brachial plexus and vessels

Question 1

what is a plexus

Answer 1

a structure where spinal nerves merge and mix to produce peripheral nerves - usuallyu with fibres from more than 1 spinal root

Question 2

illustrate the organisation of the brachial plexus - whar are the differnet levels, and name nerves that come off them *

Answer 2

roots (supraclavicular in posterior triangle between middle and anteriro scalene muscles)

trunks (supraclavicular)

divisions (supraclavicular)

cords (infraclavicular, axilla)

terminal branches/peripheral nerves (axilla)

(real teenages drink cold beer)

brachial plexus is made of spinal nerves of c5-t1

dorsal scapula nerve comes from C5

long thoracic nerve comes from C5 6 7 - supples the serratus anterior

branches from roots, trunks and divisions are suprascapular, branches from cords and terminal branches are infrascapular

Question 3

describe the path of the branches in the brachial plexus *

Answer 3

from C5-T1

C5 and 6 form the upper trunk

7 is middle trunk

8 and 1 form lower trunk

the trunks split into anterior and posterior divisions

upper and medial anterior divisions form lateral cord

all posterior divisions form posterior cord

lower anterior division becomes median cord

peripheral nerves emerge from these cords - from lateral cord have the lateral pectoral nerve, from the posterior cord have the upper and lower subscapular nerves supplying subscapularis and teres major, thoracodorsal nerve supplying latissimus dorsi

Question 4

what cords do the main nerves branch from *

Answer 4

musculocutaneous - lateral

axillary - posterior

radial - posterior

median - lateral and median

ulnar - median

Question 5

what are the names of the cords based around *

Answer 5

their position around the axillary artery ie posterior cord is posterior to artery

nerves of posterior cord generally supply posterior muscles

Question 6

what spinal nerve of the brachial plexus (and above this) supply which body region *

Answer 6

c3-7 shoulder girdle muscles

5 6 shoulder joint muscles and elbow flexors

7-8 elbow joint extensors

6-8 wrist and course hand muscles

8-t1 small muscles of hand for fine movements

Question 7

illustrate the segmental supply of the upper limb for movement

Answer 7

opposing movements are supplied by adjacent spinal nerve segments

Question 8

illustrate the dermatomes of the upper limb *

Answer 8

they go as a continuum around

Question 9

why is the sensory nerve distribution different to teh dermatomes *

Answer 9

fibres supplying the dermatome come from more tahn 1 peripheral nerve

eg superior lateral cutaneous nerve and inferior lateral cutaneous nerve both come from c5 6 but are distinct peripheral nerves

Question 10

describe the path of the axillary nerve *

Answer 10

smaller of 2 branches from the posterior cord - c5 and 6

winds round neck of the humerus

passes posteriorly then laterally

pass under shoulder

Question 11

where is the axillary nerve commonly damaged *

Answer 11

through shoulder dislocations and fracture of surgical neck of the humerus

Question 12

what does the axillary nerve supply *

Answer 12

deltoid

teres minor - this is a rotator cuff muscle

Question 13

effect of damage to the axillary nerve *

Answer 13

wasting of deltoid muscle - smoothness of shoulder lost because you can see underlying structures

loss of abduction

Question 14

how do you assess axillary nerve injury *

Answer 14

the axillary nerve branches into superior lateral cutaneous nerve of arm - supplies skin over this area - called the regiment’s patch

loss of sensation here shows lost axillary nerve function

important because you dont want to ask pt to move shoulder to test axillary nerve when they have a shoulder disslocation

Question 15

describe the path of the radial nerve *

Answer 15

larger of the 2 branches from the posterior cord c7-t1

travels out from the axillary region into posterior arm and forearm

runs posterior to the humerus on the radial/spiral groove of the humerus, artery travels with it

