The soft shell of the brain. The structure and function of the membranes of the brain, inflammation and consequences. Inflammation of the meninges
The brain is covered with three layers. The outermost of them is the dura mater, or pachymeninx; under it lies the arachnoid membrane - arachnoidea, under the arachnoid membrane, directly adjacent to the brain, lining all its furrows, is the pia mater. Arachnoidea and pia mater together form leptomeninx.
The space between the dura mater and the arachnoidea is called the subdural space - cavum subdurale. Between the arachnoidea and pia mater is the subarachnoid space - cavum subarachnoidale.
Dura mater - consists of two plates of dense connective tissue. The outer plate simultaneously serves as the periosteum of the cranial cavity. Penetrating into the openings of the skull, through which the nerves exit, it covers them in the form of a vagina. The inner plate enters into a direct connection with the brain. The hard shell is supplied with nerves and blood vessels. She gives off shoots.
Falx cerebri falx cerebrum. It is located vertically between both hemispheres of the brain. Starting in front of the cristae frontalis of the ethmoid bone, the large falciform process with its upper edge is attached to the lateral ribs of the sagittal suture and reaches the protuberantia occipitalis interna.
The crescent process of the cerebellum - falx cerebelli, starts from the protuberantiae occipital is internae and goes to the foramen occipitale magnum, penetrating between both hemispheres of the cerebellum.
The cerebellar tent, or tentorium cerebellum - tentorium cerebelli - separates the dorsal surface of the cerebellum from the lower surface of the occipital lobes of the hemispheres. In the notch of the cerebellar tentorium (incisura tentorii), the midbrain passes.
Turkish saddle diaphragm - diaphragma sellae. This small process of the dura mater is stretched over the Turkish saddle. Under the process lies the pituitary gland. In the middle of the diaphragm there is a hole through which the funnel of the pituitary gland passes.
Sinuses (sinuses) of the dura mater. Between the sheets of the dura mater and its processes are the sinuses, representing the receptacle of venous blood.
Sinus sagittalis superior - the superior sagittal sinus, runs along the convex edge of the greater falciform process of the dura mater. It goes from the cristae frontalis along the sulcus sagittalis of the skull back, gradually increasing in volume, and in the protuberantia occipitalis interna joins the sinus transversus.
Sinus sagittalis inferior - the lower sagittal sinus, runs along the lower edge of the large falciform process and flows into the sinus rectus.
Sinus transversus - transverse sinus, the largest of all venous sinuses. It is located in the sulcus transversus of the occipital bone and the sulcus sigmoideus of the temporal bone. The last section was called sinus sigmoideus. From here, the sinus descends to the foramen jugulare and passes into the bulbus superior v. jugularis.
Sinus rectus - a straight sinus, lies between the upper surface of the cerebellar tenon and the place of attachment of the lower edge of the large falciform process.
Sinus cavernosus - the cavernous sinus, is placed on the lateral surface of the Turkish saddle. In its outer wall lie n. oculomotorius, n. trochlear is, n. ophthalmicus to n. abducens. Inside the cavernous sinus are a. carotis interna with its sympathetic plexus. V flows into the cavernous sinus. ophthalmica superior. Both cavernous sinuses anastomose through the sinus intercavernosus anterior, which lies in front of the pituitary gland, and the sinus intercavernosus posterior, which lies behind the pituitary gland. Thanks to the anastomoses, a “circular sinus” is obtained, surrounding the appendage of the brain on all sides.
Sinus petrosus superior - the upper petrosal sinus, located along the upper edge of the pyramid of the temporal bone. It connects sinus cavernosus with sinus transversus.
Sinus petrosus inferior - the lower stony sinus, lies in the groove of the same name and connects sinus cavernosus with bulbus v. jugularis superior.
Sinus occipitalis - the occipital sinus, covers the lateral edges of the foramen magnum and joins the sinus sigmoideus.
The confluence of the sinus transversus, sagittalis superior, rectus and occipitalis is located at the level of the cruciate eminence of the occipital bone, eminentiae cruciatae, and is called confluens sinuum - sinus drain.
Spider web and its cisterns. The arachnoid membrane - arachnoidea - is a thin connective tissue membrane located between the dura mater and pia. The outer surface of the arachnoid membrane is covered with endothelium. It is loosely connected to the dura mater by cerebral veins that flow into the sinuses of the dura mater. The outer surface of the arachnoideae forms the inner wall of the subdural space. The inner surface of the arachnoid membrane is rough, facing the pia mater and connected with it by numerous crossbars, membranes covered with endothelium. Arachnoidea is devoid of vessels. Above the cerebral gyri, the arachnoid and pia mater merge with each other, forming one common membrane. At the level of the furrows, the arachnoidea is separated from the pia mater: the arachnoid membrane spreads from the surface of one gyrus to the surface of the other, while the soft shell penetrates into all the furrows and crevices. Due to this, between both membranes, in the region of the furrows and crevices of the brain, cavities are formed, called subarachnoid cisterns - cisternae subarachnoidales, filled with cerebrospinal fluid.
The largest are the following cisterns: a) cisterna cerebel-lo-oblongata, or cisterna cerebri magna, a large cisterna of the brain, located between the lower surface of the cerebellum and the dorsal surface of the medulla oblongata; b) cisterna fossae lateralis cerebri, located in the region of the Sylvian fissure; c) cisterna chiasmatis, located in the region of the optic chiasm; d) cisterna intcrpeduncularis, located between the legs of the brain.
