spinal nerve

spinal nerve

n.

Any of 31 pairs of nerves emerging from the spinal cord, each attached to the cord by two roots, anterior or ventral and posterior or dorsal, the latter provided with a spinal ganglion. The two roots unite in the intervertebral foramen but divide again into ventral and dorsal rami, or anterior and posterior primary divisions, the former supplying the foreparts of the body and limbs, the latter the muscles and skin of the back.

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nerve,

n a cordlike structure that conveys impulses between a part of the central nervous system and some part of the body and consists of an outer connective tissue sheath and bundles of nerve fibers. See also each of the individual nerves of the head and neck as they are listed.

nerve, abducent (VI),

n the sixth cranial nerve; a small, completely motor nerve arising in the pons, supplying the lateral rectus muscle of the eye.

nerve, accessory,

n See nerve, spinal accessory.

nerve, acoustic (VIII),

n the eighth cranial nerve; the vestibulocochlear nerve; a sensory nerve consisting of a vestibular portion and an auditory (or cochlear) portion.

nerve(s), afferent, in pulp,

n any nerve that originates as a terminal free nerve ending in the dental pulp tissue and travels to the second and third divisions (maxillary nerve and mandibular nerve) of the cranial trigeminal nerve (cranial nerve V).

nerve, alveolar,

n afferent nerves that convey impulses from the pulp tissue and periodontium of the maxillary teeth to the maxillary division of the cranial trigeminal nerve.

nerve, anterior superior alveolar,

n alveolar nerve that conveys impulses from the pulp tissue and periodontium of the maxillary anterior teeth to the infraorbital nerve.

nerve, auriculotemporal

n a nerve that transmits feeling from the external ear, scalp, and parotid salivary gland to the mandibular division of the cranial trigeminal nerve.

nerve, branchial,

n one of five cranial nerves that supply the derivatives of the branchial arches: trigeminal (V), facial (VII), glossopharyngeal (IX), vagus (X), and spinal accessory (XI). Each branchial nerve may have a variety of functions, including visceral motor and visceral and somatic sensory functions.

nerve, buccal (long),

n afferent nerve that conveys impulses from the facial periodontium of the mandibular molars and gingiva to the mandibular division of the cranial trigeminal nerve.

nerve, chiasma, optic,

n the decussation, or crossing, of optic nerve fibers from the medial side of the retina on one side to the opposite side of the brain.

nerve, chorda tympani

n a parasympathetic and special sensory branch of the facial nerve supplying the submandibular and sublingual glands and the anterior two thirds of the tongue (taste).

nerve, cochlear

n one of the two major branches of the eighth cranial nerve; a special sensory nerve for the sense of hearing that transmits impulses from the organ of Corti to the brain.

nerve, cranial,

n any one of 12 paired nerves, classified in three sets, arising directly in the brain and supplying various tissues of the head and neck. The cranial nerves are the special somatic sensory nerves: olfactory (I), optic (II), and vestibulocochlear (acoustic) (VIII); the somatic motor nerves: oculomotor (III), trochlear (IV), abducent (VI), and hypoglossal (XII); and the branchial nerves: trigeminal (V), facial (VII), glossopharyngeal (IX), vagus (X), and spinal accessory (XI).

nerve, deep temporal,

n an anterior and a posterior nerve that branch away from the mandibular nerve of the trigeminal nerve and extend deep into the temporalis muscle, which is used during mastication.

nerve degeneration,

n the reversion to a less organized and functioning state, usually detected by the loss of ability to conduct or transmit nerve impulses. Advanced degeneration might show cellular decomposition.

nerve ending,

n the terminal of a nerve fiber, usually in synapse with another fiber or in a sensory organ.

nerve, facial (VII),

n the seventh cranial nerve; a mixed nerve supplying motor fibers to the facial muscles, the stapedius, and posterior body of the digastric; sensory fibers from the taste buds in the anterior two thirds of the tongue (via the chorda tympani); and general visceral autonomic fibers for the submandibular and sublingual salivary glands. It travels unilaterally over the face and at one point is located in the parotid salivary gland, which it does not serve. However, pain in the parotid gland indicates a glandular malignancy, and complications with an inferior nerve block can also result from its location there.

