Spinal cord

The spinal cord is one of the departments of the central nervous system (CNS), which connects the body with the external environment and regulates its functions. It is thanks to the central nervous system that various human organs and systems act in concert, reacting to changes that occur in the external environment.

The connection of the brain with organs and limbs is carried out with the help of the spinal cord. It performs the conductor and reflex functions.

How the spinal cord is arranged and where is located

The structure of this department of the central nervous system is relatively simple. The spinal cord is formed by gray and white substances. White matter is a complex system of nerve fibers (myelin and bezmielinovyh), nervous tissue and blood vessels, which are insignificantly surrounded by connective tissue. Gray matter forms the bodies of nerve cells with processes that do not have a myelin sheath. The canal is located in the center of the spinal cord, which is filled with cerebrospinal fluid. With the internal organs and limbs, it is connected by numerous nerves, which are characterized by the correct periodicity of the exit.

The width of the spinal cord reaches one-and-a-half centimeters in an adult person, the length is 45 cm. Its average mass is 35 g.

The human spinal cord is located in the internal cavity of the spinal canal. Outwardly it resembles a long cord with numerous branches. Its upper end without a sharp border is connected with the medulla oblongata in the region of I cervical vertebra, the lower one is located at the level of I-II lumbar vertebrae. It passes into the terminal (spinal cord) thread. The upper parts of the end thread have fragments of the nervous tissue, in the rest it is a connecting formation. Penetrating the dura mater into the sacral canal, the spinal filament is attached at its end.

Isolate the three shells surrounding the spinal cord. The inner membrane is soft (vascular), medium - arachnoid and external - firm. From the membranes to the bone channel there are ligaments that hold the spinal cord in a constant position. The space between the inner and middle membranes fills the cerebrospinal fluid.

Thus, the cavity of the vertebral canal, where the spinal cord is located, is filled with fatty tissue, cerebrospinal fluid, brain membranes, and blood vessels.

The longitudinal grooves divide the spinal cord into right and left symmetrical halves.

Nerve roots pass through the spinal canal at a short distance. They emanate from each half, forming two longitudinal rows. They leave the vertebral canal through the foraminar openings. The spinal cord is characterized by pronounced segmentation. Segments refer to the part of the brain in which the nerves leaving the spinal canal leave them. Each segment innervates this or that area of the human body.

There are five parts of the spinal cord. Neck part is formed by eight segments, thoracic segment consists of twelve segments, lumbar - five, sacral - also five, coccygeal - 1-3 segments. Segments of the neck part innervate the arms and neck, the thoracic part - the chest and abdomen, lumbar and sacral - legs, pelvic organs and perineum. Nerve roots that extend below the level of the end of the spinal cord innervate the lower half of the body, including the pelvic organs.

An impairment of the sensitivity or motor function of a particular area of the body may indicate that part of the spinal cord in which damage could occur.

On the peripheral nerves from the spinal cord to the organs of the body come nerve impulses. They regulate the functions of all organs. Sensitive nerve fibers transmit information from tissues and organs to the spinal cord and CNS.