Nerves

Question 1

What is the root value range for the radial nerve?

Answer 1

C5 to T1

The radial nerve is a continuation of the posterior cord of the brachial plexus.

Question 2

In the axilla, where does the radial nerve lie in relation to the axillary artery?

Answer 2

Posterior

It lies on subscapularis, latissimus dorsi, and teres major.

Question 3

Where does the radial nerve enter the arm?

Answer 3

Between the brachial artery and the long head of triceps

This occurs medial to the humerus.

Question 4

What is the path of the radial nerve as it spirals around the humerus?

Answer 4

Spirals around the posterior surface in the groove for the radial nerve

At the distal third of the lateral border of the humerus, it pierces the intermuscular septum.

Question 5

At the lateral epicondyle, where does the radial nerve lie?

Answer 5

Deeply between brachialis and brachioradialis

It then divides into a superficial and deep terminal branch.

Question 6

What does the deep branch of the radial nerve become after crossing the supinator?

Answer 6

Posterior interosseous nerve

This branch innervates several muscles in the forearm.

Question 7

Name the motor innervations of the radial nerve.

Answer 7

• Triceps
• Anconeus
• Brachioradialis
• Extensor carpi radialis

The posterior interosseous branch also innervates several muscles.

Question 8

What are the muscles innervated by the posterior interosseous branch of the radial nerve?

Answer 8

• Supinator
• Extensor carpi ulnaris
• Extensor digitorum
• Extensor indicis
• Extensor digiti minimi
• Extensor pollicis longus and brevis
• Abductor pollicis longus

These muscles are primarily responsible for wrist and finger extension.

Question 9

What area does the radial nerve supply sensory innervation to?

Answer 9

Proximal phalanges on the dorsal aspect of the hand

This does not include the little finger and part of the ring finger.

Question 10

What is the effect of denervation of the long head of triceps?

Answer 10

Minor effects on shoulder stability in abduction

This is due to the anatomical location of the muscle.

Question 11

What is the effect of paralysis of the triceps muscle?

Answer 11

Loss of elbow extension

This occurs when the radial nerve is damaged in the arm.

Question 12

What are the effects of denervation on the forearm muscles innervated by the radial nerve?

Answer 12

• Weakening of supination of prone hand
• Elbow flexion in mid prone position

Affected muscles include supinator, brachioradialis, and extensor carpi radialis longus and brevis.

Question 13

What is a common pattern of damage associated with radial nerve injury?

Answer 13

Wrist drop

This condition results from paralysis of the extensor muscles of the wrist.

Question 14

What sensory loss occurs with radial nerve damage?

Answer 14

Small area between the dorsal aspect of the 1st and 2nd metacarpals

This area is affected due to the sensory innervation provided by the radial nerve.

Question 15

What happens in the case of axillary damage to the radial nerve?

Answer 15

Paralysis of triceps

This results in similar effects as above, including loss of elbow extension.

Question 16

The ulnar nerve arises from which part of the brachial plexus?

Answer 16

medial cord (C8, T1)

The ulnar nerve is a major peripheral nerve of the upper limb.

Question 17

What are the motor functions of the ulnar nerve?

Answer 17

• medial two lumbricals
• aDductor pollicis
• interossei
• hypothenar muscles: abductor digiti minimi, flexor digiti minimi
• flexor carpi ulnaris

These muscles are primarily involved in fine motor control of the hand.

Question 18

What are the sensory functions of the ulnar nerve?

Answer 18

medial 1 1/2 fingers (palmar and dorsal aspects)

This includes sensation to the little finger and half of the ring finger.

Question 19

Describe the path of the ulnar nerve.

Answer 19

travels through the posteromedial aspect of the upper arm to the flexor compartment of the forearm, enters the palm via Guyon’s canal

It is located superficial to the flexor retinaculum and lateral to the pisiform bone.

Question 20

What does the muscular branch of the ulnar nerve supply?

Answer 20

• Flexor carpi ulnaris
• Medial half of the flexor digitorum profundus

These muscles are involved in flexing the wrist and fingers.

Question 21

What does the palmar cutaneous branch of the ulnar nerve supply?

Answer 21

skin on the medial part of the palm

This branch arises near the middle of the forearm.

Question 22

What does the dorsal cutaneous branch of the ulnar nerve supply?

Answer 22

dorsal surface of the medial part of the hand

This branch provides sensory innervation to the back of the hand.

Question 23

What does the superficial branch of the ulnar nerve supply?

Answer 23

cutaneous fibres to the anterior surfaces of the medial one and one-half digits

This includes sensory innervation to the little finger and half of the ring finger.

Question 24

What does the deep branch of the ulnar nerve supply?

Answer 24

• Hypothenar muscles
• All the interosseous muscles
• Third and fourth lumbricals
• Adductor pollicis
• Medial head of the flexor pollicis brevis

These muscles are crucial for hand movements and grip.

Question 25

What is the **pattern of damage** at the wrist for the ulnar nerve?

Answer 25

'claw hand' - hyperextension of the metacarpophalangeal joints and flexion at the distal and proximal interphalangeal joints of the 4th and 5th digits ## Footnote This condition results from paralysis of intrinsic hand muscles.

Question 26

What occurs with **damage at the elbow** to the ulnar nerve?

Answer 26

as above (however, ulnar paradox - clawing is more severe in distal lesions), radial deviation of wrist ## Footnote The ulnar paradox refers to the phenomenon where clawing is more pronounced with distal lesions.

Question 27

What does the **sciatic nerve** divide into?

Answer 27

* Tibial nerve * Common peroneal nerve ## Footnote The division occurs in the lower limb, leading to different nerve functions.

Question 28

Where does injury to the **common peroneal nerve** often occur?

Answer 28

At the neck of the fibula ## Footnote This location is particularly vulnerable to injury due to its proximity to the bone.

Question 29

What is the most characteristic feature of a **common peroneal nerve lesion**?

Answer 29

Foot drop ## Footnote Foot drop is a condition where the individual cannot lift the front part of the foot.

Question 30

List other features of a **common peroneal nerve lesion**.

Answer 30

* Weakness of foot dorsiflexion * Weakness of foot eversion * Weakness of extensor hallucis longus * Sensory loss over the dorsum of the foot and the lower lateral part of the leg * Wasting of the anterior tibial and peroneal muscles ## Footnote These features indicate the extent of nerve damage and its impact on muscle function and sensation.