Located in the center of the base of the skull. 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. 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 of the sphenoid bone has the shape of an irregular cube. Inside it there is a cavity - the sphenoid sinus. 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.

On the upper (cerebral) surface there is a noticeable depression - the sella turcica. In its center there is a pituitary fossa in which the pituitary gland is located. In front of the recess there is a transversely lying tubercle of the sella. The saddle has a fairly high backrest. The lateral parts of the dorsum sella protrude forward, forming posterior inclined processes. At the base of the back of the saddle on the right and left there is a groove for the internal carotid artery - the carotid groove. Outside and somewhat posterior to the carotid sulcus there is a wedge-shaped tongue, which turns the carotid sulcus into a deep groove. This groove, together with the apex of the pyramid of the temporal bone, limits the internal carotid foramen, through which the internal carotid artery emerges from the carotid canal into the cranial cavity.

The anterior surface of the body of the sphenoid bone is elongated into a small wedge-shaped ridge. The latter continues to the lower surface in the form of a sharp wedge-shaped beak (keel); the wedge-shaped ridge, with its anterior edge, is connected to the perpendicular plate of the ethmoid bone. On the sides of the ridge there are irregularly shaped bone plates - wedge-shaped shells, limiting the opening - the aperture of the sphenoid sinus, leading into the air-bearing sphenoid sinus, most often divided by a septum into two parts.

The lateral surfaces of the body of the sphenoid bone continue anteriorly and inferiorly into the lesser and greater wings.

Small wing It 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, 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. 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. Through it, the oculomotor, lateral and abducens nerves (3, 4, 6 pairs of cranial nerves) and the optic nerve - 1 branch of the trigeminal nerve (5 pair) pass from the cranial cavity into the orbit.

Big wing paired, begins with a wide base from the lateral surface of the body of the sphenoid bone. At the very base, each wing has three holes. Above the others and anteriorly there is a round hole through which the 2nd branch of the trigeminal nerve passes, in the middle of the wing there is an oval hole for the 3rd branch of the trigeminal nerve. The foramen spinosum is smaller in size and is located in the region of the posterior corner of the large wing. Through this hole, the middle meningeal artery penetrates into the cranial cavity. The large wing has four surfaces: medullary, orbital, maxillary and temporal. The cerebral surface has well-defined finger-like impressions and arterial grooves. The orbital surface is a quadrangular smooth plate; part of the lateral wall of the orbit. The maxillary surface occupies a triangular area between the orbital surface above and the base of the pterygoid process below. On this surface, facing the pterygopalatine fossa, a round opening opens. The temporal surface is the most extensive. The infratemporal crest 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 paired, departs from the body of the sphenoid bone at the beginning 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 through which vessels and nerves pass. The anterior opening of this canal opens into the pterygopalatine fossa, the posterior opening - on the outer base of the skull near the spine of the sphenoid bone. The plates of the pterygoid process are distinguished: medial and lateral. The anterior plates are fused. Posteriorly, the plates of the pterygoid process diverge, forming the pterygoid fossa. Below, both plates are separated by a pterygoid notch. The medial plate of the pterygoid process is somewhat narrower and longer than the lateral one and below passes into the pterygoid hook.

Its role is to create the side walls of the cranial vault, fossae and cavities (cerebral and facial). The sphenoid bone has a complex shape. Such a bone consists of a body with three pairs of processes, wings (large and small), and pterygoid processes.

Sphenoid bone of the skull - description

The body of the sphenoid bone externally resembles the irregular shape of a geometric body - a cube. Inside it is the sphenoid sinus (cavity). In addition, the occipital bone has several surfaces, six in total: the medulla, the posterior (in adults it is fused with the main part of the bone, the anterior (it smoothly passes into the lower surface), two laterals.

A distinctive feature of the medullary (upper) surface is a noticeable depression called the sella turcica. In its very center is the pituitary fossa. It contains the pituitary gland. In front of the recess there is a tubercle of the sella, which has a transverse location. The back of the saddle is quite high. The lateral parts of the dorsum form inclined posterior processes. At the base of the back of the “sella turcica” there is a groove on both sides. It is also called “carotid”, since it contains a wedge-shaped uvula located on the outside, closer to the back of the carotid sulcus. This tongue helps transform the furrow into a deep groove. The groove, together with the apex of the temple bone pyramid, is the limiter of the carotid opening. The internal carotid artery emerges from the carotid canal through the internal carotid foramen into the cranial cavity.

