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

Which nerve innervates the hypothenar muscles?

1. Radial nerve

2. Ulnar nerve

3. Median nerve

4. Musculocutaneous nerve

The correct answer is: Ulnar nerve

The hypothenar muscles, which are responsible for the movement of the little finger (fifth digit), are innervated by the ulnar nerve. This group of muscles includes the abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi. These muscles play a crucial role in thumb opposition and fine motor control of the hand. The ulnar nerve is specifically responsible for motor function in the intrinsic muscles of the hand, particularly those located in the hypothenar area. Understanding the ulnar nerve's role is vital for recognizing how nerve injuries may affect hand function, particularly in relation to grip and finger movements. The radial nerve primarily innervates the extensor muscles of the arm and forearm. The median nerve mainly supplies the thenar muscles as well as the first two lumbricals, which are involved with the thumb and the index finger. The musculocutaneous nerve is responsible for innervating the muscles of the anterior compartment of the arm, such as the biceps brachii, but does not have a role in the innervation of the hypothenar muscles. Thus, knowing the specific nerves associated with different muscle groups is essential for both anatomical understanding and clinical