The grooves of the sinuses of the dura mater. Dural sinuses (venous sinuses, cerebral sinuses): anatomy, functions

The human brain has a branched and complex circulatory system. Intense arterial blood supply to the nervous tissue ensures its active functional state. The structure of the venous bloodstream is no less important for brain activity. The sinuses of the dura mater act as reservoirs of venous blood, redirecting it from the microvasculature to the venules, and then to the jugular venous system.

Features of cerebral sinuses

The brain, located in the cranium, is covered with an additional case of three shells of varying density and structure. The hard shell is formed by two layers. Of these, the outer leaf is fused to the bone structures of the skull. It plays the role of periosteum. The inner leaflet of the shell is represented by a dense plate of fibrous tissue. The leaves are tightly connected, where they diverge, venous sinuses are formed.

Structural features of venous channels:

Triangular shape. The base of the triangle is the periosteum of the cranial bones, the other two sides are formed by the inner part of the hard shell.
The sinuses are located at the base of the grooves on the inner surface of the cranial bones.
The leaves of the membrane that form the sinuses are strong and tense.
There are no valves in the sinuses, which allows blood to flow freely.
The surface of the periosteum is covered with fibrous cells, and the cavity of the canals from the inside is covered with a thin endothelial layer.

In addition, there are functional features of the venous sinuses. They play the role of blood reservoirs in the veins of the brain. Thanks to them, venous blood freely descends from the brain to the internal jugular veins. Damage to the cerebral veins is quite rare in medical practice, since there is an extensive connecting network between the superficial veins and venous vessels located deep in the brain structures.

Good shunting (venous blood discharge) often saves from congestion. If problems arise in the venous circulatory system, it can be quickly eliminated due to recanalization of the veins and the formation of collaterals.

Channel localization

The sinuses of the dura mater of the brain are classified according to intracranial localization and the presence of intersinus connections. The words “sinus” and “sinus”, as well as “reservoir” are synonymous and mean the same thing.

Superior sagittal sinus

The superior sagittal sinus is characterized by considerable length and complex structure. The falx cerebri is involved in its formation. This is what is called the crescent-shaped plate. It is formed by the dura mater. The process begins from the crest of the ethmoid bone and goes backward along the midline, filling the interhemispheric gap that separates the hemispheres from each other. The groove of the superior sagittal sinus is the base of the falx.

This canal forms numerous lateral lacunae. This is the name given to small cavities that communicate with the venous network of hard leaves.

The superior sagittal sinus is equipped with the following vascular connections:

The anterior sections of the sinus are connected to the veins of the nasal cavity.
The middle sections have a connection with the venous vessels of the parietal lobes of the brain.

This vascular reservoir gradually increases in volume and expands. Its posterior section enters the common sinus drainage.

Inferior sagittal reservoir

The inferior sagittal sinus is referred to in the medical literature as sinus sagittalis inferior. It is so called because it is located in the lower segment of the falx. Compared to the upper sinus, it is much smaller in size. Due to numerous venous anastomoses, it is connected to the straight sinus.

Direct sinus

The straight sinus is located at the junction of the falx and tentorium, which covers the cerebellum. Has a sagittal direction. The great cerebral vein flows into it. The blood flow from it is directed towards the transverse venous sinus.

Transverse sinus

The transverse sinus occupies a wide groove of the same name on the surface of the occipital bone. It is located in the area where the cerebellar tentorium extends from the dura mater. It is the largest of all venous reservoirs and continues into the sigmoid venous sinuses.

Sigmoid venous reservoir

The sigmoid sinus occupies sigmoid grooves on both sides, shaped like the letter S. The external cerebral veins are connected to it. At the level of the jugular foramen, the blood flow from the sigmoid canals is directed into the bed of the internal jugular vein.

Cavernous sinus

The cavernous sinus is localized on the sides of the sella turcica, in appearance it resembles a triangle, in the upper part of which the oculomotor nerve is located, in the lateral part there is a branch of the trigeminal nerve. Its anatomy is distinguished by a large number of internal partitions. This explains its other name - cavernous sinus.

The internal part of the structure is occupied by the abducens nerve. Inside the sinus is a section of the internal carotid artery, surrounded by the sympathetic nerve plexus. Paired ophthalmic venous vessels flow into this canal. The sphenoparietal sinuses of the dura mater are associated with it.

The cavernous sinuses are connected by venous branches running along the contours of the sella turcica. Such complex vascular relationships allow the vessels to form a fairly large sinus surrounding the pituitary gland lying in the center of the sella turcica.

A continuation of this sinus are two venous reservoirs surrounding the temporal pyramids above and below. These are called the superior and inferior petrosal sinuses. Connected by numerous venous vessels, the stony sinuses participate in the formation of the main plexus of venous vessels located in the occipital lobe of the brain.

Occipital venous canal

The occipital sinus is located at the base of the falx and the internal crest of the occipital bones. At the top it is connected to a transverse channel. In the lower section, this sinus is divided into two branches that surround the foramen magnum. They are connected to the right and left sigmoid sinuses. The superficial veins of the brain and the vertebral plexus of veins are connected to the occipital sinus.