All cisterns of the brain communicate with each other and with the subarachnoid space of the brain and spinal cord. The greatest clinical significance is cisterna cerebri magna.
A needle enters this cavity during a suboccipital puncture performed to obtain cerebrospinal fluid. Here, painful changes often develop in the membranes of the brain that form the walls of the cistern.
Pachyonic granulations - granulationes arachnoidales, located on the outer surface of the arachnoid, mainly on the sides of the sinus sagittalis superior and near other sinuses, are eversion of the arachnoid. These inversions, or villi, of the arachnoid bulge into the lower wall of the venous sinuses, thin it, the entire thickness of the dura mater, and even the bones of the skull. Through pachyonic granulations, the subarachnoid space of the brain communicates with the venous sinuses.
The impressions formed in the bones of the skull by pachyon granulations are called pits of pachyon granulations. Pachion granulations are found only in adults. In children, they are replaced by microvilli, spots and mounds of the arachnoid membrane - the rudiments of pachyon granulations.
The pia mater is abundantly supplied with blood vessels and therefore is called the choroid. It is also rich in nerves. The soft shell is directly adjacent to the surface of the brain, going into all the furrows and deepening it. Vessels pass through the pia mater into the medulla, and the pia mater forms a sheath for them. Between the wall of the vessel and the sheath of the pia mater, a perivascular space is formed, which communicates with the subarachnoid space. The soft shell penetrates in the form of a double-folded leaf into the cavity of the ventricles, taking part in the formation of telae chorioideae and plexus chorioidei of the ventricles.
The physiological role of the membranes of the brain. The membranes of the brain perform an important physiological role, protecting the brain tissue from exposure to various harmful substances. For mechanical protection, the dense dura mater with its processes, as well as the system of cisterns with which the brain is lined like water cushions, is of particular importance.
Arachnoidea and pia mater are the main parts in the cerebrospinal fluid circulation system, and the choroid plexus of the ventricles is the main organ that produces this fluid. The membranes of the brain, in addition, actively protect the brain parenchyma from exposure to infectious-toxic hazards.
Meninges (meninges)
connective tissue structures covering the head and. There are hard shell (dura mater, pachymeninx), arachnoid (arachnoidea) and vascular, or soft (vasculosa, pia mater). The arachnoid and soft shells are combined under the general name "" (leptomeninx). ANATOMY AND PHYSIOLOGY Solid M.O. is a fibrous membrane adjacent from the inside to the bones of the skull. It forms processes protruding into the cranial cavity and separating the intracranial structures: (falx cerebri), separating the cerebral hemispheres, (falx cerebelli), protruding into the posterior notch of the cerebellum, the cerebellum tentorium (tentorium cerebelli), separating the occipital lobes of the cerebellum, the diaphragm of the saddle (diaphragma sellae), stretched between its tubercle and back and limiting the cavity of the saddle from above ( rice. one
). Between solid M.o. and the bones of the cranial vault have a slit-like cavity filled with epidural fluid. The inner surface of the membrane (from the side of the subdural space) is lined with endothelium. Solid M.O. has external capillary, arteriovenous and internal capillary networks. Fluid from the epidural space flows into the external network. The arteriovenous network consists of arterial and venous parts, lies in the thickness of the membrane. It is connected to the outer and inner capillary networks. The internal capillary network is located under the endothelium of the dura mater. Large venous collectors of the hard shell of the brain are the venous sinuses: the superior sinus (sinus sagittalis sup.) with the lateral gaps flowing into it (lacunae lat.), (sinus rectus), into which the large brain (v. cerebri magna), (sinus transversus), (sinus cavernosus), through which the internal carotid and cranial nerves pass, (sinus sigmoideus), lower sagittal sinus (sinus sagittalis inf.), superior petrosal sinus (sinus petrosus sup.). The walls of the sinuses, formed by the outer and inner sheets of solid M.o., do not have muscle elements, are lined from the inside with endothelium. The lumens of the sinuses gape. In the sinuses there are various forms of trabeculae and membranes. sinuses - blood from the brain, vascular network of solid M.o. They are connected with the veins of the bones and soft tissues of the skull and partially drain them ( rice. 2
). The main arteries of solid M.o. - middle, anterior and posterior meningeal arteries (aa. meningeae, ant., post.). solid M.o. carried out by branches of the V, VI, IX-XII cranial nerves, sympathetic fibers of the periarterial plexuses. The arachnoid is stretched by the convolutions of the brain, but does not enter the furrows. It separates the subdural and subarachnoid spaces. There are no blood vessels in the membrane; it is formed by arachnoid endothelial cells and bundles of collagen fibrils, the thickness and number of which vary in different areas. Through the arachnoid membrane, which has a high permeability, the outflow of cerebrospinal fluid from the subarachnoid space to the subdural space is carried out. On its surface there are so-called reactive structures in the form of cell spots, cell mounds, arachnoid villi and arachnoid (pachyon) granulations. The latter are a protrusion of leptomeninges and can go into, into the sinuses. The functional significance of these formations is to fix (“suspend”) the brain in the cranial cavity, as well as to ensure the outflow of cerebrospinal fluid from the subarachnoid space. The pia mater lines both the gyrus and the sulci of the brain, adjoining directly to the glial border of the brain. In its thickness, in addition to pial cells and bundles of collagen fibrils, there is its own capillary network. Through it, arterial vessels pass into the brain and venous vessels exit ( rice. 3
