Muscles of the Arm

Question 1

Name the muscles of the arm and the compartments in which they are found

Answer 1

Anterior compartment
1. Biceps brachii
2. Coracobrachialis
3. Brachialis

Posterior compartment
1. Triceps brachii

Question 2

What artery supplies the anterior compartment?

Answer 2

Muscular branches of the brachial artery

Question 3

Origin of Biceps Brachii

Answer 3

has 2 heads

1. Long head - by a long tendon from the supraglenoid tubercle of the scapula
2. Short head - arises from the tip of the coracoid process of the scapula (by a common tendon with coracobrachialis)

Question 4

Insertion of Biceps Brachii

Answer 4

1. Biceps tendon - short strong tendon inserted into the posterior rough surface of the radial tuberosity
2. Bicipital aponeurosis - arises from the medial side of the biceps tendon and is inserted into the deep fascia of the medial side of upper part of forearm.

Question 5

Functions of the Bicipital Aponeurosis

Answer 5

1. Separates the medial cubital vein (superficial to it) from the brachial artery and the median nerve (deep to it)
2. Protects the underlying structures (brachial artery and the median nerve)
3. Stretches the deep fascia of the forearm

Question 6

Nerve supply to the Biceps Brachii

Answer 6

Musculocutaneous nerve, with each head supplied separately

Question 7

Actions of the Biceps Brachii

Answer 7

1. Powerful supinator and flexor of the forearm
2. Flexion of the arm
3. The long head of biceps brachii steadies the head of the humerus on the glenoid cavity during abduction of the shoulder joint
4. The bicipital aponeurosis stretches the deep fascia of the forearm and protects the brachial artery and the median nerve

Question 8

Origin of the Coracobrachialis

Answer 8

From the tip of the coracoid process of the scapula (by a common tendon with the short head of biceps brachii)
It descends along the medial side of biceps brachii

Question 9

Insertion of Coracobrachialis

Answer 9

Inserted into the middle of the medial border of the humerus

Question 10

Nerve supply to Coracobrachialis

Answer 10

Branch from Musculocutaneous nerve, before it pierces the muscle

Question 11

Actions of Coracobrachialis

Answer 11

It is a weak flexor and adductor of the arm

(represents the adductor muscle mass of the upper limb)

Question 12

Origin of Brachialis

Answer 12

1. From the lower half of the front of the humerus
2. From the medial and lateral intermuscular septa of the arm

Question 13

Insertion of Brachialis

Answer 13

By a short thick tendon into the ulnar tuberosity (on the anterior surface the coronoid process of ulna)

Question 14

Nerve supply of Brachialis

Answer 14

1. Medial part - Musculocutaneous nerve
2. Lateral part - Radial nerve

The lateral part is considered part of triceps which has migrated forwards and fused with the brachialis but retaining its nerve supply from the radial nerve

Question 15

Actions of the Brachialis

Answer 15

Main flexor of the elbow joint

Question 16

What artery supplies the posterior compartment?

Answer 16

Profunda brachii artery

Question 17

Origin of the Triceps Brachii

Answer 17

has 3 heads; the long and the lateral head lie superficial while the medial head lies in the deep part

1. Long head - Infraglenoid tubercle of scapula
2. Lateral head - Oblique ridge on the posterior surface of the humerus above the spiral groove
3. Medial head - From whole posterior surface of humerus below the spiral groove + from the medial and lateral inter muscular septa of the arm

Question 18

Insertion of the Triceps Brachii

Answer 18

The 3 heads unite about the middle of the arm forming a common tendon that is inserted into the posterior part of the upper surface of the olecranon fossa

few deep fibres are inserted into the capsule of the elbow joint forming the articularis cubiti muscle

Question 19

Nerve supply of Triceps

Answer 19

Radial nerve supplies each head separately

1. Long head - By one branch arising in the axilla
2. Lateral head - By one branch arising in the spiral groove
3. Medial head - Supplied by two branches : One arising in the axilla and the other from the spiral groove