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

The human brain has a branched and complex circulatory system. Intensive arterial blood supply to the nervous tissue ensures its active functional state. No less important for brain activity is the structure of the venous bloodstream. 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 vein system.

Features of the cerebral sinuses

The brain, located in the cranium, is covered with an additional case of three shells of different density and structure. The hard shell is formed by two sheets. Of these, the outer leaf is soldered to the bone structures of the skull. He plays the role of the 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:

1. 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.
2. The sinuses are located at the base of the grooves on the inner surface of the cranial bones.
3. The leaves of the shell that forms the sinuses are strong and tense.
4. There are no valves in the sinuses, which allows the free flow of blood.
5. 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 accumulators in the veins of the brain. Thanks to them, venous blood freely descends from the brain to the internal jugular veins. The defeat of 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 (dumping of venous blood) often saves from plethora. If problems arise in the venous circulation system, it can be quickly eliminated due to recanalization of the veins and the formation of collaterals.

Channel localization

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 crescent of the brain is involved in its formation. This is what the crescent plate is called. It is formed by the dura mater. The process starts from the crest of the ethmoid bone, goes along the midline back, filling the interhemispheric fissure that separates the hemispheres from each other. The groove of the superior sagittal sinus is the base of the crescent.

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

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

• The anterior sections of the sinus are connected with 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 drain.

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 crescent brain. Compared to the upper sinus, it has a much smaller size. Due to numerous venous anastomoses, it connects to the direct sinus.

Straight sinus

The direct sinus is located at the junction of the sickle and the tenon that covers the cerebellum. Has a sagittal direction. A large 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 mantle departs from the hard shell. It is the largest of all the venous reservoirs and runs 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 with it. At the level of the jugular foramina from the sigmoid canals, the blood flow is directed to the bed of the internal jugular vein.

Cavernous sinus

The cavernous sinus is localized on the sides of the Turkish saddle, it looks like a triangle, in the upper part of which the oculomotor nerve is located, in the lateral section - a branch of the trigeminal nerve. Its anatomy is distinguished by a large number of internal partitions. This explains the other name - the cavernous sinus.

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

The cavernous sinuses are connected by venous branches passing along the contours of the Turkish saddle. Such complex vascular relationships allow the vessels to form a rather large sinus surrounding the pituitary gland lying in the center of the Turkish saddle.

The continuation of this sinus are two venous reservoirs surrounding the top and bottom of the temporal pyramids. They are called the superior and inferior petrosal sinuses. Connecting with each other by numerous venous vessels, the petrosal sinuses are involved in the formation of the main plexus of venous vessels, located in the region of 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 bones of the occiput. At the top, it is connected to the 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 with 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 region of the cruciate eminence within 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 somehow interconnected not only with each other, but also with other cerebral structures.

Pathology of the intracranial sinuses

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

Inflammatory diseases of the brain structures can occur when infectious agents enter the venous blood flow (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 clinic of acute meningitis, encephalitis is possible. In young children, a picture of neurotoxicosis is formed.

Sometimes neurosurgeons can suspect a fracture of the base of the skull, seeing a picture of pulsating exophthalmos. In case of injury, the internal carotid artery associated with the cavernous canal is damaged. A jet of arterial blood, entering the eye veins associated with this sinus, causes pulsation, pronounced 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 blood noises in the area of ​​\u200b\u200bthe anastomosis.

When the walls of the sinus are damaged, a number of neurological symptoms appear due to damage to closely spaced branches and nuclei of the cranial nerves. With the pathology of the cavernous sinus, the appearance of oculomotor disorders, the development of trigeminal neuralgia is possible.

If the patient suffers from frequent headache attacks, intracranial hypertension, reverse (retrograde) blood flow may develop - 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 sinuses of the brain are an important component of the venous network of the brain. Knowing their functions, structural features and localization, specialists can assume the development of pathology in a certain area of ​​the brain. To clarify the diagnosis, it is necessary to conduct magnetic resonance imaging with intravascular injection of a contrast agent.

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 splittings of the hard layer of the brain. They are provided with blood from the internal and superficial vessels of the brain, participate in the reabsorption of the cerebrospinal fluid substance from the cavity between the arachnoid and nondura mater.

