8.8 Muscle Actions

This muscle closes the eye.

• orbicularis oris

• masseter

• temporalis

• orbicularis oculi

Closes and protrudes lips.

• orbicularis oris

• masseter

• temporalis

• orbicularis oculi

elevates and protracts the mandible

• orbicularis oris

• masseter

• temporalis

• orbicularis oculi

elevates and retracts the mandible

• orbicularis oris

• masseter

• temporalis

• orbicularis oculi

laterally flexed head and neck to the same side, rotates head to the opposite side

Pulls the head forward and down; also aid in forceful inhalation by elevating sternum and first ribs.

• trapezius

• teres major & latissimus dorsi

• sternocleidomastoid

• pectoralis major

Rotates and retracts scapula

Superior portion elevates scapula

Inferior portion depresses scapula

• trapezius

• teres major & latissimus dorsi

• sternocleidomastoid

• pectoralis major

Flexes arm at shoulder, adducts and medially rotates arm

• trapezius

• teres major & latissimus dorsi

• sternocleidomastoid

• pectoralis major

Extends arm at shoulder, adducts and medially rotates arm

• trapezius

• teres major & latissimus dorsi

• sternocleidomastoid

• pectoralis major

lateral portion abducts arm; anterior portion flexes arm at shoulder; posterior portion extends arm at shoulder

• deltoid

• biceps brachii

• brachialis & brachioradialis

• triceps brachii

Flexes forearm at elbow, supinates forearm and hand

• deltoid

• biceps brachii

• brachialis & brachioradialis

• triceps brachii