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Spinal Nerves
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. Structure Each spinal nerve is a mixed nerve, formed from the combination of nerve fibers from its dorsal and ventral roots. The dorsal root is the afferent sensory root and carries sensory information to the brain. The ventral root is the efferent motor root and carries motor information from the brain. The spinal nerve emerges from the spinal column through an opening ( intervertebral foramen) between adjacent ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nerve
A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the electrochemical nerve impulses called action potentials that are transmitted along each of the axons to peripheral organs or, in the case of sensory nerves, from the periphery back to the central nervous system. Each axon, within the nerve, is an extension of an individual neuron, along with other supportive cells such as some Schwann cells that coat the axons in myelin. Within a nerve, each axon is surrounded by a layer of connective tissue called the endoneurium. The axons are bundled together into groups called fascicles, and each fascicle is wrapped in a layer of connective tissue called the perineurium. Finally, the entire nerve is wrapped in a layer of connective tissue called the epineurium. Nerve cells (often called neurons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intervertebral Foramen
The intervertebral foramen (also called neural foramen, and often abbreviated as IV foramen or IVF) is a foramen between two spinal vertebrae. Cervical, thoracic, and lumbar vertebrae all have intervertebral foramina. The foramina, or openings, are present between every pair of vertebrae in these areas. A number of structures pass through the foramen. These are the root of each spinal nerve, the spinal artery of the segmental artery, communicating veins between the internal and external plexuses, recurrent meningeal (sinu-vertebral) nerves, and transforaminal ligaments. When the spinal vertebrae are articulated with each other, the bodies form a strong pillar that supports the head and trunk, and the vertebral foramen constitutes a canal for the protection of the medulla spinalis (spinal cord). The size of the foramina is variable due to placement, pathology, spinal loading, and posture. Foramina can be occluded by arthritic degenerative changes and space-occupying les ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brachial Plexus
The brachial plexus is a network () of nerves formed by the anterior rami of the lower four cervical nerves and first thoracic nerve ( C5, C6, C7, C8, and T1). This plexus extends from the spinal cord, through the cervicoaxillary canal in the neck, over the first rib, and into the armpit, it supplies afferent and efferent nerve fibers the to chest, shoulder, arm, forearm, and hand. Structure The brachial plexus is divided into five ''roots'', three ''trunks'', six ''divisions'' (three anterior and three posterior), three ''cords'', and five ''branches''. There are five "terminal" branches and numerous other "pre-terminal" or "collateral" branches, such as the subscapular nerve, the thoracodorsal nerve, and the long thoracic nerve, that leave the plexus at various points along its length. A common structure used to identify part of the brachial plexus in cadaver dissections is the M or W shape made by the musculocutaneous nerve, lateral cord, median nerve, medial cord, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cervical Plexus
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 (m. scalenus, m. levator scapulae, m. splenius cervicis) from lateral side. There is anastomosis with accessory nerve, hypoglossal nerve and sympathetic trunk. It is located in the neck, deep to the sternocleidomastoid muscle. Nerves formed from the cervical plexus innervate the back of the head, as well as some neck muscles. The branches of the cervical plexus emerge from the posterior triangle at the nerve point, a point which lies midway on the posterior border of the sternocleidomastoid. Branches The cervical plexus has two types of branches: cutaneous and muscular. *Cutaneous (4 branches): ** Lesser occipital nerve - innervates the skin and the scalp posterosuperior to the auricle (C2) ** Great auricu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nerve Plexus
A nerve plexus is a plexus (branching network) 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: *Spinal Plexuses ** Cervical plexus - serves the head, neck and shoulders **Brachial plexus - serves the chest, shoulders, arms and hands ** Lumbosacral plexus *** Lumbar plexus - serves the back, abdomen, groin, thighs, knees, and calves **** Subsartorial plexus - below the sartorius muscle of thigh *** Sacral ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rami Communicantes Ramus communicans (plural rami communicantes) is the Latin term used for a nerve which connects two other nerves, and can be translated as "communicating branch". Structure When used without further definition, it almost always refers to a |
