What Are Spinal Nerves?

Also known as spinal nerve, a pair of nerves issued by the spinal cord. There are 31 pairs in the human body, including 8 pairs of cervical nerves, 12 pairs of thoracic nerves, 5 pairs of lumbar nerves, 5 pairs of sacral nerves, and 1 pair of tail nerves. Each pair of spinal nerves is synthesized from the anterior and posterior roots at the foramen. The anterior root consists of axons of motor neurons in the anterior horn of the spinal cord and axons of sympathetic neurons or parasympathetic neurons in the lateral horns. Fibromedulla spinal nerves are distributed to skeletal muscle, cardiac muscle, smooth muscle and glands, which control and control muscle contraction and glandular secretion. There is a spinal ganglion on the posterior root, which is a collection of afferent neuron cell bodies. The posterior root is composed of axons of sensory neurons. The spinal nerve is a mixed nerve. The typical spinal nerve contains four types of fiber components: somatic movement, somatosensory, visceral movement, and visceral sensory fibers. The spinal nerve was immediately divided into the anterior and posterior branches after exiting the intervertebral foramen, and each branch contained afferent and efferent fibers. The posterior branch is generally small and is distributed in smaller areas of the skin and muscles near the spine. The anterior branch is thick and distributed to the skin and muscles of the rest of the area below the neck. Except that the anterior branches of the 2 to 11 pairs of thoracic nerves are distributed along the intercostal space, the anterior branches of the other nerves are first intertwined into plexuses, and then the plexuses branch out and distribute in the area dominated. These spinal nerves form the cervical plexus, brachial plexus, lumbar plexus, and iliac plexus, respectively, and are paired left and right.

Also known as spinal nerve, a pair of nerves issued by the spinal cord. There are 31 pairs in the human body, including 8 pairs of cervical nerves, 12 pairs of thoracic nerves, 5 pairs of lumbar nerves, 5 pairs of sacral nerves, and 1 pair of tail nerves. Each pair of spinal nerves is synthesized from the anterior and posterior roots at the foramen. The anterior root consists of axons of motor neurons in the anterior horn of the spinal cord and axons of sympathetic neurons or parasympathetic neurons in the lateral horns. Fibromedulla spinal nerves are distributed to skeletal muscle, cardiac muscle, smooth muscle and glands, which control and control muscle contraction and glandular secretion. There is a spinal ganglion on the posterior root, which is a collection of afferent neuron cell bodies. The posterior root is composed of axons of sensory neurons. The spinal nerve is a mixed nerve. The typical spinal nerve contains four types of fiber components: somatic movement, somatosensory, visceral movement, and visceral sensory fibers. The spinal nerve was immediately divided into the anterior and posterior branches after exiting the intervertebral foramen, and each branch contained afferent and efferent fibers. The posterior branch is generally small and is distributed in smaller areas of the skin and muscles near the spine. The anterior branch is thick and distributed to the skin and muscles of the rest of the area below the neck. Except that the anterior branches of the 2 to 11 pairs of thoracic nerves are distributed along the intercostal space, the anterior branches of the other nerves are first intertwined into plexuses, and then the plexuses branch out and distribute in the area dominated. These spinal nerves form the cervical plexus, brachial plexus, lumbar plexus, and iliac plexus, respectively, and are paired left and right.

Chinese name

Spinal nerve

Foreign name

spinal nerves

logarithm

31

Nature

biological

Spinal nerve cervical nerve

There are 8 pairs on the neck. The 1st to 7th pairs of cervical nerves emerge from the intervertebral foramina above the corresponding cervical vertebral arch; the 8th pair of cervical nerves emerge from the intervertebral foramen between the 7th cervical vertebra and the 1th thoracic vertebra. The anterior branch of the cervical nerve forms the cervical plexus and brachial plexus in the neck. The anterior branch of the 1st to 4th cervical nerves forms the cervical plexus, and the anterior branch of the 5th to 8th cervical nerves forms the brachial plexus. The posterior branch of the cervical nerve is thicker than the corresponding anterior branch, which is a sensory transition into the fiber, and the anterior branch is a motor fiber. Travel backward through the transverse vertebrae. The distribution of the cervical nerve is segmental according to the spinal cord segments. Cervical plexus nerves are distributed in the skin of the sternocleidomastoid muscle, diaphragm, pleura and occipital region, auricles, anterior cervical region, and shoulder skin; brachial plexus nerves are distributed in muscle and skin of the upper arm; posterior branches are distributed in the pillow, neck, and back Muscles and skin. After leaving the spinal cord, the first and second cervical nerve roots do not pass through the intervertebral foramen, but directly enter the distribution area along the vertebral body. Therefore, the first and second nerve roots are susceptible to direct trauma, but there is no possibility of being compressed by the foramen.

