The biceps brachii is the main mediocaudal muscle of the cat when the cat is standing on all fours. It is your "gun" muscle when you flex your arm. It is labeled number 3 in this picture.


The insertion:
The short head of the biceps attaches to the coracoid process at the top of the scapula. The long head originates on the supraglenoid tubercle just above the shoulder joint from where its tendon passes down along the intertubercular groove of the humerus into the shoulder joint.