Sinuses of the dura mater (venous sinuses, sinuses of the brain): anatomy, functions

The brain is the organ that ensures the regulation of all body functions. It is included in the CNS. The study of the brain involved and continues to engage leading scientists and physicians from different countries.

General information

The brain includes 25 billion neurons that form a gray matter. The weight of the organ differs depending on the sex. For example, in men, its mass is about 1375 g, for women - 1245 g. On average, its proportion in the total body weight is 2%. At the same time, scientists have established that the level of intellectual development is not related to the mass of the brain. The mental capacity is affected by the number of connections created by the body. Brain cells are neurons and glia. The former generate and transmit pulses, the latter perform additional functions. There are cavities inside the brain. They are called ventricles. In different parts of the human body, the cranial nerves depart from the organ under consideration. They are paired. A total of 12 pairs of nerves leave the brain. Cover the brain with three shells: soft, hard and spiny. There are spaces between them. In them, the cerebrospinal fluid circulates . It acts as an external hydrostatic medium for the central nervous system, and also provides the excretion of metabolic products. The shells of the brain differ in their structure and in the number of vessels that pass through them. However, they all protect the contents of the upper part of the skull from mechanical damage.

Spiderweights MO

Arachnoidea encephali is separated from the hard shell by the capillary network of subdural space. It does not go into depressions and furrows, like vascular. However, the arachnoid membrane is thrown through them in the form of bridges. As a result, a subarachnoid space is formed that fills the transparent liquid. In some areas, mainly on the basis of the brain, there is a particularly good development of subarachnoid spaces. They form deep and wide receptacles - cisterns. They contain cerebrospinal fluid.

Vascular (soft) MO

Pia mater encephali directly covers the medulla. It is presented in the form of a transparent two-layer plate, which extends into the slits and furrows. In the vascular MO, there are chromatophores - pigment cells. Especially a lot of them are revealed on the basis of the brain. In addition, there are lymphoid, mast cells, fibroblasts, numerous nerve fibers and their receptors. Parts of the soft MO are accompanied by arterial vessels (medium and large), reaching the arterioles. Between their walls and the shell are the spaces of Virchow-Roben. They are filled with cerebrospinal fluid and have a message with a subarachnoid space. Through them elastic and collagen fibrils are thrown. They are hung with vessels, through which conditions are created for their displacement during pulsation without affecting the brain substance.

TMO

It is characterized by a special strength and density. It contains a large number of elastic and collagen fibers. A hard shell is formed with a dense connective tissue.

Features

A hard shell lining the cranial cavity from the inside. Together with this, it acts as its internal periosteum. In the region of the large opening in the occipital part, the TMO passes into the hard shell of the spinal cord. It also forms the perineural vagina for cranial nerves. Penetrating into the holes, the shell fuses with their edges. The connection with the bones of the vault is fragile. The shell is easily separated from them. This causes the possibility of epidural hematomas. In the area of the cranial base, the membrane coalesces with the bones. In particular, strong fusion is noted in the areas of the joints of the elements with each other and the exit of the cranial nerves from the cavity. The inner surface of the membrane is lined with endothelium. This causes its smoothness and pearly shade. In some areas there is a splitting of the shell. Here its outgrowths are formed. They protrude deeply into the cracks that separate parts of the brain. Triangular channels are formed in the areas of the appendages, as well as in the places of attachment to the bones of the inner cranial base. They are also covered with endothelium. These channels are the sinuses of the dura mater.

Sickle

It is considered to be the largest shell process. Sickle penetrates into the longitudinal slot between the left and right hemispheres, not reaching the corpus callosum. It is a thin sickle-shaped curved plate in the form of 2 leaves. In the split base of the appendage, the upper sagittal sinus lies. The opposite edge of the sickle also has a thickening with two petals. In them lies the inferior sagittal sinus.

