MSK - arm

Question 1

what is the arm?

Answer 1

humerus (shoulder –> elbow)

Question 2

what are the bones of the arm? Name and describe its parts.

Answer 2

Humerus. ANTERIOR: Head, anatomical neck, surgical neck (Cx/axillary nerve), lesser tubercle, intertubercular sulcus, greater tubercle, deltoid tuberosity, medial epicondyle (common flexor origin), lateral epicondyle (common extensor origin), capitulum, trochlea. POSTERIOR: Radial groove (for radial nerve). *also note that the ULNAR NERVE runs just behind the medial epicondyle (funnybone nerve)

Question 3

what is so special about the surgical neck of the humerus?

Answer 3

injury/break of the surgical neck of the humerus can damage the Cx/axillary nerve (deltoid + teres minor)

Question 4

name the muscle compartments of the arm

Answer 4

anterior + posterior

Question 5

anterior compartment of arm: name the muscles and innervations + actions

Answer 5

All MUSCULOCUTANEOUS NERVE. 1) biceps brachii long head (lateral) + biceps brachii short head (medial) [ major supinator of forearm and flexes forearm]. 2) coracobrachialis (adduct + flex arm). 3) brachialis (major flexor of forearm).

Question 6

posterior compartment of arm: name muscles and innervations + actions

Answer 6

triceps brachii long head (medial), triceps brachii lateral head, triceps brachii medial head. All insert into olecranon, all extend the forearm, all innervated by RADIAL NERVE