The dura mater performs the following functions. Dura mater (fibrous)

1. Dura mater of the skull (Fig. 55) The dura mater is the most dense and resistant membrane of the brain and spinal cord, and its role is to protect these two structures. The cranial and vertebral dura mater responds to stretch with a non-linear increase in tension, which is characteristic of collagen tissues. This non-linear response is slower in its vertebral part. The cranial dura mater relaxes faster. The structural components of the dura mater are aligned axially, which is not noticeable at the cranial level, and the spinal dura mater contains more elastin. During neurocranial development, the dura mater regulates various phenomena of cellular development at the level of the brain and skull bones. The morphogenesis of the bones and sutures of the skull depends on the interaction with the dura mater, which controls both the size and shape of the bones and the potential of the sutures. The development of the brain is also associated with the dura mater involved in the formation of the hippocampal gyrus. It originates from the cranial neural crest and on the second day is infiltrated by cells derived from the circumaxial mesoderm, which later becomes predominant. , consisting of bundles of connective tissue mixed with elastic bundles that line the inner surface of the cranium and are in close contact with the periosteum, where they are very difficult to separate from each other. The difference between the periosteum and the dura mater appears at the level of the foramen magnum, where the dura mater, hitherto associated with the periosteum, separates from it and continues as the sheath of the spinal canal. shell depends on the magnitude of intracranial pressure: the higher the pressure, the thicker the shell. It has an outer and inner surface.

a) Outer surface

It lines the inner surface of the cranium along its entire length and is adjacent to this box with fibrous continuations with vessels and nerves. This fit is different on the vault and base of the skull. 1 Fig. 55. Meninges and cerebrospinal fluid On the vault there is a relatively weak fit, except for the level of the seams. It can be relatively easily peeled off in the area described by G. Marchand:

from front to back from the posterior edge of the lesser wings of the sphenoid bone, up to 2-3 cm to the internal occipital protuberance; from top to bottom a few centimeters away from the falciform ligament, to a horizontal line that runs from the posterior edge of the lesser wings, meets the upper edge of the pyramid and goes above horizontal part of the lateral sinus. 2) On the base of the skull, it fits very firmly, especially at the following points:

on the apophysis of crista galli; on the posterior edge of the small wings of the sphenoid bone; in the region of the wedge-shaped anterior and posterior apophyses; at the upper edge of the pyramid; at the circumference of the foramen magnum. The fit of the dura mater also depends on age, it is more pronounced in adults than in children, and increases with aging. And it does not depend on pathological conditions. It accompanies the vessels and nerves that exit the skull, passing with them through the corresponding openings, and then departs from the vessels and nerves behind these openings to continue along the extracranial periosteum. These sequels are accompanied by:

large glossopharyngeal nerve - to the anterior facet of the condyle; vagus nerve, glossopharyngeal nerve and spinal nerve, internal jugular vein - to exit from the posterior ragged foramen. facial and auditory nerve in the posterior auditory canal to merge with the periosteum; hole; superior maxillary nerve - in a large round hole; olfactory fibers - to the nasal fossae; at the level of the optic opening and sphenoidal fissures, the dura mater passes into the orbit, where it mixes on one side with the periosteum of the orbital cavity, and on the other hand supplies the optic nerve fibrous membrane that accompanies it to the eyeball, where it merges with the sclerotic membrane without demarcation. The Dura-mater over the optic nerve forms a crescent-shaped fold (optic nerve tent) that runs from the sphenoidal circumference to the anterior sphenoid process. In the optic nerve canal, the optic nerve itself adheres to the walls of the canal through its sheath, and this explains the fact that the nerve can be affected in canal fractures and sinus infections. These extensions further increase its fit to the base of the skull. In the region of the sutures of the skull, thin neurovascular bundles are contained in soft connective tissue and leave the dura mater to reach the scalp in tortuous transverse canals.

b) Inner surface

On the inner surface, processes extend from the dura mater, which separate the various parts inside the brain and maintain their relative position, whatever the position of the head. There are five of these processes:

