nerve injury of the upper limb

Question 1

what is the general cause of lesions of the upper trunk brachial plexus also known as erbs palsy

Answer 1

Excessive displacement of the head to opposite side and depression of shoulder on the same side (falling of motorbike or difficult during baby delivery)

Question 2

trauma to the c5,c6,c7 of the plexus can cause major issues such as ?

Answer 2

C5 is responsible for shoulder abduction , elbow flexion and sensation over lateral arm
C6 is responsible for wrist extension and sensation over lateral forearm, thumb and index.
C7 is responsible for elbow extension, wrist flexion and sensation over middle finger.

Question 3

trauma will cause sensory loss in which nerves?

Answer 3

axillary nerve and musculo-cutaneous nerve)

Question 4

many upper trunk muscles can be lost due to motor paralysis give some examples

Answer 4

Abduction of shoulder is lost because of paralysis of supraspinatus & deltoid.
Lateral rotation of shoulder is lost because of paralysis of infraspinatus and teres minor.

Question 5

what will loss of elbow extension lead to

Answer 5

paralysis of biceps and major part of brachialis.

Question 6

which muscles and skin sections does the musculocutaneous nerve supply

Answer 6

It supplies coracobrachialis, biceps and brachialis muscles & the skin of lateral forearm.

Question 7

what would cause a injury of the musculocutaneous nerve

Answer 7

• Penetrating injury of the arm

- Following shoulder surgical operations

Question 8

what effects would be seen with injury to the musculocutaneous nerve

Answer 8

Weak flexion of the elbow > lateral part of brachialis
Weak supination > supinator
Tingling, numbness over the skin of lateral part of the forearm.

Question 9

which cord of the brachial plexus does the axillary nerve come from?

Answer 9

the posterior cord of the brachial plexus

Question 10

what could cause an injury to the axillary nerve

Answer 10

Fracture surgical neck of humerus

Shoulder joint dislocation

Question 11

what would result in injury to the axillary nerve

Answer 11

Loss arm contour & loss of abduction from 15 to 90 °
Weak lateral rotation (loss of teres minor action).
Loss of sensation of the skin over the lower part of deltoid muscle.

Question 12

relate the positions of the median nerve to the brachial artery in the upper and lower arm

Answer 12

In upper arm, the median nerve is lateral to the brachial artery.
In lower arm, it is medial to the artery and lies anterior to the elbow joint.

Question 13

the cubital fossa has 2 nerves what are they

Answer 13

Anterior interosseous nerve.

Palmar cutaneous branch.

Question 14

what does the anterior interosseous nerve innervate

Answer 14

It innervates flexor pollicis longus, the lateral 1/2 of flexor digitorum profundus, and pronator quadratus

Question 15

what does the palmar cutaneous branch innervate

Answer 15

It supplies the lateral 2/3 of the skin of the palm of the hand

Question 16

why is the palmar cutaneous branch not affected by carpal tunnel syndrome

Answer 16

it passes into the hand superficial to the flexor retinaculum of the wrist, avoiding the carpal tunnel

Question 17

what causes anterior interosseous syndrome

Answer 17

Deep open trauma to the forearm (stab wound / reduction of forearm fracture).
Auto –immune inflammation (Rheumatoid).
Elbow dislocation.

Question 18

what is the main effect of having anterior interosseous nerve syndrome

Answer 18

Weak thumb and index flexion (weak pincer grip).

Question 19

how does nerve distribution occur at the wrist

Answer 19

Recurrent neve supplies the supplies the thenar muscles.
Palmar digital branches supply the palmar surface of the lateral 3 and half fingers reaching the dorsal aspect of their distal phalanges + the lateral 2 lumbricals.

Question 20

what are some symptoms of carpal tunnel syndrome

Answer 20

Tingling & numbness sensation in the lateral 3 ½ fingers due to compression of the median nerve in the carpal tunnel.

Question 21

what would occur if injury to the median nerve occurs at the elbow

Answer 21

1. Loss of pronation (loss of function of both pronator teres & quadratus).
2. Weak wrist flexion with adduction (made by the flexor carpi ulnaris & medial ½ of profundus) & loss of the other flexors.
3. Ape hand (thumb is adducted ,extended, can’t oppose the other fingers) due loss of function of thenar muscles (loss of thenar eminence contour).
4. Loss of sensation of all skin areas supplied by it.

Question 22

what would occur if injury to the median nerve occurs at the wrist

Answer 22

1. Ape hand (thumb is adducted ,extended, can’t abduct, flex or oppose the other fingers) due loss of function of thenar muscles.
2. Loss of sensation of palmar surface of the lateral 3 ½ fingers reaching the dorsal aspect of their distal phalanges