MRI of the thoracic spine

Table 16-1.

Muscles of the Back

MUSCLE	ORIGIN	INSERTION	NERVE SUPPLY
Trapezius	Medial third of the superior nuchal line, external occipital protuberance, ligamentum nuchae, spinous processes of the seventh cervical and thoracic vertebrae, and corresponding supraspinous ligaments	Lateral third of the posterior surface of the clavicle, medial side of the acromion, and upper border of the spine of the scapula	Accessory and cervical plexus
Rhomboideus major	Spinous processes and corresponding supraspinous ligaments of the first four thoracic vertebrae	Medial border of the scapula below the scapular spine	Dorsal scapular
Rhomboideus minor	Spinous processes of the sixth and seventh cervical vertebrae	Medial margin of the scapula above the scapular spine	Dorsal scapular
Levator scapulae	Posterior tubercles of the transverse processes of the four upper cervical vertebrae	Superior angle of the scapula	Dorsal scapular
Serratus posterior superior	From spinous processes of the two lower cervical and two upper thoracic vertebrae	Onto the lateral side of the angles of the second to fifth ribs	First to fourth intercostal
Serratus posterior inferior	With latissimus dorsi, from the spinous processes of the two lower thoracic and two upper lumbar vertebrae	Onto the lower borders of the last four ribs	Ninth to twelfth intercostal
Serratus anterior	From the center of the lateral aspect of the first eight or nine ribs	Superior and inferior angles and intervening medial margin of the scapula	Long thoracic from brachial plexus
Deltoid	Lateral third of the clavicle, lateral border of the acromion process, lower border of the scapular spine	Lateral margin of the proximal half of the humeral shaft	Axillary from fifth and sixth cervical nerves through brachial plexus
Latissimus dorsi	Spinous processes of the lower five or six thoracic and lumbar vertebrae, median ridge of the sacrum, and outer lip of the iliac crest	With teres major, onto the medial border of the bicipital groove of the humerus	Thoracodorsal
Infraspinatus	Infraspinous fossa of the scapula	Middle facet of the greater tuberosity of the humerus	Suprascapular from fifth to sixth cervical
Supraspinatus	Supraspinous fossa of the scapula	Greater tuberosity of the humerus	Suprascapular from fifth to sixth cervical
Teres major	Inferior angle and lower third of the border of the scapula	Medial border of the bicipital groove of the humerus	Lower subscapular from fifth and sixth cervical
Teres minor	Upper two thirds of the lateral border of the scapula	Lower facet of the greater tuberosity of the humerus	Axillary from fifth and sixth cervical
Spinalis capitis	Rarely a separate muscle; it arises with the semispinalis capitis from the upper thoracic spinous process	Inserts with the semispinalis capitis on the occiput	Branches of the dorsal primary divisions of the spinal nerves
Spinalis cervicis	Spinous processes of the sixth and seventh cervical vertebrae	Spinous processes of the axis and the third cervical vertebra	Dorsal branches of cervical
Spinalis thoracis	Spinous processes of the upper lumbar and two lower thoracic vertebrae	Spinous processes of the middle and upper thoracic vertebrae	Dorsal branches of thoracic and upper lumbar
Iliocostalis cervicis	Angles of the upper six ribs	Transverse processes of the middle cervical vertebrae	Dorsal branches of upper thoracic
Iliocostalis thoracis	Medial side of the angles of the lower six ribs	Angles of the upper six ribs	Dorsal branches of thoracic
Iliocostalis lumborum	With erector spinae, from the sacrum, ilium, and spines of the lumbar vertebrae	Angles of the lower six ribs	Dorsal branches of thoracic and lumbar nerves
Longissimus capitis	From the transverse processes of the upper thoracic and transverse and articular processes of the lower and middle cervical vertebrae	Onto the mastoid process	Dorsal branches of cervical
Longissimus cervicis	Transverse processes of the upper thoracic vertebrae	Transverse processes of the middle and upper cervical vertebrae	Dorsal branches of lower cervical and upper thoracic
Longissimus thoracis	With the iliocostalis and from the transverse processes of the lower thoracic vertebrae	By lateral slips onto most or all of the ribs between the angles and the tubercles and onto the tips of the transverse processes of the upper lumbar vertebrae, and by medial slips into the accessory processes of the upper lumbar and transverse processes of the thoracic vertebrae	Dorsal branches of thoracic and lumbar
Splenius capitis	From the ligamentum nuchae of the last four cervical vertebrae and the supraspinous ligament of first and second thoracic vertebrae	Lateral half of the superior nuchal line and mastoid process	Dorsal branches of second to sixth cervical
Splenius cervicis	From the supraspinous ligament and the spinous processes of the third to fifth thoracic vertebrae	Posterior tubercles of the transverse processes of the first and second (sometimes third) cervical vertebrae	Dorsal branches of fourth to eighth cervical
Semispinalis capitis	Transverse processes of the five or six upper thoracic and articular processes of the four lower cervical vertebrae	Occipital bone between the superior and inferior nuchal lines	Dorsal branches of cervical
Semispinalis cervicis	Transverse processes of the second to fifth thoracic vertebrae	Spinous processes of the axis and the third to fifth cervical vertebrae	Dorsal branches of cervical and thoracic
Semispinalis thoracis	Transverse processes of the fifth to eleventh thoracic vertebrae	Spinous processes of the first four thoracic and fifth and seventh cervical vertebrae	Dorsal branches of cervical and thoracic
Multifidus	From the sacrum, the sacroiliac ligament, mammillary processes of the lumbar vertebrae, transverse processes of the thoracic vertebrae, and articular processes of the last four cervical vertebrae	Onto the spinous processes of all the vertebrae, up to and including the axis	Dorsal branches of spinal
Rotatores	Primarily developed in the thoracic region from the transverse processes of the vertebrae	Into the root of the spinous processes of the next two or three vertebrae above	Dorsal branches of spinal
Interspinales cervicis	Tubercle of the spinous process of the cervical vertebrae	Tubercle of the spinous process of the next superior vertebra	Dorsal branches of cervical
Interspinales thoracis	Often poorly developed or absent between the spinous processes of the thoracic vertebrae	Spinous processes of thoracic vertebrae	Dorsal branches of thoracic
Interspinales lumborum	Superior margin of the lumbar spinous processes	Inferior margin of the next superior spinous process	Dorsal branches of lumbar
Intertransversarii anteriores cervicis	Anterior tubercle of the cervical transverse process	Anterior tubercle of the next superior transverse process	Ventral branch of cervical
Intertransversarii laterales lumbar	Transverse processes of the lumbar vertebrae	Next superior transverse process	Ventral branches of lumbar
Intertransversarii thoracis	Transverse processes of the thoracic vertebrae	Next superior transverse process	Dorsal branches of thoracic