Brachial Plexus & Neurological Patterns of the Upper Limb

-Major nerve network of the upper limb which forms in the neck -Passes through & is vulnerable to compression: b/w anterior & middle scalene muscles -through cervicoaxillary canal (a space bound by the clavicle, rib 1 & scapula) -Within the axilla -Formed by the union of lower four cervical ventral rami (C5,6,7,8) plus first thoracic ventral rami (T1), therefore (C5-T1)

Artificially divided Roots -Ventral rami of C5-T1 spinal nerves Trunks (named according to location) • Superior trunk (C5 & C6) • Middle trunk (C7) • Inferior trunk (C8 & T1) Divisions (each trunk divides into an anterior and posterior division) • Anterior divisions • Posterior divisions Cords (named according to their relation to the axillary artery) • Lateral cord • Medial cord • Posterior cord Branches • Musculocutaneous nerve – lateral cord • Median nerve – formed by the union of the medial root of median nerve from the medial cord and the lateral root of the median nerve from the lateral cord • Ulnar nerve – medial cord • Axillary nerve – posterior cord • Radial nerve – posterior cord

• From the lateral cord of the brachial plexus (C5-C7) • Enters anterior compartment of arm • Pierces coracobrachialis (supplies it) • Passes distally between biceps and brachialis (possible impingement point) • Terminal branch runs down the lateral aspect of the forearm as the lateral cutaneous nerve of the forearm (supplying skin) Supplies: • Muscles of anterior compartment of arm • Cutaneous (skin) supply- see reference diagram

joins with the medial root of the median nerve to form the median nerve supplies most of the flexor muscles of forearm

• Passes through the medial aspect of anterior compartment of arm with the brachial artery • Passes posterior to the medial epicondyle • Enters anterior forearm, between the two heads of flexor carpi ulnaris (possible impingement point) • Passes superficial to the flexor retinaculum • Passes through the ulnar canal, into the hand (possible impingement point) Supplies: -FCU and medial ½ of FDP -Many muscles in the hand Abductor DM, Flexor DMB, Opponens DM Interossei, (palmar & dorsal)

Joins the lateral root of the median nerve to form the median nerve

• Enters posterior aspect of arm via quadrangular space (possible impingement point) • Winds around surgical neck of humerus where it terminates (possible damage site eg fracture, dislocation) Supplies: Deltoid, teres minor Cutaneous – see reference diagram

• Enters the posterior compartment of the arm via lateral triangular space (possible impingement point) • Runs in the radial/spiral groove (between medial & lateral heads of triceps) with the deep artery of the arm (possible impingement point) • Passes through lateral aspect of cubital fossa At the level of the lateral epicondyle it divides into: • deep branch of radial nerve (muscles & joints) • superficial branch of radial nerve (cutaneous branch) • Superficial branch descends through forearm under the brachioradialis muscle • Runs superficial to anatomical snuffbox -Deep branch enters the posterior forearm between the two heads of the -supinator muscle (possible impingement point).

-Dorsal scapular nerve (C5, a little C4) supplies the rhomboids and levator scapulae -Long thoracic nerve (C5,6,7) supplies serratus anterior -Nerve to subclavius (C5, C6) supplies subclavius and SC joint -Suprascapular nerve (C5-6) supplies supraspinatus, infraspinatus and GH joint

-Lateral pectoral nerve (C5,6,7) supplies pectoralis major (labelled as lateral thoracic N on the diagram) -Musculocutaneous nerve (C5,6,7) supplies the flexor muscles of arm -Lateral root of the median nerve (C6,7) joins with the medial root of the median nerve to form the median nerve supplies most of the flexor muscles of forearm

-Medial pectoral nerve C8-T1 supplies pectoralis minor and major -Medial cutaneous nerve of the arm (C8-T1) skin of medial arm -Medial cutaneous nerve of the forearm (C8-T1) - skin of medial forearm -Ulnar nerve (C8-T1) Supplies muscles of the anterior (some) forearm and hand (most) -Medial root of the median nerve (C8-T1) joins the lateral root of the median nerve to form the median nerve

-Upper subscapular nerve (C5) supplies subscapularis -Thoracodorsal nerve (C6,7,8) supplies latissimus dorsi -Lower subscapular nerve (C6) supplies teres major & subscapularis -Axillary nerve (C5,6) supplies teres minor, deltoid and GH joint -Radial nerve (C5,6,7,8,T1) supplies extensor muscles of arm and forearm

-Dermatomes – spinal nerve innervation of skin -Cutaneous/Peripheral nerve supply of skin - via the branches of the brachial plexus -Myotomes – motor supply according to spinal levels

• An area of skin supplied by a single spinal nerve - useful to determine if a spinal nerve has been damaged

• an area of skin supplied by a single peripheral nerve - For example an area of skin supplied by a terminal branch of the brachial plexus eg axillary nerve

• a group of muscles innervated by a single spinal nerve - If you were to damage a spinal nerve eg C6 the muscles supplied by that level could become weak or paralysed

C4- Shoulder shrug C5- Glenohumeral abduction C6- Elbow flexion C7- Elbow extension C8- Finger flexion T1- Finger adduction/grip

• Travels on medial aspect of anterior compartment of the arm with the brachial artery • In the cubital fossa it lies medial to the brachial artery • Passes between the two heads of pronator teres (possible impingement point) • Runs within anterior compartment of forearm • Gives palmar cutaneous branch prior to entering hand • Pass through the carpal tunnel to enter the hand (possible impingement point) • supplies all anterior forearm muscles EXCEPT, FCU and medial ½ of FDP • Some muscles of hand: Abductor Pollicis Brevis, Opponens Pollicis, Flexor Pollicis Brevis (Superficial Head), Lumbricals 1&2