What is the difference between spinal nerves and peripheral nerves

Facet — A joint formed when a posterior structure of a vertebra that joins with a facet of an adjacent vertebra; this joint allows for motion in the spinal column. Each vertebra has a right and left superior upper facet and a right and left inferior lower facet. Foramen — An opening in the vertebrae of the spine through which the spinal nerve roots travel. Joint — The junction of two or more bones that permits varying degrees of motion between the bones.

Lamina — The flattened or arched part of the vertebral arch that forms the roof or back part of the spinal canal. Ligament — Fibrous connective tissue that links bones together at joints or that passes between bones of the spine. Lumbar spine — The lower back region of the spine; consists of the five vertebrae between the ribs and the pelvis. Nerves — Neural tissue that conducts electrical impulses messages from the brain and spinal cord to all other parts of the body; also conveys sensory information from the body to the central nervous system.

Nerve root — The initial portion of a spinal nerve as it originates from the spinal cord. Neural arch — The bony arch of the back part of a vertebra that surrounds the spinal cord; also referred to as the vertebral arch, it consists of the spinous process and lamina. Pedicle — The bony part of each side of the neural arch of a vertebra that connects the lamina back part with the vertebral body front part. Rotation — Twisting movement of one vertebra on another as a patient turns from one side to the other.

Sacrum — Part of the pelvis just above the coccyx tailbone and below the lumbar spine lower back. Sciatica — A lay term indicating pain along the course of the sciatic nerve; typically noted in the back of the buttocks and running down the back of the leg and thigh to below the knee. Scoliosis — An abnormal sideways curvature of the spine. Spinal canal — A bony channel located in the vertebral column that protects the spinal cord and nerve roots.

Spinal cord — The longitudinal cord of nerve tissue enclosed in the spinal canal. It serves not only as a pathway for nerve impulses to and from the brain, but also as a center for operating and coordinating reflex actions independent of the brain. Spinal stenosis — Abnormal narrowing of the vertebral column that may result in pressure on the spinal cord, spinal sac or nerve roots stemming from the spinal cord. Spine — The flexible bone column extending from the base of the skull to the tailbone.

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What Is the Somatic Nervous System? How Acetylcholine Functions in the Body. This enables them to control the contraction of muscles, as well as provide specific sensory information regarding the skin and parietal pleura. This explains why damage to the internal wall of the thoracic cavity can be felt as a sharp pain localized in the injured region.

Damage to the visceral pleura is experienced as an unlocalized ache. A dermatome is an area of skin that is supplied by a single spinal nerve, and a myotome is a group of muscles that a single spinal nerve root innervates. A dermatome is an area of skin that is supplied by a single spinal nerve. There are eight cervical nerves, twelve thoracic nerves, five lumbar nerves and five sacral nerves.

Each of these nerves relays sensation, including pain, from a particular region of the skin to the brain. Dermatomes : Dermatomes are areas of skin supplied by sensory neurons that arise from a spinal nerve ganglion. Dermatomes and the associated major cutaneous nerves are shown here in a ventral view.

Along the thorax and abdomen, the dermatomes are like a stack of discs, with each section supplied by a different spinal nerve. Along the arms and the legs, the pattern is different. The dermatomes run longitudinally along the limbs, so that each half of the limb has a different dermatome. Although the general pattern is similar in all people, the precise areas of innervation are as unique to an individual as fingerprints.

Dermatomes have clinical significance, especially in the diagnosis of certain diseases. Symptoms that follow a dermatome, such as pain or a rash, may indicate a pathology that involves the related nerve root. Examples include dysfunction of the spine or a viral infection. Viruses that remain dormant in nerve ganglia, such as the varicella zoster virus that causes both chickenpox and shingles, often cause either pain, rash, or both in a pattern defined by a dermatome.

Shingles rash : The shingles rash appears across a dermatome. In this patient, one of the dermatomes in the arm is affected, restricting the rash to the length of the back of the arm. Shingles is one of the only diseases that causes a rash in a dermatomal pattern, and as such, this is its defining symptom. The rash of shingles is almost always restricted to a specific dermatome, such as on the chest, leg, or arm caused by the residual varicella zoster virus infection of the nerve that supplies that area of skin.

Shingles typically appears years or decades after recovery from chickenpox. A myotome is the group of muscles that a single spinal nerve root innervates. The myotome is the motor equivalent of a dermatome. The testing of myotomes provides the clinician with information about the level in the spine where a lesion may be present. During testing, the clinician looks for muscle weakness of a particular group of muscles. Results may indicate lesions to the spinal cord nerve root, or intervertebral disc herniation that presses on the spinal nerve roots.

The peripheral nervous system PNS consists of the nerves and ganglia outside of the brain and spinal cord. Unlike the CNS, the PNS is not protected by the bones of the spine and skull, or by the blood —brain barrier, leaving it exposed to toxins and mechanical injuries. The peripheral nervous system is divided into the somatic nervous system and the autonomic nervous system. Spinal nerve : This diagram indicates the formation of a typical spinal nerve from the dorsal and ventral roots.

Numbers indicate the types of nerve fibers: 1 somatic efferent, 2 somatic afferent, 3—5 sympathetic efferent, 6—7 sympathetic afferent. The peripheral nervous system includes 12 cranial nerves and 31 pairs of spinal nerves that provide communication from the CNS to the rest of the body by nerve impulses to regulate the functions of the human body. The term spinal nerve generally refers to a mixed spinal nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body.

Each pair of spinal nerves roughly correspond to a segment of the vertebral column: 8 cervical spinal nerve pairs C1—C8 , 12 thoracic pairs T1—T12 , 5 lumbar pairs L1—L5 , 5 sacral pairs S1—S5 , and 1 coccygeal pair. The anterior divisions of the lumbar, sacral, and coccygeal nerves form the lumbosacral plexus, the first lumbar nerve being frequently joined by a branch from the twelfth thoracic.

For descriptive purposes, this plexus is usually divided into three parts: lumbar plexus, sacral plexus, and pudendal plexus. The sympathetic division typically functions in actions that need quick responses.

The parasympathetic division functions with actions that do not require immediate reaction. The sympathetic system is often considered the fight or flight system, while the parasympathetic system is often considered the rest and digest or feed and breed system.

Autonomic nervous sytem : The functions of the parasympathetic and sympathetic nervous systems are detailed. The somatic nervous system consists of afferent and efferent nerves and is associated with the voluntary control of skeletal muscle movements. The afferent nerves are responsible for relaying sensations from the body to the central nervous system CNS , while the efferent nerves are responsible for sending out commands from the CNS to the body to stimulate muscle contraction.

Upper motor neurons release acetylcholine. Acetylcholine is released from the axon terminal knobs of alpha motor neurons and received by postsynaptic receptors nicotinic acetylcholine receptors of muscles, thereby relaying the stimulus to contract muscle fibers. Privacy Policy. Skip to main content. Peripheral nerve disorders distort or interrupt messages sent between the brain and the rest of the body.

This can result in:. Unlike the brain and spinal cord, peripheral nerves can regrow after an injury. However, surgery is often required to reconnect the peripheral nerves so that movement and sensation can be restored. You may be trying to access this site from a secured browser on the server.