Muscles of the arm and cubital fossa

Question 1

Describe the origin, insertion and nerve innervation of the coracobrachialis;

Answer 1

'O' = Coracoid process
'I' = Medial side of humerus opposite deltoid tuberosity

nerve = Musculocutaneous

Question 2

Describe the origin, insertion and nerve innervation of the brachialis;

Answer 2

‘O’ = Anterior surface of the distal humerus (including intermuscular septa)

‘I’ = Tuberosity of ulna

Nerve = musculocutaneous

Question 3

What nerves innervate the posterior compartment?

Answer 3

Radial nerve

Question 4

Describe the origin, insertion and nerve innervation of the biceps brachii;

Answer 4

Origin;
Long head; Supraglenoid tubercle
Short head; Coracoid process

Insertion; radial tuberosity and biceptial aponeurosis

Nerve = Musculocutaneous

Question 5

Describe the movement of the different deltoid fibres;

Answer 5

Anterior fibres:

• Flex shoulder
• Internally rotates arm
• Abduct/adducts the arm (depends on position)

Posterior fibres:

• Extend shoulder
• Externally rotates arm
• Abduct/adducts arm (depends on position)

Middle fibres
- Abducts arm

Question 6

Describe the deltoid fibres;

Answer 6

Anterior fibres (Unipennate)
Posterior fibres (unipennate)
Middle fibres (Multipennate) 

Unipennate = Strong
Multipennate = Very strong

Question 7

Describe the borders of the cubtal fossa;

Answer 7

Superior border is formed by the ‘line’ between the lateral and medial epicondyles

Medial border; Pronator teres

Lateral boundary; Brachioradialis.

Question 8

Describe teres major origin, insertion and nerve innervation;

Answer 8

'O' = Inferior angle and lateral border of scapula
'I' = Medial lip of intertubercular groove

Nerve = Lower subscapular

Question 9

What muscles are found in the posterior compartment?

Answer 9

Triceps brachii

Question 10

Describe the origin and insertion of the deltoid;

Answer 10

'O' = Anatomical horseshoe
'I' = Deltoid tuberosity

Question 11

Describe the compartments of the brachium;

Answer 11

Posterior and anterior compartments at the mid level of the humerus.

At the distal end of the humerus there is also Ext./Sup. compartment on the lateral side and Flex./Pro. compartment of the medial side.

Question 12

What nerve innervates the anterior compartment?

Answer 12

Musculocutaneous nerve

Question 13

What muscles are found in the anterior compartment of the arm?

Answer 13

Biceps brachii
Coracobrachialis
Brachialis

Question 14

Describe the origin, insertion and nerve innervation of the triceps brachii;

Answer 14

‘O’

• Long head = Infraglenoid tubercle
• Medial head = medial aspect of humerus
• Lateral head = Lateral aspect of humerus

‘I’ = Olecranon (Ulna)

Nerve = Radial nerve.