Sine functions

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

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

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

The structure of the sinuses of solid MO

The development of TMT reservoirs is due to their separation into two sheets that look like channels. These ducts are designed to distribute the venous blood flow from the main human organ, which is subsequently sent to several double vessels that are located on the neck and transfer blood from the brain.

The DM 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, in no way touching the state of intracranial pressure.

In humans, the following types of TMT reservoirs are installed:

1. superior or inferior sagittal. The first one is located along the upper border of the falciform bone and ends on a fragment of the occiput, and the next one is longitudinally the border of the sickle below and flows into the straight sinus;
2. Straight. It is placed longitudinally of the fragment, where the falciform process passes into the cerebellar mantle;
3. Cross (double). Formed on a transverse growth of the skull, being longitudinally the posterior border of the cerebellar groove;
4. Occipital. It is located in the cavity of the cerebellar arch, and then spreads to the occipital junction;
5. Sigmoid. It is located in the division in the ventral fragment of the head bone tissue;
6. Cavernous (double). It is located on the sides of the formation in the body of a bone in the form of a wedge ();
7. Sphenoparietal sinus (double). Refers to a small border of bone in the form of a wedge 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 fistulas with venous vessels on the surface of the brain, through venous branches that unite the vascular sinuses of the DM with the external blood circulation vessels of the head. These depressions begin to communicate with the diploic processes, which are characterized by placement 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 DM reservoirs.

Types of sinuses TMO

Nature very thoughtfully created a person, providing the dura mater with recesses to provide the main organ with oxygen and nutrient compounds.

superior sagittal sinus

This cranial sinus is characterized by a large space with a complex structure. The crescent of the main human organ takes a significant part in its development. This is a crescent leaf. It is made from the dura mater. The process originates from the top of the ethmoid bone, passes in the middle back, penetrating into the interhemispheric foramen that separates the parts of the brain from each other. A groove-like outgrowth of the superior sagittal sinus, in fact it is the base of the falciform bone.

This duct provides numerous gaps on the sides. These are small cavities that are connected with 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 channels of the parietal fragments of the brain.

This collector of arteries and veins, as a person grows, becomes larger and wider in terms of mass capacity. Its posterior fragment protrudes into the united 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 for the reason that it is located in the lower location of the cerebral arch. Compared to the upper reservoir, it has a significantly smaller volume. Due to the large number of venous fistulas, it is attached to the direct.

Direct sine

This fragment of the cranium is, in fact, the so-called continuation of the lower cistern from the back. It combines the rear sections of the superior tanks and the lower manifold. Along with the upper, a large vessel is included in the anterior part of the non-dual sinus. The posterior part 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 cranium, which is located in the furrow of the hard tissue of the occiput, continues laterally and towards the bottom, is attached to the sinus. This fragment is called sinus 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 an extensive furrow. The venous reservoir then flows into the sigmoid sinus. Further, it deepens into the mouth of the most extensive vessel, which performs venous leakage from the head. So the transverse sinus and sigmoid sinus are characterized as the main venous reservoirs. In addition, all other pockets go to the first one. Some sinuses of the veins are directly included in it, some - through a smooth transition. On the temporal sides, the transverse pocket continues with a sigmoid deepening of the proper side. The place where the venous extensions of the sagittal, direct and occipital sinuses are included in it is called the common drain.

cave reservoir

It got this name because it has a large number of partitions. They provide the tank with an appropriate structure. Through the cavernous sinus, the abducent, ophthalmic, block, nerve fibers that move the eyes, and in addition the carotid artery (which is inside) are stretched along with the sympathetic interlacing (vegetative nerves in the thoracic-lumbar region). There are communicative connections between the right and left localizations of space. They are provided in the posterior and anterior intercavernous. Accordingly, a venous ring develops in the location of the Turkish saddle. In the cavernous sinus (in its flank fragments) it passes into the space of the sphenoid-parietal sinus, which lies on the border of a 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. In the lower part, this pocket is divided into two branches, which 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.

