The Functional Anatomy of the Shoulder


The shoulder positions the hand in space and demonstrates a wider and more varied range of movements than any other structure. Movement at three joints and a mobile base in the scapula allows the arm to move through it's full range.

The clavicle moves forward and backward, up and down, and rotates on it's own axis. Rotation accommodates scapula movement at the outer ranges of abduction while the larger movements position the shoulder at the lateral end of the pectoral girdle.

  • Place your left hand on your right clavicle, the bone running laterally from the base of the neck to the shoulder.
  • Move your shoulder back and forward, up and down and notice how the clavicle dictates the position your shoulder.
  • Lift your arm out to your side as far as it will go, the clavicle will rotate posteriorly.

The two pectoral muscles pull the shoulder forward while the rhomboids and middle trapezius pull it back, the upper trapezius and levator scapula muscles lift the shoulder and the lower trapezius, and gravity, pull it back down. Lifting your arm to the side is done initially by supraspinatus, then the larger deltoid and then through a series of events that rotate the scapula laterally.

The muscles of the shoulder

trapezius The large external muscle that acts on the upper back, neck and shoulders.
serratus anterior Connects the scapula and the rib cage and an important muscle in positioning the scapula
levator scapulae Deep to trapezius, levator scapulae is often involved in neck and shoulder problems.
pectoralis major The large muscle that covers most of your chest
pectoralis minor A deeper muscle in the upper chest that tends to pull the shoulder forward and down.
the deep flexors Similar functionally to pec minor these ones attach on to the arm.
the medial rotators Along with pec minor and the deep flexors, these will pull your shoulders in, closing off your chest
the lateral rotators At the back of the shoulder these ones rotate the arm the laterally
supraspinatus Connects the scapula and the humerus and is highly susceptible to overuse injuries.
deltoid The large muscle that covers the shoulder, also has a lot of work to do.
rhomboids Connecting the scapula to the spine they fatigue easily and can cause pain in the upper back.
‹ The Structural Anatomy of the ShoulderupTrapezius ›