Table 1.
Motor deficits associated with upper extremity peripheral nerve injuries
| Access site | Possible nerve injury | Muscles involved | Motor impairment |
|---|---|---|---|
| Ulnar artery – wrist | Ulnar nerve | Abductor digiti minimi | Small finger flexion/abduction |
| Flexor digiti minimi | All MCP joint abduction/adduction | ||
| Interosseous muscles | MCP joint flexion with IP joint extension (small and ring fingers) | ||
| Lumbricales 3 and 4 | |||
|
| |||
| Brachial or axillary artery | Median nerve (variable impairment depending on relationship of injury to site motor branches) | Hand: | |
| Opponens pollicis | Thumb abduction/flexion/opposition | ||
| Abductor pollicis brevis | |||
| Flexor pollicis brevis | MCP joint flexion with IP joint extension (index and middle fingers) | ||
| Lumbricales 1 and 2 | |||
| Palmaris brevis | |||
| Forearm: | |||
| Pronator teres | Forearm pronation | ||
| Pronator quadratus* | Wrist flexion/radial deviation | ||
| Flexor carpi radialis | MCP and PIP joint flexion | ||
| Palmaris longus | DIP joint flexion (index and middle fingers) | ||
| Flexor digitorum superficialis | |||
| Flexor digitorum profundus (index and middle fingers)* | |||
| Flexor pollicis longus* | Thumb IP joint flexion | ||
| Ulnar nerve (variable impairment depending on relationship of injury to site motor branches) | Hand: See ulnar nerve involvement from injury at the wrist | Hand: See ulnar nerve involvement from injury at the wrist | |
| Forearm: | |||
| Flexor carpi ulnaris | Wrist flexion/ulnar deviation | ||
| Flexor digitorum profundus (ring and small finger) | DIP joint flexion (ring and small fingers) | ||
| Radial nerve (variable impairment depending on relationship of injury to site motor branches) | Upper arm: | ||
| Triceps | Elbow extension | ||
| Anconeus | |||
| Brachioradialis | Elbow flexion | ||
| Brachialis** | |||
| Extensor carpi radialis longus | Wrist extension | ||
| Extensor carpi radialis brevis | |||
| Extensor carpi ulnaris | |||
| Supinator | Forearm supination | ||
| Abductor pollicis longus | Thumb abduction/extension | ||
| Extensor pollicis longus | |||
| Extensor pollicis brevis | |||
| Extensor indicis | MCP joint extension of all digits | ||
| Extensor digitorum communis | |||
| Extensor digiti minimi | |||
| Musculocutaneous nerve (variable impairment depending on relationship of injury to site motor branches) | Upper arm: | ||
| Coracobrachialis | Shoulder flexion | ||
| Biceps brachii | Shoulder flexion, elbow flexion, supination | ||
| Brachialis** | Elbow flexion | ||
|
| |||
| Subclavian artery | Brachial supplying the lower trunk, medial cord and components of the posterior cord. Ultimately impairing C8-T1 dominant components of the median, ulnar, radial, and medial pectoral nerves | Pectoralis major | |
| Pectoralis minor | |||
| Median and ulnar muscle impairments as described with brachial/axillary involvement except with sparing of the Pronator teres, | Shoulder flexion and adduction | ||
| Flexor carpi radialis, and Palmaris longus | Scapular protraction and depression | ||
| Radial nerve components: Abductor and extensor pollicis longus | Thumb abduction and extension | ||
| Less weakness involving the extensor digitorum communis, extensor indicis, and extensor digiti minimi | Extension of the metacarpophalangeal joints of the lesser 4 digits | ||
MCP, metacarpophalangeal; IP, interphalangeal; PIP, proximal IP; DIP, distal IP.
*
Branches of the anterior interosseous nerve.
**
Brachialis shares innervation from the radial and musculocutaneous nerves.