College of Massage Therapists of British Columbia (CMTBC) Practice Exam

Where would a therapist expect to see muscle wasting in a patient with Ape Hand Deformity?

1. Hypothenar Eminence

2. Thenar Eminence

3. Intrinsic muscles of the palm

4. Flexor Carpi Ulnaris

The correct answer is: Thenar Eminence

Ape Hand Deformity, also known as "simian hand," is characterized by a weakness or paralysis of the muscles that allow for thumb opposition and flexion, primarily affecting the thenar eminence. The thenar eminence is made up of the muscles that control the movement of the thumb, including the abductor pollicis brevis, opponens pollicis, and flexor pollicis brevis. In this condition, the atrophy of these muscles leads to significant weakness in thumb function, which is key to grasping and pinching movements. As a result, the deficiency in muscle strength and control in the thenar eminence becomes noticeable and is a direct consequence of the impairment associated with the median nerve, which innervates these muscles. The hypothenar eminence and the intrinsic muscles of the palm also play roles in hand function but are less affected in Ape Hand Deformity, since the condition predominantly impacts the muscles responsible for thumb movement. The flexor carpi ulnaris is primarily involved in wrist flexion and is innervated by the ulnar nerve, meaning it is not directly related to the muscular atrophy seen in Ape Hand Deformity. Thus, the observed muscle wasting primarily