). The III-XII pairs of cranial nerves, sympathetic fibers of the nerve plexuses of the arteries of the brain take part in the innervation of the pia mater. The space between the arachnoid and soft [vascular) membranes () is differentiated into a system of cerebrospinal fluid channels and a system of subarachnoid cells. CSF channels - a network of tubes with a diameter of 5-20 micron, starting from the tanks - areas of expansion of the subarachnoid space. The canals spread along the furrows of the cerebral hemispheres, pass to the convolutions, branching and anastomosing with each other. They serve as a channel for cerebrospinal fluid. Subarachnoid cells occupy the space outside the canals, they are connected to each other and to the canals by holes through which it flows. Channels and cells have a fibrous framework of thin bundles of collagen fibrils lined with arachnoid endothelial cells. Functionally, the subarachnoid cells are a protective system. cerebrospinal fluid in them is slowed down, and arachnoid endothelial cells have phagocytic activity. The cerebral arteries and their branches are located in the lumen of the CSF channels, in which they are fixed by means of collagen strings. Veins pass among the cells ( rice. four
). The largest cerebellar cistern is located between the anteroinferior surface of the cerebellum and the posterolateral surface of the medulla oblongata ( rice. 3
). Between the tonsils of the cerebellum, the median aperture of the fourth ventricle of the brain opens into this cistern. There are lateral apertures at the ends of the lateral pockets of the IV ventricle. Through these openings, cerebrospinal fluid from the ventricle enters the large cistern. In the region of the pons of the brain, the middle and two lateral cisterns of the pons are distinguished. The interpeduncular cistern is located between the legs of the brain. Enveloping (transverse) - located in the region of the quadrigemina and forms, together with the cisterns of the bridge and the interpeduncular closed cisterns, surrounding. The cisterna decussation is located in front of the funnel of the pituitary gland. Above it lies the cistern of the boundary plate. The cistern of the lateral fossa of the brain is located in the fossa of the same name of the cerebral hemispheres. Liquor circulation is a physiological process that includes liquor production, liquor circulation and outflow. Liquor production is mainly carried out in the choroid plexuses of the ventricles, liquor circulation - sequentially in the ventricles, cisterns, liquor-bearing canals and subarachnoid cells, the outflow is carried out mainly through the arachnoid membrane and arachnoid (pachion) into the circulatory system of the solid M.o., into the blood vascular membranes and into the system venous circulation of the brain. There is a close relationship between the systems of liquor circulation and blood circulation. The membranes of the brain have a protective-barrier function, creating liquor-hematic, cerebrospinal fluid and histo-hematic barriers. The first is related to the outflow of cerebrospinal fluid from the subarachnoid space, the second is related to the exchange processes between the cerebrospinal fluid and the tissue elements of leptomeninges bordering it, the third is to the exchange processes between the capillary blood and the boundary tissue elements of the dura and pia meninges. The membranes of the spinal cord ( rice. 5
) are a continuation of the M.O., covering the cerebral hemispheres, and the medulla oblongata. Solid M.O. the spinal cord, which is thinner than the hard shell of the brain, forms a case for the entire spinal cord. He. gradually narrowing, ends at the level S II -S III. Further down is a solid MO thread, attached to the coccyx. A distinctive morphological feature of the dura mater of the spinal cord is the predominance of elastic fibers in its composition. The epidural space in the spinal canal is filled mainly with adipose tissue and the internal venous vertebral plexus. In places where the roots of the spinal nerves exit the spinal canal, a solid M.o. together with the arachnoid forms fibrous sheaths, passing into the spinal nerves. The subdural space of the spinal cord is a continuation of the subdural space of the overlying parts of c. n. With. The arachnoid of the spinal cord is thinner than the arachnoid of the brain. It separates the subdural and subarachnoid spaces. Its fibrous structure is dynamically adapted to changes in the volume of the subarachnoid space of the spinal cord associated with the movement of cerebrospinal fluid. The subarachnoid space of the spinal cord is not differentiated into systems of cerebrospinal fluid channels and subarachnoid cells. It is separated by the dentate ligaments and the intermediate cervical septum, which fix the position of the spinal cord. In the lower sections, the subarachnoid space expands with the formation of a terminal cisterna, where the roots of the cauda equina are located. The soft shell has a fibrous structure that reflects the direction of physiological deformations of the spinal cord. Arteries and veins of leptomeninges of the spinal cord are located on the outer surface of the pia mater. RESEARCH METHODS Most diseases of the c.n.s. of various etiologies are accompanied by the reaction of M.o. on, therefore, one of the main methods for determining their condition is the study of cerebrospinal fluid (Cerebrospinal fluid) .
Its pressure, composition, changes in circulation are of diagnostic importance. The latter can be investigated by the method of radionuclide cisternography. One of the important functions of M.o. is the process of resorption of cerebrospinal fluid (outflow outside the subarachnoid space), which can be quantified. To measure this parameter, sodium chloride is injected into the subarachnoid space by lumbar puncture at a constant rate. In this case, the pressure of the cerebrospinal fluid rises to a certain stable level. If the rate of endolumbar injection of the solution is then increased, the pressure of the cerebrospinal fluid rises again to another stable level. Dividing the difference in pressure at these levels, expressed in millimeters of mercury, by the degree of change in the rate of administration of isotonic sodium chloride solution ( ml/min), get the resorption resistance value, which is normally 6-8 mmHg Art. (ml/min). After subarachnoid hemorrhage, leptomeningitis and other pathological processes that disrupt the outflow of cerebrospinal fluid through the arachnoid membrane and its derivatives (arachnoid granulations), the resistance to resorption of cerebrospinal fluid may increase significantly. Such a violation can cause the development of hydrocephalus or intracranial hypertension. Shunt surgery for hydrocephalus (Hydrocephalus) and intracranial hypertension, the purpose of which is to create artificial ways for the outflow of cerebrospinal fluid from the ventricles into the right or abdominal cavity, are usually effective in cases where the resorption resistance exceeds 12-14 mmHg Art. (ml/min). PATHOLOGY Malformations Malformations M.o. in an isolated form are rare, usually they are combined with malformations of the brain (Brain) .
