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 fourth cranial nerve. (The twelve cranial nerves emerge from or enter the skull as opposed to the spinal nerves which emerge from the vertebral column).
The trochlear nerve is the only cranial nerve that arises from the back of the brain stem. It follows the longest course within the skull of any of the cranial nerves.
- 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 ear, tongue, pharynx, and larynx. The vagus nerve is the […]
- 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 vestibulocochlear nerve is the eighth cranial nerve. The 12 cranial nerves, the […]
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. There it was first applied to the sinews. That […]
- 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 and wane over the years. Although the disorder can cause chronic recurrent discomfort, it does not lead […]
- Nervous system, autonomic
the sympathetic nervous system, which accelerates the heart rate, constricts blood vessels, and raises blood pressure, and the parasympathetic nervous system, which slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles.