Muscles of Spine, Trunk, Pelvic Floor Actions

neck flexion

Sternocleidomastoid (bilaterally) Anterior scalene (bilaterally) Longus capitis (bilaterally) Longus colli (bilaterally)

Neck Extension

Trapezius (upper fibers, bilaterally)

Levator scapulae (bilaterally)

Splenius capitis (bilaterally) Splenius cervicis (bilaterally)

Rectus capitis posterior major

Rectus capitis posterior minor

Oblique capitis superior

Multifidi (bilaterally)*

Rotatores (bilaterally)*

Intertransversarii (bilaterally)*

Interspinalis

Ipsilateral neck rotation

(unilaterally to the same side) Levator scapulae Splenius capitis Splenius cervicis Rectus capitis posterior major* Oblique capitis inferior* Longus colli* Longus capitis* Longissimus capitis (assists)* Longissimus cervicis (assists)* Iliocostalis cervicis (assists

contralateral neck rotation

(unilaterally to the opposite side) Trapezius (upper fibers)

Sternocleidomastoid

Anterior scalene

Middle scalene

Posterior scalene

Multifidi* Rotatores

lateral neck flexion

(unilaterally to the same side) Trapezius (upper fibers)

Levator scapulae

Sternocleidomastoid Anterior scalene (with ribs fixed)

Middle scalene (with ribs fixed) Posterior scalene (with ribs fixed)

Splenius capitis

Splenius cervicis

Longus capitis Longus colli

Oblique capitis superior*

Intertransversarii*

Trunk Flexion

Rectus abdominis External oblique (bilaterally) Internal oblique (bilaterally)* Psoas major (with the insertion fixed)* Iliacus (with the insertion fixed)*

trunk extension

Longissimus (bilaterally)

Iliocostalis (bilaterally)

Multifidi (bilaterally) Rotatores (bilaterally)*

Semispinalis capitis Spinalis (bilaterally)

Intertransversarii (bilaterally)*

Interspinalis*

Neck Extension assists

Semispinalis capitis Longissimus capitis (assists)*

Longissimus cervicis (assists)*

Iliocostalis cervicis (assists)*

Trunk Extension assists

Quadratus lumborum (assists)

Latissimus dorsi (assists when arm is fixed)

lateral neck flexion assists

Longissimus capitis (assists)*

Longissimus cervicis (assists)*

Iliocostalis cervicis (assists)*

Trunk Rotation to opposite side

External oblique (to the opposite side)

Multifidi (to the opposite side)

Rotatores (to the opposite side)

Trunk Rotation to same side

Internal oblique

Trunk Lateral Flexion

Iliocostalis

External oblique

Internal oblique Longissimus

Quadratus lumborum

Intertransversarii*

Spinalis

Trunk Lateral Flexion Assist

Psoas major. latissimus dorsi

Rib Cage Inhalation (expand)

Anterior scalene (bilaterally)

Middle scalene (bilaterally)

Posterior scalene (bilaterally)

Serratus posterior superior*

Pectoralis major (all fibers may assist if arm is fixed)*

Pectoralis minor (if scapula is fixed)*

Serratus anterior (if scapula is fixed)*

Subclavius (first rib)*

Rib Cage Inhalation assists (expand)

Sternocleidomastoid (assists)

External intercostals (assists)

Rib Cage Exhalation (rib cage depression)

Internal intercostals (assists) Serratus posterior inferior*