Ape hand

Definition
noun
A deformity marked by the extension of the thumb in the same plane as the palm and fingers or the failure to abduct the thumb
Supplement
Ape hand is a deformity that occurs in humans and is characterized by the inability to abduct the thumb, i.e. the thumb cannot be oriented perpendicularly to the palmar surface of the hand. The thumb appears extended and the hand is flattened. It is postulated that the ape hand deformity is caused by wasting on the abductor indicis, thenar and hypothenar, interosseii, and lumbrical muscles.¹ It is found to occur in individuals with median nerve injury at the elbow or at the wrist. This injury impairs the thenar muscles as well as the opponens pollicis muscle.² The name is supposed to be derived from its likeness to the hand of the ape. However, the apes have opposable thumbs as opposed to this condition. Thus, its name can be misleading.
Synonym(s):

• simian hand
• monkey hand
• monkey paw

See also:

thumb

thenar

median nerve

Reference(s):

¹ Hoppenfeld, S. & Zeide, M. (1994). Orthopaedic dictionary. Philadelphia: J.B. Lippincott Co. Page 20.

² Wikipedia.org. (2015). Ape hand deformity. Retrieved from https://en.wikipedia.org/wiki/Ape-hand-deformity