoidalis, temporal bone in the sphenosquamosal suture ( sutura sphenosquamosa). Posteriorly and outwardly, the scaly edge ends with the spine of the sphenoid bone, spina ossis sphenoidalis. Here is the place of attachment of the sphenomandibular ligament, lig. sphenomandibulare, and bundles of the muscle that strains the velum palatine, m. tensor veli palatini. Inward to the spine of the sphenoid bone, the posterior edge of the greater wing lies in front of the petrous part, pars petrosa, temporal bone and limits the sphenoid-petrosal fissure, fissura sphenopetrosa, passing medially into the foramen lacerum, foramen lacerum. This gap is filled with cartilaginous tissue, forming a wedge-shaped petrosal synchondrosis, synchondrosis sphenopetrosa.

Pterygoid processes, processus pterygoidei, extend from the junction of the large wings with the body of the sphenoid bone and are directed downwards. The pterygoid processes are formed by two plates - lateral and medial. Lateral plate, lamina lateralis processus pterygoidei, wider, but thinner and shorter than the inner one (the lateral pterygoid muscle begins from its outer surface, m. pterygoideus lateralis). medial plate, lamina medialis processus pterygoidei, narrower, thicker and slightly longer than the outer one. Both plates grow together with their anterior edges and, diverging posteriorly, limit the pterygoid fossa, fossa pterygoidea(here begins the medial pterygoid muscle, m. pterygoideus medialis). In the lower sections, both plates do not fuse and limit the pterygoid notch, incisura pterygoidea, filled with a pyramidal process, processus pyramidalis, palatine bone. The free end of the inner plate ends with a wing-shaped hook directed downwards and outwards, hamulus pterygoideus, on the outer surface of which there is a groove of the pterygoid hook, sulcus hamuli pterygoidei(the tendon of the muscle that strains the velum palatine is thrown through it, m. tensor veli palatini). The posterior-superior edge of the inner plate at the base expands and forms an oblong scaphoid fossa, fossa scaphoidea(bundles of muscles that strain the velum palatine begin in it, m. tensor veli palatini). Outward from the navicular fossa there is a shallow groove of the auditory tube, sulcus tubae audilivae, which laterally passes onto the greater wing and reaches the spine of the sphenoid bone (the cartilaginous part of the auditory tube is adjacent to this groove). Above the scaphoid fossa and medial from it there is an opening leading to the pterygoid canal, canalis pterygoideus(vessels and nerves pass through it). The canal runs in the sagittal direction in the thickness of the base of the pterygoid process and opens on the maxillary surface of the large wing of the sphenoid bone on the posterior wall of the pterygopalatine fossa. Under the exit opening, along the anterior edge of the pterygoid process, is the pterygopalatine groove. The internal plate at its base gives off an inwardly directed flat horizontally running vaginal process, processus vaginalis, which is located under the body of the sphenoid bone, covering the side of the vomer wing. As a result of this, the groove of the vaginal process facing the wing is the vomerovaginal groove, sulcus vomerovaginalis, turns into the vomerovaginal canal, canalis vomerovaginalis. Outside of the process there is sometimes a small sagittal sulcus running sagittally, sulcus palatovaginalis. In the latter case, the sphenoid process of the palatine bone, adjacent below, closes the groove into the canal of the same name (in both canals there are nerve branches of the pterygopalatine ganglion, and in the palatovaginal canal there are also branches of the sphenopalatine artery). Sometimes the pterygospinous process is directed from the posterior edge of the outer plate towards the spine of the sphenoid bone. processus pterygospinosus, which can reach the specified spine and form a hole.

Sphenoid bone, os sphenoidale, located in the center of the base of the skull.

Functions of the sphenoid bone

It participates in the formation of the lateral walls of the cranial vault, as well as the cavities and fossae of the cerebral and facial parts of the skull.

Structure of the sphenoid bone

The sphenoid bone has a complex shape and consists of a body from which 3 pairs of processes extend: large wings, small wings and pterygoid processes.

Body, corpus, the sphenoid bone has the shape of an irregular cube. Inside it there is a cavity - the sphenoid sinus, sinus sphenoidalis. There are 6 surfaces in the body: the upper, or cerebral; posterior, fused in adults with the basilar (main) part of the occipital bone; the front one, which passes without sharp boundaries into the lower one, and two lateral ones.

Small wing

Ala minor is a paired plate extending from each side of the body of the sphenoid bone with two roots. Between the latter there is the optic canal, canalis opticus, for the passage of the optic nerve from the orbit. The anterior edges of the lesser wings are serrated; the orbital parts of the frontal bone and the cribriform plate of the ethmoid bone are connected to them. The posterior edges of the small wings are free and smooth. On the medial side of each wing there is an anterior inclined process, processus clinoideus anterior. The dura mater of the brain grows to the anterior as well as to the posterior inclined processes.

The lesser wing has an upper surface facing the cranial cavity, and a lower one, participating in the formation of the upper wall of the orbit. The space between the lesser and greater wings is the superior orbital fissure, fissura orbitalis superior. The oculomotor, lateral and abducens nerves (III, IV, VI pairs of cranial nerves) and the optic nerve - I branch of the trigeminal nerve (V pair) pass through it from the cranial cavity to the orbit.

Big wing

Ala major, paired, begins with a wide base from the lateral surface of the body of the sphenoid bone (Fig. 32). At the very base, each wing has three holes. Above the others and anteriorly there is a round opening, foramen rotundum, through which the second branch of the trigeminal nerve passes, in the middle of the wing there is an oval opening, foramen ovale, for the third branch of the trigeminal nerve. The foramen spinosum, foramen spinosum, is smaller in size and is located in the region of the posterior corner of the greater wing. Through this opening, the middle meningeal artery enters the cranial cavity.

The large wing has four surfaces: medullary, orbital, maxillary and temporal. On the brain surface, fades cerebralis, finger-like impressions, impressidnes digitatae, and arterial grooves, sulci arteriosi, are well defined. The orbital surface, fades orbitalis, is a quadrangular smooth plate; part of the lateral wall of the orbit. The maxillary surface, fades maxillaris, occupies a triangular-shaped area between the orbital surface at the top and the base of the pterygoid process at the bottom. On this surface, facing the pterygopalatine fossa, a round opening opens. The temporal surface, fades tempordlis, is the most extensive. The infratemporal crest, crista infratemporalis, divides it into two parts. The upper part is larger, located almost vertically, and is part of the wall of the temporal fossa. The lower part is located almost horizontally and forms the upper wall of the infratemporal fossa.

Pterygoid process

, processus pterygoideus, paired, departs from the body of the sphenoid bone at the origin of the large wing and is directed vertically downward. The medial plate of the process faces the nasal cavity, the lateral plate faces the infratemporal fossa. The base of the process is pierced from front to back by a narrow pterygoid canal, canalis pterygoideus, in which vessels and nerves pass. The anterior opening of this canal opens into the pterygopalatine fossa, the posterior one - on the outer base of the skull near the spine of the sphenoid bone, splina ossis sphenoidalis. The plates of the pterygoid process are distinguished: medial, lamina medlis, and lateral, lamina lateralis. The anterior plates are fused. Posteriorly, the plates of the pterygoid process diverge, forming the pterygoid fossa, fossa pterygoidea. Below, both plates are separated by a pterygoid notch, incisura pterygoidea. The medial plate of the pterygoid process is somewhat narrower and longer than the lateral one and below passes into the pterygoid hook, hamulus pterygoideus.