The sphenoid bone, that is, the anterior part of its surface, has an elongated shape and resembles a ridge. The ridge in the form of a sharp keel extends onto the lower surface, connecting with the plate of the ethmoid bone. On the sides of the ridge there are irregularly shaped bone plates. They limit the openings directed into the air-bearing wedge-shaped cavity. The lateral planes of the sphenoid bone towards the front and bottom pass into the small and large wings.

Small wing — This is a paired plate extending from the body of the sphenoid bone with two processes, between which the optic canal is located. The anterior edges of the small wings have the appearance of serrations. These edges are connected to the orbital part and to the plate. The posterior edges of the minor wings are free, their surface is smooth. On each of the wings there is an anterior process on the medial side. The dura mater of the brain is attached to the anterior and posterior processes.

Big wing is paired. It begins from a wide base from the lateral surface of the sphenoid body. Each of the wings has three holes at the base. Through one hole, which is located above the others, a branch of the trigeminal nerve passes. In the center of the wing there is an opening for the passage of another. Through the openings in the area of ​​the posterior corner of the wing, the meningeal artery penetrates into the cranium. The large wing has the following surfaces: temporal, maxillary, orbital and medullary.

Pterygoid process(it is also paired) extends vertically from the body of the bone at the beginning of the large wing. There are two plates of the pterygoid process: medial and lateral. The medial plate is directed towards the side and the lateral plate is directed towards the infratemporal fossa. The plates in front are fused together. At the back, the plates diverge, forming a pterygoid fossa. Both plates are separated at the bottom by a wing-shaped notch. The medial plate is slightly longer and narrower than the lateral one.

The sphenoid bone begins to harden in the ninth week of fetal development.

17. Sphenoid bone, its parts, holes, canals and their contents.

Sphenoid bone,os sphenoidale, located in the center of the base of the skull. 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. 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, It is a paired plate extending from each side of the body of the sphenoid bone with two roots. Between the latter is the visual channel, 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 in front there is a round hole, foramen rotundum, through which the second branch of the trigeminal nerve passes, in the middle of the wing there is the foramen ovale, foramen ovale, for the third branch of the trigeminal nerve. Foramen spinosum, foramen spinosum, smaller in size, located in the region of the posterior corner of the large 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 surface of the brain fades cerebralis, finger-shaped impressions are well defined, impressidnes digitatae, and arterial grooves, sulci arteriosi. orbital surface, fades orbitalis, - quadrangular smooth plate; part of the lateral wall of the orbit. maxillary surface, fades maxillaris, occupies a triangular area between the orbital surface above and the base of the pterygoid process below. On this surface, facing the pterygopalatine fossa, a round opening opens. Temporal surface, fades tempordlis, the most extensive. infratemporal crest, crista infratempo- ralis, 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 beginning 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 blood 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, splna 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. At the bottom, 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.

One of the eight bones of the skull, the sphenoid bone has a complex structure. This article contains information about the structure and function of the sphenoid bone.

Do you know that?

The sphenoid bone articulates with all the bones of the skull, which is why it is called the “cornerstone of the skull.”

Of the 206 bones in the human body, 22 bones are found in the skull. Of these 22 bones, 8 are skull bones, the rest are facial bones. The bones of the skull include the frontal bone, 2 parietal bones, occipital bone, sphenoid bone, 2 temporal bones and the ethmoid bone. The sphenoid bone has a rather interesting shape. It is called "Os sphenoidale" in Latin. The words "Sphen" and "eidos" mean "wedge" and "shape" respectively.

Located in the center of the skull, it looks like a bat or butterfly with outstretched wings. One of the structurally complex bones of the human body, the sphenoid bone consists of a middle body, two large wings, two smaller wings, and two pterygoid plates. The main function of the sphenoid bone is that it helps in the formation of the sides of the skull, the base of the brain, as well as the bottom. It also helps in forming the walls of each of the orbits, which are the two cavities containing the eyes. This bone lies in front of the temporal bone and forms the base of the skull, just behind the eye sockets.

Location of the sphenoid bone

Side view of the skull

Bottom view of the skull

Anatomy of the sphenoid bone

In addition to playing an important role in the formation of the integral anatomical structures of the skull, this bone is also important for:

• It acts as an attachment point for the muscles that help us chew food.
• It includes several fissures and openings that have round or oval openings through which the nerves and arteries of the head and neck pass. For example, the ophthalmic nerve passes through the orbital fissure, the maxillary nerve passes through the foramen rotundum, and the mandibular nerve passes through the foramen ovale.
• It also helps in the formation of the lateral cranial vault and fossae (anatomical concavities or depressions that act as an articular surface).