tent of the cerebellum, falciform ligament of the brain, falciform ligament of the cerebellum, tent of the pituitary gland, tent of the olfactory bulbs. 1) The tent of the cerebellum (namet) This is a septum stretched horizontally between the anterior surface of the cerebellum, which it covers, and the lower surface of the occipital lobes that lie on it. It has two surfaces and two edges. a) Upper surface Higher in the central part than in the lateral ones. In the medial midline, it is adjacent to the base of the falciform ligament of the brain. On each side of it lie the occipital lobes. b) The lower surface It has the shape of a vault, lies on the cerebellum and is attached to the falciform ligament of the cerebellum along the midline. forms the foramen ovale Pacchioni through which the brainstem passes. At each of its ends, the anterior edge of the tent of the cerebellum passes over the pyramid, crosses a large circle outward from the posterior sphenoid apophysis, and is fixed on the apex and outer edge of the anterior sphenoid apophysis. The ends of the two edges of the tent of the cerebellum form a triangle, the third side of which is represented by an anterior-posterior line connecting two wedge-shaped apophyses. This triangle is filled with a plate of the dura mater, in which the oculomotor nerve passes. Three outgrowths depart from the three sides of this triangle, which descend to the base of the skull and are firmly fixed there on the front surface of the pyramid to the sphenoid bone gap, as well as on the bottom of the Turkish saddle. These outgrowths form the inner, outer and posterior surfaces of the cavernous sinus. d) The posterior edge, or greater circle. Posteriorly, it is concave, attached from the inside to the outside on the internal occipital protuberance on both sides of the groove of the right and left lateral sinus on the upper edge of the pyramid and, finally, on the posterior wedge-shaped apophysis. Along this edge are the lateral sinuses posteriorly and the superior stony sinuses on the sides. Near the top of the petrous pyramid, the posterior edge of the cerebellar tent has an opening through which the trigeminal nerve passes, giving access to the Meckel's cavity, in which the Gasser ganglion lies. In the Meckel's cavity, the rigid posterior leaf continues in the deepening of the trigeminal nerve. The roof of the cavity is denser than the bottom and covers fibrous tissues running from the tent of the cerebellum to the ganglion. Between the dural sac of the cavity and the venous space of the cavernous sinus, in half the cases there is a fibrous sheet extending from the tent of the cerebellum to the bottom of the cavernous sinus. The dura mater (periosteum) follows the bone from the middle cavity and continues into the superior periosteum. The solid wall of the cavernous sinus forms an internal lateral septum, which includes two sheets - one thin outer, the second dense inner, which then becomes thinner. It has two surfaces, two edges, a base and an apex:

surfaces

Base

top

Top edge

bottom edge

The falciform ligament of the brain may partially or completely ossify. In Chiari syndrome, the absence of the falciform ligament of the cerebellum is found. It is most likely that the tension of the cranial fossa inhibits the development of the falciform ligament and the internal occipital crest. 3) Falciform ligament of the cerebellum This is a vertical medial median plate that separates the two hemispheres of the cerebellum. The lateral surfaces correspond to the hemispheres of the cerebellum. The apex, directed downward and anteriorly, is divided at the level of the occipital foramen, and the resulting two branches surround this hole and go to the posterior ragged foramen. Each of them contains in its lower part the corresponding posterior occipital sinus. The posterior margin is convex and is attached along the internal occipital crest, it contains the posterior occipital sinuses. The anterior margin is concave and free. It is associated with the lower worm. In case of force damage, the falciform ligament of the cerebellum can be broken without damage to the bones of the skull. The falciform ligament of the cerebellum plays an important role in the control of forces during brain development, in particular during encephalization, as well as in adaptation to the bipedal position. Ontogenetic studies show that the central part rotates backwards to the base of the skull in response to the disproportionate development of the brain, the upper tentorial part of which develops more than the lower tentorial part. 4) Pituitary tent This is a horizontal septum stretched over the Turkish saddle. It is attached:

to the upper edge of the anterior surface of the square plate of the sphenoid bone behind; to the posterior lip of the optic groove and to the four sphenoid apophyses in front. It connects to the wall of the cavernous sinus along the line of connection of the upper and inner surfaces of the sinus. The roof of the cavernous sinuses and the diaphragm of the Turkish saddle is an outgrowth of the lateral sheet of the dura mater, which is connected to the anterior and posterior inclined processes of the sphenoid bone. Laterally, this sheet changes direction and forms the lateral wall of the cavernous sinuses and connects the dura with the medial part of the cerebral fossa. In the midline, it goes around the Turkish saddle, and the diaphragmatic opening creates a dural sac containing the pituitary gland and attached to the lower part of the diaphragm of the Turkish saddle. to the previous one at the level of the optical chute. The pituitary tent covers the pituitary gland, but it has an opening through which the pituitary trunk passes. The shape of the bottom of the Turkish saddle depends on the shape of the diaphragm of the Turkish saddle. If it is full, then the bottom will be convex and deep, if incomplete - convex and shallow. The shape of the Turkish saddle varies: in more than 50% of cases it is concave, in more than 30% of cases it is flat and in some cases it is convex. the shape of the Turkish saddle and its contents. In rare cases of complete or partial absence of the diaphragm, the pituitary gland is small and localized in the lower or rear part of the saddle, and the bony structures of the fundus are fragile. the anterior surface of the olfactory bulb between the apophysis crista galli and the inner edge of the orbital tubercles of the frontal bone. Often this plate is absent. The cranial dura mater and scalp are innervated by the trigeminal nerve, cavernous branches and the autonomic system. .In the lumbar and cervical dura mater, these elements are less abundant and, in contrast to the cranial dura mater, do not participate in pain processes. These elements are rather localized in the posterior vertebral ligament and epidural membranes. There are brain branches:

