Nerves of the anterior compartment of the arm and forearm

Question 1

What are the nerves of the anterior compartment of the arm and forearm?

Answer 1

• Median nerve
• Ulnar nerve
• Musculocutaneous nerve
• Lateral cutaneous nerve of the forearm
• Medial cutaneous nerve of the arm
• Medial cutaneous nerve of the forearm
• Radial nerve

Question 2

Describe the route of the median nerve in the arm

Answer 2

1) Descend arm lateral to brachial artery
2) Halfway down, it crosses and becomes medial
3) Enter cubital fossa
4) Travel down further between two heads of pronator teres
5) Gives off palmar cutaneous branch (travels above carpal tunnel)
6) Main branch enter via carpal tunnel and give tow end branches (recurrent branch and palmar digital branch)

Question 3

What does the recurrent branch of the median nerve innervate?

Answer 3

Thenar muscles (by thumb) except adductor pollicis and deep head of flexor pollicis brevis

Question 4

What does the palmar digital branch of the median nerve innervate?

Answer 4

Palmar surface and fingertips of the radial three and a half digits

Question 5

Describe the route of the ulnar nerve in the arm

Answer 5

1) Descend arm medially
2) Pass posterior to medial epicondyle of humerus (cubital tunnel)
3) Pass between two heads of the flexor carpi ulnaris
4) Gives off palmar cutaneous branch and dorsal cutaneous branch
5) Enter the wrist via Guyon’s canal (superficial to flexor retinaculum)

Question 6

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

Answer 6

Ulnar third of the palm

-Pinky and half of ring finger

Question 7

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

Answer 7

Dorsal surface of pinky finger and half of ring finger

Question 8

What does the musculucutaneous nerve innervate?

Answer 8

Muscles of the anterior arm

• Biceps brachii
• Brachialis
• Coracobrachialis

Question 9

Where is the lateral cutaneous nerve of the forearm come from and what does it innervate?

Answer 9

Continuation of the musculocutaneous nerve that is purely sensory
-Lateral forearm

Question 10

Describe the route of the musculocutaneous/lateral cutaneous nerve of the forearm

Answer 10

1) Musculocutaneous leave axilla and gives branches to corresponding muscles it innervates
2) Pierces through deep fascia lateral to biceps brachii and becomes lateral cutaneous nerve of the forearm

Question 11

Describe the route of the radial nerve

Answer 11

1) Exit the axilla posterior to axillary artery
2) Enter radial groove (spiral) of the humerus and travel inferolaterally
3) Gives two cutaneous nerves
4) Emerge from radial groove on the lateral side
5) Travel anterior to lateral epicondyle of humerus
6) Terminates into two branches in the cubital fossa

Question 12

What are the two terminal end branches of the radial nerve in the cubital fossa?

Answer 12

• Deep branch (motor)

- Superficial branch (sensory) for the dorsal hand