posterior compartment of arm (extensors)

Question 1

triceps

Answer 1

• origin:
• long head: infraglenoid tubercle,
• lateral head: posterior surface of humerus
• medial head: posteror surface of humerus inferior to radial groove
• insertion: olecranon process of the ulna
• action: extends the forearm; the long head extends arm at shoulder

Question 2

anconeus:

Answer 2

• origin: lateral epicondyle of the humerus
• insertion: olecranon
  action: extends the forearm at elbow, abducts ulna during pronation