Cervical spinal nerve 4

Cervical spinal nerve
	The plan of the cervical and brachial plexuses.
	The spinal cord with spinal nerves.
Details
Identifiers
Latin	Nervi spinalis
FMA	6445
	Anatomical terminology [ edit on Wikidata]

Last updated August 17, 2019

Cervical spinal nerve 4, also called C4, is a spinal nerve of the cervical segment. It originates from the spinal cord above the 4th cervical vertebra (C4). It contributes nerve fibers to the phrenic nerve, the motor nerve to the thoracoabdominal diaphragm. It also provides motor nerves for the longus capitis, longus colli, anterior scalene, middle scalene, and levator scapulae muscles. C4 contributes some sensory fibers to the supraclavicular nerves, responsible for sensation from the skin above the clavicle.

A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the corresponding cervical, thoracic, lumbar, sacral and coccygeal regions of the spine. There are eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves. The spinal nerves are part of the peripheral nervous system.

In tetrapods, cervical vertebrae are the vertebrae of the neck, immediately below the skull. Truncal vertebrae lie caudal of cervical vertebrae. In sauropsid species, the cervical vertebrae bear cervical ribs. In lizards and saurischian dinosaurs, the cervical ribs are large; in birds, they are small and completely fused to the vertebrae. The vertebral transverse processes of mammals are homologous to the cervical ribs of other amniotes. Most mammals have 7 cervical vertebrae, with the only 3 known exceptions being the manatee with 6, the two-toed sloth with 5–6, and the three-toed sloth with 9.

The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. It encloses the central canal of the spinal cord, which contains cerebrospinal fluid. The brain and spinal cord together make up the central nervous system (CNS). In humans, the spinal cord begins at the occipital bone, passing through the foramen magnum and entering the spinal canal at the beginning of the cervical vertebrae. The spinal cord extends down to between the first and second lumbar vertebrae, where it ends. The enclosing bony vertebral column protects the relatively shorter spinal cord. It is around 45 cm (18 in) in men and around 43 cm (17 in) long in women. The diameter of the spinal cord ranges from 13 mm in the cervical and lumbar regions to 6.4 mm in the thoracic area.

Additional Images

Cervical spinal nerve 4
Projectional radiograph of a man presenting with pain by the nape and left shoulder, showing a stenosis in the intervertebral foramen of cervical spinal nerve 4, corresponding with the affected dermatome.

Nape back of neck, important in some non-human mammals

The nape is the back of the neck. In technical anatomical/medical terminology, the nape is also called the nucha ; the corresponding adjective is nuchal, as in the term nuchal rigidity.

Intervertebral foramen Foramen between spinal vertebrae

The intervertebral foramen, is a foramen between two spinal vertebrae. Cervical, thoracic, and lumbar vertebrae all have intervertebral foramina.

A dermatome is an area of skin that is mainly supplied by afferent nerve fibers from a single dorsal root of spinal nerve which forms a part of a spinal nerve. There are 8 cervical nerves , 12 thoracic nerves, 5 lumbar nerves and 5 sacral nerves. Each of these nerves relays sensation from a particular region of skin to the brain.

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The peripheral nervous system (PNS) is one of two components that make up the nervous system of bilateral animals, with the other part being the central nervous system (CNS). The PNS consists of the nerves and ganglia outside the brain and spinal cord. The main function of the PNS is to connect the CNS to the limbs and organs, essentially serving as a relay between the brain and spinal cord and the rest of the body. Unlike the CNS, the PNS is not protected by the vertebral column and skull, or by the blood–brain barrier, which leaves it exposed to toxins and mechanical injuries.

Phrenic nerve Nerve controlling the diaphragm

The phrenic nerve is a nerve that originates in the neck (C3–C5) and passes down between the lung and heart to reach the diaphragm. It takes its name from the Ancient Greek phren, meaning diaphragm. It is important for breathing, as it passes motor information to the diaphragm and receives sensory information from it. There are two phrenic nerves, a left and a right one.

The dorsal scapular nerve arises from the brachial plexus, usually from the plexus root of the cervical nerve C5. Once the nerve leaves C5 it commonly pierces the middle scalene muscle, and continues deep to levator scapulae and the rhomboids.

Subclavian artery major arteries of the upper thorax, below the clavicle

In human anatomy, the subclavian arteries are paired major arteries of the upper thorax, below the clavicle. They receive blood from the aortic arch. The left subclavian artery supplies blood to the left arm and the right subclavian artery supplies blood to the right arm, with some branches supplying the head and thorax. On the left side of the body, the subclavian comes directly off the aortic arch, while on the right side it arises from the relatively short brachiocephalic artery when it bifurcates into the subclavian and the right common carotid artery.

