Meninges

Brain membranes (meninges) - three membranes that cover the brain: solid shell (dura mater, pachymeninx), spider shell (arachnoidea), choroid (vasculosa). Two recent United under the name soft shell (pia mater, leptomeninx).

The shell of the big hemispheres of a brain

Shell is solid - fibrous type membrane, contiguous from the inside to the bones of the skull. Forms the processes of jutting out into the cavity of the skull: the Crescent ridge large brain (lalx cerebri), sickle process of the cerebellum (falx cerebelli), namet cerebellum (tentorium cerebelli), aperture seat (diaphragma sellae), and other
Between the Dura mater and the bones of the skull is the epidural space of the brain, which is in fact the combination of numerous spaces, separated by connective tissue trabeculae. Experiencing these space after birth, during the closing springs. In the field of the code these spaces are wider as of trabeculae here a little. On the base of the skull as well as venous sinuses and cranial sutures mentioned space is less comprehensive and binding of trabeculae very thick. This explains different strength seam-Dura with the bones of the skull: in the field of the code it is easily separated from the bones, in the base - with considerable difficulty. All meeting spaces lined with endothelial tissue and fluid-filled. It is experimentally established, that epidural fluid flowing in the outer network of capillaries Dura.
Solid shell of the brain is divided into two more or less tightly bonded sheet, of which the outer is the periosteum of the skull bones. Each of the pieces is divided into layers. In all layers dominated by collagen fibers. They are collected in bunches, located in each of the layers in parallel. In the adjacent layers beams crossed, forming a lattice. Collagen bundles wrapped argyrophyllum fibers. Elastic fibers hard shell brain form a single network, which permeates all its layers, and only deepens on inner and outer surfaces of the shell. From the subdural space of the solid shell is covered by the endothelium. Variety of its sections functionally adapted to test their mechanical load. Fibres are placed in them in areas of emerging tensions. An example of such functional fitness is connected to the top longitudinal sinus plot shell, which consists of eight layers (Fig. 1).

the scheme fibrous structures Dura man
Fig. 1. The scheme fibrous structures Dura person's upper longitudinal sinus. At the confluence of the cerebral veins in sinus bundles of fibers form a loop that eliminates a losing clearance of Vienna (Wimmer).
scheme of vascularization of the Dura man
Fig. 2. Scheme of vascularization of the Dura person: 1 - outdoor network of capillaries; 2 - arteriovenous network; 3 - internal network of capillaries (N. Ya Vasino).

Blood vessels hard shell brain consists of three network: 1) outer network of capillaries, 2) arteriovenous network, and 3) the internal network of capillaries (Fig. 2). Outdoor network of capillaries is the most superficially, in direct proximity to the epidural space of the brain. Arteriovenous network lies in the inner part of the outer leaf of a hard shell, where are concentrated the major artery and vein. Highly convoluted "corkscrew" artery accompanied by the parties paired and, as a rule, much larger veins. Vascular bundles dichotomously branched. In some places pair of Vienna replaced extremely dense venous network that surrounds the artery. By branches arteriovenous network is connected with external and internal networks of the capillaries. Internal network of capillaries located under the endothelial lining facing the subdural space of the surface of the hard shell. This network is very dense and the degree of development is far superior to the outer network of capillaries. For the internal network of capillaries characteristic small length of their blood part and a much greater extent, and petitot venous parts of capillaries.
Larger venous collectors hard shell brain are the venous sinuses (Fig. 3), the walls of which, as a rule, formed the outer and inner leaflets hard shell. Venous sinuses are homologues venous plexus epidural space of the spinal cord and also develop from echominimal veins. The walls of the sinuses, educated thick cloth hard shell, do not contain muscle elements and lined inside with endothelium. Lumen them constantly yawning. In the sinuses are various forms of trabeculae and the ear, but no real valves, resulting in the sinuses possible to change the direction of blood flow.

the scheme venous sinuses Dura man
Fig. 3. The scheme venous sinuses Dura person: 1 - sinus sagittalis sup.; 2 - v. cerebri magna; 3 - v. cerebri int.; 4 - sinus sagittalis inf.; 5 - v. Trolardi; at - v. basilaris; 7 - sinus intercavernosus; 8 - sinus cavernosus; 9 - plexus pterygoideus; 10 - plexus basilaris; 11 - sinus petrosus inf.; 12 - sinus petrosus sup.; 13 - v. facialis; 14 - v. jugularis int.; 15 - v. jugularis ext.; 16 - sinus transversus dext.; 17 - sinus occipitalis; 18 - torcular Herophili; 19 - v. Labbe; 20 - sinus rectus.


In clinical respect are particularly important: the upper longitudinal sinus, sinus sagittalis superior) with the empty side lacunae (lacunae laterales), transverse sinus (sinus transversus), often exceeding the value of the rest of the sinuses, direct sinus, sinus rectus), which flows into vein of Galen (v. cerebri magna), cavernous sinus, sinus cavernosus), through which passes the internal carotid artery. Venous sinuses take away the blood from the brain, the eyeball, the middle ear and the hard shell. In addition, through diplomaticheskikh veins and Santorinian graduates, parietal (v. emissaria parietalis), mastoid (v. emissaria mastoidea), occipital (v. emissaria occipitalis) and other venous sinuses connected with the veins of cranial bones and soft tissue of the head and partially drained by them.
The blood supply to the hard shell is also related to the inherent solid shell function resorption subdural and epidural liquids.
Experimental studies set a new and, as it turned out, the main outflow of cerebrospinal fluid from the subarachnoid space, the liquid is directed through the arachnoid membrane in the subdural space and then the internal network of capillaries hard shell of the brain.
It is established that the so-called subdural liquid is the same as cerebrospinal fluid (see), allocated in the subdural space through the arachnoid membrane on the way of its outflow in the blood stream of the Dura mater.
Together with cerebrospinal fluid move along this path you entered into the subarachnoid space of different neipvengiamai paint, isotope colloidal gold (Au198), albumin and globulins whey protein labeled with methionine (S35), whole red blood cells labeled with phosphorus or chromium (P32, Cr51), etc. Especially important that the selection of the cerebrospinal fluid through the arachnoid membrane was observed in the microscope without the use of any of the indicators. The fitness of the vascular system hard shell to resorbed with the function of the shell is expressed in maximum approximation of capillaries to drained of their spaces. More powerful development of the internal network of capillaries in comparison with the external network is explained in more intensive resorption spinal fluid compared with epidural liquid. According to the degree of permeability of blood capillaries hard shell close highly permeable lymphatic vessels.
Innervation hard shell brain by all three branches V pairs of cranial nerves. Besides V, innervation take part VI, IX, X, XI, XII couples and sympathetic fibers nerve plexus of the arteries.