brachial plexus and vessels Flashcards
what is a plexus
a structure where spinal nerves merge and mix to produce peripheral nerves - usuallyu with fibres from more than 1 spinal root
illustrate the organisation of the brachial plexus - whar are the differnet levels, and name nerves that come off them *
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
describe the path of the branches in the brachial plexus *
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
what cords do the main nerves branch from *
musculocutaneous - lateral
axillary - posterior
radial - posterior
median - lateral and median
ulnar - median
what are the names of the cords based around *
their position around the axillary artery ie posterior cord is posterior to artery
nerves of posterior cord generally supply posterior muscles
what spinal nerve of the brachial plexus (and above this) supply which body region *
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
illustrate the segmental supply of the upper limb for movement
opposing movements are supplied by adjacent spinal nerve segments
illustrate the dermatomes of the upper limb *
they go as a continuum around
why is the sensory nerve distribution different to teh dermatomes *
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
describe the path of the axillary nerve *
smaller of 2 branches from the posterior cord - c5 and 6
winds round neck of the humerus
passes posteriorly then laterally
pass under shoulder
where is the axillary nerve commonly damaged *
through shoulder dislocations and fracture of surgical neck of the humerus
what does the axillary nerve supply *
deltoid
teres minor - this is a rotator cuff muscle
effect of damage to the axillary nerve *
wasting of deltoid muscle - smoothness of shoulder lost because you can see underlying structures
loss of abduction
how do you assess axillary nerve injury *
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
describe the path of the radial nerve *
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
where can the radial nerve be damaged *
humeral fractures because it runs closely opposed to the shaft of the humerus
effect of radial nerve damage *
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
describe the path of the musculocutaneous nerve *
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
what does the musculocutaneous nerve supply *
supply anterior arm, biceps and brachialis
lateral cutaneous skin of forearm
how is musculocutaenous nerve damaged *
not in trauma really because protected by muscles
may be damaged by surgery for breast cancer in removal of the axial lymph nodes
describe the path of the ulnar nerve *
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
in vague terms what does the ulnar nerve supply *
doesnt supply anything in arm
some forearm
lots in hand
what muscles does the ulnar nerve supply *
flexor carpi ulnaris
palmaris brevis
hypothenar muscles
medial lumbricles - 4 5
dorsal and palmer interossei
adductor pollicus
flexor digitorum profundus
what causes damage to the ulnar nerve *
self harm at wrist
injuries to the medial epicondyle of humerus at elbow
effect of damage to the ulnar nerve *
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
describe teh ulnar paradox *
‘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
describe the path of teh median nerve *
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
in vague terms what does the median nerve supply *
nothing in arm
most of forearm
some in hand
sensory fibres supply lateral part of hand
ulnar relation to the carpel tunnel *
not in tunnel
pass medially to it
does all of the median nerve pass through the carpal tunnel *
no - gives branch that stays superficial and supplies the palm
describe the ulnar and medial supply to the hand
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
what is the effect of carpal tunnel syndrome *
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
describe teh path of the long thoracic nerve *
comes from c5 6 7
emerges from the root of the neck over the serratus anterior
is relatively superficial - therefore easily damaged
describe attachments of the serratus anterior muscle *
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
how would you damage the long thoracic nerve *
car accident
stabbed in this region
effect of damage to the long thoracic nerve *
pressing against a wall will lead to winging of the scapula resulting from the loss of activity from the serratus anterior
what is injury to the upper roots called *
Erb-Duchenne palsy
what type of injury would damage upper roots *
falling on head
injuries during birth - pulled out by head, motorcycle injury
stretch the neck relative to the shoulder
damage c 5 6
what is damaged in the upper root injuries *
anything to the upper trunks - ie c5 6
effect of damage to the upper roots *
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
example of injury that would cause lower root injury *
during birth - pull out by arm
over abduction due to gripping overhead to break fall
what are lower root injuries *
damage to T1 and sometimes T8
called Klumpke’s palsy
‘klumpe’s monkey falls from a tree’
posterior and middle cords are affected
what will the outcomes be of a lower root injury *
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
what is the function of the brachial plexus
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
function of the lateral pectoral nerve
supplies pec major
comes of lateral cord of brachial plexus
function of the medial pectoral cord
from medial cord to supply pec minor
what is the artery supply to the scapular region *
it is form the suprascapular and transverse cervical arteries - branches of the thyrocervical trunk from the 1st part of the subclavian artery
describe the arterial supply of the upper limb*
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
describe the venous drainage of the upper limb*
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
where can you palpate the nerves
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
identify the nerves in the body *
pic from living anatomy
effect of damage to the median nerve *
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
what causes a true claw *
ulnar and median nerve damage c5-T1 roots
clawing in all 4 fingers with thumb abducted
effect of damage to the musculocutaneous nerve *
elbow flexors are effected
loss of sensation on lateral side of forearm up to wrist
describe frozen shoulder
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
describe shoulder impingement syndrome
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
describe tennis elbow
injury to extensor tendons on lateral epicondyle
because of sharp flexion of the wrist while extensors are contracted
golfer’s elbow
similar to tennis but common flexor attachment on medial epicondyole is strained
cause - sharp flexion of elbow
cause of mallet finger
avulsion of extensor igitorum longus tendon at base of distal phalanx
game keepers thumb
damage to medial collateral ligament of 1st MPJs by violent abduction
thumb becomes unstable
trigger finger
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
colle’s fracture
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
osteoarthritis
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
rheumatoid arthritis
chronic inflammatory synovitis of peripheral joints
immunological casue
swelling of joints
joint deformity
loss of function