The sinuses of the brain create a venous confluence, or drain. In Latin, this reservoir of venous blood is called “confluens sinuum”. It is located in the area of the cruciate eminence inside the occipital bone. The flow of venous blood from all intracranial vessels and reservoirs is directed to the jugular vein.

Thus, the structure of the human cerebral venous system is very complex. All venous channels are in one way or another interconnected not only with each other, but also with other cerebral structures.

Pathology of intracranial sinuses

Diseases of these vascular formations are most often caused by their occlusion, which can be caused by thrombosis, thrombophlebitis, or tumor compression of intracranial vessels.

Inflammatory diseases of brain structures can occur when infectious agents enter the venous blood stream (purulent emboli). The infection can be brought to the membranes of the brain from the superficial venous vessels of the skull. In this case, the development of a clinical picture of acute meningitis and encephalitis is possible. In young children, a picture of neurotoxicosis develops.

Sometimes neurosurgeons may suspect a fracture of the base of the skull when they see a picture of pulsating exophthalmos. When injured, the internal carotid artery associated with the cavernous canal is damaged. A stream of arterial blood, entering the ophthalmic veins associated with this sinus, causes pulsation, severe redness and protrusion of the eyeball. This pathology is otherwise called carotid-cavernous anastomosis, and this is one of the rarest conditions when listening to the head with a phonendoscope allows you to hear the sounds of blood in the area of the anastomosis.

When the walls of the sinus are damaged, a number of neurological symptoms appear due to damage to nearby branches and nuclei of the cranial nerves. With pathology of the cavernous sinus, oculomotor disorders and the development of trigeminal neuralgia may occur.

If the patient suffers from frequent attacks of headaches or intracranial hypertension, the development of reverse (retrograde) blood flow is possible - from the brain cavity to the superficial veins of the skull. Therefore, in children with intracranial hypertension, the pattern of veins on the scalp is clearly visible. Due to the flow of blood, the pressure inside the skull decreases. This is a compensatory mechanism for reducing intracranial pressure.

The cerebral sinuses are an important component of the cerebral venous network. Knowing their functions, structural features and localization, experts can assume the development of pathology in a certain area of the brain. To clarify the diagnosis, magnetic resonance imaging with intravascular injection of a contrast agent is necessary.

In medicine, the term sinus durae matris - sinuses of the dura mater, implies vascular collectors located between the plates of the dura mater. These are peculiar triangular ducts with endothelium on the surface, formed in the splits of the hard layer of the brain. They are supplied with blood from the internal and superficial vessels of the brain, and participate in the reabsorption of cerebrospinal fluid from the cavity between the arachnoid and non-solid medulla.

Functions of sines

There are specific tasks for the venous sinuses. They perform the function of uninterrupted supply of blood and oxygen to the vessels of the brain. It is through them that blood directly flows from the head organ to several double veins located in the neck, which carry blood away from the upper part of the body.

The sinuses of the dura mater perform the functions of blood vessels, and in addition take part in the metabolism of cerebrospinal fluid. The structure is very different from the cerebral vessels.

Successful drainage of blood from the cerebral vessels often saves from the occurrence of fatal pathologies. In cases where difficulties arise in the field of vascular blood circulation, it becomes possible to quickly eliminate it, thanks to the recanalization of blood vessels and the formation of collaterals.

The structure of the sinuses of the solid MO

The development of TMO collectors occurs due to their division into two sheets, which are similar to channels. These ducts are designed to distribute the venous flow of blood from the main human organ, which is subsequently sent to several double vessels that are located in the neck and transfer blood from the brain.

The dura mater plates that make up the sinus look like tightly stretched ropes that do not lose tension. This structure allows blood to flow freely from the head and neck, without in any way affecting the state of intracranial pressure.

The following types of dura mater reservoirs have been established in humans:

Superior or inferior sagittal. The first is located longitudinally along the upper border of the falx bone and ends on the occipital fragment, and the next is longitudinally along the border of the falx below and flows into the straight sinus;
Straight. It is located longitudinally of the fragment, where the falciform process passes into the cerebellar tentorium;
Transverse (double). Formed on the transverse growth of the skull, located longitudinally along the posterior border of the cerebellar groove;
Occipital. It is located in the cavity of the cerebellar arch, and then extends to the occipital junction;
Sigmoid. Located in the division in the ventral fragment of the head bone tissue;
Cavernous (double). Located on the sides of the wedge-shaped bone formation in the body ();
Sphenoparietal sinus (double). Refers to a small wedge-shaped border of bone and ends in a cavernous reservoir.

Stony (double). Located close to both borders of the pyramidal bone of the temples.

The collectors of the medulla begin to collect anastomoses with venous vessels on the surface of the brain, through venous branches that connect the vascular sinuses of the dura mater with the external circulatory vessels of the head. These depressions begin to communicate with the diploic processes, which are typically located in the cranial vault and then pass into the vessels of the head. Then the blood tends to pass through the venous plexuses and then flows into the dura mater reservoirs.

Types of dura sinuses

Nature very thoughtfully created humans, providing the dura mater with indentations to provide the main organ with oxygen and nutritional compounds.

