Arm Muscles

Question 1

Biceps brachii

Answer 1

O: short head- apex of coracoid process of scapula
long head- supraglenoid tubercle of scapula
I: distal half of anterior humerus
I: musculocutaneous nerve (c5,6,7)
A: supinates flexed forearm; flexes forearm at elbow; weak arm flexor

Question 2

Brachialis

Answer 2

O: distal half of anterior humerus
I: coronoid process and tuberosity of ulna
I: musculocutaneous nerve (c5,6,7)
A: flexes forearm at elbow in all positions

Question 3

Triceps brachii

Answer 3

O: long head- infraglenoid tubercle of scapula
lateral head- posterior humerus
medial head- posterior surface of humerus, inferior to radial groove
I: proximal end of olecranon of ulna and fascia of forearm
I: radial nerve (c6,7,8,)
A: extends forearm at elbow; is chief extensor of elbow; steadies head of abducted humerus (long head)

Question 4

Coracobrachialis

Answer 4

O: tip of coracoid process of scapula
I: middle third of medial surface of humerus
I: musculocutaneous nerve (c5,6,7)
A: helps flex and adduct arm at the shoulder

Question 5

Anconeus

Answer 5

O: lateral epicondyle of humerus
I: lateral surface of olecranon and superior part of posterior surface of ulna
I: radial nerve (c5,6,7)
A: assists triceps in extending elbow; abducts ulna during pronation