anterior - through the lattice nerves and the nasal nerve of the first branch of the trigeminal nerve; lateral branches of the trigeminal nerve. One of these cerebral branches, called Arnold's recurrent nerve, comes from the optic nerve and then divides at the tent of the cerebellum. The cerebral branch of the maxillary nerve passes through the large round hole, and the branch of the maxillary nerve through the foramen ovale. There are also posterior cerebral branches, which are branches of the vagus nerve and the large glossopharyngeal nerve. They go to the dura mater of the posterior fossa, like the rami, from C1 to C3, and pass through the foramen magnum. When the vertebral arteries penetrate the skull, they are surrounded by an arachnoid membrane. b) Venous system The cerebral venous system can be divided into superficial and deep. direct sinus, sigmoid sinus, into which deep cortical veins flow; these two systems themselves drain into the internal jugular veins. The superficial system is highly variable and includes numerous anastomoses, while the deep system is more constant. Cerebral veins follow a different path than arteries. Cerebral veins do not have muscle tissue and are not equipped with valves. They perforate the arachnoid and dura mater in order to flow into the sinuses. The peculiarity of the cerebral venous system is its length and the presence of numerous sinuses and liquid lakes. Such a system partially serves as a shock absorber and, therefore, protection of the substance of the brain, but is mainly responsible for its cooling. The venous outflow is provided by the jugular system. Here we observe the second feature of the brain. The entire vascular system of the body includes two veins per artery to ensure good venous outflow, but at the cerebral level, this ratio is not present, which can lead to a deficiency in the outflow of venous blood. The venous outflow is partially compensated by accessory veins, in particular the temporal vein. The diameter of this vein varies. Too small a diameter can lead to a deficiency in venous outflow and cause cephalalgia. This explains the effectiveness of cranial techniques in this type of pathology. 2. Dura mater of the spine (Fig. 56) The vertebral dura mater is a fibrous sleeve containing the spinal cord and vertebral roots. It runs from the occipital foramen magnum to the second sacral vertebra. Its diameter is larger than the diameter of the spinal cord, as well as the spinal canal. a) Upper end It is firmly fixed to the third cervical vertebra, and from the circumference of the large occipital foramen continues in the dura mater of the skull. The vertebral arteries cross it at the level of the occipito-atlantic articulation. b) Lower end It descends from above, from the lower end of the spinal cord, and envelops the elements of the cauda equina and terminal filaments. It ends at a dead end on the second sacral vertebra, but continues with the terminal filaments to the coccyx with the coccyx-medullary ligament. This ligament is fixed to the posterior vertebral ligament by a perforated medial membrane (anterior ligament dura-mater Trolard).

Rice. 56. Dura mater in the spinal canalc) Outer surface It is separated from the septa by the epidural space occupied by venous vessels, semi-liquid fat, especially abundant in the back. This fat enters and exits through the channel, due to variations in intra-abdominal and intra-abdominal pressure. There is no fibrous tissue in the epidural space. This space is formed from homogeneous cells surrounded by a thin membrane. The dorsal epidural fat, attached to the posterior part of the canal, is firmly attached to the dura mater in its medial part and ensures its mobility in relation to the canal. The dura mater is attached to the canal ventrally at the level of the discs. The epidural ventral space is dominated by veins. Posteriorly, it has no connection. Anteriorly, the epidural cavity is very narrow, and the dura mater is connected to the posterior vertebral ligament by fibrous extensions, especially abundant in the cervical and lumbar regions. they are limited to one vertebral segment, while others cover several segments, in particular in the lower part of the spine. They have a cranio-caudal orientation. Their function is to protect the dural sac and spinal cord. Their orientation varies from top to bottom: cranio-caudal at the top, transverse at D8-D9, and then cranio-caudal again. A greater number of these ligaments in the lumbar region can cause low back pain. anterior-posterior bridge, which in the region of the occiput connects the dura mater with the occipito-atlantoid membrane and through it with its small rectus muscle. Thus, there is continuity between the dura mater and the occipital ligament at the level of the occiput-atlanta and atlanta-axis, there is also a fascial connection between the posterior rectus capitis minor and the oblique fibers of the posterior membrane of the occiput and atlas, which extends dorsally to connect with the perivascular fascia of the vertebral arteries. The occipital ligament also extends laterally at the occiput to the temporoccipital region. This relationship should be taken into account in headaches, as well as in osteopathic treatment. The anterior dural ligaments (Hofmann's ligaments) connect the anterior surface of the dura mater to the deep bundle of the posterior vertebral ligament. These ligaments are present at all levels from C7 to L5, some are limited to a single segment, others connect to multiple segments. Their orientation varies depending on the departments: they are longitudinal in the upper thoracic part, transverse at the level of T8 - T9, and then vertical to the lumbar vertebrae. The roots of the spinal nerves pass through the dura mater and carry it along, continuing into the intervertebral dura mater to of the intervertebral foramen, where several branches are then sent to the periosteum and eventually mixed with the neurilemma (Fig. 57). nerve roots to the inside of the pedicle that runs inside the nerve canal. There is a connection between the dura mater and the nerve roots. Within these tissues there are dural veins.

