REIDER PART 1
02

92 Chaptkr 3_Elbow and Forearm

Figurę 3-44. Elbow flexion test for cubital tunnei syndrome.

elbow flexion and digital pressure over the cubital tunnei is known as the ulnar nerve compression test (Fig. 3-45).

In morę advanced cases of ulnar nerve compression, weakness and eventually atrophy of muscles innervated by the ulnar nerve are noted. The pattern of muscle weakness can be used to differentiate between ulnar nerve compression at the elbow and the less common ulnar nerve compression at the wrist. Compression at either location can produce weakness of the intrinsic muscles of the hand innervated by the ulnar nerve. This would result in weakness of finger abduction and adduction. In addi-tion to this intrinsic weakness, however, compression of the ulnar nerve at the elbow may produce weakness of the flexor digitorum profundus to the smali finger and the ring finger and of the flexor carpi ulnaris, which are innervated below the elbow but above the wrist. The doc-umentation of weakness in the flexor digitorum profundus to the little finger and the ring finger and weakness of wrist flexion in ulnar deviation thus confirms that the site of compression must be proximal to the wrist. A high ulnar nerve palsy, like a Iow ulnar nervc palsy, can cause an ulnar claw hand. The clawing is usually less marked in a high palsy than in a Iow palsy because the flexor digitorum profundus to the ring and little fingers is paralyzed as well. In the normal hand, the intact lumbricals coun-terbalance the long extensors to the index and long fingers, preventing hyperextension of the MP joints and allowing the PIP joints to extend fully. In the ulnar claw hand, the weakened lumbricals allow MP hyperextension which inhibits fuli extension of the PIP joints. (Fig. 3-46).When an ulnar claw hand is present, Bouvier*s test can be per-formed. In Bouvier s test, the examiner passiyely prevents the MP hypcrextension, allowing the PIP joints to fully extend. (Fig. 3-47)

Less Common Nerve Compression Syndromes. Less common nerve compression syndromes in the elbow and the forearm may involve the radial or median ncrvcs. The radial nerve and its major branches, the posterior interosseous nerve and the superficial sensory branch, can be compressed anywhere from the level of the lateral head of the triceps to the region of the elbow, the proxi-mal forearm, and even into the distal forearm. Possible causes inelude adhesions, muscular anomalies, vascular aberrations, fibrotic bands, inflammatory conditions,

Figurę 3-46. Ulnar claw hand.

Figurę 3-45. Ulnar nerve compression test.

Figurę 3-47. Bouvier’s test.