CN XI
Posterior cervical triangle and can be injured with cervical lymph node biopsy
-leads to shoulder drooping/weakness
Brachial Plexus: upper trunk pathology
- Nerves involved: suprascapular, musculocutaneous, axillary, partis of medial and radial
- Weakness: SHOULDER flex, abd, ext; ELBOW flex, supination, pronation WRIST flexion
- Paresthesias in lateral hand and forearm and thumb = index finger
Brachial plexus: middle trunk pathology
- Rarely injured in isolation
- presents as radial nerve palsy but affects triceps and spares BR
Brachial plexus: lower trunk lesion
- Motor weakness in muscles innervated by ulnar nerve, C8 components of radial, distal median nerve (thenar and lumbricals)
- Paresthesias at medial forearm, hand and 4th and 5th digits
Brachial plexus: lateral cord lesion
similar to upper trunk lesion but SPARES suprascapular and partially affects axillary and radial
-Look for normal shoulder function with musculocutaneous nerve palsy signs/Sx
Brachial plexus: medial cord lesion
Similar to lower trunk lesions but normal finger extension strength
Brachial plexus: posterior cord lesion:
rare in isolation
Suprascapular Nerve:
C5-6 from upper trunk
- travels through suprascapular notch under transverse scapular ligament and then through spinoglenoid notch
- *if compressed at scapular spine or spinoglenoid ligament may cause infraspinatus wasting w/ supraspinatus sparring
Axillary Nerve
C5-6 from posterior cord
- @ greatest risk with dislocation. proximal humeral Fx, shoulder surgery
- supplies delt and teres minor
Long Thoracic nerve:
C5-7 direct from roots
- supplies SA
- Ruckshack palsy: upper trunk and/or long thoracic nerve palsy (named for Vietnam soldiers who carried heavy ammunition in packs)
Musculocutaneous nerve
C5-7 from lateral cord
- Supplies b/brachii and brachialis
- also branches to supply lateral forearm (lateral antebrachial cutaneous)
- MOI: distal humeral Fx, clavicular Fx, entrapment of brachioradialis, shoulder harness after MVA
Radial Nerve: pathway
C5-C8 (sometimes T1); posterior cord
- Exits axilla distal to t.major
- Travels along humerus in radial groove
- posterior brachial cutaneous and posterior antebrachial cutaneous branch provide sensory innervation from axilla distally to wrist
- Divides into superficial and deep branches in antecubital space
- Superficial branch: sensory to distal PL wrist–> terminates as digital nerves (sensory to back of hand)
- Deep branch passes beneath supinator, innervates it, and becomes PIN (**common entrapment site)
Ulnar nerve: pathway
C8-T1; medial cord
- NO major branches in arm/brachium
- passes through medial intermuscular septum
- 1st branch @ elbow level to innervate JC-passes posterior to medial epicondyle emerging through cubital tunnel
- cutaneous branches innervate medial side of wrist and hand
Median nerve: pathyway
- medial side of antecubital fossa beneath brachial aponeurosis
- passes through P.teres and arises as AIN
- Median N innervates FCR, P.longus, and FDS
- AIN innervates FPL, lateral 1/2 of FDP, thumb intrinsics and radial lumbricals
- cutaneous innervation at posterior side digits 1-3 and 1/2 digit 4
Median nerve: motor loss, Sensory loss and Functional loss
M: P.teres, P.quadratus, FCR, P.longus, FDS, lateral 1/2 FDP, thenar eminence, lateral 2 lumbricals
S: Palmar aspect of hand with thumb, index, middle, and lateral 1/2 ring
F: pronation weakness, wrist flex/abd weak, loss RD at wrist, can’t oppose/flex thumb, thumb abduction weakness, weak grip, weak/no pinch (APE hand)
AIN: motor loss, sensory loss, functional loss
M: FPL, lateral 1/2 FDP, P.quadratus, thenar eminence mms, lateral 2 lumbricals
S: NONE
F: pronation weakness, esp in 90 deg elbow flexion, weak thumb opposition/flexion, weak finger flexion, weak pinch (no tip to tip)
Ulnar nerve: motor loss, sensory loss, functional loss
M: FCU, medial 1/2 FDP, P. brevis, hypothenar eminence, Add policis, medial 2 lumbricals, ALL interossei
S: posterior and palmar aspect of little and medial 1/2 ring finger
F: weak wrist flex, no UD, loss distal finger flex at 5th digit, loss ABD/ADD fungers, can’t extend 4th and 5th distal and middle PH, loss thumb adduction
Radial nerve loss motor, sensory, function
M: Anconeus, BR, ECRL, ECRB, ED, ECU, EPL, EPB, APL, IE, EDM
S: posterior aspect of hand (lateral 2/3), poserior and lateral aspects of thumb, prox 2/3 posterior aspect of index and 1/2 ring finger
F: loss supination, loss wrist ext, can’t grip/stabilize wrist, loss finger ext, cant abduct thumbs
PIN: motor loss, sensory loss, functional loss
M: ECRB, EPL, ED, EPB, ABD PL, ECU, EI, EDM
S: NONE
F: weak wrist/finger ext, can’t stabilize wrist, can’t grasp, can’t abduct thumb
Saphenous Nerve
largest cutaneous branch of femoral nerve; sensory to medial foot/arch
Common fibular (peroneal) Nerve: Branches and innervation
Splits into superficial and deep peroneal nerves
SUP: sensory to dorsum of foot (NOT 1st web space); motor to peroneals
DEEP: Sensory to 1st web space; motor to ankle/toe DF
Sural Nerve
Sensory to posterolateral foot
Tibial nerve divisions and innervation
sural, medial calcaneal, medial plantar and lateral plantar nerves
tibial nerve motor to PFs and intrinsics
