Anterior compartment of arm - flexor

Question 1

What muscles are in the anterior compartment of arm?

Answer 1

biceps brachii - short and long head
coracobrachialis
brachialis

Question 2

What are the attachments and actions of biceps brachii (short)?

Answer 2

origin: tip of coracoid process of scapula
insert: radial tuberosity, deep fascia of forearm via bicipital aponeurosis

actions: adduct arm, flexor at elbow joint, supinator at forearm

Question 3

What are the attachments and actions of biceps brachii (long)?

Answer 3

origin: supraglenoid tubercle of scapula, adjacent part of glenoid labrum
insert: radial tuberosity, deep fascia of forearm via bicipital aponeurosis

actions: flexor at elbow joint, supinator at forearm
functions: dynamic stability of shoulder joint anteriorly

Question 4

What are the attachments and actions of coracobrachialis?

Answer 4

origin: coracoid process of scapula
insert: middle 1/3 of anteromedial surface of humerus

actions: adductor, weak flexor at shoulder joint, protract scapula

Question 5

What are the attachments and actions of brachialis?

Answer 5

origin: distal half of anterior surface of humerus
insert: ulnar tuberosity + coronoid process of ulna, capsule of elbow joint

actions: crosses only at elbow joint, unaffected by shoulder or positions of forearm

Question 6

What are the injuries that could happen to the biceps?

Answer 6

long head - since it has a intracapsular origin and is lined with a synovial sheath along bicipital groove, irritation can occur.

Irritation from repetitive movement in synovial sheath can cause inflammation + accumulation of fluid - thus leading to inflammation of tendon (tendinitis)

tendon rupture - when resisting heavy load
the common sites are supraglenoid tubercle and entry into bicipital groove (clinically, this could appear as a shortened belly of muscle = prominent lump in middle of arm)