Arm anatomy + brachial plexus

Question 1

what structures are injured from sudden upward jerking motion of arm (e.g. bracing fall by grabbing tree branch)

Answer 1

lower trunk of brachial plexus - C8-T1
median and ulnar nerves are damaged (some radial)
lumbercals of hand and all interosseous muscles don’t work - TOTAL CLAW hand (difficulty with fine finger movements)
sensory loss over medial hand and forearm

Question 2

associated symptoms from shoulder dislocation and fracture to the proximal humerus?

Answer 2

axillary nerve damage - weakness of deltoid and teres minor - can’t abduct arm

Question 3

what is commonly injured with axillary lymph node removal?

Answer 3

long thoracic nerve - paralysis of serratus anterior

winged scapula and impaired arm abduction beyond 90 degrees

Question 4

what is consequence of injury to musculocutaneous nerve?

Answer 4

impaired arm flexion at the elbow and impaired supination (biceps, brachialis, coracobracialis)

Question 5

fraction to the midshaft of the humerus injurs what nerve?

Answer 5

radial nerve

wrist drop (paralysis of wrist extensors), impaired

extension of the arm (triceps and brachioradialis)

and posterior foram and dorsolateral hand sensory loss

Question 6

initial abduction is mediated by _____
horizontal abduction is mediated by _____ and ____
above horizontal abduction is mediated by ____ and __

Answer 6

supraspinatus
supraspinatus + deltoid
serratus anterior + trapezius

Question 7

what two muscles are innervated by the suprascapular nerve?

Answer 7

suprascapular muscle => abduction

infraspinatus muscle => lateral rotation

Question 8

what is damaged by supracondylar fracture of humerus?

Answer 8

proximal median nerve injury (C5-T1) - loss of thumb opposition, wrist flexion, flexion of lateral fingers and loss of lumbercals of 2nd and 3rd digits

Question 9

2nd and 3rd fingers stay extended when trying to make a fist. What is the injury?

Answer 9

proximal median nerve injury - supracondylar fracture of humerus

Question 10

2nd and 3rd fingers remain flexed while hand in relaxed. What is the injury?

Answer 10

distal median nerve injury (e.g. wrist laceration)

Question 11

what injury could cause loss of thenar muscle group, loss of opposition abduction and flexion of thumb, with no sensory loss?

Answer 11

palm laceration that damages recurrent branch of medial nerve

Question 12

pt. presents with flattened deltoid, loss of arm abduction at shoulder (>15 degees) and loss of sensation over deltoud muscle and lateral arm. What was the injury?

Answer 12

fractured surgical neck of humerus or anterior dislocation of the shoulder – damage to axillary nerve

Question 13

What nerve and artery are located near:

axilla/lateral thorax

Answer 13

long thoracic nerve, lateral thoraci artery

Question 14

What nerve and artery are located near:

surgical neck of humerus

Answer 14

axillary nerve, posterior circumflex artery

Question 15

What nerve and artery are located near:

midshaft of humerus

Answer 15

radial nerve, deep brachial artery

Question 16

What nerve and artery are located near:

distal humerus/cubital fossa

Answer 16

median nerve, brachial artery

Question 17

What nerve and artery are located near:

popliteal fossa

Answer 17

tibial nerve, popliteal artery

Question 18

What structures does the median nerve travel through in the forarm before reaching the carpel tunnel and passing under the flexor retinaculum?

Answer 18

gains access to the forarm at the medial aspect of the antecubital fossa and immediately courses between the humeral and ulnar heads of the pronator teres muscle at the very proximal foram. It then travels between the flexor digitorum superficialis and flexor digitorum profundus along the arm before entering the wrist withing the flexor retinaculum.

proximal median nerve injury may result from supracondylar humerus fracture or entrapment between the pronator teres

findings: sensory loss in the median nerve distribution with weakness on thumb flexion/opposition, flexion of the second/third digits and weakness with wrist flexion/abduction

Question 19

what nerve penetrates the coracobrachialis muscle and intially corses between the biceps brachii and coracobrachialis muscle before descending toward the elbow between the biceps and brachials muscles? injury would cause ____?

Answer 19

musculocutaneus nerve

paralysis of elbow flexors (biceps, brachialis and coracobrachialsis) and loss of sensation over the lateral forearm.

Question 20

what nerve travels through the supinator muscle?

Answer 20

radial nerve