Structural violations

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

Inflammation of the structures of the main human organ can appear when pathogens penetrate into the bloodstream (all kinds of unbound vascular substrate solid, liquid or vaporous, circulating through the bloodstream, uncharacteristic in the normal state, capable of provoking blockage of the artery at a fairly large distance from the site of occurrence). A pathological agent can get on the meninges and blood vessels of the head bone tissue on its surface . In this case, the appearance of symptoms of peak manifestation, and other pathologies, is likely. In preschool children, a picture of neuropoisoning is manifested.

In some cases, damage to the base of the skull can be established by neurosurgeons, seeing signs of intense exophthalmos. A fracture disrupts the integrity of the internal carotid artery in contact with the cavernous duct. The flow of venous blood, penetrating into the eye veins related to this reservoir, provokes pulsation, obvious hyperemia and protrusion of the apple of the visual 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 blood flow noises in the area of ​​​​combination of vessels.

The main recommendation of doctors is the timely appeal to a specialist for clarification of the picture and the nature of symptomatic manifestations. As well as the prevention of mechanical head injuries and protection from external factors, such as, for example, 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, it is they who for the most part become the cause of 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 at the base of the skull from the cavernous sinuses.

The main tributaries of the cavernous sinus:

1. eye veins,
2. sphenoparietal sinus,
3. superficial middle veins of the brain.

Outflow of venous blood from the cavernous sinus:

1. superior petrosal sinus,
2. inferior petrosal sinus,
3. pterygoid plexus.

The sinus is paired and is located at the base of the skull on the sides of the Turkish saddle. The sinus contains many connective tissue partitions that divide the sinus cavity into a number of separate interconnected cavities, similar to the cavernous body.

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

Rice.Side view. The cavernous sinus in the lower picture is marked in blue. FR - round hole, CC - torn hole, Se - Turkish saddle, SOF - superior torn hole, ICA - carotid artery (its cavernous segment).

Rice. Front view. The figure shows a frontal section through the cavernous sinus (blue). Through the sinus passes the cavernous part of the internal carotid artery, or arte ria carotis interna (red) and the surrounding sympathetic fibers. In addition, cranial nerves (yellow) pass through the walls of the sinus: oculomotor nerve, trochlear nerve, ophthalmic 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 is projected into the area between the orbits.

Major 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 ophthalmic veins: superior and inferior. Superior ophthalmic vein, v. ophthalmica superior exits 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 merges into the cavernous sinus.

Rice. The ophthalmic veins drain into the cavernous sinus.

The inferior branch leaves the orbit through the inferior orbital fissure and flows into 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, passes under the sphenoparietal suture. Further, the sinus passes from the cranial vault to the free edge of the small wings of the sphenoid bone, follows 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 outflow from the anterior superior temporal lobes and the posterior inferior frontal gyri.

Rice. In the diagram, the superficial venous system of the cerebral hemispheres (according to Bailey). Blue indicates the middle cerebral vein, which flows into the cavernous sinus.
1 - Trolard's vein; 2 - veins of the Roland furrow; 3 - vein Labbe; 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 to the pterygoid plexus occurs through graduate anastomoses passing through the torn, oval and Vesalian (if any) foramen of the base of the skull.

Rice. The cavernous sinus is shown in the center of the figure at the top. 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. Yes, v.v. meningeae mediae accompany the artery of the same name, connect along the way with the sphenoparietal sinus and, leaving the cranial cavity through the spinous foramen, flow into the pterygoid (venous) plexus.

Rice. The pterygoid plexus is the venous network in the center of the figure. 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, 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 Turkish saddle.

Rice. The photograph of the preparation shows the anterior (SICS) and posterior (IICS) intercavernous sinuses, on the sides of which the carotid arteries are visible.

The outflow of blood from the cavernous sinuses occurs in the dorsal direction along the upper and lower stony sinuses.

The superior petrosal sinuses originate in the posterior 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. Inferior petrosal sinuses go backward and down the slope (marked with arrows), flow into the internal jugular veins (marked with 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, 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 hard shell of the brain.

