Radial & medial nerve (411-424)

Question 1

Describe how injury to the posterior interosseous nerve presents clinically;

Answer 1

(aka deep radial nerve). Motor only. No sensory loss. Majority muscles posterior forearm affected. Wrist drop does not occure as the extensor carpi radialis longus is unaffected and maintains some extension at the wrist.

Question 2

What would be the signs and symptoms in a patient with musculocutaneous nerve injury?;

Answer 2

Motor -Biceps, Brachialis and Coracobrachialis (BBC) affected (Elbow flexion weakened but pectoralis major and brachioradialis can perform) Loss of sensation lateral part of forearm

Question 3

What is the root value of the radial nerve?;

Answer 3

C5-T1

Question 4

Name the muscles innervated by the radial nerve and its branches;

Answer 4

Upper arm (3)- Triceps, brachioradialis, extensor carpi radialis longus.

Deep branch of radial nerve (2)- extensor carpi radialis brevis, supinator.
Posterior interosseous nerve (7) (continaute of deep after supinator)- extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, extensor indicis.
{Snuff box border muscles- pollicis ones}- abductor pollicis longus, extensor pollicis brevis & extensor pollicis longus,

Question 5

What is the root value of the median nerve;

Answer 5

C5-T1

Question 6

Name the branches of the median nerve;

Answer 6

Anterior interosseous nerve (deep muscles of anterior forearm),

Recurrent brach (theanar muscles LOAF).

Palmar cutaneous nerve (skin of the lateral palm).
Palmar digital nerves (palmar surface and fingertips of lateral three and half digits)

Question 7

How would you assess a patietn for a medial nerve injury?;

Answer 7

Palmar cutaneous branch- sensation to palmer medial three and half digits.
Motor- reccurrent motor branch (abduction of thumb to little finger tip [assesses LOAF muscle- abductor pollicis brevis]),
Anterior interosseous branch (OK sign).

Phalen’s test (reverse hand back to back - tests for carpal tunnel syndrome).
Tinels test (tests for carpal tunnel sydrome).

Question 8

What is the nerve is the motor supply to the thenar eminence muscles?;

Answer 8

Reccurrent branch of median branch

Question 9

Name the muscles innervated by the anterior interosseous nerve;

Answer 9

3 deep muscles of the anterior forearm- flexor pollicus longus, pronator quadratus and lateral half of the flexor digitorum profundus (the medial half is by ulnar nerve)

[Abnormality in OK sign due to paralysis of flexor digitorum profundus and flexor pollicus longus]

Question 10

How would you assess a patient for an anterior interosseous nerve injury?;

Answer 10

Okay sign

(asseses flexor digitorum profudus [lateral half (remember ulnar half by ulnar nerve)] and flexor pollicus longus]

Question 11

What are the boundaries of the quadrangular space?;

Answer 11

Superior- teres minor (inferior margin). Lateral- surgical neck of humerus. Medial- long head of triceps. Inferior- teres major (superior aspect)

Question 12

Name the structures that pass through the quadrangular space;

Answer 12

Axillary nerve. Posterior circumflex humeral artery and vein.

Question 13

What are the boundaries of the triangular interval?;

Answer 13

Superior- teres major (inferior border). Lateral- Shaft of humerus and lateral head of triceps. Medial- long head of triceps (lateral border)

Question 14

What are the contents of the triangular interval?;

Answer 14

Radial nerve and profunda brachii artery.