Superior sagittal sinus

This cranial sinus is characterized by a large space with a complex structure. The sickle of the main human organ takes a significant part in its development. This is a crescent leaf. It is made of dura mater. The process originates from the top of the ethmoid bone, passes in the middle back, penetrating into the interhemispheric foramen, separating the brain regions from each other. The groove-like growth of the superior sagittal sinus is essentially the base of the falx bone.

This duct provides numerous lacunae on the sides. These are small cavities that are connected to a venous network of strong plates.

The superior sagittal reservoir has the following venous connections:

the anterior parts belong to the vessels of the labial cavity (near the nose);
the middle parts belong to the venous beds of the parietal fragments of the brain.

As a person grows, this collector of arteries and veins becomes larger and wider in terms of mass capacity. Its posterior fragment protrudes into the combined sinus drain.

Inferior sagittal sinus

This cistern of the structure of the cranium is presented in medical annals as sinus sagittalis inferior. It was so named because it is located in the lower location of the cerebral arch. Compared to the upper reservoir, it has a significantly small volume. Thanks to the large number of venous anastomoses, it is attached to the rectum.

Direct sine

This fragment of the skull is, in fact, the so-called continuation of the lower cistern from the rear side. It connects the rear sections of the superior tanks and the lower manifold. Along with the upper one, a large vessel is included in the anterior part of the nondual sinus. The posterior section of the cavity flows into the median fragment of the double descending duct, which developed due to the divergence of the dura mater of the skull, which is located in the groove of the hard tissue of the back of the head, extended laterally and towards the bottom, attached to the sinus. This fragment is called the sine drain.

Sigmoid venous sinus

This reservoir is the most significant and extensive. On the surface inside the scales of the occipital bone tissue, it is presented in a large groove. The venous reservoir then flows into the sigmoid sinus. Then it goes deeper into the mouth of the largest vessel, which carries out venous drainage from the head. Thus, the transverse sinus and sigmoid sinus are characterized as the main venous reservoirs. In addition, all other pockets go into the first one. Some vein sinuses are included in it directly, some through a smooth transition. On the temporal sides, the transverse recess continues with the sigmoid recess of the proper side. The place where the venous expansions of the sagittal, rectal and occipital sinuses are included in it is called the common drain.

Cavernous reservoir

It acquired this name because it has a large number of partitions. They provide the reservoir with an appropriate structure. The abducens, ophthalmic, trochlear nerve fibers that move the eyes, and in addition the carotid artery (which is inside) along with the sympathetic intertwining (autonomic nerves in the thoracolumbar region) are stretched through the cavernous sinus. Between the right and left localizations of space there are communicative connections. They are provided in the posterior and anterior intercavernous. Accordingly, a venous ring develops in the location of the sella turcica. The cavernous sinus (its flanking fragments) passes into the space of the sphenoid-parietal sinus, which lies on the border of the small branch of the bone in the form of a wedge.

Occipital venous sinus

The occipital cistern is located at the base of the arch and the upper part of the occipital region located inside. From above it refers to the transverse duct. At the bottom, this pocket is divided into two branches that encircle the joint at the back of the head. They are interconnected by sigmoid sinuses on both sides. The superficial veins of the main human organ and the veins and vessels of the spine are related to the occipital space.

Violations of structures

Pathologies of these choroid plexuses arise due to their blockage, which in turn is provoked by thrombosis, thrombophlebitis or compressive neoplasm of intracranial veins and arteries.

Inflammation of the structures of the main human organ can appear when infectious agents penetrate into the bloodstream (all kinds of unconnected vascular substrate, solid, liquid or vapor, circulating through the bloodstream, uncharacteristic in a normal state, capable of provoking blockage of an artery at a fairly large distance from the site of occurrence). The pathological agent can enter the meninges and vascular beds of the head bone tissue on its surface . In this case, symptoms of peak manifestation and other pathologies are likely to appear. In preschool children, a picture of neuropoisoning appears.

In some cases, neurosurgeons can determine damage to the base of the skull by seeing signs of intense exophthalmos. When a fracture occurs, the integrity of the internal carotid artery, which is in contact with the cavernous duct, is disrupted. The flow of venous blood, penetrating into the ophthalmic veins related to this reservoir, provokes pulsation, obvious hyperemia and protrusion of the apple of the optic organ. This deviation is otherwise called the carotid-cavernous anastomosis, and this is one of the extremely rare pathologies when listening to the skull with a phonendoscope makes it possible to hear the noise of blood flow in the area where the vessels join.

The main recommendation of doctors is a timely visit to a specialist to clarify the picture and nature of symptomatic manifestations. As well as preventing mechanical head injuries and protection from external factors, such as weather conditions.

Prevention of brain diseases is possible only if you visit a doctor and get rid of chronic diseases, in particular those that are associated with an increase in the viscosity of hemostasis or stratification of the walls of blood vessels. In addition, it is necessary to treat infectious pathologies in a timely manner; they are the ones that mostly cause deviations.

This article is about venous sinuses and blood flow through them. I will try to reproduce the explanation, after which I myself began to understand them a little, being a listener.

