Axial Muscles Function

Frontalis

raise eyebrows and draw scalp anteriorly

Temporalis

elevate (close) mandible

Masseter

elevate (close) mandible

Orbicularis oculi

close eyelid

Orbicularis oris

close lips

Risorius

abduct corner of mouth (draw laterally)

Mentalis

protrude lower lip

Buccinator

compress cheek

Zygomaticus (major and minor)

elevate corner of mouth (smiling and laughing)

Depressor labii inferioris

depress inferior lip

Levator labii superioris

elevate superior lip and flare nostril

Levator scapulae

elevate scapula; abduct and rotate neck

Scalenes

Flex and rotate neck, elevate ribs 1 and 2

Sternocleidomastoid

abduct, rotate, and flex head

Omohyoid

depress hyoid bone

Platysma

depress inferior lip; open jaw

Digastric

open mouth and depress mandible

Mylohyoid

elevate hyoid bone and tongue

Erector spinae

Extend and rotate vertebral column and head

Pectoralis major

flex, adduct, and medially rotate humerus

Pectoralis minor

depress glenoid cavity

Trapezius

extend and abduct head; rotate and adduct scapula; fix scapula

Latissimus dorsi

extend, adduct, and medially rotate humerus; draw shoulder inferiorly

Rhomboid major

adduct scapula

Rhomboid minor

adduct scapula

External abdominal oblique

compress abdominal wall and laterally rotate waist

Internal abdominal oblique

compress abdominal wall and laterally rotate waist

Transverse abdominal

compress abdominal wall and laterally rotate waist

Rectus abdominis

flex vertebral column and compress abdominal wall

Serratus anterior

abduct scapula (move it away from spine)

Quadratus lumborum

extend and abduct vertebral column

External intercostals

elevate ribs (increase thoracic volume)

Internal intercostals

elevate and depress ribs

Diaphragm

inspiration