Complete or partial underdevelopment of solid M.o. accompanied by defects of the skull (windows of the skull). Soft M.o., the substance of the brain (cerebrum) can swell through these defects. In the region of the spinal cord, malformations are manifested by local splitting of the solid MO, sometimes together with the arachnoid. more often in the lumbosacral region, less often in the cervical. This is accompanied by splitting of the arches of the vertebrae, and sometimes the outer soft tissues. At the same time, soft M.o. can swell into the opening of the split tissues. (meningocele), alone or together with a portion of the spinal cord (meningomyelocele). In such cases, malformations also capture the spinal cord. One of the types of pathology is arachnoid cysts, which are formed as a result of dysembryogenesis of the M.o. system. This is characterized by the splitting of the arachnoid, the outer and inner sheets of which form cavities of various sizes, which leads to a violation of the liquor circulation, compression of neighboring areas of the brain. Damage Damage M.o. occur with traumatic brain injury (traumatic brain injury) and spinal cord injury (spinal cord injury) .
Vascular lesions M.o. of various etiologies are manifested by hemorrhages in the subarachnoid, subdural space (see. Intrathecal hemorrhages) .
Inflammatory diseases Meningitis develops more often as influenza, sepsis, pneumonia, syphilis, tuberculosis, brucellosis, rheumatism, toxoplasmosis, tonsillitis, rhinosinusitis, osteomyelitis of the bones of the skull, otitis media, etc. Often it is the result of craniocerebral and vertebral spinal cord, is associated with endocrine and metabolic disorders , tumors of the brain and spinal cord, being a nonspecific reaction of the brain to various influences. Leptomeningitis is characterized by diffuse inflammatory changes in the pia mater, vessels of the subarachnoid space, marginal zones of the brain and cranial nerve roots. Its occurrence is also facilitated by a violation of the body's immune reactivity (for example, with influenza), the development of nonspecific sensitization. There are cerebral and spinal arachnoiditis. Cerebral arachnoiditis. Almost always, both arachnoid and soft are affected. The arachnoid membrane thickens, adhesions form between it and the soft shell. The same adhesions often occur between the arachnoid and hard shells. The adhesive process leads to the formation of arachnoid cells containing a CSF-like fluid. If it exists for a long time, its walls gradually become thicker and denser, and it turns into a tumor-like formation. The cyst fluid may become xanthochromic and contain large amounts of protein. The dura mater in the area of the pathological process is thickened, rich in blood vessels. In the future, there are liquor pathways and secondary. For arachnoiditis is characterized by the presence of fibrosis of the soft membranes of the brain, choroid plexus of the ventricles, proliferation of connective tissue. Allocate adhesive (hyperplastic), cystic, adhesive-cystic, limited and diffuse, unifocal and multifocal arachnoiditis. Depending on the pathogenesis, arachnoiditis is divided into primary and secondary, depending on the course - into acute, subacute and chronic. The clinical picture depends on the predominant localization of the pathological process. In this regard, arachnoiditis is divided into convexital, basal (optico-chiasmal, posterior cranial fossa, cerebellopontine angle) and diffuse. rhinosinusitis often causes arachnoiditis, and - arachnoiditis of the posterior cranial fossa. The purpose of the surgical treatment of arachnoiditis is the separation of membrane adhesions, the removal of scars, cysts that compress the brain structures or cause a violation of the circulation of cerebrospinal fluid. Forecast. Acute arachnoiditis can result in recovery, but more often the disease takes a chronic course. Severe forms of cystic-adhesive cerebral arachnoiditis can be fatal, especially when the process is localized in the posterior cranial fossa. With opto-chiasmatic arachnoiditis, almost half of the patients have visual impairment, and in a number of patients the disease can result in blindness. Diffuse cerebral aracchioiditis also takes a chronic course with periods of exacerbation and remission. Diffuse spinal arachnoiditis in most cases is progressive in nature: motor and pelvic disorders, sensitivity disorders may gradually increase. Under the influence of ongoing therapy, remission is possible. Prevention. The main measure for the prevention of chronic arachnoiditis is their systematic, active and prolonged in the acute period, aimed at preventing subsequent exacerbation. Pachymeningitis- inflammation of the hard shell of the brain (cerebral pachymeningitis) and spinal (spinal pachymeningitis) of the brain. Cerebral pachymeningitis. Depending on which layers of the membrane are affected, there