There was wasting of interossei, thenar and
hypothenar muscles, more marked in the left hand and clawing in both hands (fig-1).
It innervates the
hypothenar muscles, third and fourth lumbricals, dorsal and palmar interossei muscles, adductor pollicis muscle, and deep head of the flexor pollicis brevis muscle.
Variations in the motor nerve supply of the thenar and
hypothenar muscles of the hand.
Atrophy was prominent in the first dorsal interosseal muscle and less obvious in the
hypothenar muscles (Figure-1).
Inclusion criteria required a diagnosis of CubTS according to guidelines provided by the American Association of Neuromuscular and Electrodiagnostic Medicine:[sup][4] (1) symptoms of impairment of ulnar nerve, such as paresthesia of the digitus annularis and digitus minimus, hand clumsiness, atrophy of
hypothenar muscles, weakness of the muscles dominated by the ulnar nerve, pain, or numbness in ulnar nerve dominated area, positive Froment's sign, positive Wartenberg's sign, and so on; (2) routine motor NCS results suggested CubTS; (3) informed consent signed; and (4) age between 18 and 85 years old.
voluntary muscle testing showed Grade 0 power in the thenar and
hypothenar muscles bilaterally.
In another case of ulnar nerve lesion, one could not find any denervation in
hypothenar muscles. These abnormal findings can be explained by the presence of an abnormal anastomosis of nerves in the upper extremity.
On motor examination, there was wasting of thenar and
hypothenar muscles of the right side with normal left sided examination.
The deep ulnar nerve is responsible for motor control of intrinsic hand function through innervation of the dorsal and palmar interossei, the lumbricals of fourth and fifth digits, the
hypothenar muscles (abductor, flexor and opponens digiti minimi), adductor pollicis muscle and the deep head of flexor pollicis brevis.
Atrophy of the first dorsal interosseous and
hypothenar muscles is common.
The deep branch curves around the hook of the hamate and turns radially across the interossei, supplying the
hypothenar muscles, the ulnar two lumbricals, all the interossei, and the adductor pollicis.
Hypothenar muscles include the abductor digiti minimi (abducts the 5th finger), flexor digiti minimi (flexes the little finger) and oppenens digiti minimi (opposes the fifth digit).
