Posterior compartment of arm - extensor

Question 1

What are the muscles in the posterior compartment of arm?

Answer 1

triceps brachii - long, medial, lateral heads

Question 2

What are the attachments of long headed triceps?

Answer 2

origin: intraglenoid tubercle of scapula, capsule of shoulder joint
insert: olecranon process of ulna, capsule of elbow joint

Question 3

What are the attachments of lateral head of triceps?

Answer 3

origin: ABOVE radial groove of posterior surface humerus
insert: olecranon process of ulna, capsule of elbow joint

Question 4

What are the attachments of medial head of triceps?

Answer 4

origin: BELOW radial groove of posterior surface humerus
insert: olecranon process of ulna, capsule of elbow joint

Question 5

What are the actions of triceps?

Answer 5

extends arm at shoulder joint

extend forearm at elbow joint

Question 6

What is the nerve supply to triceps brachii?

Answer 6

radial nerve - it passes through lateral and medial heads

Question 7

What happens if the radial nerve to triceps is being compromised?

Answer 7

paralysis of triceps - loss of elbow extensor strength, decreased elbow stability.

Radial n. is susceptible to injury when there is a mid shaft fracture of humerus.