Inability to adduct the thumb is due to the injury of: March 2009
Correct Answer: Ulnar nerve
Description: Ans. B: Ulnar Nerve Ulnar Nerve I. Lesion at the elbow The term cubital tunnel syndrome is often used for ulnar nerve compression at the elbow. Total paralysis of the nerve, including those branches of the nerve serving the flexor digitorum profundus and flexor carpi ulnaris muscles, causes wasting along medial side of forearm. Paralysis of the nerve also leads to weakness of flexion of fouh and fifth fingers; if proximal poions of these fingers are held steady, patient is unable to flex terminal phalanges. With paralysis of hypothenar muscles, abduction of fifth finger is impossible. Paralysis of interossei and medial two lumbricals causes 'claw hand' deformity, mainly seen in the ulnar fingers. There may be wasting of hypothenar muscles, interossei and medial pa of thenar eminence. Also there is weakness in movement of fingers and abduction to the extended thumb against the palm. There is sensory loss of the dorsal and palmar aspects of the medial side of the hand together with the medial one and a half fingers. With compression of the ulnar nerve, the ulnar nerve is often palpably enlarged in the ulnar groove and for a sho distance proximal to the elbow. II. Lesion at the wrist Cutaneous sensation of hand and fingers is often spared. If lesion is just proximal to the wrist, it causes impaired sensation on the palmar aspects of hand and the fouh and fifth fingers and muscle weakness, especially in the hypothenar eminence. Adductor pollicis will be injured in ulnar nerve injuries so patient will hold the book by using the flexor pollicis longus (supplied by median nerve).This is the basis of book test/froment sign. Positive Tinel's sign on percussion over ulnar nerve at wrist (light percussion over the nerve causes a sensation of "pins and needles" in the distribution of the nerve, i.e. ulnar side of hand and fouh and fifth fingers). Positive Phalen's test with paraesthesias in fouh and fifth fingers (patient holds their wrist in maximum flexion for 30-60 seconds
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Surgery
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