The cranial nerves.

nerve fiber,

n a slender process of a neuron, usually the axon. Each fiber is classified as myelinated or unmyelinated.

nerve, frontal,

n afferent nerve from the union of the superorbital and supratrochlear nerves that carries information from the forehead, scalp, nose, and upper eyelids to the ophthalmic division of the cranial trigeminal nerve.

nerve, glossopharyngeal (IX)

n the ninth cranial nerve; a mixed motor and sensory nerve arising in the medulla and supplying motor efferents to stylopharyngeal muscles and other pharyngeal muscles; visceral motor efferents via the otic ganglion for the parotid gland; special visceral afferents from the taste buds in the posterior third of the tongue; and general sensory afferents from the pharynx and posterior aspects of the oral cavity. It is essential to the sense of taste.

nerve, greater (anterior) palatine,

n the nerve originating in the pterygopalatine ganglion that supplies the hard palate, part of the soft palate, and its associated lingual mucosa.

nerve, greater petrosal

n one of the two nerves that branch off of the facial nerve and help control the muscles used in facial expression; this nerve also carries impulses to the lacrimal gland and the nasal cavity, and to and from the palate. The nerve has both afferent and efferent fibers.

nerve, hypoglossal (XII),

n the twelfth cranial nerve; a motor nerve that arises in the medulla and supplies extrinsic and intrinsic muscles of the tongue. Each nerve has four major branches, communicates with the vagus nerve, and connects to the nucleus XII in the brain.

nerve, incisive,

n afferent nerve that merges with the mental nerve to later create the inferior alveolar nerve in the mandibular canal. This nerve transmits feeling from the pulp tissue and facial periodontium of the mandibular anterior teeth and premolars to the mandibular division of the cranial trigeminal nerve.

nerve, inferior alveolar,

n a motor and general sensory branch of the mandibular nerve, with mylohyoid, inferior dental, mental, and inferior gingival branches.

nerve, infraorbital,

n afferent nerve that enters through the infraorbital foramen and canal to merge with the maxillary branch of the cranial trigeminal nerve.

nerve, intermediate,

n the parasympathetic and special sensory division of the facial nerve with chorda tympani and greater petrosal branches.

nerve, lacrimal,

n afferent nerve that is part of the ophthalmic division of the cranial trigeminal nerve and controls secretions in the upper eyelid, lacrimal gland, and the conjunctiva.

nerve, lingual,

n a general sensory branch of the mandibular nerve having sublingual and lingual branches and connections with the hypoglossal nerve and chorda tympani.

nerve, mandibular,

n the mandibular division of the trigeminal nerve, arising in the trigeminal ganglion and supplying general sensory and motor fibers via mesenteric, pterygoid, buccal, auriculotemporal, deep temporal, lingual, inferior alveolar, and meningeal branches.

nerve, maxillary,

n the maxillary division of the trigeminal nerve arising in the trigeminal ganglion and supplying general sensory fibers via zygomatic, posterosuperior alveolar, infraorbital, pterygopalatine, and nasopalatine branches.

nerve, mental,

n a nerve that branches off the inferior alveolar nerve, emerging from the mandible through the mental foramen and branching further to provide sensory innervation to the tissues of the chin and lower lip and the labial mucosa of the mandibular premolars and anterior teeth.

nerve, middle superior alveolar,

n alveolar nerve that conveys impulses from the pulp tissue and periodontium of the gingiva and the maxillary premolar teeth to the infraorbital nerve. This nerve is not always present in all persons. If not present, the premolars are innervated by the posterior superior alveolar nerve.

nerve, mylohyoid,

n a branch of the mandibular division of the cranial trigeminal nerve that serves the mylohyoid and digastric muscles of the oral cavity. It is thought to be a possible alternative innervation for the pulp tissues of the mandibular first molar in some cases.

nerve, nasociliary

n one of three branches of the cranial trigeminal nerve that controls parts of the eyes, nasal cavity, and paranasal sinuses.

nerve, nasopalatine

n afferent nerve that conveys impulses from the lingual periodontium of the maxillary anterior teeth bilaterally and the anterior hard palate to the maxillary division of the cranial trigeminal nerve.

nerve, oculomotor (III)

n the third cranial nerve; primarily a motor nerve arising from the midbrain and supplying motor efferents to the superior rectus, medial rectus, inferior rectus, and inferior oblique eye muscles, as well as autonomic fibers via the ciliary ganglion to the ciliary body and the iris.

nerve, olfactory (I)

n the first cranial nerve; a special sensory nerve for the sense of smell.

nerve, ophthalmic

n the ophthalmic division of the trigeminal nerve, arising in the trigeminal ganglion and supplying general sensory fibers via the frontal, lacrimal, and nasociliary branches.

nerve, optic (II),

n the second cranial nerve; a special sensory nerve for vision. It consists mainly of coarse, myelinated fibers that arise in the retinal ganglionic layer of the eye, traverse the thalamus, and connect with the visual cortex of the brain.

