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a collection of funiculi or bundles of nerve fibers enclosed in a connective tissue sheath, the epineurium.
The main stem of a nerve, consisting of a bundle of nerve fibers bound together by a tough sheet of connective tissue.
nerve trunk(nĕrv trŭngk)
Collection of funiculi or bundles of nerve fibers enclosed in a connective tissue sheath, the epineurium.
a macroscopic cordlike structure of the body, comprising a collection of nerve fibers that convey impulses between a part of the central nervous system and some other body region. For a complete list of the named nerves of the body, see Table 14.
Depending on their function, nerves are known as sensory, motor or mixed. Sensory nerves, or afferent nerves, carry information from the periphery of the body to the brain and spinal cord. Sensations of heat, cold, pressure and pain are conveyed by the sensory nerves. Motor nerves, or efferent nerves, transmit impulses from the brain and spinal cord to the periphery, especially the muscles. Mixed nerves are composed of both motor and sensory fibers, and transmit messages in both directions.
Together, the nerves make up the peripheral nervous system, as distinguished from the central nervous system, which consists of the brain and spinal cord. There are 12 pairs of cranial nerves, which carry messages to and from the brain. Spinal nerves arise from the spinal cord and pass out between the vertebrae. The various nerve fibers and cells that make up the autonomic nervous system innervate the glands, heart, blood vessels and involuntary muscles of the internal organs. For a complete list of nerves, see Table 14.
the cardiac sympathetic nerves, which, when stimulated, accelerate the heart rate.
specimens taken from representative nerves by separation and removal of fascicles may provide useful information in the investigation of neuromuscular disorders or neuropathies. Consideration must be given to any resulting motor or sensory deficits that might result from the procedure. In dogs, the common peroneal, ulnar and tibial nerves are the usual sources.
device used in the surgical repair of nerves to protect the site of anastomosis from an in-growth of connective tissue and to promote linear regeneration of neural elements.
1. an inhibitory nerve whose stimulation depresses a motor center.
2. a nerve that lessens activity of an organ.
dermal nerve network
the organization of sensory nerve fibers to the dorsal root ganglia found in the dermis.
comprise afferent and efferent endings. Afferent endings transform sensations into acceptable stimuli by the CNS; include diffuse-free endings, free, modified free or encapsulated (e.g. tactile corpuscles, Krause's endbulbs, Golgi-Mazzoni corpuscles, genital corpuscles, lamellated corpuscles, Herbst corpuscles, Uffini corpuscles). Efferent endings transform nerve impulses into stimuli delivered to effector end organs; they include neuromuscular spindles, Golgi tendon organs.
encapsulated nerve endings
see nerve endings (above).
one that transmits impulses resulting in an increase in functional activity.
a visceral nerve that produces reflex action.
a process of a neuron, especially the long slender axon which conducts nerve impulses away from the cell. It may be medullated or nonmedullated.
free nerve endings
see nerve endings (above).
those that innervate the intrafusal fibers of the muscle spindle.
any nerve of the sympathetic nervous system. Called also ganglionated.
organophosphorus compounds specially selected for their toxicity to humans and used in chemical warfare.
nerve growth factor
a protein dimer composed of two identical polypeptide chains secreted by nerve cells and necessary for the growth and survival of certain classes of nerve cells during development.
the physicochemical change in a nerve fiber's membrane which is caused by stimulation, e.g. from a stretch receptor, and which transmits a record of the sensation, or, in another case, of a motor instruction to an effector organ.
one that transmits impulses resulting in a decrease in functional activity.
modified free nerve endings
see nerve endings (above).
one whose axons are encased in a myelin sheath.
nerves of the parasympathetic outflow. See Table 14.
any nerve outside the central nervous system. Injury to a nerve causes pain initially and if tissue is destroyed, loss of function follows; signs are weakness or paralysis, atrophy, lower temperature and depressed reflexes.
those that supply the arrector muscles of hair.
an afferent nerve whose impulses stimulate a vasomotor center and increases intravascular tension.
retinal nerve fiber layer
layer number 9 of the retina; axons of ganglion cells, make up bundles of nerve fibers and pass to the optic disk and lamina cribrosa; from there on they become the optic nerve.
an efferent nerve whose stimulation increases glandular activity.
nerve sheath tumor
neurilemmoma or schwannoma.
the sensory and motor nerves supplying skeletal muscle and somatic tissues.
somatic afferent n's
sensory neurons whose cell bodies reside in spinal and cranial nerve ganglia.
somatic efferent n's
motor neurons originating in ventral gray columns of the spinal cord and certain parts of the brain and are connected to striated muscles derived from embryonic somites.
a segmental nerve which consists of afferent and efferent axons from its dorsal and ventral roots.
those of the blood vessels and viscera, especially the visceral branches of the thoracic, lumbar and pelvic parts of the sympathetic trunks.
an electrical device used to deliver a short stimulus to a peripheral nerve as a test of its function. It can be used to assess the effects of a neuromuscular blocking agent during clinical anesthesia.
those that innervate the sweat glands.
1. see sympathetic trunk.
2. any nerve of the sympathetic nervous system.
one concerned with regulation of nutrition.
the main body of a nerve; subsequently divides into branches.
one whose axons are not encased in a myelin sheath.
one whose stimulation causes narrowing of blood vessels.
one whose stimulation causes dilatation of blood vessels.
one concerned in controlling the caliber of vessels, whether as a vasoconstrictor or vasodilator.
any nerve supplying sensory fibers to the vessels.
visceral afferent n's
nerves with cell bodies in spinal and cranial ganglia and which provide sensory innervation to thoracic and abdominal tissues.
visceral efferent n's
the parasympathetic component of the autonomic nervous system.