are external and intrasheath pachymeningitis; by the nature of inflammation - serous, and purulent; downstream - sharp and. Serous cerebral pachymeningitis can occur with common infectious diseases, intoxications and allergic reactions; hemorrhagic internal and intradural - with trauma, atherosclerosis, decompensated heart defects, blood diseases, infectious diseases of various etiologies, increased intracranial pressure of various origins. External purulent cerebral pachymeningitis occurs when pathogens enter the cranial cavity from the middle ear (with purulent otitis media), paranasal sinuses (with purulent sinusitis), as well as from festering wounds, carbuncles, boils of the head and other areas of the body. external purulent cerebral pachymeningitis develops more often in the posterior cranial fossa, less often in the middle to anterior cranial fossae. With otogenic and rhinogenic pachymeningitis, infectious agents penetrate into the cranial cavity by contact and hematogenous routes, as well as through the perineural spaces, from distant foci - by hematogenous and lymphogenous routes. Sometimes, as a result of pachymeningitis, extradural is formed. Internal purulent cerebral pachymeningitis is a complication of purulent sinusitis. In some cases, it proceeds in the form of otogenic and metastatic subdural abscesses. In most cases, the process is localized on the upper lateral surface of the cerebral hemispheres. Perhaps a combination of subdural abscess with extradural or thrombosis of the sinuses of the dura mater. Sometimes the course of the disease is complicated by purulent leptomeningitis. Pathological changes in serous pachymeningitis are characterized by loosening, edema and a sharp plethora of the hard shell of the brain and spinal cord. With hemorrhagic internal pachymeningitis, the dura mater of the brain is involved in the pathological process, more often the upper lateral surfaces of the frontal and temporal lobes of the cerebral hemisphere, sometimes both hemispheres of the cerebellum, less often the region of the Turkish saddle. With this form of the disease, hemorrhagic impregnation or stratification of the dura mater occurs due to rupture of the walls or phlebitis of the cerebral veins in the area where they flow into the sinuses of the dura mater. Macroscopically, the affected membrane is variegated due to the alternation of brownish-brown old foci and accumulation of blood in the cavities formed as a result of repeated hemorrhages. In the future, the contents of the cavities are completely discolored and the so-called hygromas of the hard shell of the brain are formed. Microscopically, with hemorrhagic pachymeningitis, foci of hemorrhages of various prescriptions and cavities are found, the inner surface of which is lined with ectoderm. A feature of hemorrhagic pachymeningitis is the slow development of the processes of organizing hemorrhagic masses and insufficiently pronounced coagulation of the outflowing blood due to the low content of fibrinogen in it or the admixture of cerebrospinal fluid. With purulent pachymeningitis, the hard shell of the brain and spinal cord is plethoric, purulent or fibrinous-purulent is located on its outer surface or in the subdural space. Gradually, it organizes itself and is limited to spikes. In this case, extra- or subdural abscesses are formed. Microscopically, perivascular infiltrates of segmented leukocytes and varying degrees of maturity are found in the dura mater of the brain and spinal cord. When the pathological process subsides, membranes develop. In chronic pachymeningitis, fibrosis of the hard shell of the brain and spinal cord develops, and it fuses with surrounding tissues. The spread of the process along the length of the hard shell of the spinal cord contributes to the formation of a muff-like thickening, followed by compression of the roots of the spinal nerves and their atrophy. Serous cerebral pachymeningitis clinically proceeds, as a rule, asymptomatically and therefore is practically not diagnosed. Hemorrhagic internal and intradural pachymeningitis manifests itself in a variety of ways. Small hemorrhages in the dura mater do not give any symptoms. With extensive hemorrhages, the headache that occurs in the acute period gradually takes on a character, accompanied by vomiting and sometimes loss of consciousness. Often there is a decrease in memory, sometimes, on the contrary, - psychomotor. Focal neurological symptoms depend on the location of the hemorrhage. There are mild meningeal symptoms. Some patients have congestive optic nipples with retinal hemorrhages or optic neuritis. During a lumbar puncture, cerebrospinal fluid flows out under increased pressure. It sometimes shows an increase in protein content, slight pleocytosis, mild xanthochromia. In some cases, hemorrhagic cerebral pachymeningitis is complicated by swelling of the brain (Edema of the brain) .
