MSK ILS 5 / TBL 8: Brachial Plexus

pronator teres

median

palmaris longus

flexion at wrist

median

flexor carpi radialis

flexion & adduction of wrist

median

flexor digitorum superficialis

flexion at proximal interphalangeal joints 2nd-5th fingers

median

pronator quadratus

median

flexor digitorum profundus

flexion of wrist at metacarpophalangeal & interphalangeal joints

median & ulnar

flexor pollicis longus

flexion at thumb phalanges

median

flexor pollicis brevis

flexion at metacarpophalangeal joint

median

abductor pollicis brevis

median

opponens pollicis

median

1st & 2nd lumbricals

flexion at metacarpophalangeal joint, while extending interphalangeal joints of index & middle fingers

median

brachioradialis

weak flexion of forearm

radial

extensor carpi radialis longus, brevis

extension & abduction of wrist

radial

supinator

radial

extensor carpi ulnaris

extension & adduction of wrist

radial

all other extensor muscles

radial

abductor pollicis longus

radial

flexor carpi ulnaris

flexion & adduction at wrist joint

ulnar

palmaris brevis

tenses skin of palm during gripping action

ulnar

dorsal interossei

abduction of 2nd to 4th fingers

ulnar

palmar interossei

adduction of 2nd to 4th fingers

ulnar

adductor pollicis

ulnar

3rd & 4th lumbricals

flex at metacarpophalangeal joints while extending at interphalangeal joints

ulnar

cutaneous branches of ulnar nerve

1. medial brachial cutaneous nerve

2. medial antebrachial cutaneous nerve

cutaneous branches of radial nerve

1. posterior brachial cutaneous nerve

2. posterior antebrachial cutaneous nerve

3. inferolateral brachial cutaneous nerve

cutaneous branches of axillary nerve

1. superolateral brachial cutaneous nerve

cutaneous branches of musculocutaneous nerve

1. lateral antebrachial nerve

middle subscapular nerve is also known as

thoracodorsal nerve

lateral pectoral nerve

• innervates pectoralis major [adducts & medially rotates humerus]

• some fibers pass to pectoralis minor via branch to medial pectoral nerve

• innervates AC and shoulder joint

medial pectoral nerve

• passes btwn axillary artery & axillary vein

• pierces pectoralis minor, & enters deep surface of pectoralis major

• lies lateral to lateral pectoral nerve

• innervates pec minor [depresses point of shoulder, draws scapula superior toward thorax & moves its inferior angle posteriorly]

• innervates pec major sternocostal part

carpal tunnel syndrome

compression of median nerve

• tingling, burning, & needle/pin pain over outer fingers

• radiating up arm w/ weakness in thumb & first 2 fingers

supracondylar fracture

median nerve injury

hand of benediction

fracture of mid-shaft of radial groove

radial nerve injury

fracture to lateral epicondyle of humerus

radial nerve injury

improper crutches use

radial nerve injury

saturday night palsy

radial nerve injury

radial nerve injury →

wrist drop

loss of sensory & motor functions in posterior arm, forearm & hand

which nerves are lateral and medial to brachial artery?

lateral - median nerve

medial - ulnar nerve

canal of guyon

space at ulnar [medial] border of wrist created by superficial part of flexor retinaculum btwn pisiform bone & hook of hamate bone

possible site of compression of ulnar nerve

houses ulnar nerve and artery [nerve medial to artery]

guyon tunnel syndrome

compression of ulnar nerve → weakness of innervated muscles in distal forearm and hand

fracture of medial epicondyle of humerus

ulnar nerve injury → numbness & tingling in little & ring fingers [funny bone sensation]

brachial plexus nerves pass between which 2 muscles?

scalenus anterior

scalenus medius

trunks cross the

posterior triangle of the neck

transverse laterally

divide into anterior & posterior divisions

divisions leave posterior triangle and pass into axilla

cords name for

their position relative to axillary artery

axillary sheath

connective tissue wrapping enclosing the brachial plexus & axillary blood vessels

roots, trunks, & divisions reside

supraclavicular

cords reside

infraclavicular

damage to musculocutaneous nerve may result from

overuse of muscles innervated by it

trauma to nerve

violent abduction of shoulder

erb-duchenne palsy

• injuries to upper [superior] part of brachial plexus [C5 & C6]

• causes

  • excess stretching of neonate neck [shoulder dystocia]

  • fall landing on shoulder

  • prolonged hyperduction of arm

  • compression of nerves

• symptoms

  • affect limb hangs limply, adducted & medially rotated at shoulder joint due to unopposed action of pectoralis major

  • excess extension at elbow joint

  • forearm pronated due to loss of biceps

  • wrist weakly flexed [waiter’s tip position]

• nerves often affected

  • suprascapular, subclavian, axillary, musculocutaneous

klumpke’s paralysis

• injuries to [inferior] part of brachial plexus [C8 & T1]

• causes

  • upper limb suddenly pulled superiorly

  • neonates upper limb pulled excessively [hard vaginal delivery]

  • injury/avulsion to roots

• nerves affected

  • median & ulnar

• affects intrinsic muscles of hand

• symptoms

  • claw hand appearance