Median Nerve Distribution

The median nerve provides sensory and motor innervation to the anterior compartment of the forearm and hand.

  • Motor branches
    • Pronator teres
    • Flexor carpi radialis
    • Flexor carpi sublimis
  • Anterior interosseus (motor)
    • Flexor pollicis longus
    • Flexor digitorum profundus to 2nd & 3rd fingers
    • Pronator quadratus
  • Palmar cutaneous
    • Sensory distribution: Skin over thenar eminence
  • Terminal motor
    • Abductor pollicis brevis
    • Opponens pollicis
    • Lumbricals: 1st & 2nd
    • ± Flexor pollicis brevis: Also innervated by ulnar nerve
  • Terminal sensory
    • Sensory to palmar surface of thumb, 2nd, 3rd & lateral 1/2 of 4th finger

Physical exam for different muscles supplied by median nerve

  • Flexor digitorum superficialis: patient flexes fingers at PIP joint against resistance
  • Flexor digitorum profundus: patient flexes fingers at DIP joint against resistance
  • Flexor pollicis longus (anterior interosseous nerve): flexes distal phalanx of thumb against resistance
  • Abductor pollicis brevis: patient abducts thumb at right angles to palm against resistance
  • Opponens pollicis: patient touches base of little finger with the thumb, examiner tries to pull  apart
  • 1st lumbrical interosseous: patient extends finger at the PIP joint against resistance with the MCP joint hyperextended and fixed

Neural control of micturition

Nerve control of the bladder

  1. Sympathetic: hypogastric nerve (T10-L2), involuntary control of bladder neck and intrinsic sphincter
  2. Parasympathetic: pelvic nerve (S2-S4), involuntary contraction of detrusor
  3. Somatic: pudendal nerve (S2-S4), voluntary contraction/relaxation of external sphincter