Rice. Volumetric reconstruction of the venous sinuses of the dura mater.

The volumetric course of these venous channels is difficult to project onto any one plane. Let's approach the sines from several projections. Let's start from the base of the skull from the cavernous sinuses.

The main tributaries of the cavernous sinus are:

veins of the orbit,
sphenoparietal sinus,
superficial middle veins of the brain.

Outflow of venous blood from the cavernous sinus:

superior petrosal sinus,
inferior petrosal sinus,
pterygoid plexus.

The sinus is paired and is located at the base of the skull on the sides of the sella turcica. The sinus contains many connective tissue septa that divide the sinus cavity into a number of separate interconnected cavities, like the corpus cavernosum.

Rice. View from above. The cavernous sinus is marked with blue dots.

Rice.Side view. The cavernous sinus is marked in blue in the bottom picture. FR - foramen rotundum, CC - foramen lacerum, Se - sella turcica, SOF - superior foramen lacerum, ICA - carotid artery (its cavernous segment).

Rice. Front view. The picture shows a frontal section through the cavernous sinus (blue). The cavernous part of the internal carotid artery, or arteria carotis interna (red) and the surrounding sympathetic fibers pass through the sinus. In addition, cranial nerves (yellow) pass through the walls of the sinus: oculomotor nerve, trochlear nerve, orbital nerve (first branch of the trigeminal nerve), maxillary nerve (second branch of the trigeminal nerve), abducens nerve.

Rice. In the frontal plane, the cavernous sinus projects into the area between the orbits.

Main tributaries of the cavernous sinus.

Rivers through which venous blood fills the lake of the cavernous sinus.

Superior and inferior ophthalmic veins

There are two orbital veins: superior and inferior. Superior ophthalmic vein, v. ophthalmica superior leaves the orbit through superior orbital fissure into the cranial cavity, where it flows into the cavernous sinus. The inferior ophthalmic vein anastomoses with the superior ophthalmic vein and divides into two branches. The superior branch passes through the superior orbital fissure into the cranial cavity and joins the cavernous sinus.

Rice. The orbital veins drain into the cavernous sinus.

The inferior branch leaves the orbit through the inferior orbital fissure and enters the deep vein of the face, v. faciei profunda.

Rice. The superior and inferior ophthalmic veins drain into the cavernous sinus.

The sinus descends along the cranial vault along the coronal suture and passes under the sphenoparietal suture. Next, the sinus passes from the cranial vault to the free edge of the small wings of the sphenoid bone, following them in the medial direction until it flows into the cavernous sinus.

Rice. The sphenoparietal sinuses are shown by arrows.

Superficial middle veins of the brain.

The middle (Sylvian) veins drain into the cavernous and sphenoparietal sinuses. The middle veins provide drainage from the anterior superior parts of the temporal lobes and the posterior parts of the inferior frontal gyri.

Rice. The diagram shows the superficial venous system of the cerebral hemispheres (according to Bailey). The middle cerebral vein, which flows into the cavernous sinus, is marked in blue.
1 - vein of Trolard; 2 - veins of the Rolandic groove; 3 - Labbe vein; 4 - middle cerebral vein; 5 - anastomosis between the branches of the frontal veins and the branches of the middle cerebral vein.

Pterygoid plexus

The venous pterygoid plexus is located between the pterygoid muscles.
The cavernous sinus is connected by a series of anastomoses with the venous pterygoid plexus. The outflow of venous blood from the cranial cavity into the pterygoid plexus occurs through anastomoses passing through the lacerated, oval and Vesalian (if present) foramina of the base of the skull.

Rice. In the center of the picture at the top is the cavernous sinus. Its relationship with the pterygoid plexus is visible.

The middle meningeal veins are such anastomoses that carry venous blood from the cranial cavity to the outside. So, vv. meningeae mediae accompany the artery of the same name, connect along the way with the sphenoid-parietal sinus and, leaving the cranial cavity through the foramen spinosum, flow into the pterygoid (venous) plexus.

Rice. The pterygoid plexus is the venous network in the center of the picture. The plexus is connected to the deep facial vein (Fac) and the maxillary vein (Max), which in turn drain into the internal jugular vein.

In addition to connections with the cranial cavity, blood flows into the pterygoid plexus from the nasal cavity through the sphenopalatine vein, from the temporal fossa through the deep temporal veins, and from the masticatory muscles through the masticatory veins.

Intercavernous sinus

The right and left cavernous sinuses are connected to each other by two transverse anastomoses: the anterior and posterior intercavernous, or intercavernous sinuses, or sinus intercavernosi.

Rice. Anterior and posterior intercavernous, or intercavernous sinuses, orsinus intercavernosi are located between the cavernous sinuses.

Due to this, a closed ring of venous cavities is formed around the sella turcica.

Rice. The photograph of the specimen shows the anterior (SICS) and posterior (IICS) intercavernous sinuses, flanked by the carotid arteries.

The outflow of blood from the cavernous sinuses occurs in the dorsal direction along the superior and inferior petrosal sinuses.

The superior petrosal sinuses originate in the posterior part of the cavernous sinus, pass along the upper edge of the pyramid of the temporal bone and empty into the sigmoid sinus.