Rice. 57. Continuations of the dura mater

d) Inner surface

It corresponds to the parietal layer of the arachnoid membrane. By connecting passages, it is connected with the pia mater:

in the anterior-posterior direction, it is nothing more than simple threads (network); in the transverse direction, it is a true membrane extending in height along the entire spinal cord - the dentate ligament. All these continuations aim to fix and maintain the spinal cord in the center of the dura mater fibrous canal, as well as protect it. There are two systems of innervation:

a segmental system derived directly from the accessory nerve; a non-segmental system derived from the sympathetic system, which is also involved in proprioception.

(dura mater; synonym pachymeninx) external M. o., consisting of dense fibrous connective tissue, adjacent to the inner surface of the bones in the cranial cavity, and in the spinal canal separated from the surface of the vertebrae by loose connective tissue of the epidural space.

- 1. A thin layer of mesoderm that surrounds the brain of the embryo. A large part of the skull and the membranes surrounding the brain subsequently develop from it. See also Cartilaginous skull. 2. See the meninges...
medical terms
- the innermost of the three membranes surrounding the brain and spinal cord. Its surface adheres tightly to the surface of the brain and spinal cord, covering all the furrows and convolutions present on it ...
medical terms
- the outer thickest of the three meninges, surrounding the brain and spinal cord. Consists of two plates: outer and inner, and the outer plate is also the periosteum of the skull ...
medical terms
- the outer of the three meninges covering the brain and spinal cord. Source: "Medical ...
medical terms
- an altered uterine mucosa, which is formed during pregnancy and is rejected with the placenta after the birth of a child ...
medical terms
- Sinuses of the hard shell. sickle of the brain; inferior sagittal sinus; anterior intercaval sinus; wedge-parietal sinus; posterior intercaval sinus; superior petrosal sinus; cerebellum...
Atlas of human anatomy
- 1) see the list of anat. terms 2) see the list of anat. terms...
Big Medical Dictionary
- intracranial G., due to an increase in the volume of the medulla and interstitial fluid ...
Big Medical Dictionary
- the general name of the connective tissue membranes of the brain and spinal cord ...
Big Medical Dictionary
- M. o., adjacent directly to the substance of the brain and spinal cord and repeating the relief of their surface ...
Big Medical Dictionary
- M. o., located between the dura and pia mater ...
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- see. The meninges are soft ...
Big Medical Dictionary
- collective, free discussion of a problem, idea, with the possibility of offering the most non-standard options ...
Glossary of business terms
- search for an unconventional solution to the problem by discussing it according to the developed rules by several specialists of various profiles ...
Glossary of business terms
- From English: Brain storming. This is how the participants in the group sessions, which the American psychologist Alex F. Osborne led since 1938, called the method he proposed for intensive discussion of any problem ...
Dictionary of winged words and expressions

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Shells of the brain

The brain, like the spinal cord, is surrounded by three meninges. These connective tissue sheets cover the brain, and in the region of the foramen magnum they pass into the membranes of the spinal cord. The outermost of these membranes is the dura mater of the brain. It is followed by the middle - arachnoid, and medially from it is the inner soft (vascular) membrane of the brain, adjacent to the surface of the brain.

Hard shell of the braindura mater encephali \ cra- nialis]. This shell differs from the other two in its special density, strength, and the presence in its composition of a large number of collagen and elastic fibers. Lining the inside of the cranial cavity, the dura mater is also the periosteum of the inner surface of the bones of the cerebral part of the skull. With the bones of the vault (roof) of the skull, solid

Rice. 162. Relief of the hard shell of the brain and the exit of the cranial nerves; bottom view. [The lower part of the skull (base) has been removed.]

1-dura mater encephali; 2 - n. opticus; 3-a. carotis interna; 4 - infundibulum; 5 - n. oculomotorius; 6n. trochlearis; 7-n. trigeminus; 8-n. abducens; 9-n. facialis et n. vestibulocochlearis; 10-nn. glossopharyn-geus, vagus et accessorius; 11-n. hypoglossus; 12-a. vertebralis; 13 - n. spinalis.

the membrane of the brain is not firmly connected and is easily separated from them. In the region of the base of the skull, the shell is firmly fused with the bones, especially at the junctions of the bones with each other and at the points of exit from the cranial cavity of the cranial nerves (Fig. 162). The hard sheath surrounds the nerves for some distance, forming their sheaths, and fuses with the edges of the holes 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. In some places, the dura mater of the brain

Rice. 163. Hard shell of the brain, dura mater encephali [ cranialisj.

