Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «N»:
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Nerve, sixth cranial
Nerve, sixth cranial: The sixth cranial nerve is the abducent nerve, a small motor nerve that has one task: to supply a muscle called the lateral rectus muscle that moves the eye outward.
Paralysis of the abducent nerve causes inward turning of the eye (internal strabismus) leading to double vision...
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Nerve, spinal
Nerve, spinal: One of the nerves that originates in the spinal cord.
There are 31 pairs of spinal nerves. They consist of the 8 cervical nerves, 12 thoracic nerves, 5 lumbar nerves, 5 sacral nerves, and 1 coccygeal nerve....
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Nerve, tenth cranial
Nerve, tenth cranial: The tenth cranial nerve, and one of the most important, is the vagus nerve. All twelve of the cranial nerves, the vagus nerve included, emerge from or enter the skull (the cranium), as opposed to the spinal nerves which emerge from the vertebral column. The vagus nerve origin...
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Nerve, third cranial
Nerve, third cranial: The third cranial nerve is the oculomotor nerve. The cranial nerves emerge from or enter the skull (the cranium), as opposed to the spinal nerves which emerge from the vertebral column. There are twelve cranial nerves.
The oculomotor nerve is responsible for the nerve supply t...
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Nerve, trigeminal
Nerve, trigeminal: This nerve functions both as the chief nerve of sensation for the face and as the motor nerve controlling the muscles of mastication (chewing).
Problems with the sensory part of the trigeminal nerve result in pain or loss of sensation in the face. Problems with the motor root of ...
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Nerve, trochlear
Nerve, trochlear: The trochlear nerve controls the superior oblique muscle of the eye, one of the extraocular muscles, the muscles that move the eye. Paralysis of the trochlear nerve results in rotation of the eyeball upward and outward (and, therefore, double vision).
The trochlear nerve is the fou...
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Nerve, twelfth cranial
Nerve, twelfth cranial: See: Twelfth cranial nerve....
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Nerve, vagus
Nerve, vagus: A remarkable nerve that supplies nerve fibers to the
pharynx (throat), larynx (voice box), trachea (windpipe), lungs, heart,
esophagus, and the intestinal tract as far as the transverse portion of the
colon. The vagus nerve also brings sensory information back to the brain from
the...
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Nerve, vestibulocochlear
Nerve, vestibulocochlear: A nerve that is responsible for the sense of hearing and which is also pertinent to balance, to the body position sense.
Problems with the vestibulocochlear nerve may result in deafness, tinnitus (ringing or noise in the ears), dizziness, vertigo and vomiting.
The vestib...
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Nerves, cranial
Nerves, cranial: Nerves that
emerge from or enter the skull (the cranium), as opposed to the spinal nerves which emerge from the vertebral column.
Cranial nerves come directly from the brain through the skull.
There are 12 cranial nerves each of which is accorded a Roman numeral and a name:
Crani...
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Nervine
Nervine: A nerve tonic, a medicine that acts therapeutically upon the nerves, particularly in the sense of a sedative that serves to calm ruffled nerves.
The word nervine comes from the Latin nervinus, belonging to a sinew. Nervine travelled across the Channel from France to 17th-century England. ...
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Nervous colon syndrome
Nervous colon syndrome: A common gastrointestinal disorder involving an abnormal condition of gut contractions (motility)
characterized by abdominal pain, bloating, mucous in stools, and irregular bowel
habits with alternating
diarrhea and constipation, symptoms that tend to be chronic and to wax ...
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Nervous system, autonomic
Nervous system, autonomic: Part of the nervous system
that was once thought to be functionally independent of the brain.
The autonomic nervous system regulates key functions of the body
including the activity of the heart muscle (see below), the smooth
muscles (e.g., the muscles of the intestina...
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Nervous system, central (CNS)
Nervous system, central (CNS): That part of the nervous system that consists of the brain and spinal cord.
The central nervous system (CNS) is one of the two major divisions of the nervous system. The other is the peripheral nervous system (PNS), that part of the nervous system that lies outside t...
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Nervous system, human
Nervous system, human: The sum total of the tissues that record and distribute information within a person, and does so by electrical and chemical means.
The nervous system has two distinct parts -- central and peripheral. The central part is made up of the brain and spinal cord. Together they are ...
