BRACHIAL PLEXUS PERIPHERAL NERVES (COURSE AND INNERVATION) N. Medianus: From the medial and lateral cords of the brachial plexus (C 5,6,7,8, T 1) No branches in the upper arm Runs with the brachial artery up to the cubital fossa Branches supplying the elbow joint -enters forearm between the two heads of pronator teres a)Anterior interosseus nerve branch - runs in the forearm between FDP and FDS b)Palmar cutaneous branch c)Recurrent branch - enters the palm of the hand deep in relation to the flexor retinaculum running through the carpal tunnel d)Palmar digital nerve a) Supplies all the deep muscles in the flexor compartment of the forearm, EXCEPT the ulnar ½ of the FDP and the wrist joints. b) Skin on the radial side of the palm (thenar area). c) Thenar muscles and the 1st and 2nd lumbrical muscles. d) Skin lateral 3½ fingers palmar and dorsal distal phalanxes only. N. Radialis: Continuation of the posterior cord of the brachial plexus (C 5,6,7,8, T 1). In the upper arm branches to the 3 heads of triceps; anconeus; brachiradialis and ECRL. Cutaneous branches: Posterior cutaneous nerve (posterior aspect of the upper arm) Distal lateral cutaneous nerve (lateral and anterior aspect of the upper arm) Posterior cutaneous nerve (forearm posterior up to the wrist) Continued in the forearm: -cubital fossa a) Superficial branch b) Deep branch (posterior interosseous nerve) -runs distally, covered by brachioradialis, together with the radial artery -runs between the 2 heads of supinator; around the lateral side of the radius to reach the posterior aspect of the forearm -at the wrist: turns posterior over the tendons of the anatomical snuff box -runs further distally on the interosseus membrane up to the wrist c) Dorsal digital nerves a) Contains sensory fibres only. b) Innervates the wrist joint. Innervates all the extensor compartment muscles, except anconeus and ECRL. c) Skin of the radial 3½ fingers on the dorsum of the hand (distal phalanxes excluded). N. Ulnaris: Continuation of the medial cord of the brachial plexus (C 8; T 1). No branches in the upper arm. Enters the forearm between the 2 heads of FCU. Runs with the ulnar artery up to the pisiform bone, covered by FCU. Supply branches a)Several branches in the forearm b)Palmar cutaneous branch d)Superficial branch e)Deep branch c)Dorsal cutaneous branch -enters the palm of the hand superficially to the flexor retinaculum on the lateral side of the pisiform bone -runs with the deep palmar arterial arch d) Branches to the elbow and wrist joints. Muscle branches to FCU and the medial ½ of FDP. e) Skin on the ulnar side of the palm. f) Skin of 1½ fingers (little finger and ½ ring) dorsal side. g) Palmaris brevis and ends as 2 palmar digital nerves that supplies the skin of the medial 1½ fingers on the palmar side. h) Hipothenars; interosseï; medial 2 lumbricals and adductor pollicis. (Thus intrinsic hand muscles except 1½ group supplied by median nerve.) SEGMENTAL SUPPLY OF THE HAND AND THE FOREARM (MIOTOMES) Radial nerve Deep interosseus nerve: Supinator C 6;7;8 ECU C7;8 Ext digitorum C7;8 Ext dig min C7 EPL & EPB Ext indic APL ECRB C7 C7 C7 C6;7 Median nerve Anterior interosseus nerve: FPL C8;T1 Triceps C7;8 Brachioradialis FDP C6;8 Anconeus C7;8 ECRL C6;7 C8;T1 Pron quadratus C8;T1 Thenare muscles: T1 FPB; APB; OP; 1e & 2e lumbricals Ulnar nerve FCU Pronator FDP C8;T1 teres C6 Palmaris Hipothenar longus C8 T1 Flex dig min; abd dig min; opp dig min FCR C6;7 Palmaris brevis T1 FDS C6;7;8 Interosseï T1 palmar and dorsal; 3rd & 4th lumbricals; add poll. SEGMENTAL SUPPLY OF THE HAND AND THE FOREARM (ACCORDING TO FUNCTION) Function Fine movements of the fingers Flexion of the fingers Flexion of the wrist Flexion of the elbow Extension of the fingers and wrist C7;8 Supply T1 C8; T1 C7; C8 C5; C6 C7 SEGMENTAL SUPPLY OF THE HAND AND THE FOREARM (DERMATOMES) Anterior aspect of the arm C 5 From the “trapezius-area” lateral part of the upper arm and forearm up to the thenar muscles. C 6 From the middle of the upper arm lateral aspect of the upper arm and forearm (to ± middle of the arm) thumb, index finger and lateral part of the palmar aspect of the hand. C 7 From the middle of the upper arm downwards in the middle of the upper arm and forearm: middle palmar aspect of the palm of the hand index finger: middle finger: and ½ ring finger. C 8 Medial part of the fore arm just above the wrist joint medial part of the palmar aspect of the palm of the hand little finger; ring finger and middle finger. T 1 Medial aspect of the forearm (up to ± middle of the forearm); from the proximal part of the hypothenars up to just proximal of the elbow joint. Posterior aspect of the arm C 5 Same as for the anterior aspect, but the lateral dermatome does not really run “deep”posterior. C 6 From the axilla latreral aspect of the upper arm and forearm (to ± middle posterior aspect) dorsal lateral part of the hand thumb and index finger. C 7 Middle aspect of the upper arm and forearm (a somewhat wider aspect than seen anteriorly) dorsal middle and lateral part of the hand index finger and middle finger. C 8 From the elbow – middle and medial forearm medial aspect dorsal of the hand middle finger; ring finger and little finger. T 1 Medial aspect of the forearm (just proximal to the wrist) and upper arm (up to ± middle of the upper arm). Thus axillary area excluded.