Sheath of the spinal cord
The cavity is filled with liquid, parts of the bone structure and the spinal cord. Sheath that surround the spinal cord itself, are:
- Solid (upper). Functional value it is to limit the epidural space. Here is located the venous weave. Of the hard shell formed sinuses and appendages.
- Arachnoid (middle). This sheath holds the nerve roots and spinal fluid, blood vessels are absent. The middle layer forms the subdural space.
- Soft shell (bottom). Its functional significance is the connection of the cerebrospinal fluid and the secondary shell. In this layer there are blood vessels in large quantity.
Soft layers form interlacing of the elastic mesh and the collagen beams covered with the epithelial layer. There are blood vessels, macrophages, fibroblasts. The layer has a thickness of approximately 0.15 mm. In its properties to the lower shell tightly hugs the surface of the spinal cord and has high strength and elasticity. From the outside it unites with the arachnoid layer using a kind of spars.
The middle sheath of the spinal cord is called the arachnoid because it is formed from a large number of trabeculae, which are loosely located. However, she is as strong as possible. Also has the characteristic appendages extending from its lateral surface and contains the nerve roots and dentate ligaments. The Dura of the spinal cord covers the other layers. Its structure is a tube of connective tissue, its thickness is not more than 1 mm.
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Soft and arachnoid are separated by the subarachnoid space. It contains the cerebrospinal fluid. It has another name – the subarachnoid. The arachnoid and the Dura separates the subdural space. And finally, the space between the solid layer and the periosteum is called the epidural (the epidural). It fill the internal venous weave in combination with the fatty tissue.
What is the functional significance of the sheath of the spinal cord? Each of them plays a role.
|The name of the shell
|Solid (upper).||Provides natural cushioning.
Participates in the processes of blood supply.
|Arachnoid (middle).||Participates in the processes of metabolism. Contributes to the process of formation of certain hormones.|
|Soft (lower).||Helps the blood supply of the brain and maintenance of viability of the human body.|
The subarachnoid space of the spinal cord plays a crucial role. It contains the cerebrospinal fluid. It performs a cushioning function and is responsible for the creation of nervous tissue, is the catalyst of metabolic processes.
The relationship of the membranes of the spinal cord and brain
The brain is covered by the same layers, and the spinal cord. In fact, some are a continuation of the other. Hard shell of the brain is formed of two levels of connective tissue that are tight to the bones of the skull from the inside. In fact, form a his periosteum. While the hard layer surrounding the spinal cord, separated from the periosteum of the vertebrae by a layer of adipose tissue in combination with the venous plexus in the epidural space.
The top layer is the Dura surrounding the brain and forming its periosteum, forming in the recesses of the skull of the funnel, which is the seat of the cranial nerves. The lower layer of the hard shell is interconnected with the arachnoid layer with strands of connective tissue. For her answer innervation nerves — trigeminal and vagus. In certain parts of the solid layer forms the sinuses (splitting), which represent reservoirs for venous blood.
The average brain membrane formed of connective tissue. To the soft meninges is mounted by means of threads and processes. In the subarachnoid space, they form a gap in which there are cavities, called subarachnoid cisterns.
The arachnoid layer connected to the solid shell is quite loose, has granulation processes. They penetrate a hard layer and embedded in the skull or sinuses. In places of entry of granulations of the arachnoid granulation pits occur. They provide a message to the subarachnoid space and venous sinuses.
Soft shell tightly hugs the brain. It localized a lot of blood vessels and nerves. Features of its structure are the sheaths, which are formed around the blood vessels and pass into the brain. The space that is formed between the blood vessel and the vagina, called perivascular. It is interconnected with the extracellular and subarachnoid space in different ways. In the extracellular space is the cerebrospinal fluid. Soft shell forms part of a vascular basis, as deeply included in the cavity of the ventricles.
Diseases of shells
Sheath the brain and spinal cord affected diseases which can be caused by trauma to the vertebral column, oncological process in the body or infection:
- Meningitis. Is an infectious inflammatory process, which causes a viral or bacterial infection (pneumococcus, meningococcus).
- Fibrosis. The disease is manifested in the thickening of the membranes and inflammation of all three layers. Brought to him of the injury, failed spinal surgeries, cancer.
- Suppurative inflammation. Infectious inflammatory process in this case leads to swelling of the brain. The symptoms are initially similar to flu symptoms, as include fever that causes delirium in humans. Later there is photophobia, and seizures of epilepsy.
- Trauma disorders. As a result of injury or fractures cerebrospinal fluid circulates incorrectly, which can lead to paralysis or hydrocephalus.
- Arachnoiditis. Occurs due to inflammation of the lumbar spinal area and affects all shells. While clinical manifestations of content metabolicheskikh spaces are the same as in the cancer process.
To identify diseases of the membranes is carried out differential diagnosis, which includes magnetic resonance imaging. Damaged shell and bezobolochnoe space of the spinal cord often lead to disability and even death. To reduce the risk of diseases helps vaccination and careful attention to the health of the spine.