Muscles! A Handbook for Bodyworkers This concise, brilliantly illustrated manual covers the origin, insertion and actions of all the major muscles in the body. It is an exceptionally valuable resource for bodywork instructors and an essential clinical reference. TERES MINOR Origin: upper 2/3 of the lateral border of the scapula. Insertion: posterior surface of the greater tubercle of the humerus (inferior to the infraspinatus tendon). Action: extends, horizontally extends and outwardly rotates the humerus.