Rice. The superior petrosal sinuses are marked with arrows. They start from the cavernous sinus (marked with blue dots), pass along the upper edge of the pyramid of the temporal bone and flow into the sigmoid sinus.

Rice. The inferior stony sinuses run along the slope backwards and downwards (marked by arrows), flow into the internal jugular veins (marked by circles) of the corresponding side.

In the posterior cranial fossa, the foramen magnum is surrounded by a venous ring, similar to the venous rings of the spinal canal. This unpaired plexus, called the main one, connects in front with the cavernous sinuses, and on the sides with the lower stony sinuses. In addition to the connections described, the main plexus also communicates with the venous plexuses of the spinal canal and through the occipital sinus with the transverse sinus.

This concludes the first part about sines.

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Sinuses of the dura mater, sinus durae matris , are a kind of venous vessels, the walls of which are formed by sheets of the dura mater of the brain.

What the sinuses and venous vessels have in common is that both the inner surface of the veins and the inner surface of the sinuses are lined with endothelium.

The difference lies primarily in the structure of the walls. The wall of the veins is elastic, consists of three layers, their lumen collapses when cut, while the walls of the sinuses are tightly stretched, formed by dense fibrous connective tissue with an admixture of elastic fibers, the lumen of the sinuses gapes when cut.

In addition, the venous vessels have valves, and in the cavity of the sinuses there is a number of endothelium-covered fibrous crossbars and incomplete septa that spread from one wall to another and reach significant development in some sinuses. The walls of the sinuses, unlike the walls of the veins, do not contain muscle elements.

1. Superior sagittal sinus, sinus sagittalis superior, has a triangular lumen and runs along the upper edge of the falx cerebri (a process of the dura mater of the brain) from the cock's crest to the internal occipital protuberance. It most often flows into the right transverse sinus, sinus transversus dexter. Along the course of the superior sagittal sinus, small diverticula emerge - lateral lacunae, lacunae laterales.

2.Inferior sagittal sinus, sunus sagittalis inferior, stretches along the entire lower edge of the falx cerebri. At the lower edge of the falx it flows into the straight sinus, sinus rectus.

3. Direct sinus, sinus rectus, located along the junction of the falx cerebrum with the tentorium cerebellum. Has the shape of a quadrangle. Formed by the sheets of dura mater of the tentorium cerebellum. The straight sinus runs from the posterior edge of the inferior sagittal sinus to the internal occipital protuberance, where it flows into the transverse sinus, sinus transversus.

4. Transverse sinus, sinus transversus, paired, lies in the transverse groove of the skull bones along the posterior edge of the tentorium of the cerebellum. From the area of the internal occipital protrusion, where both sinuses widely communicate with each other, they are directed outward, to the area of the mastoid angle of the parietal bone. Here each of them passes into the sigmoid sinus, sinus sigmoideus, which is located in the groove of the sigmoid sinus of the temporal bone and through the jugular foramen passes into the superior bulb of the internal jugular vein.

5.Occipital sinus, sinus occipitalis, passes in the thickness of the edge of the cerebellar falx along the internal occipital crest, from the internal occipital protuberance to the foramen magnum. Here it splits into marginal sinuses, which bypass the foramen magnum on the left and right and flow into the sigmoid sinus, less often - directly into the superior bulb of the internal jugular vein.

The sinus drain, confluens sinuum, is located in the area of the internal occipital protrusion. Only in a third of cases are the following sinuses connected here: both sinus transversus, sinus sagittalis superior, sinus rectus.

6. Cavernous sinus, sinus cavernosus, paired, lies on the lateral surfaces of the body of the sphenoid bone. Its lumen has the shape of an irregular triangle.

The name of the sinus “cavernous” is due to the large number of connective tissue septa that penetrate its cavity. In the cavity of the cavernous sinus lie the internal carotid artery, a. carotis interna, with the surrounding sympathetic plexus, and the abducens nerve, n. abducens.

In the outer superior wall of the sinus pass the oculomotor nerve, n. oculomotorius, and trochlear, n. trochlearis; in the outer lateral wall - optic nerve, n. ophthalmicus (first branch of the trigeminal nerve).

7. Intercavernous sinuses, sinus intercavernosi, located around the sella turcica and pituitary gland. These sinuses connect both cavernous sinuses and form a closed venous ring with them.

8.Sphenoparietal sinus, sinus sphenoparietalis, paired, located along the small wings of the sphenoid bone; drains into the cavernous sinus.

9. Superior petrosal sinus, sinus petrosus superior, paired, lies in the superior stony groove of the temporal bone and comes from the cavernous sinus, reaching the sigmoid sinus with its posterior edge.

10. Inferior petrosal sinus, sinus petrosus inferior, paired, lies in the lower stony groove of the occipital and temporal bones. The sinus runs from the posterior edge of the cavernous sinus to the superior bulb of the internal jugular vein.

11. Basilar plexus, plexus basilaris, lies in the area of the slope of the sphenoid and occipital bones. It looks like a network that connects both cavernous sinuses and both inferior petrosal sinuses, and below it connects with the internal vertebral venous plexus, plexus venosus vertebralis internus.

