ptosis

n. (pl. ptoses) the sinking or dropping of an organ or part of the body, especially drooping of the eyelid. This may be caused by injury to the third cranial (oculomotor) nerve or the eye muscles. It is also a characteristic sign of myasthenia gravis and Horner’s syndrome. —ptotic adj.

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Psychology term of the day

February 24th 2025

motor neuron disease

any one of a group of degenerative disorders of the lower motor neurons or both the lower and upper motor neurons, marked by progressive weakness and wasting of skeletal muscles and paralysis. This group of disorders includes several forms, but—especially in the United States—the term often is applied specifically to amyotrophic lateral sclerosis.