Skeletal Muscles Gross Anatomy I - Actions

Frontalis

Raises eyebrows

Occipitalis

Fixes apeneurosis and pulls scalp posteriorly

Orbicularis Oculi

Closes eye and produces blinking

Orbicularis Oris

Closes lips

Auricularis Group

Elevates the ear, draws anteriorly and posteriorly

Temporalis

Closes jaw, elevates and retracts the mandible

Nasalis

Flares nostrils

Zygomaticus

Raises lateral corners of mouth upward

Risorius

Draws corners of lips laterallly

Buccinator

Compresses cheek

Masseter

Prime mover of jaw closure

Mentalis

Wrinkles chin

Depressor Anguli Oris

Draws corners of mouth downward and laterally

Depressor Labii Inferioris

Draws lower lip inferiorly

Platysma

Tenses skin of neck

Sternocleidomastoid

Flexes and laterally rotates head

Scalene Group

Elevate the first two ribs

Rhomboid Major

Stabilizes Scapula

Rhomboid Minor

Stabilizes Scapula

Levator Scapulae

Elevates and adducts scapula

Serratus Anterior

Rotates scapula so that the infeerior angle moves laterally and upward

Pectoralis Major

Prime mover of arm adduction

Pectoralis Minor

Pulls scapula forward and downward

External intercostals

Pull ribs toward each other to elevate the rib cage

Internal intercostals

Pull ribs together to depress the cage

Diaphragm

Prime mover of inspiration

External Oblique

Flex vertebral column and compress abdominal wall

Internal Oblique

Flex vertebral column and compress abdominal wall

Rectus Abdominis

Flex and rotate lumbar region

Transversus Thoracis

Depress ribs and costal cartilage

Transversus Abdominis

Compress Abdominal contents

Trapezius

Stabilizes, elevates and rotates scapula

Latissiumus Dorsi

Prime mover of arm extension

Iliocostalis

Extend the vertebral column

Longissimus

Extend and rotate head

Spinalis

Extends vertebral column

Supraspinatus

Initiates adduction of arm

Infraspinatus

Rotates arm laterally

Subscapularis

Rotates arm medially

Deltoid

Prime mover of arm abduction

Teres Major

Extends and medially rotates arm

Teres Minor

Rotates arm laterally