This bone consists of the following structures:

• Two big wings
• Two smaller wings
• Two pterygoid processes

View from the back of the skull

Body median

The body, which is also called the body of the wings, is a sphenoid bone with a cuboidal cross-section, which is located in the center. In general, there are six surfaces, which include the top, bottom and back surfaces on both sides. The body contains the sphenoid sinuses, one of four air-filled cranial cavities that are connected to the nasal cavity. Located on the sides of the body is the carotid groove (canal-like passage) for the internal carotid artery. On the upper surface of the body is the sella turcica, which contains a large cavity for the pituitary gland. The sellae include the square-shaped dorsum sella (posteriorly), tubercle sella (facially), posterior sphenoid, and pituitary fossa (inside the sella turcica). The posterior wedge-shaped extends to the left and right sides of the dorsum of the sella turcica. The posterior and anterior wedge-shaped parts are enclosed in the posterior and anterior walls of the sella turcica around the pituitary gland, respectively. The sphenoid crest (narrow ridge, bone) is located in front of the sphenoid bone and sphenoid concha, which lie on either side of the crest and limit the opening of the sphenoid sinus.

View from the top of the skull

Smaller wings

The lesser wings, also called A minor, are actually the smaller of two flattened, triangular-shaped, pterygoid bone plates that extend along the lateral surface on either side of the body of the sphenoid bone. Beneath them lie pairs of large wings. The optical channels that lead to the orbits of the eyes are located at the base of the small wings. The lesser wings are a tiny part of the medial posterior wall of the orbit, and act with their free edges as a boundary between the anterior and middle cranial fossae. The ribs in the anterior part of the lesser wings connect to the orbital part of the frontal bone, as well as the cribriform plate of the ethmoid bone. The orbital fissure, which is a narrow opening located between the greater and lesser wings, runs diagonally along the back of the orbit. The oculomotor, trochlear, trigeminal and abducens nerves pass through these fissures. The optic nerve and ophthalmic artery pass through the optic canal located along the wings.

Big wings

These bony plates are curved upward, to the side and backward. They help in the formation of the bottom of the skull, as well as the lateral walls of the middle cranium. They have four surfaces. The large wings begin from a wide base on the lateral surface of the body of the sphenoid bone. Each of these wings has four surfaces (brain, orbit, temporal and maxillary). On the surface of the brain, which faces the cranial cavity, lies a round opening called the foramen rotundum, through which the maxillary nerve and branches of the trigeminal nerve pass. The medial foramen, which is the foramen ovale, acts as a passage for the mandibular nerve, an accessory to the meningeal artery, the lesser petrosal nerves. Posterior to the foramen ovale lies the spinosum. The middle meningeal artery and the meningeal branches of the mandibular nerve pass through the spinosum foramina. The orbital surface forms the lateral wall in the corresponding orbit, and the infratemporal surface lies on the temporal surface.

Pterygoid processes

The pterygoid processes are two bony processes that descend down from the junction of the greater wings and the body of the sphenoid bone. At the base of each pterygoid process there runs a pterygoid canal from the back to the front. Each of these processes constitutes a lateral and medial plate. The pterygoid fossa is a cavity or depression that is located between the lateral and medial plates. The lateral pterygoid muscle facilitates the movement of the lower jaw during chewing and is attached to the lateral plate. The muscles involved in swallowing are attached to the medial plate. The hook-shaped extension of the medial pterygoid plates is called the hamulus, which also helps in the process of swallowing.

In conclusion, I would like to note that the complex structure of the sphenoid bone is explained by the fact that it articulates with several bones of the skull. It helps in the formation of the orbits and also serves as an attachment for important muscles that facilitate chewing and swallowing. It also acts as a passageway for important nerves and blood vessels.

Sphenoid bone, os sphenoidale, unpaired, resembles a flying insect, which explains the name of its parts (wings, pterygoid processes).

The sphenoid bone is the product of the fusion of several bones that independently exist in animals, therefore it develops as a mixed bone from several paired and unpaired ossification points, forming 3 parts at the time of birth, which in turn fuse into a single bone by the end of the first year of life.

It has the following parts:

1) body, corpus;

2) big arms, alae majores;

3) small wings,alae minores;

4)pterygoid processes, processus pterygoidei(its medial plate is the former double pterygoid, develops on the basis of connective tissue, while all other parts of the bone arise on the basis of cartilage).