1/3 above the elbow it enters the lateral compartment of the arm

divides at elbow into deep branch and cutaneus branch

Question 16

where can the radial nerve be damaged *

Answer 16

humeral fractures because it runs closely opposed to the shaft of the humerus

Question 17

effect of radial nerve damage *

Answer 17

wrist drop - damage supply to the posterior muscles which would normally extend the wrist

anaesthesia of the lateral dorsal of hand - effects a variable area on posterior surface of the thumb because of substantial overlap of other nerves

loss of muscle mass in arm and forearm - wastage of muscle if happens further up - lose functioning of arm

lose the power grip - need the extensor muscles to get the most efficient power grip - when hand extended flexor muscles are already stretched so when they start working to make the grip they are already half way there

elbow extended because cant innervate triceps

supinator effected

Question 18

describe the path of the musculocutaneous nerve *

Answer 18

come from the lateral cord = c5-7

extend in the axilla into arm and pierce coracobrachialis muscle

give off lateral branch to reach forearm - lateral cutaneous nerve of forearm - supplies the skin of the lateral part of forearm

Question 19

what does the musculocutaneous nerve supply *

Answer 19

supply anterior arm, biceps and brachialis

lateral cutaneous skin of forearm

Question 20

how is musculocutaenous nerve damaged *

Answer 20

not in trauma really because protected by muscles

may be damaged by surgery for breast cancer in removal of the axial lymph nodes

Question 21

describe the path of the ulnar nerve *

Answer 21

biggest branch from the middle cord - c8-T1

emerges in teh axilla and continues down the arm

runs medial to the brachial artery

pierces the medial intermuscular septum to enter the posterior compartment of the arm - lies in groove for the ulnar nerve between medial epicondyle and olecranon

goes behind the medial epicondyle of humerus

passes between 2 heads of flexor carpi ulnaris - enters flexor compartment fo teh forearm, descends on FDP to wrist

goes to ulnar canal at the wrist and passes into hand on flexor retinaculum along the pisiform

divides into superior and deep branches

Question 22

in vague terms what does the ulnar nerve supply *

Answer 22

doesnt supply anything in arm

some forearm

lots in hand

Question 23

what muscles does the ulnar nerve supply *

Answer 23

flexor carpi ulnaris

palmaris brevis

hypothenar muscles

medial lumbricles - 4 5

dorsal and palmer interossei

adductor pollicus

flexor digitorum profundus

Question 24

what causes damage to the ulnar nerve *

Answer 24

self harm at wrist

injuries to the medial epicondyle of humerus at elbow

Question 25

effect of damage to the ulnar nerve \*

Answer 25

claw deformity - hand at rest automatically claws lumbricles are affected - lumbricles normally extend the digits by pulling on the extension expansion on the surface of the digit (they flex the MPJ and extend the IPJ) after ulnar nerve injury - loss of lumbricles means loss of flexion in MPJ and weakened extension of IPJs also lose abduction and adduction from dorsnal and palmar interosseis respectively (DAB and PAD) many small muscles of the hand are effected but the thumb and index finger are spared because tehse lumbricles not affected sensory problems along medial part of hand and medial 1.5 fingers are inconvenient - less serious than loss of the median nerve weakness and wasting of small muscles of the hand muscles affected - FCU FDP (Medial) medial lumbricles and all interossei and hypothenar difficulty making a fist - flexion of distal IPJs is not complete so unopposed action of extensor digitorum so MPJs are hyperextended loss of sensation of medial hand

Question 26

describe teh ulnar paradox \*

Answer 26

'the closer to the paw the worse the claw' ulnar inhury at the wrist = more damage than injury at the elbow if damage is at elbow - also lose innervation to the medial side of FDP so there fwould be less flexion of the IPJs. at the wrist the FDP is spared causing more unopposed flexion at the IPJs = more claw like appearance

Question 27

describe the path of teh median nerve \*

Answer 27

lateral and median cords c6-t1 leave axilla pass with the brachial artery to enter teh cubital fossa - medial to brachial artery here go medially down forearm between 2 heads of pronator teres ansd passes beneath FDS - branches to superficial and deep forearm muscles go medially down the forearm at wrist it emerges between the tendons of the FDS and palmaris longus into the carpal tunnel

Question 28

in vague terms what does the median nerve supply \*

Answer 28

nothing in arm most of forearm some in hand sensory fibres supply lateral part of hand

