Muscles: Facial Expression, Mastication, Head, Respiration, Anterior Abdomen, and Back

Flexors of the Neck

Sternocleidomastoid

Scalenes (Anterior, Middle, and Posterior)

Sternocleidomastoid

contralateral rotation of the head

Scalenes (Anterior, Middle, and Posterior)

unilateral contraction causes ipsilateral flexion. Bilatera contraction causes forward flexion of head

Extensors of Neck

Upper Trapezius

Splenius Capitis / Semispinalis Capitis

Upper Trapezius

extends and laterally flexes neck

Splenius Capitis / Semispinalis Capitis

extends head

Muscles of Respiration

diaphragm

external intercostals

internal intercostals

Diaphragm

prime mover of inspiration (inhaling)

External Intercostals

expanding thoracic cavity

Internal Intercostals

retracting thoracic cavity

Muscles of Anterior Abdomen

External Abdominal Oblique

Internal Abdominal Oblique

Transverse Abdominal

Rectus Abdominis

External Abdominal Oblique

increases intraabdominal pressure, unilateral contraction causes contralateral rotation of waist

Internal Abdominal Oblique

increases intraabdominal pressure, unilateral contraction causes ipsilateral rotation of the waist

Transverse Abdominal

increases pressue

Rectus Abdominis

produces forward bending at the waist

Muscles of the Back

Erector Spinae (Iliocostalis, Longissimus, Spinalis)

Quadratus Lumbrorum

Multifidus

Erector Spinae (Iliocostalis, Longissimus, Spinalis)

extension and lateral flexion of vertebral column

Quadratus Lumborum

unilateral contraction causes ipsilateral flexion, bilateral contraction aids in extension of lumbar spine

Multifidus

maintenance of posture and stabilization of adjacent vertebrae

Muscles of Facial Expression

Frontalis

Orbicularis Oculi

Orbicularis Oris

Buccinator

Frontalis

elevates eyebrows, draws scalp forward, wrinkles

Orbicularis Oculi

closes eye lid in blinking

Orbicularis Oris

encircles mouth, closes and portrudes lips

Buccinator

compresses cheek against teeth and gums

Muscles of Mastication (chewing)

Temporalis

Masseter

Medial Pterygoid

Lateral Pterygoid

Temporalis

elevation and retraction of mandible

Masseter

elevation of mandible

Medial Pterygoid

elevation and protraction of mandible

Lateral Pterygoid

depression and protraction of mandible