Sphenoid bone of the skull. Description.

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

Sphenoid bone of the skull - description

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

A distinctive feature of the cerebral (upper) surface is a marked indentation called the “Turkish saddle”. In its very center is the pituitary fossa. It contains the pituitary gland. In front of the recess is a saddle tubercle having a transverse arrangement. The back of the saddle is quite high. The lateral parts of the back form inclined posterior processes. At the base of the back of the “Turkish saddle”, a groove runs from two sides. It is also called the "carotid", as the carotid artery is located in it . On the outside, closer to the back of the carotid groove, there is a wedge-shaped tongue. This tongue helps to turn the furrow into a deep groove. The groove, in conjunction with the apex of the temple bone pyramid, is the limiter of the carotid opening. Through the internal carotid opening, the carotid internal artery exits from the carotid canal into the cranial cavity.

The sphenoid bone, that is, the front of its surface, has an elongated shape and resembles a crest. The crest in the form of an acute keel enters the lower surface, connecting with the ethmoid bone plate. Bone plates of irregular shape are located on the sides of the crest. They limit the openings directed into the airy wedge-shaped cavity. The lateral planes of the wedge-shaped bone pass to the front and bottom into small and large wings.

The small wing is a paired plate extending from the body of the bone to the sphenoid with two processes between which there is an optic canal. The front edges of the small wings look like notches. These edges are connected with the orbital part of the frontal bone and with the plate of the ethmoid bone. The hind margins of small wings are free, their surface is smooth. On each of the wings on the medial side is the anterior process. The dura mater is anteriorly attached to the dura mater.

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

The process is pterygoid (he also paired) moves away from the body of the bone at the beginning of the large wing in a vertical downward direction. There are two plates of the pterygoid process: medial and lateral. The medial plate is directed towards the nasal cavity, and the lateral plate - towards the infratemporal fossa. The plates are spliced ​​in front of each other. The back of the plate diverges, forming a pterygoid fossa. Both plates below are divided by a pterygoid notch. The medial plate is slightly longer and already lateral.

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


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