Common to the sinuses and venous vessels 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 fibrous crossbars covered with endothelium and incomplete septa, which are thrown 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 cerebrum (a process of the hard shell of the brain) from the cockscomb to the internal occipital protrusion. It flows most often into the right transverse sinus, sinus transversus dexter. Along the course of the superior sagittal sinus, small diverticula extend - lateral lacunae, lacunae laterales.

2.Inferior sagittal sinus, sunus sagittalis inferior, stretches along the entire lower edge of the falx cerebrum. At the lower edge of the crescent joins the direct sinus, sinus rectus.

3. Direct sinus, sinus rectus, located along the junction of the falx cerebrum with the cerebellum. Has the shape of a quadrangle. Formed by sheets of the dura mater of the cerebellum. The direct sinus is directed 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 bones of the skull along the posterior edge of the cerebellum tenon. From the area of ​​​​the internal occipital protrusion, where both sinuses are widely communicated with each other, they are directed outward, to the area of ​​\u200b\u200bthe 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 opening passes into the superior bulb of the internal jugular vein.

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

Sinus drain, confluens sinuum, is located in the region of the internal occipital protrusion. Only in a third of cases the following sinuses are 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 partitions that permeate its cavity. The internal carotid artery lies in the cavity of the cavernous sinus, a. carotis interna, with the sympathetic plexus surrounding it, and the abducens nerve, n. abducens.

In the outer upper wall of the sinus pass the oculomotor nerve, n. oculomotorius, and blocky, n. trochlearis; in the outer side wall - the ophthalmic nerve, n. ophthalmicus (first branch of the trigeminal nerve).

7. Intercavernous sinuses, sinus intercavernosi, located around the Turkish saddle and pituitary gland. These sinuses connect both cavernous sinuses and together form a closed venous ring.

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

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

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

11. Basilar plexus, plexus basilaris, lies in the region of the clivus of the sphenoid and occipital bones. It has the appearance of a network that connects both cavernous sinuses and both lower stony sinuses, and below it connects to the internal vertebral venous plexus, plexus venosus vertebralis internus.

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

This shell is distinguished by its special density, the presence in its composition of a large number of collagen and elastic fibers. The hard shell of the brain from the inside lines the cavity of the skull, at the same time it 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 with the bones of the vault (roof) of the skull and is easily separated from them. In the region of the base of the skull, the shell is firmly fused with the bones. The hard sheath surrounds the cranial nerves emerging from the brain, forming their sheaths and growing together with the edges of the openings through which these nerves leave the cranial cavity.

On the inner base of the skull (in the region of the medulla oblongata), the dura mater fuses with the edges of the foramen magnum and continues into the dura mater of the spinal cord. The inner surface of the hard shell, facing the brain (to the arachnoid), is smooth, covered with flat cells. In some places, the hard shell of the brain splits. Its inner leaf (duplicature) deeply bulges in the form of processes into the cracks separating parts of the brain from each other. In places where the processes originate (at their base), as well as in areas where the hard shell is attached to the bones of the inner base of the skull, in the splits of the hard shell 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, the sickle of the cerebrum, or the large sickle-shaped process (falx cerebri) This is a thin crescent-shaped plate of the hard shell, which penetrates in the form of two sheets into the longitudinal fissure of the brain. Before reaching the corpus callosum, this plate separates the right and left cerebral hemispheres from each other. In the split base of the falx cerebrum, 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 cerebrum, between its two leaves, there is the inferior sagittal sinus. In front, the crescent of the brain is fused with the cockscomb of the ethmoid bone. The posterior part of the sickle at the level of the internal occipital protrusion fuses with the tentorium of the cerebellum. Along the line of fusion of the posterior lower edge of the falx cerebrum and the cerebellum in the cleavage of the dura mater, there is a straight sinus connecting the inferior sagittal sinus with the superior sagittal, transverse, and occipital sinuses.

The namet (tent) of the cerebellum (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 cerebellum tenon separates the occipital lobes of the cerebrum from the cerebellar hemispheres. The anterior margin of the cerebellum is uneven. It forms a notch of the tentorium (incisura tentorii), to which the brain stem is attached in front.