Question 29

ulnar relation to the carpel tunnel \*

Answer 29

not in tunnel pass medially to it

Question 30

does all of the median nerve pass through the carpal tunnel \*

Answer 30

no - gives branch that stays superficial and supplies the palm

Question 31

describe the ulnar and medial supply to the hand

Answer 31

when median nerve exits carpal tunnel it gives off a recurrent branch to thenar muscles median gives sensory branches to the thumb, index, middle and half of ring finger ulnar branch gives sensation to little finger and half of the ring finger there is a communicating branch between ulnar and median nerves for sensory - but notrmally clear cut off between sensation

Question 32

what is the effect of carpal tunnel syndrome \*

Answer 32

wasting of the thenar eminance abductor pollicus is evident - supplied by the unlnar nerve loss of sensation and movement in lateral digits causes severe disability - because lateral lumbricals are effected and loss of thenar muscles = loss of fine movement loss of sensation in thumb, index middle and hald of ring finger

Question 33

describe teh path of the long thoracic nerve \*

Answer 33

comes from c5 6 7 emerges from the root of the neck over the serratus anterior is relatively superficial - therefore easily damaged

Question 34

describe attachments of the serratus anterior muscle \*

Answer 34

attaches to the medial ege of the scapula and fibres come around surface of the thoracic wall and insert into ribs 1 to 9 it attaches the trunk to the medial side of the scapular func: hold scapula down and protration

Question 35

how would you damage the long thoracic nerve \*

Answer 35

car accident stabbed in this region

Question 36

effect of damage to the long thoracic nerve \*

Answer 36

pressing against a wall will lead to winging of the scapula resulting from the loss of activity from the serratus anterior

Question 37

what is injury to the upper roots called \*

Answer 37

Erb-Duchenne palsy

Question 38

what type of injury would damage upper roots \*

Answer 38

falling on head injuries during birth - pulled out by head, motorcycle injury stretch the neck relative to the shoulder damage c 5 6

Question 39

what is damaged in the upper root injuries \*

Answer 39

anything to the upper trunks - ie c5 6

Question 40

effect of damage to the upper roots \*

Answer 40

waiter's tip position many muscles affected - shoulder and anterior arm forearm pronated because of lack of biceps supination (loss of function of musculocutaneos nerve) anterior arm affected - flexion of elbow is difficult wrist has unopposed flexion - radial nerve affected arm adducted, medially rotated get wasting of the limb

Question 41

example of injury that would cause lower root injury \*

Answer 41

during birth - pull out by arm over abduction due to gripping overhead to break fall

Question 42

what are lower root injuries \*

Answer 42

damage to T1 and sometimes T8 called Klumpke's palsy 'klumpe's monkey falls from a tree' posterior and middle cords are affected

Question 43

what will the outcomes be of a lower root injury \*

Answer 43

T1 mainly supples small muscles of hand via ulnar and median nerves - loss of their activity results in a clawed hand loss of ulnar and median = loss of lumbricles so loss of extension of ICJs and loss of flexion MPJs = claw

Question 44

what is the function of the brachial plexus

Answer 44

rearrange the nerve fibres from c5 - T1 into bundles travelling to appropriate parts of the limbs all nerves supplying extensor muscles pass through posterior cord all nerves supplying flexor muscles pass through lateral and medial cord

Question 45

function of the lateral pectoral nerve

Answer 45

supplies pec major comes of lateral cord of brachial plexus

Question 46

function of the medial pectoral cord

Answer 46

from medial cord to supply pec minor

Question 47

what is the artery supply to the scapular region \*

Answer 47

it is form the suprascapular and transverse cervical arteries - branches of the thyrocervical trunk from the 1st part of the subclavian artery

Question 48

describe the arterial supply of the upper limb\*

Answer 48

enters the axilla as a continuation of the subclavian artery thoracoacromial and superior thoracidc arteries arise in the most prox part at the level of the neck of humerus - there are the anterior and posterior circumflex humoral branches and the subscapular artery becomes the brachial artery in the arm, distal to inferior border of teres major muscle at the cubital fossa the brachial artery bifurcates into ulnar and radial arteries the ulnar gives off a short common interosseous branch that divides to give anterior, posterior and recurrent interossous arteries the ulnar artery crosses the wrist to form the superficial palmar arch and contribute to the deep palmar arch teh radial artery passes distally in forearm and crosses wrist entering the thenar eminence forming the deep palmar arch and contributing to the superficial palmar arch at wrist a branch of the radial artery passes dorsally to anastomose with the distal end of the anterior and posterior interosseous arteries to form the dorsal carpal arch