External purulent cerebral pachymeningitis is characterized by localized headache. With percussion of the skull, pain is noted according to the localization of the process. With pachymeningitis and extradural abscess in the middle cranial fossa, the most severe headache is localized in the temporal region. Sometimes develop, epileptic seizures, paresis of the limbs. The inflammatory process at the apex of the temporal pyramid causes severe pain on the side of the lesion in the frontal, temporal regions and the eyeball, skin hyperesthesia in the area of innervation of the optic nerve, combined with paralysis of the genus nerve. For an abscess in the posterior cranial fossa, pain during percussion of the occipital region, limitation of movements and forced position of the head are most characteristic. The defeat of the trigeminal nerve in pachymeningitis can be combined with damage to the facial and vestibulocochlear nerves and be accompanied by nystagmus and severe dizziness. with pachymeningitis and extradural abscess, usually not changed. At lumbar puncture, there is an increased pressure of cerebrospinal fluid, some increase in protein and a small pleocytosis with a predominance of neutrophils. Internal purulent cerebral pachymeningitis is characterized by an increase in body temperature up to 38-40 °, chills, headache, and sometimes vomiting. Are noted, apathy,. The syndrome is pronounced. In some cases, congestive nipples of the optic nerves are detected. Monoparesis or aphasia are observed. In the blood, a pronounced shift of the leukocyte formula to the left, an increase in ESR are noted. During lumbar puncture, cerebral fluid flows out under increased pressure, the number of cells in it may be normal or moderately increased. The protein content is increased. The diagnosis of cerebral pachymeningitis is made on the basis of the patient's complaints, anamnesis, clinical picture, as well as data from a laboratory study of blood and cerebrospinal fluid. It is necessary to take into account the data of the study of the fundus, radiography of the skull and paranasal sinuses. With otogenic external purulent pachymeningitis, an increase in purulent discharge from the ear may be of great diagnostic value. Of the auxiliary diagnostic methods, it is necessary to use echoencephalography, as well as computed tomography. Differential diagnosis is carried out with cerebral stroke, subarachnoid hemorrhage, meningitis, brain tumor and abscess, cerebral arachnoiditis. Treatment in most cases is surgical. With external purulent pachymeningitis, large doses of antibiotics are simultaneously administered. With internal purulent cerebral pachymeningitis, treatment is usually conservative; it is aimed at the underlying disease and is combined with anti-inflammatory and dehydration therapy. In the presence of a subdural abscess, it is necessary, as with an extradural abscess. The prognosis for timely treatment is usually favorable. Spinal pachymeningitis more common than cerebral. In most cases, external spinal pachymeningitis is observed, in which the inflammatory process usually begins in the epidural tissue and then spreads to the outer layer of the dura mater of the spinal cord. It is also called epiduritis. Along the course, it can be acute and chronic, and by the nature of the process - serous, purulent and chronic hyperplastic. Serous spinal pachymeningitis is latent, asymptomatic and practically undiagnosed. Purulent spinal pachymeningitis (purulent) is usually secondary - a complication of purulent processes that can be localized both near the epidural space (spine), and at a considerable distance from it (furunculosis, tonsillitis, etc.). The pathogen enters the epidural space by lymphogenous, hematogenous and contact routes. The purulent process in the epidural tissue can be limited or diffuse, more often localized in the middle and lower thoracic regions of the spinal canal. Purulent spinal pachymeningitis begins acutely (rarely subacute), accompanied by weakness, malaise, lack of appetite, headache. The temperature curve has a hectic character. In the blood, significant leukocytosis, a shift of the leukocyte formula to the left, and an increase in ESR are detected. Against this background, there are radicular pain, paresthesia, positive symptoms of root tension, and paralysis of the limbs, more often in the form of spastic lower paraplegia, conduction type sensitivity disorders, dysfunction of the pelvic organs. Along with this, the absence or lethargy of some tendon reflexes, and atrophy of individual muscle groups, are possible. In acute cases, after 2-3 days. after the appearance of radicular pain, central paresis or paralysis and dysfunction of the pelvic organs are detected. In the cerebrospinal fluid, xanthochromic large amounts of protein and moderate pleocytosis are noted. (see Cerebrospinal fluid) ,
as a rule, CSF protein is detected, which is confirmed by pneumomyelography. Chronic hyperplastic spinal pachymeningitis (chronic hyperplastic epiduritis) occurs as a result of an injury to the spine, its chronic inflammatory or dystrophic disease (spondylosis, brucellosis, etc.). Separate forms of chronic hyperplastic pachymeningitis are purulent hypertrophic syphilitic and tuberculous spinal pachymeningitis. The disease often begins subacutely. There are severe radicular pains, pains in the region of the spine, sometimes resembling, accompanied by tension in the muscles of the back. in the spine are limited due to pain. The initial period is followed by, after which the pain resumes. Paresthesias, radicular hyperesthesia appear. Increasing phenomena of spastic lower paraparesis (rarely tetraparesis), conduction disorders of sensitivity. Sometimes Brown-Séquard syndrome develops (see Brown-Séquard syndrome) .
The blood picture does not change, protein-cell dissociation is found in the cerebrospinal fluid. The general condition of the patient in most cases remains satisfactory. The diagnosis of spinal pachymeningitis presents significant difficulties. It is necessary to take into account the patient's complaints, as well as laboratory data from blood and cerebrospinal fluid tests. Of the auxiliary diagnostic methods, pneumomyelography, epidurography and spondylography can be used. Differential diagnosis is carried out with acute myelitis, spondylitis, abscess and tumor of the spinal cord, spinal arachnoiditis. Treatment of purulent spinal pachymeningitis is aimed at the underlying disease and is combined with the use of large doses of antibacterial drugs. In the presence of an epidural abscess, surgery is indicated. In chronic hyperplastic pachymeningitis, treatment is usually surgical. Antibiotics are prescribed before and after surgery. With purulent hyperplastic syphilitic and tuberculous pachymeningitis, the treatment is conservative (specific). The prognosis of purulent spinal pachymeningitis is serious. It depends not only on the severity of the purulent process, the timeliness of the treatment started, but also on the nature and course of the underlying disease. The prognosis for chronic hyperplastic pachymeningitis with timely treatment is favorable. Tumors The meninges can be affected by benign and malignant tumors. In the dura mater or its processes, less often in the pia mater, arachnoid endotheliomas (meningiomas) occur, which grow towards the brain, pushing and squeezing it. Macroscopically, it is usually a well-demarcated dense rounded shape of various sizes. The clinical course is slow, the duration of the disease is often calculated for many years. may be different; as a rule, primary focal symptoms are observed (see Brain ,
tumors). Malignant tumors most often affect M. about. metastatic way with the development of single or multiple nodes. Primary malignant tumors of the meninges occur, such as melanoma .