Sternocleidomastoid muscle A paired muscle of the neck that traverses the neck between the manubrium sterni and the mastoid process.

The sternocleidomastoid muscle is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and flexion of the neck. The sternocleidomastoid is innervated by the accessory nerve.

The cervical plexus is a plexus of the anterior rami of the first four cervical spinal nerves which arise from C1 to C4 cervical segment in the neck. They are located laterally to the transverse processes between prevertebral muscles from the medial side and vertebral from lateral side. There is anastomosis with accessory nerve, hypoglossal nerve and sympathetic trunk.

The vertebral arteries are major arteries of the neck. Typically, the vertebral arteries originate from the subclavian arteries. Each vessel courses superiorly along each side of the neck, merging within the skull to form the single, midline basilar artery. As the supplying component of the vertebrobasilar vascular system, the vertebral arteries provide supply blood to the upper spinal cord, brainstem, cerebellum, and posterior part of brain.

Scalene muscles Muscles on the sides of the neck

The scalene muscles are a group of three pairs of muscles in the lateral neck, namely the anterior scalene, middle scalene, and posterior scalene. They are innervated by the fourth, fifth, and sixth cervical spinal nerves (C4-C6).

The ansa cervicalis is a loop of nerves that are part of the cervical plexus. It lies superficial to the internal jugular vein in the carotid triangle. Its name means "handle of the neck" in Latin.

A nerve plexus is a plexus of intersecting nerves. A nerve plexus is composed of afferent and efferent fibers that arise from the merging of the anterior rami of spinal nerves and blood vessels. There are five spinal nerve plexuses, except in the thoracic region, as well as other forms of autonomic plexuses, many of which are a part of the enteric nervous system. The nerves that arise from the plexuses have both sensory and motor functions. These functions include muscle contraction, the maintenance of body coordination and control, and the reaction to sensations such as heat, cold, pain, and pressure. There are several plexuses in the body, including:

The posterior triangle is a region of the neck.

The ventral ramus is the anterior division of a spinal nerve. The ventral rami supply the antero-lateral parts of the trunk and the limbs. They are mainly larger than the dorsal rami.

The cervical spinal nerve 1 (C1) is a spinal nerve of the cervical segment. C1 carries predominantly motor fibres, but also a small meningeal branch that supplies sensation to parts of the dura around the foramen magnum.

The cervical spinal nerve 5 (C5) is a spinal nerve of the cervical segment.

The cervical spinal nerve 6 (C6) is a spinal nerve of the cervical segment.

The cervical spinal nerve 8 (C8) is a spinal nerve of the cervical segment.

The spinal root of accessory nerve is firm in texture, and its fibers arise from the motor cells in the lateral part of the anterior column of the gray substance of the medulla spinalis as low as the fifth cervical nerve.

The sympathetic root of ciliary ganglion is one of three roots of the ciliary ganglion, a tissue mass behind the eye. It contains postganglionic sympathetic fibers whose cell bodies are located in the superior cervical ganglion. Their axons ascend with the internal carotid artery as a plexus of nerves, the carotid plexus. Sympathetic fibers innervating the eye separate from the carotid plexus within the cavernous sinus. They run forward through the superior orbital fissure and merge with the long ciliary nerves and the short ciliary nerves. Sympathetic fibers in the short ciliary nerves pass through the ciliary ganglion without forming synapses.

References

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v t e Spinal nerves
Cervical	C1 C2 C3 C4 C5 C6 C7 C8 anterior Cervical plexus Brachial plexus posterior Posterior branches of cervical nerves Suboccipital – C1 Greater occipital – C2 Third occipital – C3
Thoracic	T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 anterior Intercostal Intercostobrachial – T2 Thoraco-abdominal nerves – T7–T11 Subcostal – T12 posterior Posterior branches of thoracic nerves
Lumbar	L1 L2 L3 L4 L5 anterior Lumbar plexus Lumbosacral trunk posterior Posterior branches of the lumbar nerves Superior cluneal L1–L3
Sacral	S1 S2 S3 S4 S5 anterior Sacral plexus posterior Posterior branches of sacral nerves Medial cluneal nerves
Coccygeal	anterior Coccygeal plexus posterior Posterior branch of coccygeal nerve