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jaw jerk

a reflex test used in the diagnosis of lesions of the corticospinal tract: The examiner taps downward on a person’s lower jaw while it hangs open; if the lesion is present, the jaw closes reflexively. Also called chin reflex; jaw reflex; mandibular reflex; masseter reflex.

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Psychology term of the day

January 26th 2025

congenital oculomotor apraxia

congenital oculomotor apraxia

a condition, present at birth, in which a child is unable to fixate objects normally (see oculomotor apraxia). It is characterized by the absence of saccades and smooth-pursuit eye movements in the horizontal plane, but vertical eye movements are preserved: Children with this condition are often mistakenly thought to be blind. Between the ages of 4 and 6 months, they develop thrusting, horizontal head movements, sometimes blinking prominently or rubbing their eyelids when they attempt to change fixation. The cause of congenital oculomotor apraxia is unknown, but there is usually an improvement with age.