OS 203 2 Axilla and Brachial Plexus - Sheet1 (1) Flashcards
PE of nerve injury: cooperative patient (2)
2-pt discrimination (innervation density), semmes-weinstein test (touch threshold)
PE of nerve injury: unconscious patient (3)
Wrinkle test (10 mins; if smooth, nerve injury); tactile adherence (smooth & slipper, nerve injury); sensory testing
sensory testing: tests for median, radial, ulnar nerves
median - test for abductor pollicis brevis; radial - extensor digitorium communis or pollicis longus; ulnar - flexor digiti minimi
2 main categories of nerve injuries (which is shorter)
Seddon (shorter), Sunderland
Seddon & Sunderland equivalents
Neurpraxia = 1st deg; Axonotmesis = 2nd deg; Neurotmesis = 3rd-5th deg
Injury, degeneration, regeneration in 1st degree
Myelin sheath, conduction block, complete recovery
Injury, degeneration, regeneration in 2nd degree
MA, Wallerian degeneration, complete recovery
Injury, degeneration, regeneration in 3rd degree
MAE, Wallerian degeneration, incomplete recovery
When is electromyogram and nerve conduction velocity test done?
10-14 days after injury
Motor and sensory axons are excitable up to?
motor - 7 days; sensory - 11 days
Wallerian degeneration starts when?
10-14 days after injury
Stimulation distal to the site of injury…
Normal or slightly abnormal, so you can’t differentiate between neuropraxia and neurotmesis
Stages of nerve regeneration
axon fragmented -> macrophage clean distal to injury -> axon sprouts/filaments through regeneration tube formed by Schwann cells -> axon regenerates, new myelin sheath
Posterior triangle borders
anterior - sternocleidomastoid, posterior - anterior border of the trapezius, inferior - middle third of the clavicle (M3)
from the posterior triangle, brachial plexus emerges where
between the anterior and middle scalene muscles
main supinator of the forearm
biceps
musculocutaneous supplies what? (3)
coracobrachialis, biceps brachii, brachialis
what supplies the brachialis? it will eventually become a what?
musculocutaneous nerve; becomes a sensory nerve called the lateral antebrachial cutaneous nerve
the median nerve distally supplies the? passes through? and supplies recurrent muscle
AIN / anterior interosseus nerve, passes through carpal tunnel
supplies intrinsic muscles of the hand
ulnar nerve
when the ulnar nerve gets trapped in the cubital tunnel behind the medial epicondyle…
cubital nerve syndrome (tardy ulnar palsy)
fracture of the elbow can result to
paralysis of the ulnar nerve
prolonged ulnar nerve palsy can cause
claw hand deformity or ape hand/papal benediction sign (*EH DAPAT MEDIAN NERVE TONG APE/PAPAL EH…)
radial nerve goes into the what of the humerus and divides into what?
radial groove in distal 1/3 humerus, superficial cutaneous (dorsal web space) and deep motor (extensors of wrist) -> posterior interosseus -> extensors of fingers
radial paralysis leads to? and if more proximal?
wrist drop, numbness of dorsal web space, if more proximal, loss or weakness of elbow extension
(axillary) the posterior cord goes out to the quadrangular space to supply what?
motor and sensory function of the deltoid (also, teres minor)
how can the axillary nerve be injured? effects?
proximal fractures of humerus, surgical neck, dislocation of humerus; lack of abduction, weakness in external rotation, numbness of deltoid patch
regions on skin from which sensation is carried by cutaneous branches of a spinal nerve
dermatomes
long thoracic nerve: innervates what? action? injury?
serratus anterior, laterally rotates outwards/protracts scapula, scapular winging
dorsal scapular nerve innervates what? action?
major & minor rhomboids, medially rotates/retracts scapula
the only branch at the trunk level; innervation? action?
suprascapular nerve; supraspinatus (shoulder abduction) and infraspinatus (external rotation)
lateral pectoral nerve innervates? action?
clavicular head of pec major, adducts and internally rotates shoulde
medial pectoral nerve innervates? action?
sternal head of pec major & minor, adducts shoulder
subscapular nerve innervates? action?
subscapularis and teres major; internally rotates shoulder
thoracodorsal nerve innervates? action?
latissimus dorsi; adduction and internal rotation of shoulder
innervates thenar muscles (except…)
median nerve; except deep head of flexor pollicis brevis and adductur pollicis
median nerve: roots and respective innervations and actions
C6: forearm pronator; C7: wrist flexor; C8 - long finger flexor; T1: small hand (intrinsic)
brachial plexus injuries (3)
stretch (neuropraxia), rupture, avulsion
pre & post ganglionic injury: what kind of injury? scapular winging? suture?
pre: avulsion, present (serratus anterior damage *recall: innervated by long thoracic nerve), can’t be sutured (also: normal in NCV… so normal sensory?);; post: rupture, none, can be sutured
causes of upper and lower brachial plex injury
upper: extreme lateral flexion; lower: extreme abduction
upper & lower: damaged roots
upper - C5-C6; lower - C8-T1
extreme lateral flexion caused by
shoulder dystocia in babies, fall in adults
upper brachial plexus injury results to
erb-duchenne paralysis
extreme abduction caused by
babies arms pulled during delivery, adults breaking fall
lower brachial plexus injury results to
klumpke’s paralysis (claw hand)
treatment priority (adult)
elbow flexion, shoulder stability/abduction, hand sensation, hand function
treatment priority (obstetric)
hand function/sensation, elbow function, shoulder stability/abduction, shoulder external rotation
for neuromas-in-continuity
neurolysis
for post-ganglionic/rupture/graftable proximal nerve
nerve repair/grafting
if pre-ganglionic/not graftable
nerve transfer
artificial bridges for axons; length limited to? ECM?
conduits,
late treatment (>12 mos.) (2)
muscle transfers, tendon transfers
rate of axons regeneration
1mm/day or 1 in/month
motor end plates degenerate at
12-18 months
