Muscles of Arm

Question 0

brachialis

Answer 0

O: distal 1/2 of ant surface of humerus
I: coronoid process and tuberosity of ulna
N: musculocutaneous (C5, C6)
A: flexes forearm in all positions

Question 1

biceps brachii

Answer 1

O: short head– tip of coracoid process
long head– supraglenoid tubercle
I: radial tuberosity, fascia of forearm via bicipital aponeurosis
N: musculocutaneous (C5, C6)
A: supinates forarm, while supinated flexes forearm,
flexes arm, short head resists dislocation

Question 2

coracobrachialis

Answer 2

O: tip of coracoid process of scapula
I: middle 1/3 of medial surface of humerus
N: Musculocutaneous (C5, C6, C7)
A: helps flex and adduct arm, resists dislocation

Question 3

triceps brachii

Answer 3

O: long head– infraglenoid tubercleof scapula
lateral head– post surface of humerus sup to radial groove
medial head– post surface of humerus, inf to radial groove
I: prox end of olecranon of ulna and fascia of forearm
N: radial nerve (C6, C7, C8)
A: chief extensor of arm
long head– extends arm and resists dislocation

Question 4

anconeus

Answer 4

O: lateral epicondyle of humerus
I: lateral surface of olecranon, sup part of post surface of ulna
N: radial nerve (C7, C8, T1)
A: assists triceps in extending forearm, stabilizes elbow joint,
abducts ulna during pronation