Back muscles - lateral tract

General information

The lateral tract is made up of a complex of long muscles. A distinction is made between the saccrospinal (M. iliocostalis and M. longissimus), spinotransversal (Mm. intertransversarii and levatores costarum) and intertransversals (Mm. intertransversarii and levatores costarum) System.

A schematic drawing of the muscles (M. iliocostalis, M. longissimus etc.) can be displayed by clicking on the respective name in the "WebViewer".

Sacrospinal System

	M. iliocostalis	M. longissimus
origin	1) M. iliocostalis lumborum: Fascia thoracolumbalis, Os sacrum, Crista iliaca 2) M. iliocostalis thoracis: 7th-12th rib 3) M. iliocostalis cervicis: 3rd-7th rib	4) M. longissimus thoracis: spinous processes of the lumbar spine, transverse processes of the lower section of the thoracic spine, Os sacrum, Crista iliaca 5) M. longissimus cervicis: 1st-6th thoracic vertebrae (transverse processes) 6) M. longissimus capitis: 1st-3rd thoracic vertebrae (transverse processes) and 4th-7th cervical vertebrae (transverse and articular processes)
insertion	1) 6th-12th rib, transverse processes of the upper lumbar spine, Fascia thoracolumbalis 2) 1st-6th rib 3) 4th-6th cervical vertebrae (transverse processes)	4) 2th-12th rib, transverse processes of the thoracic spine, rib processes of the lumbar spine 5) 2nd-5th cervical vertebrae (transverse processes) 6) Wart process (Proc. mastoideus) of the temporal bone (Os temporale)
function	In case of one-sided contraction these muscles cause lateral flexion on the same side of the body (ipsilateral), in case of bilateral activation dorsal extension.	The M. longissimus additionally causes a rotation of the head to the ipsilateral side.
innervation	lateral branches of the Rami posteriores spinal nerves (C8-L1)	lateral branches of the Rami posteriores spinal nerves (C1-L5)

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Spinotransverse and intertransverse system

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	M. splenius	Mm. intertransversarii	Mm. levatores costarum
origin	7) M. splenius cervicis: 3rd-6th thoracic vertebra (spinous processes) 8) M. splenius capitis: 3rd cervical to 3rd thoracic vertebra (spinous processes)	9) Mm. intertransversarii medial lumborum: between adjacent Procc. mamillares of the lumbar spine 10) Mm. intertransversarii lateral lumborum: between adjacent Procc. costales of the lumbar spine 11) Mm. intertransversarii posterior cervicis: between adjacent Tubercula posteriora of the 2nd-7th cervical vertebra	12) Mm. intertransversarii costarum breves: 7th cervical and 1st-11th thoracic vertebrae (transverse processes) 13) Mm. intertransversarii costarum longi: 7th cervical and 1st-11th thoracic vertebrae (transverse processes)
insertion	7) 1st and 2nd cervical vertebrae (spinous processes) 8) Proc. mastoideus, upper cervical line (lateral Linea nuchalis	9) to 11) insertion and origins are congruent	12) Rib angle (Angulus costae) of the underlying rib 13) Rib angle (Angulus costae) of the next but one rib
function	In case of bilateral activation these muscles cause a dorsal extension of the cervical spine, in case of one-sided contraction rotation and ipsilateral lateral flexion.	One-sided activation of these muscles leads to lateral flexion of the lumbar and cervical spine, bilateral contraction to stabilization and dorsal extension of the lumbar and cervical spine	Both-sided contraction causes dorsal extension of the thoracic spine, one-sided contraction causes ipsilateral flexion and contralateral rotation.
innervation	lateral branches of the rami posteriores spinal nerves (C1-C6)	lateral branches of the Rami posteriores and the corresponding spinal cord segment	Rami posteriores spinal nerves

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Further links

Exercises

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