Editing Upper limb (section)

== '''Nerves''' ==

=== '''Musculocutaneous''' ===

** Origin
*** C5/C6/C7 - anterior       divisions of superior and middle trunks form the lateral cord, then       musculocutaneous nerve
** Course
*** Pierces coracobrachialis       and passes down anterior compartment of arm beneath biceps muscle
*** Then becomes lateral       cutaneous nerve of forearm
** Supplies
*** Sensory - lateral forearm
*** Motor - anterior       compartment of arm - BBC (biceps brachii, brachialis, coracobrachialis)
** Injuries
*** Rare - protected by bulk of       biceps muscle. Sometimes stab wounds to upper arm.
*** Sensory loss to lateral       forearm
*** Weak elbow flexion, forearm       supination, absent biceps reflex
** Deformity
*** Wasting of biceps

=== '''Axillary''' ===

** Origin
*** C5/C6 - posterior division       of superior trunk, then posterior cord
** Course
*** Passes beneath shoulder       joint, through quadrangular space, into posterior compartment of arm
*** Wraps around SNOH
** Supplies
*** Sensory - sergeant's patch       over lower deltoid
*** Motor - deltoid, teres       minor
** Injuries
*** Fracture SNOH, stab wounds       to posterior shoulder, compression by shoulder dislocation or crutches       in armpits
*** Sensory loss - sergeant's       patch
*** Motor deficit - very weak       shoulder abduction from 15-90 degrees; weak shoulder flexion and       extension; weak shoulder external rotation
*** Deformity - wasting of       deltoid

=== '''Median nerve''' ===

** Origin
*** Medial root and lateral       root combine to form main nerve
*** C5-T1
** Course
*** Runs down arm with brachial       artery
*** Through ACF into forearm,       between pronator teres and biceps tendon
*** Central route down forearm.       Travels between the layers of FDS and FDP. At the wrist, found ulnar to       the tendon of FCR, between the tendons of FPL and FDP.
*** Main branch passes through       carpal tunnel and gives off digital nerves. Supplies cutaneous       innervation to distal phalanges of index and middle fingers.
*** Branches
**** Palmar cutaneous nerve        arises in the mid-forearm. This penetrates the deep fascia at the wrist        and supplies the skin over the thenar eminence.
**** Anterior interosseous
**** Deep palmar cutaneous
**** '''Recurrent        muscular branch'''        ('million dollar nerve') - to thenar muscles
***** This nerve is the reason         for not straying radially during CTR
***** 50% take-off distal to         flexor retinaculum
***** 30% branch within (then         still recurrent to thenar muscles)
***** 20% pass through the         retinaculum (non-recurrent)
**** Digital cutaneous branch
** Supplies:
*** Most of the flexor muscles       of the forearm - all of anterior compartment except FCU and medial parts       of FDP
**** Wrist and finger flexors
**** Pronator teres and        quadratus
*** LOAF muscles in hand
**** Lateral two lumbricals
**** Opponens pollicis
**** Abductor pollicis brevis
**** Flexor pollicis brevis
*** Cutaneous to the flexor       surfaces of 3.5 radial digits and palm
** Injuries
*** Most commonly injured at       the wrist - lacerations, compression in carpal tunnel
*** Sensory loss radial 3.5       fingers of palm
*** Weakness and eventually       wasting of thenar eminence
*** High lesion
**** Wasting of front of        forearm because the long flexors (except FCU and half of FDP) and the        pronators are paralysed
**** Hand of benediction - on        attempted finger flexion, held with the index/middle finger straight,        with all other fingers flexed
****
**** Test FPL and finger        flexors by pinching together pads of thumb and index finger
*** Lesion at the wrist
**** Test abductor pollicis        brevis (not flexor because of uncertain nerve supply)

=== '''Ulnar nerve''' ===

** Origin
*** Direct continuation of the       medial cord (C8, T1) but 95% pick up C7 fibres from the lateral cord
** Course
*** Runs down arm with brachial       artery
*** Penetrates medial       intermuscular septum in mid-arm and passes posteriorly, reaching the       groove behind the medial epicondyle of the humerus.
*** In the forearm, lies close       to distal ulnar artery.
*** Enters palm of hand via       Guyon's canal
*** Main branch gives off       digital nerves, and also supplies superficial palmaris brevis.
*** Branches
**** Dorsal branch - arises in        the distal forearm 5cm from the wrist flexion crease and passes between        FCU and the distal ulna to reach the ulnar side of the dorsum of the        hand
** Supplies
*** Flexor muscles of the ulnar       side of the forearm - FCP and medial two parts of FDP
*** Most of the intrinsic       muscles of the hand - HILA
**** Hypothenar eminence
**** Interossei
**** Lumbricals (medial two)
**** Adductor pollicis
*** Cutaneous to the skin of       the ulnar 1.5 digits, and hypothenar eminence
** Injuries:
*** Most commonly injured       behind the elbow or at the wrist
*** Low lesion (at the wrist       e.g. lacerations)
**** Claw hand on attempted        finger extension - hyperextension of the MCPJ of the ring and little        fingers, and flexion of IPJ (unopposed action of the extensors and FDP)
****
**** Sensory loss 1.5 fingers
*** High lesion (elbow or above       e.g. fracture, dislocation, damage behind medial epicondyle)
**** Paradoxical straighter        fingers because loss of the ulnar half of FDP - can't flex the distal        IPJs of the ring and little fingers
**** Sensory loss 1.5 fingers
*** Deformity - wasting of       hypothenar eminence and intrinsic muscles of hand

=== '''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

=== '''Smaller     forearm nerves''' ===

** Medial antebrachial      cutaneous nerve - travels alongside basilic vein to supply skin on medial      forearm
** Lateral antebrachial      cutaneous nerve - continuation of musculocutaneous nerve - emerges      lateral to biceps tendon, supplies lateral arm skin
** Posterior antebrachial      cutaneous nerve - arises from radial nerve in the spiral groove
*

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