DELTOIDS: The deltoids aka delts are built up of three different heads, the anterior deltoid (front delt), the lateral deltoid aka middle delt, and the posterior delt aka rear delt.
The Anterior delt acts to flex the shoulder (raise the arm up).
The Lateral delt acts to abduct the upper arm (raise your upper arm out directly to your sides).
The Posterior delt acts to abduct the shoulder (pull the shoulder back when the elbows are raised).
ORIGIN: Clavicle, acromion process, spine of scapula
INSERTION: deltoid tuberosity of humerus
Training Movements: Barbell bench press (anterior), barbell overhead press (anterior, lateral), Arnold press (anterior, lateral, posterior), chest-supported T-bar row (posterior), cable lateral raise (lateral), cable rope upright row (lateral), dumbbell incline press (anterior), dumbbell lateral raise (lateral), Pendley row (posterior), reverse pec deck (posterior), and seated face pull (posterior)