Composition
C5 - T1
- prefixed: C4 (more common)
- post fixed: T2
Roots (3 Branches / LSD)(Interscalene)
Trunks (1 Branch)(Posterior Triangle)
Division (Clavicle)
Cords (5,5,3)(Axillary Artery)
Nerve roots
Formed by ventral and dorsal nerve rootlets
- in foramen
- DRG has cell bodies of sensory nerves
- rupture proximal to DRG indicates preganglionic
Run between scalenius anterior and medius
Branches
- long thoracic nerve (C5/6/7)(serratus anterior)
- nerve to subclavius (C5/6)
- dorsal scapula nerve (C5)(rhomboids)
T1 sympathetic ganglion close to T1 nerve root
- frequently injured together
Trunks
A. Upper
- C 5/6
- merger is Erb's point
- where SSN exits
- injury: SSN, axillary, MCN (lose SS, IS, deltoid, biceps)
B. Middle
- C7
C. Lower
- C8/T1
Branches
- suprascapular nerve (C5,6) from upper trunk
Divisions
Trunks divide into anterior and posterior
- behind clavicle
Cords
A. Posterior cord (5)
- all three posterior divisions
- C5 - T1
- posterior to axillary artery
Branches
- radial is terminal branch
- axillary
- upper and lower subscapular
- thoracodorsal
B. Lateral cord (3)
- anterior divisions of upper and middle trunk
- C5/6/7
- lateral to axillary artery
Branches
- MCN lateral to artery
- lateral branch of median nerve / runs across artery
- lateral pectoral
C. Medial cord (5)
- anterior division of lower trunk
- C8 / T1
- medial to axillary artery
Branches
- medial median
- medial pectoral
- MCNA, MCNFA (medial cutaneous nerve of arm and forearm)
- ulna nerve is terminal branch (runs medial to artery)
Sensation
Roots / ASIA
Peripheral nerves
Supraclavicular region C4
Regimental patch C5
- axillary nerve
Radial forearm C6
- LCNFA / MCN
Dorsal first web space C6
- radial nerve
Thumb and thenar eminence C6
- median nerve
Middle finger C7
- median nerve
Little finger C8
- ulnar nerve
Ulnar forearm T1
- MCNFA
Medial arm T2
- MCNA
Motor
Nerve roots / ASIA
C5 / deltoid / bicep
C6 / wrist extensors
C7 / tricep
C8 / MF FDP
T1 / interossei
Adjacent nerves
Trapezius (CN Xl)
- patient shrugs shoulders against resistance
Branches from roots
Rhomboid (C5)
- dorsal scapular nerve
- patient retracts scapula
- examiner uses hand to palpate
Serratus anterior (C567)
- long thoracic nerve
A. Patient pushes against wall
- observe for winging
- patient protracts shoulder against resistance
B. Some pateints won't be able to get arm up to wall
- raise arm for them
- get them to push arm away
Branches from the trunks
Supraspinatus (C5)
- suprascapular neve
- patient tries to initiate abduction of the arm from the side
Infraspinatus (C5)
- suprascapular nerve
- patient tries to externally rotate shoulder with arm by side
Branches of the posterior cord (C5-T1)
Deltoid (C5)
- axillary nerve
- patient abducts arm against resistance
Latissimus Dorsi (C7)
- thoracodorsal nerve
- patient adducts horizonal arm against resistance
Subscapularis
- upper and lower subscapular
Radial nerve
1. Triceps (C78)
- patient extends elbow against resistance
2. Brachioradialis (C6)
- patient flexes the elbow with forearm pronated
3. ECRL (C67)
- radial nerve
- extend IF against resistance
4. ECRB (C67)
- PIN
- extend MF
5. Wrist extension (C67-ECR, C67-ECU)
- radial and posterior interosseous nerve
- patient extends wrist
5. Supinator (C6)
- patient supinates forearm in extension
6. EDC (C8)
- PIN
- patient extends MCPJ
7. ECU (C67)
- PIN
- extend wrist
8. Extensor pollicis longus (C7)
- PIN
- patient extends thumb IPJ against resistance
Branches of the lateral cord (C5,6,7)
Pectoralis major (clavicular fibres) (C6)
- lateral pectoral nerve
- patient pushes arm forwards with arm horizontal
Biceps (C56)
- musculocutaneous nerve
- patient tries to flex elbow with forearm supinated
Lateral median nerve
1. PT (C6)
- pronate in flexion
2. FCR (C6)
- wrist extension
Branches of the medial cord (C8 / T1)
Pectoralis major (sternocostal fibres) (C7,8)
- medial pectoral nerve
- patient places hand on hip and pushes in
Medial branch median nerve
Flexor digitorum profundus (C8)
- AIN
- patient makes fist and resists extension of index finger
Flexor pollicis longus (C8)
- AIN
- patient flexes distal phalanx of thumb against resistance
Abductor pollicis brevis (TI)
- patient abducts thumb at right angles to palm against resistance
Ulna nerve
Flexor carpi ulnaris (C8)
- patient flexes wrist against resistance
Flexor digitorum profundus (C8)
- patient makes fist and resists extension of little finger
Interossei (TI)