MSK - Upper Limb 2

Question 1

Can you name 16 sites on the humerus? Roughly from proximal -> Distal?

Answer 1

Head - articulates with scapula
Anatomical neck - posterior to head
Greater tubercle - prominence lateral at proximal end
Lesser Tubercle - Prominence medial at proximal end
Intertubecular sulcus - sulcus between tubercles
Surgical Neck - Narrowing between tubercles & shaft
Shaft
Deltoid tuberosity - prominence on ant middle shaft
Radial Groove - Groove on post shaft for radial nerve
Lateral & Medial epicondyles - prominences on medial/lateral distal humerus
Capitulum - rounded prominence on anterolateral distal humerus
Trochlea - prominence on anteromedial distal humerus (articulates with ulna)
Radial fossa - Fossa above capitulum
Coronoid fossa - fossa above trochlea
Olecranon fossa - Fossa above trochlea posteriorly that holds ulnar olecranon process

Question 2

Heres some points to make it easier to spot the different arm nerves

Answer 2

Ulnar - passes over the medial epicondyle
Median - Tightly follows the brachial artery
Musculocutaneous - Tight to the underside of the biceps

Question 3

What are the muscles of the anterior (flexor) compartment of the arm?

Answer 3

Biceps Brachii
Coracobrachialis
Brachialis

Question 4

Describe the attachments of the biceps brachii?

Answer 4

Arises from 2 heads:

• Short head arises from coracoid process of scapula
• Long head arises from supraglenoid tubercle of scapula

Inserts on radial tuberosity distally

Question 5

What is the action of the biceps brachii?

Answer 5

Flexes shoulder & elbow

Supinates proximal radio-ulnar joint

Question 6

Nerve supply of the biceps brachii?

Answer 6

Musculocutaneous nerve which arises from the lateral cord or C5-7.

Question 7

Describe the attachments of the coracobrachialis?

Answer 7

Arises from the tip of the coracoid process (along with the short head of the biceps)
Inserts onto medial humerus at the middle of the shaft.

Question 8

Actions of the coracobrachialis?

Answer 8

Flexion & Adduction of shoulder

Question 9

Nerve supply of the coracobrachialis?

Answer 9

Musculocutaneous nerve - Lateral cord (C5-7)

Question 10

Attachments of the brachialis?

Answer 10

Arises from anterior distal humeral shaft.

Inserts onto coronoid process of ulna

Question 11

Action of the brachialis?

Answer 11

Flexion of elbow

Question 12

Innervation of brachialis?

Answer 12

Musculocutaneous

Question 13

Where does the musculocutaneous arise and travel?

Answer 13

Arises from lateral cord of brachial plexus (C5-7)
It perforates the coraco-brachialis to enter the ant compartment of the arm.
Then descends between biceps & brachialis.

Question 14

What happens to the musculocutaneous nerve after it supply’s the anterior compartment of the arm with innervation?

Answer 14

It continuous as the lateral cutaneous nerve of the forearm.

Question 15

What does the musculocutaneous nerve supply?

Answer 15

Ant Muscle compartment of the forearm:

• Brachialis
• Biceps Brachii
• Coracobrachialis

Also cutaneous sensation to the lateral forearm

Question 16

What happens if the musculocutaneous nerve is damaged?

Answer 16

Paralysis of shoulder/elbow flexors and loss of sensation to the lateral forearm

Question 17

When do the axillary artery and then brachial artery start?

Answer 17

Subclavian -> Axillary at the lateral border of the 1st rib

Axillary -> Brachial at the inf margin of the Teres Major

Question 18

When does the brachial artery end?

Answer 18

It divides into the radial & ulnar arteries at the cubital fossa

Question 19

If there is major haemorrhage of the arm how would you compress the artery to prevent blood loss?

Answer 19

Compress the brachial artery at the middle of the arm

Question 20

From where does the median nerve arise?

Answer 20

From the medial and lateral cords of the brachial plexus. With roots in C5/6 + C8/T1