Connection with the elements of the cerebellum

In front of the sickle it fuses with the cock's comb on the trellised bone. The posterior region of the appendage at the level of the occipital inner ligament is connected to the hint of the cerebellum. He, in turn, hangs over the cranial fossa with a two-tented tent. In it lies the cerebellum. His nametas penetrate into the transverse slit in the large brain. Here it separates the hemispheres of the cerebellum from the occipital lobes. Unevenness is present on the leading edge of the hack. Here, a notch is formed, to which the cerebral trunk lies in front. Lateral sections of the lump grow together with the edges of the sulcus in the posterior sections on the transverse sinus of the occipital bone and with the upper edges of the pyramids on the temporal bones. The joint extends to the posterior processes of the wedge-shaped element in the front parts on each side. In the saggital plane there is a sickle of the cerebellum. Its front edge is free. It divides the hemispheres of the cerebellum. The back of the sickle is located along the occipital inner crest. It runs to the edge of a large hole and covers it with two legs on both sides. At the base of the sickle there is an occipital sinus.

Other elements

In the Turkish saddle a diaphragm is allocated. It is a plate arranged horizontally. In its center is a hole. The plate is stretched over the pituitary fossa and forms its roof. Under the diaphragm is the pituitary gland. It is connected through a hole with the hypothalamus by means of a funnel and a leg. In the area of trigeminal depression near the top of the temporal bone, the dura mater diverges into 2 leaves. They form a cavity in which there is a nerve node (trigeminal).

Sinuses of the dura mater

They are sinuses formed due to the splitting of TMO into two sheets. Sinuses of the brain act as peculiar vessels. Their walls are formed by plates. Sinuses and veins of the brain have a common feature. Their inner surface is lined with endothelium. Meanwhile, the sinuses of the brain and the vessels differ directly in the structure of the walls. In the latter they are elastic and include three layers. When a cut is made, the lumen of the veins falls off. The walls of the sinuses, in turn, are tight. They are formed by a fibrous dense connective tissue, in which elastic fibers are present. With a cut, the lumen of the sinuses gapes. In addition, there are valves in the venous vessels. In the cavity of the sinuses there are several incomplete rails and undulating crossbeams. They are covered with endothelium and are transferred from the wall to the wall. In some sinuses, these elements are distinguished by significant development. There are no muscle elements in the sinus walls. Sinuses of the dura mater have a structure that allows blood to flow unhindered under the influence of its severity, regardless of fluctuations in intracranial pressure.

Kinds

Distinguish the following sinuses of the dura mater:

1. Sinus sagittalis superior. The upper saggital sinus runs along the upper edge of the large sickle, from the cock's crest to the occipital inner ledge.
2. Sinus sagittalis inferior. The lower saginal sinus is located in the thickness of the free edge of the large sickle. It flows into the sinus rectus in the back. The joint is located on the site where the lower edge of the large crescent fuses with the anterior margin of the cerebellar nest.
3. Sinus rectus. A straight sine is located in the cleavage of the nematode along the line of attachment to it of a large sickle.
4. Sinus transversus. The transverse sinus is located at the point of departure of the nerve of the cerebellum from the membrane of the brain.
5. Sinus occipitalis. The occipital sinus lies in the base of the cerebellum sickle.
6. Sinus sigmoideus. The sigmoid sinus is located in the same sulcus on the inner cranial surface. It looks in the shape of the letter S. In the area of the jugular aperture, the sinus passes into the internal vein.
7. Sinus cavernosus. The twin cavernous sinus is located on both sides of the Turkish saddle.
8. Sinus sphenoparietalis. The wedge-parietal sinus adjoins the posterior free area on the small wing of the sphenoid bone.
9. Sinus petrosus superior. The upper stony sine is at the upper edge of the temporal bone.
10. Sinus petrosus inferior. The stony sine of the lower one is between the occipital stump and the pyramid of the temporal bones.