1 - falx cerebri; 2 - sinus rectus; 3 - tentorium cerebelli; 4 - diaphragma sellae; 5 - n. opticus et a. carotis interna.

it splits and its inner leaflet (duplicature) deeply bulges in the form of processes into the cracks separating parts of the brain from each other (Fig. 163). In the 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 - sinuses of the dura matershells,sinus Durae tnatris.

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 crescent cerebrum (large falciform process), falx cerebri. This is a thin sickle-shaped plate of the hard shell, which in the form of two sheets penetrates into the longitudinal fissure of the cerebrum. 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 large sickle

the brain also between its two leaves is the lower 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.

Namet(tent) 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 of the cerebellum, the cerebellar mantle separates the occipital lobes from the cerebellar hemispheres. The anterior margin of the cerebellum is uneven. It forms a notch, 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 dura mater of the brain forms a transverse sinus adjacent to the occipital sulcus of the same name.

Falx cerebellum(small falciform process), fdlx cerebelli, like a sickle of the brain, located in the sagittal plane. Its anterior margin is free and penetrates between the hemispheres of the cerebellum. The posterior edge of the falx cerebellum continues to the right and left into the inner sheet of the dura mater of the brain, extending from the inner 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) saddles,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.

Sinuses of the dura mater of the brain. 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 (Fig. 164).

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,

Rice. 164. The relationship of the membranes of the brain and the superior sagittal sinus with the vault of the skull and the surface of the brain; incision in the frontal plane (scheme).

1 - dura mater; 2-calvaria; 3 - granulationes arachnoidales; 4 - sinus sagittalis superior; 5 - cutis; 6-v. emissaria; 7 - arachnoidea; 8 - cavum subarachnoidale; 9 - pia mater; 10 - encephalon; 11 - falx cerebri.

there are corresponding grooves. There are the following sinuses of the hard shell of the brain (Fig. 165).

1. superior sagittal sinus,sinus sagittalis superior, located along the entire outer (upper) edge of the crescent of the brain, from the cockscomb 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 lateral lacunae communicating with it, lacunae laterdles. 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 diploic veins flow into them.

Rice. 165. Sinuses of the hard shell of the brain; side view.

1 - sinus cavernosus; 2 - sinus petrosus inferior; 3 - sinus petrosus superior; 4 - sinus sigmoideus; 5 - sinus transverse; 6 - sinus occipitalis; 7 - sinus sa-gittalis superior; 8 - sinus rectus; 9 - sinus sagittalis inferior.

inferior sagittal sinus,sinus sagittalis inferior, 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.

straight sinus,sinus rectus, located sagittally in the splitting of the cerebellar tentorium along the line of attachment of the falx 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 direct sinus. Behind the straight 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 into this.

transverse sinus,sinus transverse, lies at the place where the cerebellum is separated from the dura mater of the brain. On the inner surface of the scales of the occipital bone, this is

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 (sinus fusion), confluens sinuum. On the right and left, the transverse sinus continues into the sigmoid sinus of the corresponding side.

occipital sinus,sinus occipitalis, lies at the base of the falx cerebellum. Descending along the internal occipital crest, it reaches the posterior edge of the large occipital foramen, 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.

sigmoid sinus,sinus sigmoideus (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.

cavernous sinus,sinus cavernosus, paired, located on the base of the skull on the side of the Turkish saddle. The internal carotid artery and some cranial nerves pass through this sinus. This 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 Turkish saddle, in front of and behind the funnel of the pituitary gland. The sphenoid-parietal sinus and the superior ophthalmic vein flow into the anterior sections of the cavernous sinus.

sphenoparietal sinus,sinus sphenoparietalis, paired, adjacent to the free posterior edge of the small wing of the sphenoid bone, in the splitting of the hard shell of the brain attached here.

superior and inferior petrosal sinuses,sinus petrosus su perior et sinus petrosus inferior, paired, lie 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 stony 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 dura have communications with the diploic veins, vv. dipioicae located in the spongy substance of the bones of the cranial vault and flowing into the superficial

head veins. 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, suboccipital, pterygoid, etc.), venous blood from the brain can flow into the superficial veins of the head and neck.

