Editing Upper limb (section)

=== '''Radial nerve''' ===

** Origin
*** Direct continuation of the       posterior cord
*** C5-T1
** Course
*** Passes posteriorly below       latissimus dorsi tendon and spirals behind the humerus, between the       origins of the lateral and medial heads of triceps.
*** Subsequently penetrates the       lateral intermuscular septum in mid-arm, through ACF, to reach the       forearm extensor compartment, emerging lateral to distal brachialis.
*** '''Branches       into'''
**** '''Superficial        radial nerve'''
***** Primarily sensory
***** Lies close to the distal         radial artery, then passes under the tendon of brachioradialis and         crosses the anatomic snuffbox. It divides over the first extensor         compartment into lateral and medial branches.
***** Lateral branch of         superficial radial nerve supplies the skin at the radial side of the         thenar eminence and dorsal thumb.
***** Medial branch of         superficial radial nerve supplies the remainder of the dorsum.
**** '''Deep        radial nerve/posterior interosseous nerve.''' Primarily motor.
** Supplies:
*** Extensor compartment of the       arm and forearm
*** Cutaneous to the skin over       them (posterior arm/forearm) and on the lateral half of dorsum of the       hand
** Injuries:
*** Most commonly injured by       fractures of the shaft of humerus, or transient paralysis due to       improper use of crutch of 'Saturday night palsy'
*** Wrist drop - inability to       extend the wrist and MCPJ (but the interphalangeal joints can still be       straightened by the interossei and lumbricals)
*** Sensory loss minimal       overlying the first dorsal interosseous (much overlap from medial and       ulnar) - test over dorsum of first web space)
*** Deformity - wasting of       triceps and posterior compartment of forearm