Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «N»:
Nerve, fifth cranial
Nerve, fifth cranial: The fifth cranial nerve is the trigeminal nerve.
The trigeminal nerve is quite complex. It functions both as the chief nerve of sensation for the face and the motor nerve controlling the muscles of mastication (chewing).
Problems with the sensory part of the trigeminal nerve r...
Nerve, first cranial
Nerve, first cranial: The first cranial nerve is the olfactory nerve, the nerve that carries impulses for the sense of smell from the nose to the brain.
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 ...
Nerve, fourth cranial
Nerve, fourth cranial: The fourth cranial nerve, the
trochlear nerve, is the nerve supply to the superior oblique muscle
of the eye, one of the muscles that moves the eye. Paralysis of the
trochlear nerve results in rotation of the eyeball upward and outward
(and, therefore, double vision).
Nerve, glossopharyngeal: The glossopharyngeal nerve is the ninth cranial nerve. The 12 cranial nerves, the glossopharyngeal nerve included, emerge from or enter the skull (the cranium), as opposed to the spinal nerves which emerge from the vertebral column.
The glossopharyngeal nerve supplies the...
Nerve, hypoglossal: The hypoglossal nerve is the twelfth cranial nerve. The twelve cranial nerves, the hypoglossal nerve included, emerge from or enter the skull (the cranium), as opposed to the spinal nerves which emerge from the vertebral column.
The hypoglossal nerve supplies the muscles of the...
Nerve, ninth cranial
Nerve, ninth cranial: The ninth cranial nerve is the glossopharyngeal nerve. All 12 cranial nerves, the glossopharyngeal nerve included, emerge from or enter the skull (the cranium), as opposed to the spinal nerves which emerge from the vertebral column.
The glossopharyngeal nerve supplies the to...
Nerve, oculomotor: The oculomotor nerve is the third
cranial nerve. (The cranial nerves emerge from or enter the cranium,
the skull, as opposed to the spinal nerves which emerge from the
The oculomotor nerve is responsible for the nerve supply to
muscles about the eye:
Nerve, olfactory: See: Olfactory nerve....
Nerve, optic: The optic nerve connects the eye to the
brain. The optic nerve carries the impulses formed by the retina. The
retina is the nerve layer that lines the back of the eye that senses
light and creates impulses. These impulses are dispatched through the
optic nerve to the brain, which...
Nerve, pinched: See: Nerve compression....
Nerve, pressor: A pressor nerve is a nerve which, when stimulated, causes the blood pressure to rise.
The word "pressor" refers to raising the blood pressure. It comes from the French "presser" meaning "to exert pressure" or "to squeeze."...
Nerve, recurrent laryngeal
Nerve, recurrent laryngeal: One of the best known branches of the vagus nerve, a very long nerve that originates in the brainstem. After the recurrent laryngeal nerve leaves the vagus nerve, it goes down into the chest and then loops back up ("recurs") to supply nerves to the larynx (the voice box)...
Nerve, sciatic: The largest nerve in the body, the sciatic nerve begins from nerve roots in the lumbar part of the spinal cord (in the low back) and extends through the buttock area to send nerve endings down to the legs.
Pain resulting from irritation of the sciatic nerve is called sciatica. The p...
Nerve, second cranial
Nerve, second cranial: Also known as the optic nerve. This nerve connects the eye to the brain and carries the impulses formed by the back layer of the eye (retina) to the brain, which interprets them as images.
The cranial nerves emerge from or enter the skull (the cranium), as opposed to the spina...
Nerve, seventh cranial
Nerve, seventh cranial: The seventh cranial nerve is the facial nerve, a mixed nerve that has fibers both going out and coming in (both efferent and afferent fibers). It supplies the muscles of facial expression.
Paralysis of the facial nerve causes a characteristic picture with drooping of one side...