Sinus sagittalis superior

In the anterior sections, the upper sinus anastomoses (connects) to the veins of the nasal cavity. The posterior part runs into the transverse sinus. To the left and to the right of it there are lateral lacunas communicating with it. They are small cavities located between the outer and inner leaves of the TMO. Their number and magnitude are very different. Lacunas communicate with the cavity sinus sagittalis superior. They include vessels of the hard shell and brain, as well as diploic veins.

Sinus rectus

Direct sinus acts as a kind of continuation of sinus sagittalis inferior posterior. It joins the backs of the sinuses superior and inferior. In addition to the upper sinus, a large vein enters the anterior end of the sinus rectus. Behind the sinus falls into the middle part of the sinus transversus. This site is called a sink runoff.

Sinus transversus

This sinus is the largest and widest. On the inside of the scales of the bone of the occiput, it corresponds to a wide furrow. Further sinus transversus passes into a sigmoid sinus. Then he goes to the mouth of the internal jugular vessel. Sinus transversus and Sinus sigmoideus, thus, act as main venous reservoirs. In this case, all other sinuses fall into the first. Some venous sinuses enter into it directly, some - indirectly. On the right and left, the transverse sinus continues in the sinus sigmoideus of the corresponding side. The site where the venous sinuses sagittalis, rectus and occipitalis flow into it, is called drainage.

Sinus cavernosus

Its other name is cavernous sinus. This name he received in connection with the presence of numerous partitions. They give the appropriate structure to the sinus. Through the cavernous sinus pass the leading, ocular, block, oculomotor nerve, as well as the carotid artery (internal) along with the sympathetic plexus. There is a message between the right and left parts of the sinus. It is represented as a posterior and anterior intercellular sinus. As a result, a vascular ring forms in the region of the Turkish saddle . In the cavernous sinus (in its anterior regions) sinus sphenoparietalis empties.

Sinus petrosus inferior

It enters the upper bulb of the jugular (internal) vein. To the sinus petrosus inferior the vessels of the labyrinth are also suitable. Stony sinuses of the hard shell of the brain are connected by several vascular channels. On the basilar surface of the occipital bone, they form the same plexus. It is formed by the fusion of the venous branches of the right and left sinus petrosus inferior. Through the occipital foramen connect the basilar and internal vertebral vascular plexus.

Additionally

In some areas, the sinuses of the membrane form anastomoses with external venous vessels of the head with the help of graduates - emissary veins. In addition, sinuses communicate with diploid branches. These veins are located in the spongy substance in the bones of the cranial arch and flow into the superficial vessels of the head. The blood thus flows along the vascular branches into the sinuses of the TMO. Then it flows into the left and right jugular (internal) veins. Due to anastomosis of the sinuses with diploid vessels, graduates and plexuses, the blood can flow into the superficial networks of the face.

Vessels

A meningeal (middle) artery (branch of the maxillary) approaches the hard membrane through the left and right spinous apertures. In the temporomandibular portion of the TMO, it branches. The shell of the anterior fossa of the skull is supplied with blood from the anterior artery (branch of the larvae from the eye vessel system). In the TMO of the posterior fossa of the skull, the meningeal posterior branch, the branches of the vertebral column and the mastoid branch of the occipital artery branch.

Nerves

The hard shell is innervated by various branches. In particular, branches of the wandering and trigeminal nerves are suitable for it. In addition, innervation is provided by sympathetic fibers. They enter the hard shell in the thickness of the outer wall of the blood vessels. In the area of the cranial fossa, TMO receives sprouts from the optic nerve. Its branch - the tentorial one - provides the innervation of the cerebellar nest and the sickle of the brain. The supply of the cranial middle fossa is due to the meningeal process of the maxillary and part of the mandibular nerves. Most branches lie along the course of the vessels of the shell. In the hint of the cerebellum, however, the situation is somewhat different. There are few vessels, and branches of nerves are located in it independently of them.