The diagnosis is based on clinical data and the results of additional research methods, in particular, the detection of tumor cells in the cerebrospinal fluid. Treatment of limited tumors operational. With diffuse lesions M.o. applied, chemotherapy. Bibliography: Baron M.A. Reactive structures of inner shells, p. 67, L., 1949; Baron M.A. and Mayorova N.A. Functional stereomorphology of the meninges, M., 1982, bibliogr.; Bekov D.B. and Mikhailov S.S. Atlas of arteries and veins of the human brain. M., 1979; Gusev E.I., Grechko V.E. and Burd G.S. Nervous diseases, p. 319, M., 1988; Dobrovolsky G.F. The role of the system of barriers of the membranes of the brain in subarachnoid hemorrhage, Zhurn. neuropath. and psychiat., vol. 79, no. 7, p. 833, 1979; he, Paracerebral barriers of the membranes of the brain, ibid., vol. 82, no. 7, p. 1, 1982; Majidov N.M. and diagnosis of chronic fibrosing leptomeningitis - arachnoiditis of the posterior cranial fossa, Tashkent, 1969, bibliogr.; he, Cerebral leptomeningitis and chorioependymatitis (arachnoiditis), L., 1986; Macheret E.L., Samosyuk I.Z. and Garkusha L.G. Cerebral arachnoiditis, Kyiv, 1985, bibliogr.; Mikheev V.V. and others. Spinal cord lesions in diseases of the spine, p. 291. M., 1972. brain; 6 - epidural space; 7 - subdural space; 8 - subarachnoid space; 9 - liquor-bearing channels; 10 - subarachnoid cells; 11 - arteries in the liquor-bearing channels; 12 - veins in the system of subarachnoid cells; 13 - strings - structures that stabilize the arteries in the lumen of the liquor channels: the arrows indicate the direction of the outflow of the epidural fluid into the outer (a) and inner (b) capillary network of the dura mater "\u003e Rice. 4. Scheme of the structure of the meninges of the cerebral hemispheres: 1 - a fragment of the bone of the cranial vault; 2 - hard shell of the brain; 3 - arachnoid shell; 4 - soft (vascular) membrane; 5 - brain; 6 - epidural space; 7 - subdural space; 8 - subarachnoid space; 9 - system of liquor-bearing channels; 10 - subarachnoid cells; 11 - arteries in the liquor-bearing channels; 12 - veins in the system of subarachnoid cells; 13 - strings - structures that stabilize the arteries in the lumen of the CSF channels: the arrows indicate the direction of the outflow of the epidural fluid into the external (a) and internal (b) capillary network of the dura mater. Vascular plexus of the IV ventricle; 9 - arachnoid; 10 - cerebellar-cerebral cistern; 11 - medulla oblongata; 12 - ; 13 - interpeduncular cistern; 14 - optic nerve; 15 - cross tank; 16 - ; 17 - vascular base and choroid plexus of the III ventricle "\u003e Rice. 3. The arachnoid and soft membranes of the brain, subarachnoid cisterns (median section of the brain; the area of the arachnoid membrane in the region of the medial surface of the hemisphere is removed): 1 - artery of the soft membrane; 2 - arachnoid membrane (partially removed); 3 - roller of the corpus callosum; 4 - a large cerebral vein; 5 - transverse fissure of the large brain; 6 - IV ventricle; 7 - cerebellum; 8 - vascular base and choroid plexus of the IV ventricle; 9 - arachnoid; 10 - cerebellar-cerebral cistern; 11 - medulla oblongata; 12 - bridge; 13 - interpeduncular cistern; 14 - optic nerve; 15 - cross tank; 16 - thalamus; 17 - vascular base and choroid plexus of the third ventricle. Rice. Fig. 1. Dura mater of the brain, right and top view (the right part of the skull roof was removed by horizontal and sagittal cuts): 1 - crescent of the brain; 2 - upper longitudinal sinus; 3 - lower longitudinal sinus; 4 - intercavernous sinus; 5 - wedge-parietal sinus; 6 - seat diaphragm; 7 - intercavernous sinus; 8 - cavernous sinus; 9 - basilar plexus: 10 - right upper petrosal sinus; 11 - superior bulb of the internal jugular vein; 12 - sigmoid sinus; 13 - a hint of the cerebellum; 14 - transverse sinus; 15 - sinus drain; 16 - direct sine; 17 - a large cerebral vein; 18 - left upper stony sinus; 19 - left lower stony sinus. Big Medical Encyclopedia
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Connective tissue membranes surrounding the brain and spinal cord in vertebrates. Fish have a primary medulla. In terrestrial vertebrates, it differentiates into hard and soft, which in mammals is divided into arachnoid and vascular ... ... encyclopedic Dictionary
Connective tissue membranes surrounding the brain and spinal cord in vertebrates and humans. The embryos develop primary M. o., which then differentiates into a hard, adjacent to the periosteum, and primary soft, ... ... Great Soviet Encyclopedia
Meninges- (anat. meninges). The connective tissue membranes of the brain and spinal cord are soft, adjacent directly to the brain; arachnoid, located between soft and hard; hard, outer... Explanatory Dictionary of Psychiatric Terms
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Meninges- (Latin meninges) connective tissue membranes of the brain and spinal cord: dura mater (outer, adjacent to the bones), pia mater (adjacent to the brain) and arachnoid, located between the dura and ... ... Encyclopedic Dictionary of Psychology and Pedagogy
The head of the brain is surrounded by three meninges: hard, arachnoid and soft.
hard shell of the brain(dura mater encephali) is the outermost. It is quite thick, very strong and dense connective tissue plate. It consists of two sheets, loosely connected to each other due to the presence of a thin layer of loose fiber between them. Thanks to this, in particular, the superficial layer can be easily separated from the deep layer and used for plastic replacement of a defect in the dura mater.
