L3 The arm and elbow

Question 1

What does each branch of the brachial plexus innervate?

Answer 1

Musculocutaneous (C5-C7): anterior compartment of arm

Axillary (C5, C6): deltoid and teres minor

Radial (C5-T1): extensors of arm and forearm

Median (C6-T1): most flexors of anterior arm, some intrinsic hand muscles

Ulnar (C8, T1): some flexors of anterior arm, most intrinsic hand muscles

Question 2

Mid shaft fracture of humerus potentially risks which nerve?

Answer 2

Radial nerve

Question 3

In which age group are supracondylar fractures most common?

a) children
b) young adults
c) middle aged adults
d) elderly

Answer 3

a) children

Question 4

What immediate risks are posed by a supracondylar fracture?

Answer 4

Injury to median nerve and brachial artery (and potentially causing ischaemia in forearm)

Question 5

Which three bones compose the elbow?

Answer 5

Humerus

Ulna

Radius

Question 6

Which bones articulate at the elbow?

Answer 6

Humeroulnar joint: trochlea of humerus, trochlear notch of ulna

Humeroradial joint: capitulum of humerus and radial head

Question 7

Which joint allows supination/pronation of the forearm?

Answer 7

Supination and pronation of the forearm occurs at the radioulnar joint.

Question 8

What structure reinforces the elbow joint medially and laterally?

Answer 8

Elbow is reinforced laterally by the radial collateral ligament and medially by the ulnar collateral ligament

Question 9

What are the attachments and functions of biceps brachii?

Answer 9

Origin: Scapula (short head coracoid process, long head supraglenoid tubercle)

Insertion: Radius (tuberosity of radius) and bicipital aponeurosis

Functions:

• Flexion at elbow and shoulder
• Powerful supinator
• Short head resists shoulder dislocation

Question 10

What are the attachments and functions of brachialis?

Answer 10

Origin: Shaft of humerus (distal half or anterior side)

Insertion: Coronoid process and ulnar tuberosity