Muscles of the trunk

Anterior muscles

Posterior muscles (two groups)

DEEPER GROUP
(transverso-spinalis mm.)

MORE SUPERFICIAL GROUP:

rotatores
multifidus
semispinalis (except s. capitis)

erector spinae
splenius capitis
splenius cervicis

The inferior attachments are more lateral than the superior attachments.

Therefore, this group causes contralateral rotation*.

The inferior attachments are more medial than superior attachments.

Therefore, this group causes ipsilateral rotation * of the trunk.

Transverse plane illustration of muscles' effects on rotation. Point of application is drawn on superior vertebra. Line of application follows muscle fibers medially or laterally, depending on group, to their attachment on inferior vertebra.

The terms "ipsilateral and contralateral trunk rotation" refer almost exclusively to muscles' effects on trunk rotation.


Last updated 10-18-00 ©Dave Thompson PT
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