The lateral edges of the cerebellum tenon are fused with the upper edge of the pyramids of the temporal bones. Behind the cerebellum, the cerebellum passes into the hard shell of the brain, lining the occipital bone from the inside. At the site of this transition, the hard shell of the brain forms a split - a transverse sinus adjacent to the occipital bone groove of the same name.

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

Diaphragm (Turkish) saddle

(diaphragma sellae) is a horizontal plate with a hole in the center, stretched over the pituitary fossa and forming its roof. Under the diaphragm of the saddle in the fossa is the pituitary gland. Through a hole in the diaphragm, the pituitary gland is connected to the hypothalamus with the help of a funnel.

The sinuses (sinuses) of the hard shell 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 the hard shell that form the sinus are tightly stretched and do not fall off. Therefore, on the cut, the sinuses gape. 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 bones of the skull, at the locations of the sinuses of the hard shell, there are corresponding grooves. The following sinuses of the hard shell of the brain are distinguished.

1. The superior sagittal sinus (sinus sagittalis superior) is located along the entire outer (upper) edge of the crescent of the brain, from the cocks crest of the ethmoid bone to the internal occipital protrusion. 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 are the lateral lacunae (lacunae laterales) that communicate with it. These are small cavities between the outer and inner layers (sheets) of the hard shell 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 veins of the brain, and the dyschial veins flow into them.
2. The lower sagittal sinus (sinus sagittalis inferior) is located in the thickness of the lower free edge of the falx cerebrum. It is much smaller than the top. 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 cerebrum fuses with the anterior edge of the cerebellum tenon
3. The direct sinus (sinus rectus) is located sagittally in the splitting of the cerebellar plaque along the line of attachment of the crescent cerebrum to it. The straight sinus connects the posterior ends of the superior and inferior sagittal sinuses. In addition to the inferior sagittal sinus, a large cerebral vein flows into the anterior end of the straight sinus. Behind the direct sinus flows into the transverse sinus, into its middle part, called the sinus drain. The posterior part of the superior sagittal sinus and the occipital sinus also flow here.
4. The transverse sinus (sinus transversus) lies at the point of origin of the cerebellum from the hard shell of the brain. On the inner surface of the scales of the occipital bone, this sinus corresponds to a wide groove of the transverse sinus. The place where the superior sagittal, occipital and direct sinuses flow into it is called the sinus drain (confluens sinuum, confluence of the sinuses). On the right and left, the transverse sinus continues into the sigmoid sinus of the corresponding side.
5. The occipital sinus (sinus occipitalis) lies at the base of the falx cerebellum. Descending along the internal occipital crest, this sinus reaches the posterior edge of the foramen magnum, where it divides into two branches, covering this foramen from behind and from the sides. Each of the branches of the occipital sinus flows into the sigmoid sinus of its side, and the upper end into the transverse sinus.
6. The sigmoid sinus (sinus sigmoideus) is paired, located in the sulcus of the same name on the inner surface of the skull, has an S-shape. In the region of the jugular foramen, the sigmoid sinus passes into the internal jugular vein.
7. The cavernous sinus (sinus cavernosus) is paired, located at the base of the skull on the side of the Turkish saddle. The internal carotid artery and some cranial nerves pass through this sinus. 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 messages (anastomoses) in the form of anterior and posterior intercavernous sinuses (sinus intercavernosi), which are located in the thickness of the diaphragm of the Turkish saddle, in front of and behind the pituitary funnel. The sphenoid-parietal sinus and the superior ophthalmic vein flow into the anterior sections of the cavernous sinus.
8. The sphenoparietal sinus (sinus sphenoparietalis) is paired, adjacent to the free posterior edge of the small wing of the sphenoid bone, which is attached here by the hard shell of the brain in splitting.
9. The upper and lower 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 outflow tracts of venous blood from the cavernous sinus to the sigmoid. The right and left lower petrosal sinuses are connected by several veins lying in the splitting of the hard shell in the region of the body of the occipital bone, which are called the basilar plexus. This plexus connects through the foramen magnum with the internal vertebral venous plexus.