Vessels and nerves of the hard shell of the brain. TO The middle meningeal artery (a branch of the maxillary artery), which branches in the temporo-parietal section of the membrane, approaches the hard shell of the brain through the right and left spinous foramina. The dura mater of the brain lining the anterior cranial fossa is supplied with blood by the branches of the anterior meningeal artery (a branch of the anterior ethmoidal artery from the ophthalmic artery)". the jugular foramen, as well as the meningeal branches from the vertebral artery and the mastoid branch from the occipital artery, which enters 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 (Fig. 166).

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. The dura mater in the region of the anterior cranial fossa receives branches from the optic nerve (the first branch of the trigeminal nerve). The branch of this nerve, the tentorial (shell) branch, 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, approach the membrane in the middle cerebral fossa. In the sheath lining the posterior cranial fossa, the meningeal branch of the vagus nerve branches.

arachnoid membrane of the brain,arachnoidea mater (encephali) [ cranialis]. This shell 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 pia mater of the brain subarachnoid(subarachnoid) space,cavitas [ spdtium] sub- arachnoidalis [ subarachnoideum], which contains cerebrospinal fluid liquor cerebrospindlis. In places,

Rice. 166. Veins of the pia mater of the brain.

1 confluence of veins in the superior sagittal sinus; 2 - superficial cerebral veins; 3 - sigmoid sinus.

where the arachnoid membrane is located above the wide and deep furrows, the subarachnoid space is expanded and forms a larger or smaller size subarachnoid cisterns,cister- paesubarachnoideae.

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.

cerebellar cistern,clsterna cerebellomedulla- ris, located between the medulla oblongata ventrally and the cerebellum dorsally. Behind, it is limited by the arachnoid membrane. This is the largest of all tanks.

Cistern of the lateral fossa of the brain,cisterna fos sae laterdlls 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.

cross tank,cisterna chiasmatis [ chiasmatica], located at the base of the brain, anterior to the optic chiasm.

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.

The cerebrospinal fluid that fills the subarachnoid space is produced by the choroid plexuses of the ventricles of the brain. From the lateral ventricles through the right and left interventricular openings, cerebrospinal fluid enters III ventricle, where there is also a choroid plexus. From III ventricle through the cerebral aqueduct, cerebrospinal fluid enters the IV ventricle, and from it through an unpaired opening in the posterior wall and a paired lateral aperture 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. Near the sinuses of the hard shell of the brain, the arachnoid membrane forms a kind of protrusion - arachnoid granulation,gra- nulationes arachnoideae (pachion 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. Granulations of the arachnoid membrane are organs where the outflow of cerebrospinal fluid into the venous bed is carried out.

Soft(vascular) shell of the brainRia mater encephali [ cranialis]. 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 shell penetrates into the cavities of the ventricles of the brain and forms vascular plexus,plexus choroidus, producing cerebrospinal fluid.

Review questions

Name the processes of the hard shell of the brain. Where is each process located in relation to the parts of the brain?

List the sinuses of the dura mater of the brain. Where does each sinus fall into (open)?

Name the cisterns of the subarachnoid space. Where is each tank located?

Where does the cerebrospinal fluid drain from the subarachnoid space? Where does this fluid enter the subarachnoid space?

Age features of the membranes of the brainand 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 of the brain and spinal cord 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 of 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) varies from 0.8 to 1.8 cm.

Dura mater, dura mater, It is a shiny, whitish sheath of dense fibrous tissue with a large number of elastic fibers.

Its outer rough surface faces the inner surface of the spinal canal and the bones of the skull; with its inner smooth shiny surface, covered with flat epithelioid cells, it is directed towards the arachnoid membrane.

Dura mater of the spinal cord

Dura mater spinalis , forms a wide, cylindrical bag elongated from top to bottom.

The upper border of this shell is located at the level of the large occipital foramen, along the inner surface of which, as well as the cervical vertebra lying below, fuses with their periosteum. In addition, it is tightly connected to the integumentary membrane and to the posterior atlantooccipital membrane, where it is perforated by the vertebral artery. With short connective tissue strands, the sheath is attached to the posterior longitudinal ligament of the spinal column.

Meninges medullae spinalis ;

In the downward direction, the bag of the hard shell expands somewhat and, having reached the II-III lumbar vertebra, i.e., below the level of the spinal cord, it passes into the thread (hard shell) of the spinal cord, filum terminale externum, which is attached to the periosteum of the coccyx.

The hard shell extending from the spinal cord envelops the roots, nodes and nerves in the form of sheaths, expanding towards the intervertebral foramens and taking part in fixing the shell.

membranes of the spinal cord,
meninges medullae spinalis;

view from above.

Dura mater of the spinal cord innervate branches of the meninges of the spinal nerves; supply blood branches of the vertebral arteries and branches of the parietal arteries of the thoracic and abdominal parts of the aorta; venous blood is collected in the venous vertebral plexuses.

Dura mater encephali , is a strong connective tissue formation, in which the outer and inner plates are distinguished.

