jaw jerk


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jerk

 [jerk]
a sudden reflex or involuntary movement.
Achilles jerk (ankle jerk) plantar extension of the foot elicited by a tap on the achilles tendon, while the patient is seated on a bed or chair, with feet hanging freely; called also Achilles reflex and triceps surae jerk or reflex.
biceps jerk biceps reflex.
elbow jerk involuntary flexion of the elbow on striking the tendon of the biceps or triceps muscle.
jaw jerk jaw-jerk reflex.
knee jerk see knee jerk.
tendon jerk tendon reflex.
triceps surae jerk ankle jerk.

jaw re·flex

a spasmodic contraction of the temporal muscles following a downward tap on the loosely hanging mandible.

jaw jerk

an abnormal reflex elicited by tapping the chin with a rubber hammer while the mouth is half open and the jaw muscles are relaxed. A quick snapping shut of the jaw implies damage to the area of cerebral cortex governing motor activity of the fifth cranial nerve. Also called chin reflex, chin-jerk reflex, mandibular reflex.

jerk

(jerk)
A colloquial term for reflex.

Achilles jerk

Achilles tendon reflex.

ankle jerk

See: ankle clonus reflex

biceps jerk

See: biceps reflex

elbow jerk

Triceps reflex.

jaw jerk

Chin reflex.

knee jerk

The extension of the lower leg upon striking the patellar tendon when the knee is flexed at a right angle. Knee jerk is absent in locomotor ataxia, infantile paralysis, meningitis, destructive lesions of the lower part of the spinal cord, and certain forms of paralysis. It is increased in lesions of pyramidal areas, brain tumors, spinal irritability, and cerebrospinal sclerosis.
See: knee-jerk reflex

tendon jerk

The contraction of a muscle after tapping its tendon.

triceps surae jerk

Achilles tendon reflex.