The spinal cord has the form of a cylinder 40-45 cm long, and is located in the spinal canal (diagram 148). From above, it goes directly into the med

Spinal cord structure [Structucture]

The spinal cord has the form of a cylinder 40-45 cm long, and is located in the spinal canal (diagram 148). From above, it goes directly into the medulla. Below, in the lumbar spine, the spinal cord becomes thinner until the end yarn (ponytail). In adults its diameter is 1 cm, weight — 35 g or 2% by mass of the brain.

From the outside the spinal cord is protected by three layers of connective tissue — the brain membranes. It is provided with additional protection by the cerebrospinal fluid contained between the shells and in the central channel which communicates with the brain ventricles. Inside the spinal cord there is a gray matter — a bodies of gusset (95%), motor and secretory (5%) neurons. On cross-section, it forms a figure similar to a butterfly. There are front and rear horns of the spinal cord gray matter. Anterior horns are formed by the accumulation of motor neurons bodies, the rear — by the afferent neurons of ascending pathways. In addition to front and rear horns, gray matter forms the lateral horn in the thoracic and lumbar spinal cord. They contain the cell bodies of the autonomic nervous system. Taken from http://worldofschool.org

Diagram 148. The structure of the spinal cord: 1 — nerve fibers; 2 — white matter; 3 — gray matter; 4 — sensitive spine; 5 — spinal nerve; 6 — motor root; 7 — brain membranes; 8 — the central channel; 9 — anterior horns; 10 — lateral horns; 11 — posterior horns

The axons of neurons that extend from the anterior horns form a motor (front) root of the spinal nerve. Axons of sensory neurons, whose bodies are placed in the sensor (back) node of spine, ascend to the rear horns. From the lateral horn through the motor (front) roots depart axons of the autonomic nervous system neurons. Front and rear roots, uniting, form 31 pairs of mixed spinal nerves.

White matter consists of the processes of neuronal brain and spinal cord. They are collected in bundles that form ascending and descending pathways through which nerve impulses come from the receptors to the nerve centers of the spinal cord and brain, or vice versa — from the nerve centers to the working organs.

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Questions:
  • Determine the relationship of the spinal cord structure and functions.