spinal nerves are metamernoraspolozhennye, paired nerve trunks.The number of spinal nerves, or rather, their pairs corresponds to the number of pairs of segments of the spinal cord and is equal to thirty-one: eight pairs of cervical nerves, twelve pairs of thoracic, five lumbar, five crusades and one pair of coccygeal nerves.With their help, analyzes the state of spinal cord and controls the trunk, pelvis, legs, internal organs of the abdominal and thoracic cavity.
In its origin spinal nerves associated with a specific part of the body, that is innervated developed from a certain area of the skin somite - derived dermatosis of myotome - muscles of sclerotome - bone.Every nerve originates from the "personal" intervertebral foramen, while formed from connecting to a front trunk (motor) and posterior (sensitive) roots.
spinal nerves reach a length of just one and a half centimeters, after they branch out in the same way on the front and rear shell branch.
posterior branch extends between the vertebrae and the transverse processes of the pair in the back, which contributes to the innervation of the deep muscles (unbend the trunk) and skin.Posterior branches of the spinal nerves come back between the lateral vertebrae in particular between their processes and skirting their articular processes.Excluding the first cervical and the fourth, fifth coccyx and sacrum, the vertebrae are divided into ramus medialis and lateralis, which supply the rear surface of the skin of the neck and the back, neck, deep back muscles.
addition of spinal nerves depart two branches: the connection - to the sympathetic trunk (for innervation of blood vessels and internal), and returns the branch - going to the intervertebral foramen (for the innervation of the spinal cord membranes).
Plexus spinal nerves anterior branches arranged in a complex manner and a leather cover and innervate the muscles of the ventral wall of the trunk and two pairs of limbs.Since the lower part of his abdominal skin takes an active part in the formation of the external genitalia, the skin that covers them as well innervated anterior branches.Except for the first two, the last branch of the much larger rear.
Plexus spinal nerves anterior branches in its original Meto-dimensional structure is only stored in the thoracic region.In other parts, which are connected to the extremities (the development of which is lost segmental), extending from the anterior branches of spinal fibers intertwined.Thus, there is the formation of nerve plexus (plexus), and where takes place the interchange of different fibers nevromerov.The large amount of data plexuses spinal nerve participates in a very complicated process in which there is a redistribution of the fibers: the peripheral nerves is received from each of the front branches of the spinal nerve fibers, which means that each comprises a peripheral nerve fibers to many segments of the spinal cord.
Plexus distinguished into three types: lumbosacral, shoulder and neck.Lumbosacral, in turn subdivided into coccygeal, sacral and lumbar.
From the above it can be concluded that the loss or damage to certain nerve does not entail a violation of the functionality of all the muscles that receive innervation of the segments, giving rise to this nerve.Spinal nerves extending from the tangles are mixed, so that the picture is made up of nerve lesion sensitivity disorders, autonomic disorders, as well as movement disorders.
