Axial Muscles

muscles of facial expression

Orbicularis oris, Orbicularis oculi, Buccinator, Platysma

Orbicularis oris

Closes lips

Orbicularis oculi

Closes eye

Buccinator

Compresses cheek

Platysma

Tenses skin of neck, pulls lower lip back and down

Muscles of Mastication

Temporalis, Masseter

Temporalis

insertion: Coronoid process of mandible

action: Elevates and retracts mandible

Masseter

Elevates mandible

Muscles that move the head and neck

Sternocleidomastoid, Splenius capitis, Semispinalis capitis

Sternocleidomastoid

origin: Manubrium and sternal end of clavicle

insertion: Mastoid process

action: Unilateral – laterally flexes head to same side and rotates head to opposite side

Bilateral – flexes head

Splenius capitis

Unilateral – laterally flexes and rotates head to same side

Bilateral – extends head

Semispinalis capitis

Unilateral – rotates vertebral column and head to opposite side

Bilateral - extends vertebral column and head

Deep Back Muscles/Erector Spinae Group

Spinalis group, Longissimus group, Iliocostalis group

Spinalis group

Extends vertebral column

Longissimus group

Unilateral – laterally flexes vertebral column to same side and rotates head to same side

Bilateral – extends vertebral column and head

Iliocostalis group

Unilateral – laterally flexes vertebral column to same side

Bilateral - extends vertebral column

Respiratory muscles

Diaphragm, External intercostals, Internal intercostals

Diaphragm

Prime mover of inspiration

External intercostals

Pulls ribs toward one another to elevate rib cage; aids in inspiration

Internal intercostals

Draws ribs together to depress rib cage; aids in forced expiration

Abdominal Muscles

Rectus Abdominis, External Oblique, Internal Oblique, Transversus Abdominis

Rectus Abdominis

origin: pubic crest and symphysis

insertion: xiphoid process; costal cartilages of ribs 5-7

action: Flexes and rotates vertebralcolumn; compresses abdominal wall

External Oblique

Unilateral – rotates and laterally flexes vertebral column to same side

Bilateral – flexes vertebral column and compresses abdominal wall

Internal Oblique

Unilateral – rotates and laterally flexes vertebral column to same side

Bilateral – flexes vertebral column and compresses abdominal wall

(same as external oblique)

Transversus Abdominis

Compresses abdominal wall