The spinal cord consists of numerous plexuses that form the spinal nerves, which represent paired trunks. Each pair corresponds to a certain part of the body, internal organs, and performs its unique functions. Only 31 pairs, which corresponds to the number of pairs of segments of the spinal cord. It is important to understand what a person’s nerve plexuses are, why they are necessary, what functions will be performed in the body during their work.
What are spinal nerves?
In the spinal canal is the spinal cord, which represents the initial structure of the central nervous system. This important part of the body, flattened in front, has a cylindrical shape. Structurally, it has anterior branches and posterior roots, which serve to transmit impulses to the cerebral cortex. The answer to the question of how many spinal nerves departs from the spinal cord is simple - 31 pairs. This amount is the same for women, men, does not depend on the age of the patients.
The spinal nerve consists of a large number of cells - neurons that provide reflex, sympathetic and motor functions of the body. Each such process originates from the intervertebral foramen, is formed from sensitive and motor roots. Individual nerves are woven into bundles, which have an official name, move along afferent paths (ascending) and descending paths. Formed spinal plexuses are of three types: lumbosacral, brachial, cervical.
The nerves of the spinal cord are short structures, since their length is 1.5 cm. Further, they branch from all sides, forming the posterior and anterior membranous branches. Structurally, the posterior branches of the spinal nerves stretch between the transverse processes of the pair of the back region, contributing to the flexion and extension of the body. On the front surface is the median gap. Such structural elements conditionally divide the brain into the right, left halves, closely interconnected in functionality.
In each component, lateral grooves are distinguished anterior and posterior. The first is the site with the exit of the posterior sensitive roots of the spinal nerves, and the second provides a branch of the motor nerves. Lateral grooves are considered conditional boundaries between the posterior, lateral, anterior cords. In the cavity of the spinal cord, a central channel is localized - a gap filled with a special substance called cerebrospinal fluid.
The number of spinal nerves
An adult has 31 pairs of spinal nerves, and such elements are characterized by their conditional classification. This division is represented by 8 cervical, 5 lumbar, 12 thoracic, 5 sacral, 1 coccygeal plexuses. The total number of nerves is 62 positions, they are part of most internal organs, systems (parts of the body). Without their presence, muscle activity is excluded, normal brain activity is also pathologically reduced.
Studying the structural parts of the human spine, it is necessary to highlight those important structures that are pierced by nerve fibers, contain the spinal cord. They are responsible for the motor activity of the musculoskeletal system, sensitivity to provoking factors from the outside. These are the following departments of the spinal column:
- If you study the neck area, then the cervical plexus is formed by the front branches, localized between the deep muscle structures. Nerve cell supply is observed in the areas of the occiput, ear canal, clavicle, muscle tissue of the neck, and peritoneum. In this way, nerve impulses are transmitted in order to ensure mobility of the upper limbs. In the case of pathology, the occipital region is the first to suffer.
- The spinal structures of the sacral and lumbar region are responsible for the mobility of the lower extremities, the formation and maintenance of muscle tone. At the same time, the pelvic area and all internal organs are controlled. Especially sensitive sciatic, coccygeal and femoral nerves, the pinching of which leads to acute pain syndrome. If such unpleasant sensations are present, this means that a pathological process is occurring in the body.
- The nerves of the chest are represented in the amount of 12 pairs, located in the intercostal space. The main task is to ensure mobility of the chest, muscles of the thin walls of the peritoneum. In this area, the spinal plexuses do not form, go directly to the muscles. Pathologies of a characteristic site are accompanied by soreness, but with timely treatment, the pain syndrome will descend.
Spinal roots have the main center - the spinal cord, the shell of which is filled with cerebrospinal fluid. It contains gray and white matter. Each structure performs its unique functions. For example, white matter consists of neurons that form three columns - lateral, anterior and posterior. Each element in the context takes the form of horns and carries out its task.
So, the front horns contain motor nerves, the rear horns are made up of sensitive fibers, and the lateral ones directly communicate with the gray matter of the spinal cord. In each nervous structure, there are spinal plexuses, numerous nodes. Gray matter is surrounded by white, forming the cord of the spinal cord from longitudinally located nerve fibers.
The main tasks of the spinal nerves are conduction and reflex. In the first case, we are talking about the passage of nerve impulses to the cerebral cortex in order to further ensure a natural reaction to external and internal irritating factors, for example, pain, temperature, cold, irritation. The reflex function carried out by the nerve centers provides the innervation of skeletal muscles, provides the work of all internal organs and systems. Given this classification, spinal nerves are:
- sensitive - provide the reaction of the body (skin) to the effects of external and internal stimuli mainly through the skin;
- motor - take and control the physical activity of muscles, maintain balance, provide coordination of movements, tone smooth muscles;
- mixed - these are spinal plexuses formed from motor and sensory fibers. The functions of such nodes are numerous, and depend on the localization of nerve endings.
Nerve fibers differ not only in their functionality, but also in the area of action in the human body (innervation). Such solid structures are found and spread throughout the body, and inflammation of the nodes leads to irreversible consequences for the body. Habitual motor activity and sensitivity do not return immediately, conservative treatment is required.
How do nerves form
Nerve endings have a standard structure, and their differences are explained by the functional features of the roots. Structurally, the anterior branches and posterior roots are distinguished. In the first case, we are talking about motor neurons formed by axons, which are responsible for the mobility of the limbs. As for the posterior roots, these are the formations of the spinal nerve and its branches, which are connected in series with the posterior horns and the sensitive nuclei of the spinal cord. Such anatomical structures quickly transmit nerve impulses.