In some places, the sinuses of the hard shell of the brain form anastomoses with the external veins of the head with the help of emissary veins - graduates (vv. emissariae). In addition, the sinuses of the hard shell have messages with diploic veins (vv. diploicae), located in the spongy substance of the bones of the cranial vault 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 hard shell of the brain and further into the right and left internal jugular veins.

In addition, due to sinus anastomoses with diploic veins, venous graduates and venous plexuses (vertebral, basilar, under the occipital, 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 foramen middle meningeal artery(branch of the maxillary artery), which branches in the temporo-parietal region of the membrane. The dura mater of the brain lining the anterior cranial fossa is supplied with blood by branches anterior meningeal artery(a branch of the anterior ethmoid artery from the ophthalmic artery). In the shell of the posterior cranial fossa branch posterior meningeal artery - 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 soft shell of the brain flow into the nearest sinuses of the hard shell, 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 the blood vessels. In the region of the anterior cranial fossa, it receives branches from the optic nerve (the first branch of the trigeminal nerve). branch of this nerve tentorial(shell) branch- also supplies the cerebellum and the crescent of the brain. The middle meningeal branch from the maxillary nerve, as well as the branch from the mandibular nerve (respectively, the second and third branches of the trigeminal nerve), approach the shell in the middle cerebral fossa.

Arachnoid membrane of the brain

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

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

The largest subarachnoid cisterns are as follows.

1. The cerebellar cistern (cisterna cerebellomedullaris) is located in the depression between the medulla oblongata ventrally and the cerebellum dorsally. Behind it is limited by the arachnoid membrane. This is the largest of all tanks.
2. The cistern of the lateral fossa of the brain (cisterna fossae lateralis cerebri) is located on the lower lateral 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.
3. Cistern of chiasm (cisterna chiasmatis) is located at the base of the brain, anterior to the optic chiasm.
4. The interpeduncular cistern (cisterna interpeduncularis) is determined in the interpeduncular fossa between the legs of the brain, downwards (anteriorly) 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.

Spinal (cerebrospinal) fluid

The cerebrospinal (cerebrospinal) fluid (liquor cerebrospinalis), which is formed in the ventricles of the brain, is poor in protein substances, there are no cells in it. The total amount of this liquid is 100-200 ml. It is produced by the choroid plexuses of the lateral, III and IV ventricles from their blood capillaries. The walls of the blood capillaries, the basement membrane, the epithelial plate covering the capillaries form the so-called blood-brain barrier. This barrier from the blood in the cavity of the ventricles selectively passes some substances 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 (Monroy) holes, 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 an unpaired opening in the posterior wall (hole of Magendie) and paired lateral aperture (hole of Lushka) flows into the cerebellar-cerebral cistern of the subarachnoid space.

The arachnoid membrane is connected to the pia mater 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 hard shell of the brain, the arachnoid membrane forms peculiar outgrowths, protrusions - granulations of the arachnoid membrane (granulationes arachnoideae; pachyon granulations). These protrusions protrude into the venous sinuses and lateral lacunae of the hard shell. On the inner surface of the bones of the skull, at the location of the granulations of the arachnoid membrane, there are impressions - dimples of granulations, where the outflow of cerebrospinal fluid into the venous bed is carried out.

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

It is the innermost layer of the brain. It is tightly attached to the outer surface of the brain and goes into all the cracks and furrows. The soft shell consists of loose connective tissue, in the thickness of which there are blood vessels that go to the brain and feed it. In certain places, the soft membrane penetrates into the cavities of the ventricles of the brain and forms the choroid plexuses (plexus choroideus), which produce cerebrospinal fluid.

Age 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 shell processes are poorly developed. The sinuses of the dura mater 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 15 mm posterior to the tympanic ring of the external auditory canal. There is a greater than in an adult, asymmetry in the size of the sinuses. 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, delicate. The subarachnoid space is relatively large. Its capacity is about 20 cm 3, it increases rather 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 cerebellar, interpeduncular and other cisterns at the base of the brain in a newborn are quite large. So, the height of the cerebellar-cerebral cistern is about 2 cm, and its width (at the upper border) is from 0.8 to 1.8 cm.

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