Humeral heads articulate with scapulas' glenoid fossas. Glenoid fossas have very shallow sockets. While shallowness decreases shoulder joint stability, shallowness increases shoulder joints' motion ranges. Glenoid labrums attach to glenoid fossas' rims and around humeral heads' rims. Glenohumeral ligaments anteriorly stabilize humeral heads.
Coracohumeral ligament suspend humeral heads from above and limit humeral rotations.
Anterior Surface Humeral anterior surfaces have thirteen bony landmarks, seven tendon attachments and nine areas from which muscles arise. Proximal ends have four bony landmarks, five tendon attachments and no areas from which muscles arise. Bicipital grooves divide lateral greater tuberosities from medial lesser tuberosities and extend one-quarter down the shafts. Tendons of biceps brachiis' long heads course through bicipital grooves. Pectoralis major tendons attach on bicipital grooves' lateral lips.