VERIFIED CONTENTAuthor: lek. med. Grzegorz Prasałek, pediatrician

The spinal cord is part of the central nervous system designed to help the brain communicate efficiently with the rest of the body. If it weren't for the spinal cord, we wouldn't be able to live: move, feel pain or caress, breathe or eat. Our heart could not contract and relax. How is the spinal cord built?

Due to the fact thatthe spinal cordcan change its shape, adapting it to changes in body position, we can perform bends, "flips" or complicated dance stunts without fear of damaging it. Fortunately, the core is hard to damage. However, it is possible if the vertebrae are dislocated or fracturedof the spine , or if the spine itself is pierced.

Spinal cord protected by the spine

To protect such a precious organ, the spinal canal is lined inside with three connective tissue membranes. They hug the core on all sides and are called tires. The outermost is the hard tire. Between it and the wall of the spinal canal there is a space called the epidural cavity, filled with connective tissue, fatty tissue and venous plexuses. It is here that anesthetics (called epidural anesthesia) are injected during certain abdominal or lower limb operations. The anaesthesiologist chooses the lumbosacral region, because this is the widest of the epidural cavity. Under the dura mater is the spider mite and the subarachnoid cavity with the greatest amount of cerebrospinal fluid. It covers the spinal cord with a kind of water jacket. This is where the fluid is taken for examination, e.g. in suspected meningitis (the needle is inserted into the space between the 3rd and 4th lumbar vertebrae). Under the subarachnoid cavity lies the soft dura, "hugging" the spinal cord itself.

Important

The spinal cord runs through almost the entire channel in the center of the spine, inside the vertebrae. It resembles a slightly flattened oval, 8-14 mm in diameter and 40-45 cm long. At the top, in the skull, it becomes the so-called medulla, which - contrary to its name - is already the lower part of the brain. At the bottom it ends with a cone at the level of 1-2 lumbar vertebrae. Another extension of the cone is the residual section of the core, the so-called end thread. It departs from the core31 pairs of spinal nerves.

Spinal cord at the beginning of fetal life

In the beginning of our fetal life, the spinal cord occupies the entire length of the spinal canal. Spinal nerves depart from it horizontally. Later, the spine grows faster than the core. As a result, in a newborn baby, the spine ends between the 2nd and 3rd lumbar vertebrae. In an adult, which is no longer growing, it ends at the level of the 1st or 2nd lumbar vertebrae. For this reason, it is better, for example, to fall on the tailbone, because there is no longer a delicate core there, than to get in the neck, because this place is particularly sensitive to injuries. This unequal growth of the spine and core forces you to lengthen the so-called nerve roots, departing from the lower sections of the spine. The bundle of these roots, together with the end thread of the core, hangs freely in the cerebrospinal fluid of the subarachnoid cavity, forming the so-called horse's tail. The fluid protects delicate roots from damage, e.g. with a needle during lumbar puncture, in order to e.g. collection for the examination of the cerebrospinal fluid.

Structure of the spinal cord: pairs of nerves

Nerve roots join in pairs before they go beyond the vertebrae: the anterior (ventral) root is selected with the posterior (dorsal) root. Each resulting spinal nerve performs specific functions in our body. We have 31 pairs of spinal nerves that feed (innervate) our entire body. The spinal cord is divided into segments. There are 31 of them - as many as pairs of spinal nerves:

  • 8 cervical,
  • 12 pectoral,
  • 5 lumbar,
  • 5 cross,
  • 1 consistent.

If we look at our innervation (sensory and motor), it would turn out that it is divided into horizontal segments, similar to an earthworm. For example, the cervical nerves from the cervical spine innervate the shoulders, arms and hands, the nerves from the thoracic and torso sections, and the nerves from the lumbar and sacral sections - the buttocks, legs and the genitourinary system (in men they are responsible for: for erection). This horizontal division is especially noticeable in spinal injuries with a discontinuity of the spine. In this case, the paresis covers all parts of the body below the site of the injury, as if the person were cut by an invisible, horizontally positioned glass.

Nerve cells that conduct motor and sensory impulses

In the very center of the spinal cord, there is a narrow canal that is a remnant of the original neural tube (the nucleus of the entire nervous system). He is surrounded by the so-called gray matter. Its cross-section shape resembles a thickly drawn letter "H", although it may also be associated with the silhouette of a butterfly with outstretched wings. Gray mattersurrounds the so-called white matter. The arrangement of both is therefore the opposite of that in the brain (the gray one is on the outside). In the gray matter there are many nerve cells which give it this color. In white, however, there are only the projections of these cells - "cables" that allow the exchange of impulses. Imagine that each vertical line of the letter "H" is divided in half. The front part is the front corner and the rear part is the rear corner. In the thoracic spine there is also the so-called lateral horn (responsible for the so-called vegetative innervation, controlling digestion, blood pressure, and the work of various glands). In the front horns of the spine there are large nerve cells which (to put it very simply) conduct the so-called movement impulses, i.e. stimuli ordering, for example, contracting and relaxing our muscles. Related to the posterior horn of the spine are cells that (simplified again) conduct sensory impulses to the central nervous system. Thanks to them, information about heat, cold, pain etc. reaches the brain.

The spinal cord is responsible for communication between the brain and the rest of the body

The spinal cord is part of the central nervous system. Its primary task is efficient communication between the brain and the rest of our body. The spinal cord is a "cable", a multi-strand electrical bus that transmits impulses from the body to the brain and vice versa. Spinal nerves are made up of millions of individual nerve fibers, i.e. the projections of neurons:

  • motor - centrifugal, which control the movements of our muscles,
  • sensory - afferent, which conducts stimuli from peripheral sensory nerve endings throughout the body to the spinal cord and brain.

But in fact, all spinal nerves are mixed, made up primarily of motor and sensory fibers (some also vegetative, since all nerves also contain vegetative fibers). In one direction, sensory stimuli conduct to the brain (thanks to this we can feel, for example, pain, touch, cold, heat), and in the other direction, movement stimuli to the so-called circumference, i.e. to all parts of our body (this makes us walk, dance or move our hands, eating, drinking, playing tennis, etc.).

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Neurology