On the vault of the skull, the dura mater is loosely connected with the bones and separated from them by a slit-like epidural space (cavilas epiduralis). At the base of the skull, the dura mater is firmly connected to the bones, especially in the circumference of the Turkish saddle and in the area of the pyramid of the temporal bones.
The dura mater gives three processes inside the skull: the crescent of the cerebrum (falx cerebri), which separates the cerebral hemispheres from each other, the crescent of the cerebellum (falx cerebelli), which separates the hemispheres of the cerebellum, and the cerebellum (teniorium cerebelli), which separates the cerebrum and cerebellum. In places of attachment of the dura mater to the bones of the skull, venous sinuses are formed - sinuses. The sinuses of the dura mater, unlike the veins, do not have valves.
The processes of the hard shell of the brain are a kind of shock absorbers that protect the substance of the brain from injury. Anteriorly, the falx cerebri is fused with the cockscomb of the ethmoid bone. The lower edge of the sickle of the brain reaches the corpus callosum, and its posterior section is connected to the cerebellum. The latter is located almost horizontally, forming some kind of arch, and is attached behind - on the occipital bone (along the transverse furrows), from the sides - on the upper edge of the pyramids of the temporal bones, in front - on the anterior inclined process (processus clinoideus anterior) of the sphenoid bone. A small crescent of the cerebellum extends from the lower surface of the cerebellum along the median sagittal line, penetrating into the groove between the hemispheres of the cerebellum.
Arachnoid membrane of the brain(araebnoidea encephali) thin, does not contain blood vessels. It passes over the furrows of the brain without entering them. The arachnoid membrane forms outgrowths - granulations of the arachnoid membrane (granulationes arachnoideales), which penetrate into the lumen of the venous sinuses and through which the outflow of cerebrospinal fluid into the bloodstream is carried out.
The arachnoid membrane is separated from the dura mater by a slit-like subdural space (spatium subdurale), which, in the foramen occipilale magnum, passes into a wide sac-like subdural space of the spinal canal. The arachnoid membrane is separated from the pia mater by the subarachnoid (subarachnoid) space (cavitas subarachnoidealis). However, both membranes are interconnected by numerous thin connective tissue bundles, more developed where the soft and arachnoid membranes are adjacent directly to each other, topographically making up one whole, i.e., at the tops of the gyri of the brain.
The subarachnoid (subarachnoid) space directly passes into the same space of the spinal cord and contains cerebrospinal fluid. Where the arachnoid membrane covers more significant depressions between individual parts of the brain, the subarachnoid space forms extensions called subarachnoid cisterns (cisternae subarachnoideales). They are located mainly on the basis of the brain, freely communicate with each other and with the subarachnoid space.
soft shell of the brain(pia mater encephali) is rich in vessels. It is closely adjacent to the brain, covering the gyrus and going into all the furrows of the cerebrum and cerebellum, giving small vessels everywhere to the superficial gray matter. Penetrating into the cavities of the ventricles of the brain, the pia mater forms the choroid plexuses (plexus choroideus venlriculi).
It is an organ of the central nervous system, which consists of a huge number of interconnected processes of nerve cells and is responsible for all body functions. The cavity of the cranial region, which contains the medulla, protects the bones from external mechanical influences. The brain, as well as the spinal cord, is covered with three membranes: hard, soft and arachnoid, each of which performs its own functions.
The structure of the hard shell of the brain
A strong hard shell is a dense periosteum of the skull, with which it has a strong connection. The inner surface of the shell has several processes penetrating into the deep brain fissures in order to separate the departments. The largest such process is located between the two hemispheres, being a kind of sickle, the posterior part of which fuses with the cerebellum and limits it from the occipital lobes. On the surface of the dense membrane of the brain, there is another process, which is placed around, forming a kind of diaphragm and protecting the pituitary gland from excessive pressure of the brain mass. In the corresponding areas there are special sinuses, called sinuses, through which venous blood flows out.
The structure of the arachnoid membrane of the brain of the head
The arachnoid membrane of the brain is located on the inside of the hard shell. Although it is very thin and transparent, it does not penetrate into the fissures and furrows of the hemispheres, while covering the entire surface of the medulla and passing from one part to another. From the choroid of the brain, the arachnoid separates which is filled. Where the membrane is located above the deep and wide furrows, the subarachnoid space becomes wider, forming tanks of various sizes. Above the convex parts, especially above the convolutions, the soft and arachnoid membranes of the brain are closely pressed against each other, so the subarachnoid space in these areas is significantly narrowed and is a capillary gap.
Names of large subarachnoid cisterns:
- the cerebellar sinus is located in the depression between the cerebellum and the place where it is located;
- the sinus of the lateral fossa is located on the lower lateral side of the cerebral hemisphere;
- the cistern of the chiasm functions at the base of the brain of the head, from the front of the optic chiasm;
- localization of the interpeduncular cistern - between the legs of the brain in the interpeduncular fossa.
The membranes of the brain are connective tissue structures that also cover the spinal cord. They perform the function of protection, creating histohematic, cerebrospinal fluid and cerebrospinal fluid barriers, which are related to metabolic processes and the outflow of cerebrospinal substance. Without these structures, the normal functioning of the brain and the sufficient supply of all vital substances to it are impossible.
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.