The outer plate, lamina externa, has a rough surface, rich in blood vessels, and is adjacent directly to the bones of the skull, being their internal periosteum. Penetrating into the openings of the skull, through which the nerves exit, it covers them in the form of a vagina.

The hard shell of the brain is weakly connected with the bones of the cranial vault, with the exception of the places where the cranial sutures pass, and at the base of the skull it is firmly fused with the bones.

In children, before the fusion of the fontanelles, according to their location, the hard shell of the brain fuses tightly with the membranous skull and is closely connected with the bones of the cranial vault.

hard shell of the brain
brain, dura mater encephali;

right and top view.

Inner plate, lamina interna, The dura mater of the brain is smooth, shiny and covered with endothelium.

The hard shell of the brain forms processes that are located between the parts of the brain, separating them.

Along the lines of attachment of the processes of the hard shell of the brain, spaces are formed in it that have a prismatic or triangular shape in a transverse section - sinuses of the dura mater , which are collectors through which venous blood from the veins of the brain, eyes, hard shell and cranial bones is collected in the system of internal jugular veins.

These spaces - sinuses - have tightly stretched walls, do not collapse during the cut, there are no valves in them. A number of sinuses open into the cavity emissive veins, through which the sinuses through channels in the bones of the skull communicate with the veins of the integuments of the head.

hard shell of the brain innervated meningeal branches of the trigeminal and vagus nerves, sympathetic nerves from the periarterial plexus (middle meningeal artery, vertebral artery, and cavernous plexus), branches of the greater petrosal nerve and ear node; sometimes in the thickness of some nerves there are intrastem nerve cells. Most of the nerve branches of the meninges follow the course of the vessels of this membrane, with the exception of the cerebellum, where, unlike other parts of the dura mater of the brain, there are few vessels and where most of the nerve branches follow independently of the vessels.

Nerves of the dura mater :

A-region of the middle cranial fossa:

1 - trigeminal node; 2 - plexus of arcades; 3 - middle meningeal artery; 4 - meningeal branch of the mandibular nerve; 5-middle meningeal nerve; 6 - petrosal branch of the middle meningeal artery and its accompanying nerves; 7 - superior tympanic artery and its accompanying nerves.

The first branch of the trigeminal nerve - the ophthalmic nerve sends trunks to the dura mater of the anterior cranial fossa, the anterior and posterior sections of the cranial vault, as well as to the falx cerebrum, reaching the inferior sagittal sinus, and to the cerebellum (branch of the skull). The second and third branches of the trigeminal nerve, the maxillary nerve and the mandibular nerve, send the middle branch of the meninges to the sheath of the region of the middle cranial fossa, the cerebellum and the falx cerebrum. These branches are also distributed in the walls of the nearby venous sinuses.

The vagus nerve sends a thin branch of the meninges to the dura mater of the region of the posterior cranial fossa, up to the tentorium of the cerebellum, and to the walls of the transverse and occipital sinuses. In addition, the trochlear, glossopharyngeal, accessory, and hypoglossal nerves may be involved to varying degrees in the innervation of the hard shell of the brain.

Blood supply to the dura mater of the brain branches coming from the maxillary artery (middle meningeal artery); from the vertebral artery (branches to the meninges); from the occipital artery (meningeal branch and mastoid branch); from the ophthalmic artery (from the anterior ethmoid artery - the anterior meningeal artery). Venous blood is collected in the nearby sinuses of the dura mater.

The dura mater (DM) is a very strong connective tissue structure with external and internal layers.

Inside the cranium, this layer is tightly attached to the bone tissue, growing into the periosteum of its base.

The inner side of the meninges adjacent to the brain is smoothed with the presence of endothelium.

General information

In the middle of the dura mater and the arachnoid there is a small subdural cavity filled with a small amount of interstitial fluid - CSF.
In some fragments, the dura mater grows in the form of processes into the narrow spaces of the brain. In the areas of germination of the processes, the membrane bifurcates, forming triangular sinuses also covered with endothelium - the sinuses of the dura mater.

The plates of these reservoirs are very tight and do not move, even when cutting.

These tanks are designed to contain venous blood, which gradually drains from the veins that supply the brain with food and oxygen in the cranium. From the sinuses, blood flows into the internal jugular veins, in addition, there is a communication of these recesses with the arteries of the outer surface of the head thanks to spare arterial graduates.

Structure

The hard shell is a fibrous-type protective plate that adheres from the inside to the bone tissue of the cranium. Forms processes that grow into the cranial space: crescent-shaped continuation of the cerebrum, continuation of the cerebellum in the form of a sickle, cerebellar tenon, saddle plate, etc.