Plexus (6 photos)

Spinal nerve thoracic nerve

There are 12 pairs in total. The posterior branch and the anterior branch are separated after the intervertebral foramen. The posterior branch is short and is distributed on the back side of the trunk. The muscles innervate the pectoralis semispinalis, multifidus, circumflex, pectoralis spines, intertransverse muscles, interspinous muscles, pectoral ribs, and longest chest muscles; skin The branch manages the skin sensation of the shoulders, back, and buttocks (outside). The anterior branch of the thoracic nerve is longer. Except for the majority of the 1st pair participating in the brachial plexus and the small part of the 12th pair participating in the lumbar plexus, the rest are not clustered. The 1st to 11th pairs, each located in the corresponding intercostal space, are called intercostal nerves; the 12th pair are located below the 12th rib, and are called subcostal nerves. The intercostal nerve lies between the intercostal internal and external muscles, below the intercostal blood vessels, and advances along the costal grooves, on the side of the chest and abdomen wall, emitting lateral cutaneous branches, which are distributed on the skin of the chest and abdomen sidewall. The lateral cutaneous branches of the intercostal nerves from the 4th to the 6th, also sent out the lateral branches of the breast to the breast, and the trunk continued to move forward. Among them, the upper 6 pairs of intercostal nerves were shallow to the lateral edge of the sternum. Go forward and down between the internal oblique and transverse abdominal muscles, and then pass through the rectus abdominis sheath to shallow the skin. These shallow anterior cutaneous branches are distributed on the skin of the anterior wall of the chest and abdomen; the anterior branches of the 2nd to 4th intercostal nerves also emit the medial branch of the breast to distribute in the breast; in addition, the intercostal nerves also issue thin branches to distribute in Chest and peritoneal wall. The muscle branches of the intercostal and subcostal nerves control the internal and external intercostal muscles, the internal and external oblique muscles, transverse abdominal muscles, and rectus abdominis.

Spinal nerve lumbar nerve

A total of 5 pairs, from the lumbar section of the spinal cord. After the lumbar nerves have penetrated the intervertebral foramen, they are divided into posterior and anterior branches.

The posterior branch of the lumbar nerve runs backward on the medial side of the transverse medial muscle, that is, it is divided into the medial and lateral branches. The medial branch of the posterior branch of the lumbar nerve is distributed in the multifidus muscle. The lower 3 pairs of lumbar nerves also emit thin branches to the skin of the crotch. The upper 3 pairs of the lateral branches of the posterior branch of the lumbar nerve, obliquely outward, and the hair branches dominate the nearby erector spinae; its cutaneous branches penetrate the latissimus dorsi, and cross the posterior condyle at the lateral edge of the erector spinalis, to The hip is subcutaneous and is called the hip epithelial nerve. The lateral branch of the first lumbar nerve is smaller and distributed on the upper surface of the gluteal muscle; the lateral branch of the second lumbar nerve is distributed on the lower surface of the gluteal muscle and the superficial layer of the gluteus maximus; the lateral branch of the fourth lumbar nerve is small and finally The lower part of the spinal muscle; the lateral branch of the fifth lumbar nerve, which is distributed in the sacrospinous muscle, and communicates with the first sacroiliac nerve.

The anterior branch of the lumbar nerve gradually grows from top to bottom. The anterior branches of the 1st to 4th lumbar nerves mostly constitute the lumbar plexus (50% of the anterior branches of the 12th thoracic nerve join the lumbar plexus). The small part of the 4th lumbar nerve and the 5th lumbar nerve synthesize the lumbosacral trunk and participate in the formation of the sacral plexus.

Spinal nerve crest nerve

There are 5 pairs, divided into posterior branch and anterior branch in the sacral canal.

Posterior branch of the phrenic nerve: the upper 4 pairs penetrate through the posterior iliac foramen, and the fifth pair exits from the iliac canaliculus between the posterior iliac tail ligaments. The upper 3 pairs of exits are covered by multifidus muscles, which are also divided into medial and lateral branches. The posterior branches of the 4th and 5th phrenic nerves are unbranched.

Lateral branches: The lateral branches of the posterior branches of the 3 phrenic nerves are combined with each other and the lateral branches of the posterior branch of the 5th phrenic nerve. From this branch, the second line of neural crests is formed behind the patellar tubercle ligament. Divide two to three cutaneous branches from the second row of iliac crests, penetrate the gluteus maximus and the inherent fascia to the superficial fascia, and distribute on the medial gluteal skin from the posterior superior iliac spine to the tip of the coccyx. .

Medial branch: small, finally multifidus.

Anterior branch of the phrenic nerve: the upper 4 pairs enter the pelvis through the anterior foramen, and the fifth pair enters the pelvis between the sacrum and coccyx. Each branch varies in size, the upper one is larger, and the smaller it is, the lower it is. The anterior branches of these nerves combine with each other to form the plexus plexus.

Spinal nerve and tail nerve

There is a pair, which is divided into posterior branch and anterior branch in the sacral canal.

Posterior branch of the coccyx: after the sacral canal is separated from the anterior branch, it passes through the sacral canal and passes through the ligament at the lower part of the sacral canal. Dermal branches distributed on the skin of the covered tailbone.

The anterior branch of the tail nerve: forms the tail plexus with the anterior branch of the 5th phrenic nerve, and the anterior branch of the 4th phrenic nerve joins the tail plexus in a small part. The anterior branch of the 5th phrenic nerve exits from the hiatal canal hole, turns to the front of the zygomatic bone around the lateral side of the sacrum, penetrates the coccyx muscle to the pelvic surface, and combines with the descending branch of the anterior branch of the 4th phrenic nerve to form a small trunk. The pelvic surface of the coccyx muscle drops. The anterior branch of the coccyx exits from the sacral hiatus around the lateral edge of the coccyx and penetrates the coccyx muscle. The cohesion of the coccyx pelvic surface and the anterior branch of the coccyx nerve is formed to form the tail plexus. The anal and tail nerves are separated from the tail plexus and distributed on the skin near the coccyx.