Anatomy of the Muscles of the Back

Muscles of the Back Region - Listed Alphabetically
Muscle	Origin	Insertion	Action	Innervation	Artery	Notes
erector spinae	iliac crest, sacrum, transverse and spinous processes of vertebrae and supraspinal ligament	angles of the ribs, transverse and spinous processes of vertebrae, posterior aspect of the skull	extends and laterally bends the trunk, neck and head	segmentally innervated by dorsal primary rami of spinal nerves C1-S5	supplied segmentally by: deep cervical a., posterior intercostal aa., subcostal aa., lumbar aa.	the erector spinae m. is separated into 3 columns of muscle: iliocostalis laterally, longissimus in an intermediate position and spinalis medially; each of these columns has multiple named parts
iliocostalis	iliac crest and sacrum	angles of the ribs	extends and laterally bends the trunk and neck	dorsal primary rami of spinal nerves C4-S5	supplied segmentally by: deep cervical a., posterior intercostal aa., subcostal aa., lumbar aa.	the most lateral part of the erector spinae; it may be subdivided into lumborum, thoracis and cervicis portions
interspinales	upper border of spinous process	lower border of spinous process above	extend trunk and neck	dorsal primary rami of spinal nerves C1-L5	supplied segmentally by: deep cervical a., posterior intercostal aa., subcostal aa., lumbar aa.	these are small and fairly insignificant muscles
intertransversarii	upper border of transverse process	lower border of transverse process above	laterally bend trunk and neck	dorsal primary rami of spinal nerves C1-L5	supplied segmentally by: deep cervical a., posterior intercostal aa., subcostal aa., lumbar aa.	these are small and fairly insignificant muscles
longissimus	transverse process at inferior vertebral levels	transverse process at superior vertebral levels and mastoid process	extends and laterally bends the trunk, neck and head	dorsal primary rami of spinal nerves C1-S1	supplied segmentally by: deep cervical a., posterior intercostal aa., subcostal aa., lumbar aa.	the intermediate part of the erector spinae;it may be subdivided into thoracis, cervicis and capitis portions
multifidus	sacrum, transverse processes of C3-L5	spinous processes 2-4 vertebral levels superior to their origin	extend and laterally bend trunk and neck, rotate to opposite side	dorsal primary rami of spinal nerves C1-L5	supplied segmentally by: deep cervical a., posterior intercostal aa., subcostal aa., lumbar aa.	semispinalis, multifidus and rotatores make up the transversospinal muscle group
obliquus capitis inferior	spinous process of the axis	transverse process of atlas	rotates the head to the same side	suboccipital nerve (DPR of C1)	occipital a.	greater occipital nerve (DPR of C2) passes superiorly around the inferior margin of inferior oblique
obliquus capitis superior	transverse process of atlas	occipital bone above inferior nuchal line	extends the head, rotates the head to the same side	suboccipital nerve (DPR of C1)	occipital a.	the suboccipital triangle is formed by obliquus capitis superior and inferior and rectus capitis posterior major
rectus capitis posterior major	spinous process of axis	inferior nuchal line	extends the head, rotate to same side	suboccipital nerve (DPR of C1)	occipital a.	none
rectus capitis posterior minor	posterior tubercle of atlas	inferior nuchal line medially	extends the head	suboccipital nerve (DPR of C1)	occipital a.	rectus capitis posterior minor is deeper and inserts more medial than rectus capitis posterior major
rotatores	transverse processes	long rotatores: spines 2 vertebrae above origin; short rotatores: spines 1 vertebrae above origin	rotates the vertebral column to the opposite side	dorsal primary rami of spinal nerves C1-L5	supplied segmentally by: deep cervical a., posterior intercostal aa., subcostal aa., lumbar aa.	semispinalis, multifidus and rotatores make up the transversospinal muscle group
semispinalis	transverse processes of C7-T12	capitis: back of skull between nuchal lines; cervicis & thoracis: spines 4-6 vertebrae above origin	extends the trunk and laterally bends the trunk, rotates the trunk to the opposite side	dorsal primary rami of spinal nerves C1-T12	supplied segmentally by: deep cervical a., posterior intercostal aa., subcostal aa., lumbar aa.	three parts are named based on their insertions: capitis, cervicis and thoracis; semispinalis, multifidus and rotatores make up the transversospinal muscle group
spinalis	spinous processes at inferior vertebral levels	spinous processes at superior vertebral levels and base of the skull	extends and laterally bends trunk and neck	dorsal primary rami of spinal nerves C2-L3	supplied segmentally by: deep cervical a., posterior intercostal aa., subcostal aa., lumbar aa.	most medial part of the erector spinae; may be subdivided into thoracis, cervicis and capitis portions
splenius	ligamentum nuchae and spines C7-T6	capitis: mastoid process & superior nuchal line laterally; cervicis: posterior tubercles of C1-C3 vertebrae	extends and laterally bends neck and head; rotates head to same side	dorsal primary rami of spinal nerves C2-C6	supplied segmentally by: deep cervical a., posterior intercostal aa.	splenius means bandage; it gets its name from its broad, flat shape
splenius capitis	ligamentum nuchae and spines of C7-T6 vertebrae	mastoid process and lateral end of the superior nuchal line	extends and laterally bends the neck and head, rotates head to the same side	dorsal primary rami of spinal nerves C2-C6	supplied segmentally by: deep cervical a., posterior intercostal aa.	named for its shape: splenius means bandage and capitis refers to the insertion of this portion of the muscle
splenius cervicis	ligamentum nuchae and spines of C7-T6 vertebrae	posterior tubercles of the transverse processes of C1-C3 vertebrae	extends and laterally bends neck and head, rotates head to the same side	dorsal primary rami of spinal nerves C2-C6	supplied segmentally by: deep cervical a., posterior intercostal aa.	named for its shape: splenius means bandage and cervicis refers to the insertion of this portion of the muscle