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33 terms

17.2 Spinal Nerves

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Spinal Nerves
Parallel bundles of axons and their associated neuroglial cells wrapped in several layers of connective tissue. Connect the CNS to sensory receptors, muscles, and glands in all parts of the body.
31
How many pairs of spinal nerves are there?
Intervertebral Foramina
The spinal cord appears segmented because the spinal nerves emerge at regular intervals from the spinal cord throught the ________ ___________.
8
How many pairs of cranial nerves are there?
12
How many pairs of thoracic nerves are there?
5
How many pairs of lumbar nerves are there?
5
How many pairs of sacral nerves are there?
Nerve Fiber
Made up of the axon and associated glial cells of a nerve.
Endoneurium
Covers nerve fibers; consists of a mesh of collagen fibers, fibroblasts, and macrophages surrounded by endoneurial fluid.
Perineurium
Thicker sheath of connective tissue that holds many nerve fibers together into bundles.
Fasciculi
Bundles of nerve fibers.
Perineurium
What maintians the osmotic environment and fluid pressure within the endoneurium?
Epineurium
Outer connective tissue covering of a nerve; bundles all the fasciculi together to form a single nerve.
Dura Mater
The epineurium is continuous with the ____ _____ .
Anterior Rootlets
Emerge from the spinal cord in 2 or 3 irregular rows; contain axons of multipolar motor neurons arising from cell bodies in the anterior regions of the spinal cord gray matter.
Posterior Rootlets
Project from the posterolateral sulcus of the spinal cord; contain central processes the sensoty unipolar neurons.
Posterior Root Ganglion
The swelling of each posterior root.
Roots
The anterior and posterior ____ on each side of the spinal cord correspond to one developmental segment or level of the body.
Spinal Nerve Trunk
As the sensory posterior root and motor anterior root project laterally from the spinal cord, they converge to form a mixed nerve called the _____ _____ _____.
Ramus
Spinal nerve branch that follows a specific course to different peripheral regions.
Posterior Ramus
Ramus that serves the deep muscles and skin of the posterior surface of the trunk.
Anterior Ramus
Ramus that serves the muscle and structures of the upper and lower limbs, and the muscles and skin of the lateral and anterior regions of the trunk.
Meningeal Branch
Reenters the vertebral canal through the intervertebral foramen and supplies the vertebrae, vertebral ligaments, blood vessels of the spinal cord, and meninges.
Plexus
Network of on left and right sides of body formed by axons joining with various numbers of axons from anterior rami of adjacent nerves.
Thoracic
There are no _______ plexuses.
Cervical, Brachial, Lumbar, Sacral, and Coccygeal
Name the 5 plexuses.
Cervical Plexus
Plexus that supplies the skin and muscles of the head, neck, and superior part of the shoulders and chest. Phrenic nerve arises here. Branches run parallel to the accessory and hypoglossal nerves.
Brachial Plexus
Plexus that extends laterally on either side of C5-C8 and T1.Divided into roots, trunks, divisions, and cords. Associated with the axillary, musculocutaneous, radial, median, and ulnar nerves.
Lumbar Plexus
Plexus that supplies the anterolateral abdominal wall, external genitals, and part of the lower limbs.
Sacral Plexus
Plexus that supplies the buttocks, perineum, and lower limbs. Associated with sciatic nerve.
Coccygeal Plexus
Plexus that supplies a small area of skin in the coccygeal region.
Intercostal or Thoracic
Nerves known as segmental because they connect directly to the structures that supply the intercostal space.
Cutaneous Fields
Regions of the skin supplied by a specific nerve arising from a plexus.