Question 49

describe the venous drainage of the upper limb\*

Answer 49

digital veins run into teh dorsal venous network of the hand they form the cephalic and basilic veins - superficial they run subcutaneously into forearm and arm with a communicating branch just distal to elbow region - median cubital vein cephalic vein passes between the deltoid and pec major muscles (the delto-pectoral groove) to pierce the clavipectoral fascia to drain into the prox axillary vein the basilic vein passes deeply, approx mid arm, runs with the brachial artery and joins its venae comitantes to form the axillary vein the deep veins are the venae comitantes of teh arteries - they form a plexus around teh arteries - the venae comitantes increase in calibre as they pass proximally there are perforating branches connecting the deep and superficial veins

Question 50

where can you palpate the nerves

Answer 50

trunks - supraclavicular fossa median nerve - cubital fossa, medial to brdachial artery radial nerve - cubital fossa lateral to biceps tendon ulnar - medial epicondyle median - wrist ulnar - wrist - medial to ulnar pulse

Question 51

identify the nerves in the body \*

Answer 51

pic from living anatomy

Question 52

effect of damage to the median nerve \*

Answer 52

muscles involved - FDP (lateral half), lumbricles of lateral side when makuing a fist 2nd and 3rd fingers fail to flex completely - thumb unable to oppose MPJs are hyperextended because of unopposed action of the extensor digitorum thumb unable to oppose because of paralysis of opponens pollicis and FPB wrist flexors are affected - wrist adducted pronators affected - wrist in supine position thenar muscles paralysed loss of sensation to lateral half of palm and lateral digits

Question 53

what causes a true claw \*

Answer 53

ulnar and median nerve damage c5-T1 roots clawing in all 4 fingers with thumb abducted

Question 54

effect of damage to the musculocutaneous nerve \*

Answer 54

elbow flexors are effected loss of sensation on lateral side of forearm up to wrist

Question 55

describe frozen shoulder

Answer 55

pain and stiffness of the shoulder especially during external rotation have shoulder pain for 2 to 9 months - severe followed by increasing stiffness localised autoimmune response is a possible cause

Question 56

describe shoulder impingement syndrome

Answer 56

pain and weakness when you raise your arm because of tendon 'catching' in shoulder it involves the supraspinatous tendon in the subacromial space cause * bone spurs under acromion at top of subacromial space - can narrow the space and catch on the tendon * swelling or thickening of the rotator cuff tendon - from injury or general overuse of the shoulder * inflammation of the fluid filled sac that lies between the rotator cuff tendons and the acromion - bursitis * a build up of ca deposits within the rotator cuff tendon treatment * avoid provokative activities * hydrocortisone injections * LA * exision or aspiration of calcified materaial * decompression of impingement

Question 57

describe tennis elbow

Answer 57

injury to extensor tendons on lateral epicondyle because of sharp flexion of the wrist while extensors are contracted

Question 58

golfer's elbow

Answer 58

similar to tennis but common flexor attachment on medial epicondyole is strained cause - sharp flexion of elbow

Question 59

cause of mallet finger

Answer 59

avulsion of extensor igitorum longus tendon at base of distal phalanx

Question 60

game keepers thumb

Answer 60

damage to medial collateral ligament of 1st MPJs by violent abduction thumb becomes unstable

Question 61

trigger finger

Answer 61

flexor profundus longus tendon causes friction to tendinous sheath and results in swelling of tendon which irritates sheath causing it to narrow when finger is flexed it gets stuck in the sheath in a flexed position becasue the extensors are not string enough to straighten finger

Question 62

colle's fracture

Answer 62

fracture of the distal radius within 1inch of wrist joint and ulnar styloid dorsal displacement and dorsal angulation prox impaction and radial deviation in severe cases the distal radio-ulnar joint may be dislocated

Question 63

osteoarthritis

Answer 63

irreversible degenerative changes in cartilage loss of articular cartilage and periarticular bone narrowing of joint spaces in the interphalangeal joints causes pain, stiffness and discomfort

Question 64

rheumatoid arthritis

Answer 64

chronic inflammatory synovitis of peripheral joints immunological casue swelling of joints joint deformity loss of function