The dural sinuses receive the following veins: veins of the orbit and eyeball, veins of the inner ear, diploic veins and veins of the dura mater, veins of the cerebrum and cerebellum.

This shell is particularly dense and contains a large number of collagen and elastic fibers. The dura mater of the brain lines the inside of the cranial cavity, and at the same time is the periosteum of the inner surface of the bones of the cerebral part of the skull. The hard shell of the brain is loosely connected to the bones of the vault (roof) of the skull and is easily separated from them. In the area of the base of the skull, the shell is firmly fused with the bones. The hard shell surrounds the cranial nerves emerging from the brain, forming their sheaths and fused with the edges of the openings through which these nerves leave the cranial cavity.

At the inner base of the skull (in the region of the medulla oblongata), the dura mater of the brain fuses with the edges of the foramen magnum and continues into the dura mater of the spinal cord. The inner surface of the dura mater, facing the brain (towards the arachnoid), is smooth and covered with flat cells. In some places, the dura mater of the brain is split. Its inner leaf (duplication) is deeply indented in the form of processes into the cracks that separate parts of the brain from each other. In places where the processes arise (at their base), as well as in areas where the dura mater is attached to the bones of the internal base of the skull, in the splits of the dura mater of the brain, triangular-shaped channels lined with endothelium are formed - the sinuses of the dura mater (sinus durae matris)

The largest process of the dura mater of the brain is located in the sagittal plane and penetrating into the longitudinal fissure of the cerebrum between the right and left hemispheres of the falx cerebri, or large falx cerebri. This is a thin sickle-shaped plate of the dura mater, which penetrates in the form of two sheets into the longitudinal fissure of the cerebrum. Without reaching the corpus callosum, this plate separates the right and left hemispheres of the cerebrum from each other. In the split base of the falx cerebri, which in its direction corresponds to the groove of the superior sagittal sinus of the cranial vault, lies the superior sagittal sinus. In the thickness of the free edge of the falx cerebri, between its two layers there is the inferior sagittal sinus. In front, the falx cerebri is fused with the cock's crest of the ethmoid bone. The posterior part of the falx at the level of the internal occipital protrusion fuses with the tentorium of the cerebellum. Along the line of fusion of the posteroinferior edge of the falx cerebellum and the tentorium cerebellum, in the fissure of the dura mater of the brain, there is a straight sinus connecting the inferior sagittal sinus with the superior sagittal, transverse and occipital sinuses.

The tentorium (tentorium cerebelli) hangs in the form of a gable tent over the posterior cranial fossa, in which the cerebellum lies. Penetrating into the transverse fissure, the tentorium cerebellum separates the occipital lobes of the cerebrum from the cerebellar hemispheres. The anterior margin of the tentorium cerebellum is uneven. It forms a notch of the tentorium (incisura tentorii), to which the brain stem is adjacent in front.

The lateral edges of the tentorium cerebellum are fused with the upper edge of the pyramids of the temporal bones. Posteriorly, the tentorium of the cerebellum passes into the dura mater of the brain, lining the inside of the occipital bone. At the site of this transition, the dura mater of the brain forms a split - the transverse sinus, adjacent to the groove of the same name in the occipital bone.

The cerebellar falx, or small falx cerebelli, like the falx cerebellum, is located in the sagittal plane. Its anterior edge is free and penetrates between the cerebellar hemispheres. The posterior edge (base) of the falx cerebellum continues to the right and left into the dura mater of the brain from the internal occipital protuberance above to the posterior edge of the foramen magnum below. The occipital sinus forms at the base of the falx cerebellum.

Diaphragm (Turkish) sella

(diaphragma sellae) is a horizontal plate with a hole in the center, stretched over the pituitary fossa and forming its roof. The pituitary gland is located in the fossa under the diaphragm of the sella. Through an opening in the diaphragm, the pituitary gland is connected to the hypothalamus using a funnel.

The sinuses (sinuses) of the dura mater of the brain, formed by splitting the shell into two plates, are channels through which venous blood flows from the brain into the internal jugular veins.

The sheets of hard shell that form the sinus are stretched tightly and do not collapse. Therefore, the sinuses gape on the cut. Sinuses do not have valves. This structure of the sinuses allows venous blood to flow freely from the brain, regardless of fluctuations in intracranial pressure. On the inner surfaces of the skull bones, at the locations of the sinuses of the dura mater, there are corresponding grooves. The following sinuses of the dura mater of the brain are distinguished.

