The 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 lateral walls of the cranial vault, cavities and cavities (cerebral and facial). The sphenoid bone is distinguished by the complexity of its shape. This bone consists of a body with three pairs of processes, wings (large and small), pterygoid processes.

Crowned skull - description

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

A distinctive feature of the cerebral (upper) surface is a noticeable depression called the "Turkish saddle". In its very center is the pituitary fossa. It contains the pituitary gland. In front of the depression there is a saddle bump, which has a transverse arrangement. The back of the saddle is quite high. The lateral parts of the back form the inclined posterior processes. At the base of the back of the "Turkish saddle" on both sides is a groove. It is also called "sleepy", since it contains the carotid artery. 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 tip of the pyramid of the temple bone, is the limb of the carotid opening. Through the internal carotid opening, a carotid inner artery emerges from the carotid canal into the cranial cavity.

The sphenoid bone, that is, the anterior part of its surface, is elongated and resembles a crest. The comb in the form of an acute keel comes to the lower surface, connecting with a plate of bone lattice. On the sides of the ridge are located irregular plates of bone. They restrict the openings directed into the airy wedge-shaped cavity. The lateral planes of the bone are wedge-shaped toward the front and toward the bottom, and they transform into small and large wings.

The small wing is a paired plate that spans from the body of the bone with a wedge-shaped two processes, between which is the visual canal. The leading edges of the small wings are notched. These edges are connected to the orbital part of the frontal bone and to the plate of the lattice bone. The back edges of the wings of small are free, their surface is smooth. On each of the wings on the medial side is the anterior process. To the anterior and posterior processes the hard shell of the brain is incremented.

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 opening, which is located above the others, the branch of the trigeminal nerve passes. In the center of the wing there is an opening for passage of another trigeminal nerve. Through the holes in the zone of the posterior angle of the wing, the meningeal artery penetrates into the skull. The large wing has the following surfaces: temporal, maxillary, ophthalmic and cerebral.

Scaly apical (he Also paired) departs from the body of the bone in the place where the large wing begins, downwards vertically. There are two plates of the pterygoid process: medial and lateral. The medial plate is directed towards the nasal cavity, and the lateral plate is directed towards the pterygoal fossa. The plates in front are fused together. Behind the plate diverge, forming a pterygoid fossa. Both plates below are separated by a pterygoid cutout. The medial plate is slightly longer and already lateral.

The sphenoid bone begins to harden during the ninth week of intrauterine development of the fetus.