Sphenoid bone. Back view. 1. Visual channel; 2. Saddle back; 3. Posterior inclined process; 4. Anterior inclined process; 5. Small wing; 6. Superior orbital fissure; 7. Parietal angle; 8. Large wing (cerebral surface); 9. Round hole; 10. Pterygoid canal; 11. Scaphoid fossa; 12. Lateral plate (pterygoid process); 13. Pterygoid notch; 14. Groove of the pterygoid hook; 15. Vaginal process; 16. Wedge-shaped ridge; 17. Body of the sphenoid bone; 18. Medial plate (pterygoid process); 19. Wing-shaped hook; 20. Pterygoid fossa; 21. Groove of the internal carotid artery.

Body, corpus, on its upper surface has a depression along the midline - saddle turcica, sella turcica, at the bottom of which lies hole For pituitary gland, fossa hypophysialis.In front of it there is an elevation, tuberculum sellae, along which passes transversely sulcus chiasmatis for cross ( chiasma) optic nerves; at the ends sulcus chiasmatis visible visual channels, canales optici, through which the optic nerves pass from the cavity of the orbits to the cavity of the skull. Posteriorly, the sella turcica is limited by a bony plate, back of the saddle, dorsum sellae. On the lateral surface of the body there is a curved carotid sulcus, sulcus caroticus, trace of the internal carotid artery.

On the anterior surface of the body, which is part of the posterior wall of the nasal cavity, is visible crest, crista sphenoidalis, below entering between the wings of the opener. Christa sphenoidalis connects anteriorly with the perpendicular plate of the ethmoid bone. Irregularly shaped holes are visible on the sides of the ridge, aperturae sinus sphenoidalis, leading to air sinus, sinus sphenoidalis, which is placed in the body of the sphenoid bone and is divided partition, septum sinum sphenoidalium, in two halves. Through these openings the sinus communicates with the nasal cavity. In a newborn, the sinus is of very small size and only around the 7th year of life begins to grow rapidly.

Small wings, alae minores, are two flat triangular plates, which with two roots extend anteriorly laterally from the anterosuperior edge of the body of the sphenoid bone; between the roots of the small wings are the mentioned visual channels, canales optici. Between the lesser and greater wings there is the superior orbital fissure, fissura orbitalis superior, leading from the cranial cavity to the orbital cavity.

Big wings, alae majores, extend from the lateral surfaces of the body laterally and upward. Near the body, behind fissura orbitalis superior available round hole, foramen rotundum, leading anteriorly into the pterygopalatine fossa, caused by the passage of the second branch trigeminal nerve, n. trigemini. At the back, a large wing in the form of an acute angle protrudes between the scales and the pyramid of the temporal bone. There is a foramen spinosum, foramen spinosum, through which it passes a. meningea media. Much more is visible in front of him foramen ovale, foramen ovale, through which the third branch passes n.trigemini.

Large wings have four surfaces: brain,facies cerebralis, orbital,facies orbitalis, temporal, facies temporalis, And maxillary, facies maxillaris. The names of the surfaces indicate the areas of the skull where they face. The temporal surface is divided into the temporal and pterygoid parts by infratemporal crest, crista infritemporalis.

Pterygoid processes, processus pterygoidei extend vertically downward from the junction of the greater wings and the body of the sphenoid bone. Their base is pierced by a sagittal canal, canalis pterygoideus, - the place of passage of the named nerve and vessels. The anterior opening of the canal opens into the pterygopalatine fossa.

Each process consists of two plates - lamina medialis And lamina lateralis, between which a fossa, fossa pterygoidea, is formed at the back.

The medial plate is bent at the bottom crochet, hamulus pterygoideus, through which the tendon that begins on this plate is thrown m. tensor veli palatini(one of the muscles of the soft palate).

Sphenoid bone. Front view. 1. Aperture of the sphenoid sinus; 2. Saddle back; 3. Wedge-shaped shell; 4. Small wing; 5. Superior orbital fissure; 6. Zygomatic edge; 7. Infratemporal surface, 8. Spine of the sphenoid bone; 9. Pterygopalatine groove; 10. Lateral plate; 11. Wing-shaped hook; 12. Medial plate of the pterygoid process; 13. Vaginal process; 14. Wedge-shaped ridge; 15. Pterygoid notch; 16. Pterygoid canal; 17. Round hole; 18. Infratemporal crest; 19. Orbital surface of the greater wing; 20. Temporal surface of the greater wing.

Variants and anomalies

Failure of fusion of the anterior and posterior halves of the body of the sphenoid bone leads to the formation of a narrow, so-called craniopharyngeal canal, in the center of the sella turcica. The foramen ovale and foramen spinosum sometimes merge into one common foramen; the foramen spinosum may be absent.