There is an epidural cavity between the dura mater and the bone tissue of the skull, which essentially means the union of multiple spaces separated by connective tissue bases (rods). These areas develop after birth, during the closing of pulsating fontanelles. In the place of the arch, these spaces expand, since there are not so many cartilaginous bases here. On the vault of the skull, and in the direction of the venous sinuses and cranial joints, the mentioned cavities become narrower and the binding of the strands is very thick. All joining cavities are provided with endothelium and filled with fluid. With the help of the experiments, it has been scientifically proven that the epidural fluid flows into the external network of small vessels of the DM.

The dura mater of the brain is divided into two more or less reinforced plates, of which the outer one is the periosteum of the skull. Each of the plates is stratified. Without exception, all layers are equipped with fibrillar protein, in fact the basis of the connective material. They are connected in bundles, placed equally horizontally in each of the layers. In neighboring layers, the beams intersect, forming a cross.

Sinuses and processes of the dura mater

TMO processes are considered:

A large crescent-shaped continuation, or crescent-shaped process of the largest hemispheres of the brain - is located between both large parts of the brain;
A small falciform process, or falciform process near the cerebellum - extends into the cavity between the hemispheres of the cerebellum, joining the bone tissue of the occiput from the internal occipital indentation to a considerable opening of the occiput;
Cerebellar mantle - located between parts of the cerebral hemispheres on the back of the head and cerebellum;
Plate - located above the Turkish saddle; in the middle it has a hole through which a funnel passed.

The sinuses (lacunae) of the dura mater of the brain, formed due to the splitting of the dura mater into two casts, are essentially channels through which blood from the veins is drained from the head into the internal dual veins.

The plates of the hard shell that form the gaps are tightly fixed and do not move. Therefore, in the context of these sinuses are viewed. They are not equipped with valves. The similar structure of these tanks allows venous blood to flow freely from the brain completely autonomously from pressure surges inside the cranium. On the inner walls of the bone tissue of the skull, in the areas where these depressions of the hard shell are located, there are proper markings. In medical practice, the following names of dura sinuses are used:

The upper vertically dividing sinus is located along the entire upper-outer border of the sickle of the cerebral hemispheres, from the edge resembling a cockscomb of the ethmoid bone to the indentation of the occiput inside. In the anterior parts, this cistern is equipped with fistulas with veins of the paranasal space. Its completion at the back is included in the transverse collector.
The lower vertically separating gap is located within the lower spacious border of the crescent of the cerebral hemisphere. It is much less than the top.
The direct sinus is placed vertically in the splitting of the cerebellar membrane in the direction of attachment to it of the sickle of the cerebral hemisphere. This collector combines the posterior ends of the superior and inferior sagittal sinuses.
is located in the part of the separation from the dura mater of the brain of the cerebellar plate. On the inner side of the scales of the bone tissue of the occiput, an extensive groove of the transverse sinus is related to this recess.
The occipital lacuna lies at the bottom of the falx cerebellum. Descending longitudinally from the inside of the occipital border, this cistern extends to the posterior border of the foramen magnum of the occiput, where it diverges into two furrows framing the foramen from behind and on both sides.
The sigmoid collector is double, located in the sigmoid branch on the inside of the skull, characterized by an S-shaped appearance. In the region of the opening of the large veins, this cistern flows into the jugular vein.
The cavernous sinus is double, lies on the vault of the skull away from the Turkish saddle. The carotid artery and some intracranial arteries pass through this cistern. The recess has a very intricate structure in the form of interconnected caves, which is why it got its name.
The sphenoparietal lacuna is double, refers to the spacious posterior border of a small wedge-shaped bone fragment, in splitting it connects in this place with the brain dura mater.
The upper and lower stony depressions are double, they lie longitudinally along the upper and lower borders of the triangle of the bone tissue of the temporal region.

In some areas, all these cisterns form fistula connections with the external veins of the skull through vascular connections. In addition, the TO sinuses connect with diploic arteries located in the spongy structure of the bones of the base of the skull and included in the superficial vessels of the head. So, blood from the veins of the brain flows down the branches of its located on the surface and in the depth of the vessels into the sinuses of TO and then into both sides of the large internal veins.

Functions

The key tasks of the TMO mainly include:

ensuring the removal of blood from the vessels of the head and, accordingly, blood circulation;
protective function - TMF is the densest structure among the existing protective layers;
providing a shock-absorbing effect due to the circulation of cerebrospinal fluid.

Comparison with soft shell

The most basic difference between the dura and the pia mater is the presence of double layers, a large number of veins and capillaries in the second. In addition, the pia mater is closest to the gyri, glia, and wattles, separated only by the glial diaphragm. In specific areas, the soft shell is introduced into the spaces of the ventricles of the brain and forms vascular tangles that synthesize cerebrospinal fluid. While the TMT has the presence of sinuses, and has a slightly different structure and functional tasks.