N. medianus, anatomy
- Follows the front of the upper arm down to the elbow and divides into three branches in the forearm
- N. interosseous anterior is a motor branch that runs along the anterior interosseous membrane
- Deep motor branch that enters the hand in the carpal tunnel
- Superficial cutaneous branch that enters the hand over the carpal ligament
Median nerve, motor function
- Forearm pronation (M. pronator teres, M. pronator quadratus)
- Wrist flexion (M. flexor carpi radialis, M. flexor pollicis longus)
- Finger flexion (M. flexor digitorum superficialis 2nd to 5th finger, M. flexor digitorum profundus 2nd and 3rd finger)
- MCP flexion and PIP/DIP extension 2nd and 3rd finger
- Thumb flexion (M. flexor pollicis longus), abduction (M. abductor pollicis brevis), and opposition (M. opponens pollicis)
Median nerve, sensory function
- Large parts of the palm are innervated by r. palmaris of the median nerve, which branches off before the carpal tunnel
- Nn. digitalis palmares communes and proprii branch off after the carpal tunnel and innervate the thumb, 2nd-3rd fingers, and half of the 4th finger
Injury to the median nerve in the upper arm, causes
- Soft tissue injury to the upper arm
- Puncture wound
- Contusion
- Humerus fracture
Injury to the median nerve in the upper arm, clinical findings
- Pronation of the forearm abolished
- Wrist flexion weak and only in the ulnar direction
- Abolished strength in thumb opposition, flexion, and abduction
- Weakness in flexion of the index finger and middle finger
- When attempting to make a fist, no flexion in the thumb, only partial flexion in the 2nd finger and weak flexion in the 3rd finger. Normal flexion in the 4th and 5th fingers
- Sensory loss in the median nerve area
Injury to the median nerve in the upper arm, Benedictine sign
Benedictine sign, Pope's hand, and oath hand occur when attempting to make a fist
- The patient is unable to make a fist with all fingers
- Unable to flex in the MCP joint of the index and middle finger
Key diagnostics, N. medianus