The superior sagittal sinus (sinus sagittalis superior) is located along the entire outer (upper) edge of the falx cerebri, from the crest of the ethmoid bone to the internal occipital protuberance. In the anterior sections, this sinus has anastomoses with the veins of the nasal cavity. The posterior end of the sinus flows into the transverse sinus. To the right and left of the superior sagittal sinus there are lateral lacunae (lacunae laterales) communicating with it. These are small cavities between the outer and inner layers (sheets) of the dura mater of the brain, the number and size of which are very variable. The cavities of the lacunae communicate with the cavity of the superior sagittal sinus; the veins of the dura mater of the brain, the cerebral veins and the dyshuic veins flow into them.
The inferior sagittal sinus (sinus sagittalis inferior) is located in the thickness of the lower free edge of the falx cerebri. It is significantly smaller than the top one. With its posterior end, the inferior sagittal sinus flows into the straight sinus, into its anterior part, in the place where the lower edge of the falx cerebellum fuses with the anterior edge of the tentorium cerebellum
The straight sinus (sinus rectus) is located sagittally in the splitting of the tentorium cerebellum along the line of attachment of the falx cerebellum to it. The straight sinus connects the posterior ends of the superior and inferior sagittal sinuses. In addition to the inferior sagittal sinus, the great cerebral vein drains into the anterior end of the straight sinus. At the back, the straight sinus flows into the transverse sinus, into its middle part, called the sinus drainage. The posterior part of the superior sagittal sinus and the occipital sinus also flow here.
The transverse sinus (sinus transversus) lies at the point where the tentorium cerebellum departs from the dura mater of the brain. On the inner surface of the squama of the occipital bone, this sinus corresponds to a wide groove of the transverse sinus. The place where the superior sagittal, occipital and straight sinuses flow into it is called sinus drainage (confluens sinuum, confluence of sinuses). On the right and left, the transverse sinus continues into the sigmoid sinus of the corresponding side.
The occipital sinus (sinus occipitalis) lies at the base of the cerebellar falx. Descending along the internal occipital crest, this sinus reaches the posterior edge of the foramen magnum, where it divides into two branches, covering the back and sides of this foramen. Each of the branches of the occipital sinus flows into the sigmoid sinus on its side, and the upper end into the transverse sinus.
The sigmoid sinus (sinus sigmoideus) is paired, located in the groove of the same name on the inner surface of the skull, and has an S-shape. In the area of the jugular foramen, the sigmoid sinus passes into the internal jugular vein.
The cavernous sinus (sinus cavernosus) is paired, located at the base of the skull on the side of the sella turcica. The internal carotid artery and some cranial nerves pass through this sinus. The sinus has a very complex structure in the form of caves communicating with each other, which is why it got its name. Between the right and left cavernous sinuses there are communications (anastomoses) in the form of anterior and posterior intercavernous sinuses (sinus intercavernosi), which are located in the thickness of the diaphragm of the sella turcica, in front and behind the pituitary infundibulum. The sphenoparietal sinus and the superior ophthalmic vein flow into the anterior parts of the cavernous sinus.
The sphenoparietal sinus (sinus sphenoparietalis) is paired, adjacent to the free posterior edge of the lesser wing of the sphenoid bone, in the split it is attached here by the dura mater of the brain.
The superior and inferior petrosal sinuses (sinus petrosus superior et sinus petrosus inferior) are paired, located along the upper and lower edges of the pyramid of the temporal bone. Both sinuses take part in the formation of pathways for the outflow of venous blood from the cavernous sinus to the sigmoid sinus. The right and left inferior petrosal sinuses are connected by several veins lying in the cleft of the dura in the area of the body of the occipital bone, which are called the basilar plexus. This plexus connects through the foramen magnum to the internal vertebral venous plexus.

In some places, the sinuses of the dura mater of the brain form anastomoses with the external veins of the head using emissary veins - graduates (vv. emissariae). In addition, the sinuses of the dura mater have communications with diploic veins (vv. diploicae), located in the spongy substance of the bones of the calvarium and flowing into the superficial veins of the head. Thus, venous blood from the brain flows through the systems of its superficial and deep veins into the sinuses of the dura mater of the brain and further into the right and left internal jugular veins.

In addition, due to the anastomoses of the sinuses with diploic veins, venous graduates and venous plexuses (vertebral, basilar, suboccipital, pterygoid, etc.), venous blood from the brain can flow into the superficial veins of the head and neck.

Vessels and nerves of the dura mater of the brain

Approaches the dura mater of the brain through the right and left spinous foramina middle meningeal artery(branch of the maxillary artery), which branches in the temporo-parietal part of the membrane. The dura mater of the brain lining the anterior cranial fossa is supplied with blood by branches anterior meningeal artery(branch of the anterior ethmoidal artery from the ophthalmic artery). In the shell of the posterior cranial fossa they branch posterior meningeal artery - a branch of the ascending pharyngeal artery from the external carotid artery, penetrating into the cranial cavity through the jugular foramen, as well as meningeal branches from the vertebral artery and mastoid branch from the occipital artery, entering the cranial cavity through the mastoid foramen.

The veins of the pia mater of the brain drain into the nearest sinuses of the dura mater, as well as into the pterygoid venous plexus.

The dura mater of the brain is innervated by the branches of the trigeminal and vagus nerves, as well as by sympathetic fibers entering the shell in the thickness of the adventitia of blood vessels. In the region of the anterior cranial fossa, it receives branches from the optic nerve (the first branch of the trigeminal nerve). The branch of this nerve is tentorial(shell) branch- also supplies the tentorium cerebellum and the falx cerebellum. The middle meningeal branch from the maxillary nerve, as well as a branch from the mandibular nerve (corresponding to the second and third branches of the trigeminal nerve), approach the shell in the middle medullary fossa.

