Brachial Plexus + cases

Question 1

which nerve causes wrist drop

Answer 1

radial nerve palsy

Question 2

start of brachial plexus

Answer 2

ventral/anterior rami of C5-T1
-run between scalenes
-below clavicle and down the arm

Question 3

roots, trunks, divisions, cords, branches

Answer 3

-Read That Damn Cadaver Book
-Roots- C5-T1
-Trunks (lower neck past scalenes)- superior, middle, inferior
-Divisions (under clavicle)- 3 anterior and 3 posterior
-Cords (at axilla)- lateral, posterior, medial
-terminal branches (arm)- 5 musculocutaneous, axillary, median, radial, ulnar

Question 4

brachial branches

Answer 4

-musculocutaneous- originates from C5-C7 and FLEXES muscles in upper arm at shoulder and elbow -> injury to lateral cord would affect this
-axillary nerve- C5-C6 and helps shoulder ROTATE and enables arm to lift away from body -> injury from shoulder dislocation or proximal humeral fracture
-median nerve- C6-T1 and enables MOVEMENT in forearm and part of hand -> injured by supraepicondylar fracture
-radial nerve- C5-T1 and controls various muscles in upper arm, elbow, forearm and hand -> saturday night nerve palsy-arm handing over the chair/honeymoon nerve palsy- sleeping on medial arm
-ulnar nerve- C8-T1 allows for FINE MOTOR control of fingers -> injury from medial epicondylar fracture

Question 5

brachial plexus injuries

Answer 5

-most heal 90%
-unless severe- severed -> surgery
-injury to neck or shoulder and cant feel or move hand -> indication of injury
-MC in childbirth- can be upper (upper root) or lower

Question 6

Erb’s palsy: upper trunk injury

Answer 6

-upper root injury C5-C6
-stretching injury
-commonly from pulling on baby during delivery
-injury to musculocutaneous, axillary, suprascapular end nerves to subclavius
-supraspinatus, infraspinatus, subclavius, biceps, brachialis, deltoid, teres minor are affected
-sensation affected on lateral aspect of upper limb- C5-C6 dermatome
-arm hangs limp, medially rotated at shoulder
-cant flex at elbow
-unopposed action of pec major
-supraspinous arnt pulling it back
-forearm pronated due to loss of biceps brachi
-wrist flexed -> normal tone of wrist flexors (extensions weakened)
-waiters tip deformity- pronation, forearm extension, wrist flexed

Question 7

erbs palsy nerves affected

Answer 7

-suprascapular nerve -> motor flexor muscles of supraspinatus, infraspinatus -> unable to keep lateral rotation of shoulder
-musculocutaneous nerve -> motor flexor of anterior arm -> unable to flex biceps, brachioradialis flexion at elbow and supination
-axillary nerve -> motor deltoid and teres major -> able to abduct arm
-some branches to posterior cord- radial nerve -> forearm extensors

Question 8

Klumpke’s Palsy: Lower trunk injury

Answer 8

-less common
-C8-T1
-limb presentation during delivery -> stretch injury of axilla
-injury to T1 (ulnar and median)
-intrinsic hand muscle injury
-medial side of upper limb sensation- C8-T1 dermatome
-loss of motion and/or sensation in wrist and hand -> cant move fingers
-claw hand
-lumbricals- flex metacarpals and extend interphalangeal joints -> paralysis -> extended metacarpals and flexed interphalangeal

Question 9

thoracic outlet syndrome

Answer 9

-overuse, compression of brachial plexus
-collar bone, first rib compression
-pain, numbness
- 20-40 yo- repetitive physical activity or heavy lifting
-1. neurogenic- nerve roots or any part of brachial plexus -> 3 areas of concern
-scalene triangle- posterior and medius scalene
-costoclavicular junction- cords
-interpectoral space- branches or divisions
- 2. vascular impingement - compression of subclavian artery or vein
-gamer posture

Question 10

gamer posture

Answer 10

-thoracic outlet syndrome
-hypertonic or spasm from poor posture
-unconscious contraction of pec muscles (not stretched)
-leaning head forward- scalenes unconscious contracted
-weakening of posture muscles- lower trap, serratus anterior, flexor muscles at neck
-numbness and weakness

Question 11

slips and falls forward on neck, neck bends laterally to left, pain in neck and numbness in her right arm

Answer 11

-forced left lateral flexion of neck -> right is stretched out
-numbness to superior lateral right arm -> decreased sensation
-right arm internally rotate and pt is unable to bend at elbow or lift arm > 0 degrees
-no flexion, no abduction
-no abduction- potential rotator cuff injury -> supraspinatus (deltoid is > 15 degrees)
-C5-C6 injury!!
-very high up
-this is stretch tear
-can see this with supraclavicular injury, stretch
-erb palsy- waiters tip deformity

Question 12

sargents patch

Answer 12

-numbness is lateral superior area (around deltoid)
-C5 injury
-axillary nerve

Question 13

dermatomes

Answer 13

-C5- superior lateral -> axillary
-cont…

Question 14

right hand pain after falling on outstretched arm

Answer 14

-point tenderness** inbetween tendons on dorsum of hand -> extensor pollicus longus nad extensor pollicus brevis/abductor pollicus longus
-tendons are dorsal
-snuff box- scaphoid bone fracture
-may not appear on x-ray at first -> worry ab ischemia

Question 15

fingers 1 and 2 unable to crossed over

Answer 15

-ulnar nerve
-crossing fingers -ADDucting
-PAD

Question 16

patient is unable to make a first with 1st and second fingers

Answer 16

-median nerve
- flexor digitorum superficialis/profundus (fingers), flexor pollicus longus/brevis
-abduct thumb in fist- Abductor Pollicus Brevis

Question 17

claw hand, 3 and 4 finger cant extend

Answer 17

-ulnar nerve

Question 18

pinch test

Answer 18

-normal- fingers pinch with pinch
-nerve injury- froments positive sign
-thenar- ulnar- recruits median to help

Question 19

wrist drop

Answer 19

-radial nerve
-wrist cant extend- (what muscle extends?)
-if you can extend the arm- the injury is probably lower down