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Introduction
  • Standard: C5, C6, C7, C8, T1 – 77% of patients                                                                     
  • Prefixed: Prefixed (contributions from C3, C4) – 22%
  • Postfixed (roots caudal to T1) – 1% 
Anatomy 
  • Remember: Robert Turner Drinks Cold Beer
  • Roots (5):  ventral rami of C5-T1, superior and posterior to subclavian
    • dorsal scapular nerve (C5): through levator scapula to supply levator scapula, rhomboid major & minor
    •  long thoracic nerve (C5, 6, 7): posterior to plexus onto thoracic wall to supply serratus anterior
  • Trunks (3): emerge from triangle formed by anterior scalene, middle scalene, first rib
    • superior (C5,6 roots)
      • suprascapular nerve (C5, 6): through suprascapular notch to supraspinatus, infraspinatus, AC and glenohumeral joints
      • nerve to subclavius (C5, 6)
    • middle (C7)
    • inferior (C8, T1)
  • Divisions (6): 3 anterior, 3 posterior (each trunk gives 1 anterior and 1 posterior division)
  • Cords (3):
    • Posterior Cord:  formed from 3 posterior division
      •  upper subscapular nerve (C5, 6):  subscapularis
      •  lower subscapular nerve (C5,6):  subscapularis, teres major           
      •  thoracodorsal nerve (C6, 7, 8):  latissmus dorsi
    •  Lateral Cord:  ant divisions of superior & middle trunks (C5, 6, 7)
      • lateral pectoral nerve (C5, 6, 7):  pectoralis major, communication with medial pectoral nerve
    • Medial Cord:  anterior division of inferior trunk (C8, T1)
      • medial pectoral nerve (C8, T1): pierces pec minor; supplies pec minor and major
      • medial brachial cutaneous nerve (T1)
      • medial antebrachial cutaneous nerve (C8, T1)
      Branches (6) – 2 terminal branches from each cord
      • Posterior cord:
        • axillary nerve (C5, 6):  through quadrilateral space to teres minor, deltoid, major nerve supply to glenohumeral joint, superior lateral brachial cutaneous nerve
        • radial nerve (C5 – T1): runs with long head of triceps (triangular interval) into radial groove on posterior humerus; supplies elbow & forearm extensors,  supinator; posterior brachial cutaneous, inferior lateral brachial cutaneous, posterior antebrachial cutaneous, superficial radial (post. radial hand)
      • Lateral cord:              
        • lateral cord of median nerve (C5 – C7): joins medial cord anterior to axillary artery then travels with artery: wrist flexors (except FCU, ulnar ½ FDP), pronators, radial two lumbricals, OP, APB, superficial head FPB); sensory distribution in hand
        • musculocutaneous (C5, 6, 7):  most superficial branch, pierces coracobrachialis (1.5-9 cm from origin) to supply biceps, coracobrachialis, brachialis, ends as lateral antebrachial cutaneous nerve
      • Medial cord:   
        • medial cord of median nerve (C8, T1):  see above
        • ulnar nerve (C8, T1):  FCU, ½ FDP, adductor pollicus, deep head FPB, hypothenar, intrinics (except radial 2 lumbricals), sensory to hand
 
 
 

 

 

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