Arachnoid membrane of the brain

The arachnoid membrane of the brain (arachnoidea mater encephali) is located medially from the dura mater of the brain. The thin, transparent arachnoid membrane, unlike the soft membrane (vascular), does not penetrate into the cracks between individual parts of the brain and into the sulci of the hemispheres. It covers the brain, moving from one part of the brain to another, and lies over the grooves. The arachnoid is separated from the soft membrane of the brain by the subarachnoid space (cavitas subaracnoidalis), which contains cerebrospinal fluid. In places where the arachnoid membrane is located above wide and deep grooves, the subarachnoid space is expanded and forms subarachnoid cisterns of greater or lesser size (cisternae subarachnoideae).

Above the convex parts of the brain and on the surface of the convolutions, the arachnoid and pia mater are tightly adjacent to each other. In such areas, the subarachnoid space narrows significantly, turning into a capillary gap.

The largest subarachnoid cisterns are the following.

The cerebellar cistern (cisterna cerebellomedullaris) is located in the recess between the medulla oblongata ventrally and the cerebellum dorsally. At the back it is limited by the arachnoid membrane. This is the largest of all tanks.
The cistern of the lateral fossa of the cerebrum (cisterna fossae lateralis cerebri) is located on the inferolateral surface of the cerebral hemisphere in the fossa of the same name, which corresponds to the anterior sections of the lateral sulcus of the cerebral hemisphere.
The chiasm cistern (cisterna chiasmatis) is located at the base of the brain, anterior to the optic chiasm.
The interpeduncular cistern (cisterna interpeduncularis) is determined in the interpeduncular fossa between the cerebral peduncles, downward (anterior) from the posterior perforated substance.

The subarachnoid space of the brain in the region of the foramen magnum communicates with the subarachnoid space of the spinal cord.

Cerebrospinal fluid

Cerebrospinal fluid (liquor cerebrospinalis), formed in the ventricles of the brain, is poor in protein substances and lacks cells. The total amount of this liquid is 100-200 ml. It is produced by the choroid plexuses of the lateral, third and fourth ventricles from their blood capillaries. The walls of blood capillaries, the basement membrane, and the epithelial lamina covering the capillaries form the so-called blood-brain barrier. This barrier of blood in the cavity of the ventricles selectively allows some substances to pass through and retains others, which is an important circumstance for protecting the brain from harmful influences.

From the lateral ventricles through the right and left interventricular (Monroys) openings, cerebrospinal fluid enters the third ventricle, where there is also a choroid plexus. From the third ventricle, through the cerebral aqueduct, cerebrospinal fluid enters the fourth ventricle and then through the azygos foramen in the posterior wall. (Magendie hole) and paired lateral aperture (Lushka hole) flows into the cerebellocerebral cistern of the subarachnoid space.

The arachnoid membrane is connected to the soft membrane lying on the surface of the brain by numerous thin bundles of collagen and elastic fibers, between which blood vessels pass. Near the sinuses of the dura mater of the brain, the arachnoid membrane forms peculiar outgrowths, protrusions - granulations of the arachnoid membrane (granulationes arachnoideae; Pachionian granulations). These protrusions protrude into the venous sinuses and lateral lacunae of the dura mater. On the inner surface of the skull bones, at the location of the granulations of the arachnoid membrane, there are depressions - dimples of granulations, where the outflow of cerebrospinal fluid into the venous bed occurs.

Soft (vascular) membrane of the brain (pia mater encephali)

This is the innermost layer of the brain. It adheres tightly to the outer surface of the brain and extends into all the cracks and grooves. The soft shell consists of loose connective tissue, in the thickness of which there are blood vessels leading to the brain and feeding it. In certain places, the soft membrane penetrates the cavities of the ventricles of the brain and forms the choroid plexus (plexus choroideus), which produces cerebrospinal fluid.

Age-related features of the membranes of the brain and spinal cord

The dura mater of the brain in a newborn is thin, tightly fused with the bones of the skull. The processes of the shell are poorly developed. The sinuses of the dura mater of the brain are thin-walled and relatively wide. The length of the superior sagittal sinus in a newborn is 18-20 cm. The sinuses are projected differently than in an adult. For example, the sigmoid sinus is located 15 mm posterior to the tympanic ring of the external auditory canal. There is a greater asymmetry in the size of the sinuses than in an adult. The anterior end of the superior sagittal sinus anastomoses with the veins of the nasal mucosa. After 10 years, the structure and topography of the sinuses are the same as in an adult.

The arachnoid and soft membranes of the brain and spinal cord in a newborn are thin and delicate. The subarachnoid space is relatively large. Its capacity is about 20 cm 3, and increases quite quickly: by the end of the 1st year of life up to 30 cm 3, by 5 years - up to 40-60 cm 3. In children 8 years old, the volume of the subarachnoid space reaches 100-140 cm 3, in an adult it is 100-200 cm 3. The cerebellocerebral, interpeduncular and other cisterns at the base of the brain in a newborn are quite large. Thus, the height of the cerebellocerebral cistern is approximately 2 cm, and its width (at the upper border) is from 0.8 to 1.8 cm.

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