The military press is a variation of the overhead press weight training exercise using very strict form and no pre-movement momentum.
The military press targets the deltoid muscles in the shoulders as well as the triceps. Additionally, it works the core and legs, which the lifter uses to help stabilize the weight.
The lift begins with the lifter standing with both feet together and the barbell on the anterior deltoids. The lifter then raises the barbell overhead by pressing the palms of the hands against the underside of the barbell.
Military press Wikipedia
The deltoid muscle has a dynamic activation of about 90–120 degrees of abduction. Afterwards it has an almost static function during the remainder of the lift. The rest of the movement is mainly due to contraction of Trapezius muscle pars acendens, Serratus anterior muscle and trapezius pars descendens. They work together to tilt the Scapula to a position that makes the glenoid cavity point superiorly, enabling the last degrees of abduction of the shoulder. Other contributing muscles include the Supraspinatus muscle and biceps brachii muscle caput longum. The rotator cuff is also active to pull the caput humeri into the glenoid cavity and counteract the superior forces of caput humeri created by the deltoid. The triceps contribute to the extension of the elbow, and counteract the force from biceps caput longum.