Ulnar nerve

Genetic testing

Neurosurg. exploration

Ulnar Nerve Dorsal Branch MriFlexor Carpi Ulnaris
Fig. 16. Medial epicondyle and cubital tunnel. 1 Right ulnar nerve. 2 Medial epicondyle. 3 Aponeurosis. 4 Flexor carpi ul-naris
Pisohamate Tunnel

Fig. 18. Ulnar nerve lesion. A Complete transsection at lower arm level by a glass pane. Note the typically flexed finger 4 and 5. B Distal ulnar nerve lesion with a 50 year duration. C Distal ulnar lesion, after the exit of the branch to the hypoth-enar. Note the atrophy of the interosseus I. D Long lasting ulnar nerve palsy. Atrophy of in-terosseus I and other interossei

Atrophie Der Interossei Palm

Fig. 19. Traumatic ulnar nerve lesion at the elbow, during intensive care treatment and mal-positioning. A Atrophy of the small hand muscles with protruding flexor tendons and preserved thenar, and atrophied opponens muscles. B Dorsal view with interosseus atrophy. C Unusual atrophy of the oppon-ens muscles, leaving a groove over hypothenar

Anatomy The nerve fibers arise from C8 and T1, and pass through the lower trunk and medial cord of the brachial plexus. The nerve continues along the humerus and the ulnar condylar groove (the humeroulnar arcade).

Motor branches innervate the flexor carpi ulnaris, flexor digitorum profundus, most of the hand muscles (abductor digiti minimi, flexor digiti minimi, interossei I—IV, lumbricals III, IV, adductor pollicis, flexor pollicis brevis).

Sensory branches (superficial terminal, palmar cutaneous, dorsal cutaneous nerves) innervate the hand (see Fig. 15 through 17).

Symptoms

Signs

Causes

Axilla and upper arm Elbow

Forearm Wrist and hand

Diagnosis

Numbness and tingling (exacerbated by arm use). Pain is restricted to the hypothenar region of palm. Also, loss of dexterity and loss of control of the small finger.

Sensory distribution of the ulnar nerve: ulnar aspect of the palm, volar surface of the fifth digit, and ulnar half of the fourth digit.

Sensory distribution of the dorsal sensory branch: ulnar aspect of dorsum of hand, and fourth and fifth digit.

Motor disability: weakness of pinch between thumb and adjacent digits (Froment's sign- weakness of first dorsal interosseus muscle). Weakness of the flexor pollicis brevis muscle and adductor pollicis muscle. Weak digital flexion during grasp (digits 4 and 5) (see Figs. 18 and 19).

Full blown ulnar lesion results in claw deformity (see Fig. 18). Tinel's sign may be elicited by palpation of the ulnar nerve at the elbow.

Entrapment at the arcade of Struthers External pressure: crutch palsy

Deformities of joint

Elbow deformity with chronic stretch

External pressure

Fibrous band

Fractures

Mass: gangloid, sesamoid bone Recurrent subluxation Repetitive flexion Supracondylar spurs Trauma

Hypertrophic flexor carpi ulnaris

Forced use: Bicycle (Loge de Guyon)

Injuries

Lacerations

Pressure: Ganglion, pisohamate ligament

Nerve conduction studies:

Motor

Sensory

Dorsal sensory ramus EMG

MRI, Ultrasound

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