We'll discuss the function and anatomy. ... Rhomboid major helps keep the shoulder blade attached to the rib cage and allows you to pull your shoulder blades back. Rotator cuff muscles.

Rotator Cuff Anatomy Explained. Medically reviewed by Timothy Gossett, ... The head of your upper arm bone, also called the humerus, fits into the socket of your shoulder blade, or scapula.

Shoulder blade (scapula) Upper arm bone (humerus) Your deltoid muscles start near your clavicle and scapula. The end of the muscles, or insertion point, attaches near your humerus.