The deltoid has three distinct sections - the anterior, middle and posterior portion, which cover the front, top, and rear of the shoulder respectively.

Origin

The middle deltoid originates on the top of the acromion.

Insertion

It inserts on the deltoid tuberosity of the humerus (just above the center of the bone).

Function

Moving the arms laterally.

Lateral Dumbell Arms Raise

Lateral Prone Raise (Reverse Fly)

Upright Row

Overhead Press

Machine Overhead Press