auubar
Forum Senior
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Hello,
I am now studying anatomy using high yield and I found that ulnar nerve lesion can cause claw hand.
Could someone please how Ulnar nerve palsy cause claw hand?
I really appreciate your explanation.
Thanks in advance.
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| dxtxpx
Forum Guru
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ULNAR NERVE INJURIES
Anatomical factors: The ulnar nerve arises in the axilla from the medical cord of the brachial plexus (C7,C8,T1). It runs along the medial epicondyle of humerus at the elbow to enter the forearm. It enters the palm by passing in front of the flexor retinaculum through a fibrous canal (Guyon's Canal). It supplies the muscles of the forearm and the intrinisic muscles of the hand.
Etiology :Injuries to the ulnar nerve commonly occur a) at the level of the elbow region and b) at the level of the wrist.
Traction injuries result from violent valgus injuries to the elbow as in avulsion fracture of the medial epicondyle and lateral dislocation of the elbow. It can also be directly damaged in supra condylar fracture of humerus. Tardy or late ulnar neuritis with palsy is caused by increasing valgus deformity due to non union of the fracture of the lateral condyle humerus. Recurrent dislocation of the ulnar nerve also causes ulnar neuritis and paralysis.
At the level of the wirst, cuts and lacerations are the common causes of injury.
Clinical features: Injury at the elbow: The patient presents with typical ulnar claw hand deformity of the ring and little fingers, wasting of the hypothenar muscles and depresion in the interosseous spaces in the dorsal aspect of the hand.
There is paralysis of Flexor carpi ulnaris and medical half of flexor digitorum profundus in the forearm and intrinsic muscles in the hand.
The ulnar claw hand deformity is charcterised by extension deformity at the metacarpo phalangel joints and flexion deformity at the interohalangeal joints of the little and ring fingers. The deformity is due to the paralysis of the lumbricals which flex the M.P. joing and extends the I.P. joints allowing the unopposed action of the long extensors at the M.P. joint and the long flexors at the I.P.Joint.
The interosseous function of abduction and adduction of the fingers are tested. Adduction is tested by asking the patient to hold a card or paper tightly between two fingers. The patient will be unable to grip the card. Abduction of the index fingers is tested by asking him to abduct the index finger against resistance. The contractions of the first dorsal interossei is palpated and is found missing.
The abduction of the little finger against resistance tests the integrity of the abductor digiti minimi.
Test for adductor pollicis (Froments test) with both palms held together, keep a card or book between the thumbs and index finger. Ask the patinet to grip the card tightly. The thumb on the affected side goes into flexion at the interphalangeal joint due to the action of flexor pollicis longus which compensates the action of the paralysed adductor. The power of flexion with adduction (ulnar deviation) at the wrist is tested against resistance. This power is weak or absent.
Sensory loss is confined to the little finger and medial half of the ring finger and the ulnar border of the hand.
The functional disability of ulnar paralysis is not very disabling except in people who need the fine movements of the fingers as Veena and Violin players. It is not a mahor diability in manual workers.
Treatment The treatment of cut injuries to the ulnar nerve follows the general principles of treatment of cut nerves. The cut nerve is explored and managed by neurolysis or nerve repair as required.
The anterior transposition of the ulnar nerve is a very useful operation to remove local irritation to the nerve following elbow injuries and to prevent tension on the nerve suture line in all cases of repair of the injurd nerve. The management of irrepairable damage to ulnar nerve is by tendon transfer operation. In the Bunnell's operation the Flexor digitorum sublimis to the ring finger is disinserted, split into two, rerouted and attached to the extensor expansion of the ringer and little finger.
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| auubar
Forum Senior
Topics: 30
Posts: 182
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Hello dxtxpx,
Thanks you very much in deed for your explanation. I appreciate your help.
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| dxtxpx
Forum Guru
Topics: 259
Posts: 1,233
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just got it from a site, i didnt know it either
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