Brachial plexus

Divisions

- no nerves originate from divisions of brachial plexus - anterior division of upper & middle trunk form lateral cord - anterior of lower trunk becomes medial cord - 3 posterior divisions form posterior cord

Deep branch of radial nerve

- pierces supinator to enter posterior forearm as posterior interosseus nerve - innervates extensors of forearm & wrist

Ulnar nerve (little C7, mostly C8-T1)

- runds down medial respct of arm w/ superior ulnar collateral artery - passes posteroir to elbow in groove - enters forearm passing btwn 2 heads of FCU (ulnar tunnel) - innervates ulnar half of FDP & FCU - divides into deep & superficial branches

Posteror cord

- upper subscapular nerve (c5-c6): innervates upper portion of subscapularis - thoracodorsal (c7-c8): behind axillary artery, innervates latissimus dorsi & accompanied by TD artery - lower subscapular nerve (c5-c6): runs w/ subscapular vessels, innervates lower part of subscapularis & teres major - Axillary nerve (c5-c6): passes through quadrangular space w/ p. circumflex humeral artery, innervates deltoid & teres minor, & skin of shoulder as upper lateral cutaneous nerve of arm - radial nerve (some c5, c6, c7 & little c8): innervates posterior arm & forearm

Brachial plexus possible lesions

- C5 or C6 spinal cord or nerve roots will be seen as problems w/ scapula & shoulder - C8 or T1: will be expressed as weakness or problems in hand - C6, C7 & C8: have contributions that supply arm and fore am - intermediate segments supply middle of limb

Branches from roots

- Dorsal scapular nerve C5: innervates levator scapulae, rhomboid major & minor; pierces middle scalene & descends deep to levator scapulae - Long thoracic nerve C5-C7: descends behind brachial plexus & runs along serratus anterior (innervates it)

Medial Cord

- Medial pectoral (C8-T1): passes btwn axillary artery & nerve and innervates pect minor & major - Medial brachial cutaneous nerve (C8-T1): along medial side of axillary vein; innervtes skin on medial side of arm - Medial Antebrachial cutaneous nerve (c8-t1): btwn axillary artery & vein & medial to brachial artery, innervates skin on medial side of forearm down wrist - Ulnar Nerve (c8-t1): continuation of medial cord & along medial side of forearm - medial head of median nerve: mostly C8 w/ few fibers of t1 that contribute to median nerve

Nerves from Upper Trunk

- Suprascapular (C5-C6): runs laterally across posterior cervical triangle to pass through scapular notch under the suprascapular (transverse scapular) ligament & innervates SUPRASPINATUS & INFRASPINATUS & shoulder joint - Nerve to subclavius (C5-C6): descends in front of brachial plexus & subclavian artery to innervate SUBCLAVIUS MUSCLE behind clavicle

brachial plexus

- composed of nerve fibers of ventral primary rami (from spinal nerves C5-T1) - nerve fibers exit through posterior cervical triangle - nerve fibers include somatic efferent, somatic afferent, visceral efferent & visceral afferent: provide motor and sensory innervation to muscles, skin & blood vessels of upper extremities - divided into roots, trunks, divisions, chords & terminal branches (proximal to distal)

Superficial branch of radial nerve

- descends under brachioradialis - innervates skin of radial aide of hand & 1/2 digits over proximal to middle phalanx

Musculocutaneous C5-C7

- innervates corachiobrachialis - other muscles of anterior compartment of arm, biceps brachii & brachial is - runs deep into tendon of biceps brachia & laterally to run into forearm as lateral antebrachial cutaneous nerve

Deep of Ulnar

- innervates hypothenar, medial 2 lumbricals, all interossei, adductor pollicis & deep head of FCB

Superficial of Ulnar

- innervates palmaris brevis & skin over palmar & dorsal surfaces of medial 1/3rd of hand - terminates by dividing into 3 palmer digital branches that supply little finger & medial side of ring finger

Radial nerve (c5-t1)

- largest branch of brachial plexus - through triceps, passes spiral groove (radial sulcus) of humerus w/ deep brachii artery - innervates posterior arm - enters cubital fossa anterior to lateral epicondyle (btwn brachialis & brachioradialis) & divides into deep & superficial branch

Lateral cord

- lateral pectoral nerve (C5-C7): pierces clavipectoral fascia & innervates pect major - Musclocutaneous (C5-C6): passes through coracobrachialis to innervate antrior arm => becomes lateral cutaneous in forearm - Lateral head of median nerve: brings C6 & C7 to median nerve

Median nerve (C5-T1)

- lateral root from lateral cord & medial root from medial cord - runs down arm (no innervation) - passes through cubital fossa deep to biceps aponeurosis, medial biceps tendon & brachial artery - supplies all flexors of forearm & wrist (except FCU, Ulnar half of FDP & brachioradialis) - median tunnel: passes through biceps tendon, 2 heads of origin of pronator trees, & humoral and radial heads of FDS - carpal tunnel: jumps btwn FDS & FCR, btwn Flexor reticunaculum & FDS - supplies 3 thenar muscles, lateral 2 lumbrical, supplies skin of palm, lateral 3 & 1/2 digits & dorsal aspect of those fingers

Trunks

Upper: formed from combination of C5 & C6 a. only trunk that gives off nerves Middle: direct continuation of C7 Lower: formed by junction of C8 & T1