Shoulder Anatomy and Movements
The shoulder is composed of four articulations - the sternoclavicular, the acromioclavicular, the glenohumoral, and the scapulothoracic.
- bones of the shoulder
- sternoclavicular joint
- acromioclavicular joint
- glenohumoral joint
- scapulothoracic joint
- rotator cuff
Bones of the Shoulder
Sternoclavicular Joint
The sc joint involves the clavicle and both the sternum and manubrium. A fibrocartilaginous disc and both anterior and posterior SC ligaments stabilize the joint.
Acromioclavicular Joint
The AC joint, together with the SC joint, are particularly involved with abduction and rotation.
Rotator Cuff
supraspinatus: abducts arm
teres minor: externally rotates
infraspinatus: externally rotates
subscapularis: internally rotates
Abduction
Up to 30 degrees, abduction is carried out primarily by the supraspinatus