nerve, palatine,

n the two afferent nerves of the maxillary division of the cranial trigeminal nerve. The greater palatine nerve innervates the posterior hard palate and lingual periodontium of the maxillary molar teeth, while the lesser palatine nerve innervates the soft palate and palatine tonsillar tissue.

nerve, posterior superior alveolar,

n alveolar nerve that conveys impulses from the maxillary sinus, gingiva, pulp tissue, and periodontium of the maxillary molar teeth to the infraorbital nerve or to the maxillary nerve directly.

nerve regeneration,

n the reconstruction and renewal of cell structure and function; generally restricted to myelinated nerve fibers.

nerve repositioning,

n the surgical redirecting of the inferior alveolar and/or mental nerve to allow longer implants to be placed in a mandible that has extensive deterioration of the posterior ridge. Some temporary or long-term loss of sensation to the lip, tongue, chin and/or gingival tissue may result. Also known as
nerve lateralization and
nerve transpositioning.

nerve(s), somatic motor,

n (cranial), the somatic motor nerves–oculomotor (III), trochlear (IV), abducent (VI), and hypoglossal (XII)–largely comparable to the ventral motor roots of the spinal nerves. They are composed almost entirely of somatic motor fibers that emerge ventrally from the brainstem. Their arrangement is closely correlated with the distribution of the myotomes in the head. The oculomotor, trochlear, and abducent nerves, which supply the eye musculature, have the same myotomic origin and arrangement as the somatic muscles of the trunk and extremities.

nerve(s), special somatic sensory,

n the structural arrangements from typical sensory nerves by which the three main sense organs, nose, eyes, and ears, are innervated. The sensory nerves are the olfactory (I), optic (II), and vestibulocochlear (acoustic) nerves (VIII).

nerve(s), spinal,

n any one of 31 pairs of mixed peripheral nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal) that are connected segmentally with the spinal cord, dorsal sensory trunk, and ventral motor root.

nerve, spinal accessory (XI),

n the eleventh cranial nerve; a motor nerve that derives its origin in part from the medulla and in part from the cervical spinal cord. Its internal ramus joins with the vagus nerve to supply some of the muscles of the larynx. Its external ramus joins with the spinal nerves to supply the sternocleidomastoid and trapezius muscles. The nerve and its relationship to head posture is important in maintaining stable occlusal relationships of vertical dimension and centric relation.

nerve, tensor tympani,

n a small motor branch of the mandibular nerve.

nerve, trigeminal (V)

n the fifth cranial nerve; a mixed motor and sensory nerve connected with the pons through three roots (motor, proprioceptive, and large sensory), the latter root expanding into the trigeminal ganglion, from which arise the ophthalmic, masseteric, and mandibular divisions. It serves the muscles of mastication and cranial muscles through its motor root and serves the teeth, tongue, and oral cavity and most of the facial skin through its sensory root.

nerve, trochlear (IV)

n the fourth cranial nerve; a small motor nerve arising ventrally in the midbrain and supplying the inferior oblique muscle of the eye.

nerve trunk,

n a particularly sizeable bundle of axons or nerve fibers.

nerve, vagus (X)

n the tenth cranial nerve; a mixed parasympathetic, visceral, afferent, motor, and general sensory nerve with laryngeal, pharyngeal, bronchial, esophageal, gastric, and many other branches.

nerve, vestibular (VIII),

n one of the two major branches of the eighth cranial nerve; a special sensory nerve for the sense of balance and the transmission of space-orientation impulses from the semicircular canals to the brain.

nerve, vestibulocochlear (VII),

n the seventh cranial nerve; acoustic nerve; a sensory nerve consisting of a vestibular portion and an auditory, or cochlear, portion.

nerve, zygomatic

n the afferent nerve of the maxillary division of the cranial trigeminal nerve that serves the skin of the cheek and temple. It also innervates the lacrimal gland.

nerve(s), dentinal,

n any of the afferent or sensory neurons associated with the odontoblastic processes in the dentinal tubules and the attached cell body of the odontoblasts within the pulp tissue. These nerves may allow for an awareness of pain due to their monitoring of environmenal changes within the dentin. There is some controversy about their overall location in the dentin tubule (full length, partial, or not at all).

nerves, efferent,

n motor nerves that carry impulses from the brain or spinal cord toward the periphery of the body to activate muscles, usually in response to impulses received from sensory nerves.

nerve(s), periodontal ligament,

n the sympathetic fibers of the autonomic nervous system with enclosed nerve endings that control blood flow within the vessels and register pressure changes. Sensory or afferent fibers with free nerve endings cause an awareness of pain.

nerve(s), pulp,

n the sympathetic fibers of the autonomic nervous system located within the tissue that control blood flow within the vessels. Sensory or afferent fibers with free nerve endings in close proximity to the odontoblasts may cause an awareness of pain.

