Symptoms of a deltoid muscle strain may include: The rotator cuff is a group of tendons and muscles that cover the top of the humerus (a bone in your upper arm) and attach to the shoulder.

Ball and socket joints also allow flexion and extension. Flexion of the shoulder joint occurs when the humerus (upper arm) moves forwards from the rest of the body, which happens at the end of an ...

Deltoid Abduction of the shoulder (moving the arm outwards and away from the body) Outward arm action in a jumping jack Rotator cuffs A group of stabilising muscles of the shoulder which helps to ...