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nerve

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.

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accelerator n's

the cardiac sympathetic nerves, which, when stimulated, accelerate the heart rate.

nerve biopsy

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.

nerve cuff

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.

depressor nerve

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.

nerve endings

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).

excitor nerve

one that transmits impulses resulting in an increase in functional activity.

excitoreflex nerve

a visceral nerve that produces reflex action.

nerve fiber

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).

fusimotor n's

those that innervate the intrafusal fibers of the muscle spindle.

gangliated nerve

any nerve of the sympathetic nervous system. Called also ganglionated.

nerve gas

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.

nerve impulses

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.

inhibitory nerve

one that transmits impulses resulting in a decrease in functional activity.

medullated nerve

myelinated nerve.

modified free nerve endings

see nerve endings (above).

myelinated nerve

one whose axons are encased in a myelin sheath.

pelvic n's

nerves of the parasympathetic outflow. See Table 14.

peripheral nerve

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.

pilomotor n's

those that supply the arrector muscles of hair.

pressor nerve

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.

secretory nerve

an efferent nerve whose stimulation increases glandular activity.

nerve sheath

see neurilemma.

nerve sheath tumor

neurilemmoma or schwannoma.

somatic n's

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.

spinal nerve

a segmental nerve which consists of afferent and efferent axons from its dorsal and ventral roots.

splanchnic n's

those of the blood vessels and viscera, especially the visceral branches of the thoracic, lumbar and pelvic parts of the sympathetic trunks.

nerve stimulator

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.

sudomotor n's

those that innervate the sweat glands.

sympathetic n's

1. see sympathetic trunk.

2. any nerve of the sympathetic nervous system.

nerve terminal

nerve ending.

trophic nerve

one concerned with regulation of nutrition.

nerve trunk

the main body of a nerve; subsequently divides into branches.

unmyelinated nerve

one whose axons are not encased in a myelin sheath.

vasoconstrictor nerve

one whose stimulation causes narrowing of blood vessels.

vasodilator nerve

one whose stimulation causes dilatation of blood vessels.

vasomotor nerve

one concerned in controlling the caliber of vessels, whether as a vasoconstrictor or vasodilator.

vasosensory nerve

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.

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spinal

pertaining to a spine or to the vertebral column and in many instances to the spinal cord.

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spinal abscess

infection may be introduced hematologically from navel infection to a vertebral body or up the vertebral canal from an infected docking wound. Clinically there is a development of paresis over a few days then paraplegia when the abscess is in the lumbar region or quadriplegia when it is located in the cervical area.

spinal accessory nerve

see accessory nerve, Table 14.

congenital spinal stenosis

stenosis of the vertebral canal present at birth; recorded in calves.

spinal fibrocartilaginous emboli

see fibrocartilaginous embolic myelopathy.

focal symmetrical spinal poliomalacia

see focal symmetrical spinal poliomalacia.

spinal fusion

surgical creation of ankylosis of contiguous vertebrae.

spinal meninges

see meninges.

spinal meningitis

usually part of cerebrospinal meningitis. May be local related to spinal cord abscess and cause localized pain and muscle rigidity.

spinal muscular atrophy

see hereditary spinal muscular atrophy, hereditary neuronal abiotrophy of Swedish Lapland dogs.

spinal myelitis

see myelitis.

spinal myelopathy

see myelopathy.

spinal nerve

any of the paired nerves arising from the spinal cord and passing out between the vertebrae.

spinal puncture

introduction of a hollow needle into the subarachnoid space of the spinal canal, usually for the purpose of collecting a sample of cerebrospinal fluid, to introduce radiopaque material for myelography, or the injection of an anesthetic.

spinal reflex

any reflex action mediated through a center at the spinal cord.

spinal stenosis

see spinal cord compression (above).

spinal tap

see spinal puncture (above).

spinal trauma

temporary or permanent dislocation of one or more spinal vertebrae; or fracture; causes immediate flaccid paralysis caudal to injury due to spinal shock, followed by residual signs due to damage to spinal cord tissue.

spinal walking

see reflex walking.

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spinal nerve

Anatomy Any one of the 31 pairs of nerves that arise from the spinal cord