Back Muscles Simplified

Trapezius: Attachments

Attachments: Superior nuchal line/ligamentum nuchae, external occipital protuberance, spinous processes C7-T12 → lateral clavicle, acromion, scapula

Trapezius: Action

Action: rotate scapula during humeral abduction, upper fibers elevate, middle adduct/retract, and lower depress scapula

Trapezius: Innervation

Innervation: Cranial Nerve (CN) XI

Lat. Dorsi: Attach

Attachments: Spinous process of T7-L5, sacrum, iliac crest, and ribs 10 -12 to intertubercular sulcus of humerus

Lat. Dorsi: Action

Action: extend, adduct, and medially rotate humerus at shoulder

Lat. Dorsi: Innervation

Innervation: Thoracodorsal nerve (C6-8)

Rhomboid Major: Attachments

Spinous processes of T2-5 to lower medial border of scapula

Rhomboid Major: Action

retract and elevate scapula

Rhomboid Major: Innervation

Dorsal scapular nerve (C4-5)

Rhomboid Minor: Attachments

ligamentum nuchae, spinous processes of C7-T1 to medial border of scapula

Rhomboid Minor: Action

retract and elevate scapula

Rhomboid Minor: Innervation

Dorsal scapular nerve (C4-5)

Levator Scapulae: Attachments

Transverse processes of C1-4 to upper medial border of scapula

Levator Scapulae: Action

elevate scapula

Levator Scapulae: Innervation

Dorsal scapular nerve (C4-5)

Serratus Posterior Superior: Attachments

spinous processes of C7 to T3 to ribs 2-5

Serratus Posterior Superior: Action

elevate ribs 2-5

Serratus Posterior Superior: Innervation

anterior rami of T2-5

Serratus Posterior Inferior: Attachments

spinous processes of T11 to L3 to ribs 9-12

Serratus Posterior Inferior: Action

depress ribs 9-12

Serratus Posterior Inferior: Innervation

anterior rami of T9-12

Splenius capitis: Attachments

SP C8 to T4 to mastoid process

Splenius capitis: Action

Bilaterally—draw head backward, extending neck; unilaterally—draw and rotate head to one side (turn face to same side)

Splenius cervicis: Attachments

SP T3 to T6 to TP of C1-C3

Splenius cervicis: Action

Bilaterally— extending neck; unilaterally—draw and rotate head to one side (turn face to same side)

Splenius cervicis: Innervation

Erector Spinae Iliocostalis: Attachments

generally attaches to SP and angles of ribs to upper ribs and TPs

Erector Spinae Longissimus: Attachments

generally attaches to TP to TP higher up

Erector Spinae Spinalis: Attachments

generally attaches to SP to SP higher up

Erector spinae: Action

primary extensors of the vertebral column and head.

• Bilaterally, straighten back, returning it to the upright position from a flexed position, and pull the head posteriorly.

• Also control vertebral column flexion by contracting and relaxing in a coordinated fashion.

• Unilaterally, they bend the vertebral column laterally or turn head to side

Transversopsinales Semispinalis: Attachments

TPs in lower thoracic to SPs 4-6 vertebra up

Transversopsinales Multifidus: Attachments

Sacrum, posterior superior iliac spine , mammillary processes of lumbar vertebrae, thoracic TPs to SPs 2-4 vertebra up

Transversopsinales Rotatores: Attachments

Mammillary process/TP to SP to 1 (short) or 2 (long) vertebra up

Transversospinales: Action

- Bilaterally: extend vertebral column

- Unilaterally: rotate/turn trunk in contralateral direction (opposite side)

Levatores costarum: Attachments

TP of C7 to T11 to rib below vertebra of origin

Levatores costarum: Action

elevate rib

Interspinales: Attachments

SP to SP, one on each side of interspinous ligament

Interspinales: Action

postural muscle that stabilizes vertebral column

Intertransversarii: Attachments

TP to TP

Intertransversarii: Action

postural muscle that stabilizes vertebral column

rectus capitis posterior major: Attachments

P of C2 (axis) to occipital bone

rectus capitis posterior major: Action

extend head, rotate head to ipsilateral side

rectus capitis posterior major: Innervation

posterior ramus of C1

rectus capitis posterior minor: Attachments

posterior tubercle of C1 (atlas) to occipital bone

rectus capitis posterior minor: Action

extend head

rectus capitis posterior minor: Innervation

posterior ramus of C1

obliquus capitis superior: Attachments

TP of C1 (atlas) to occipital bone

obliquus capitis superior: Action

extend head, bend head to ipsilateralside

obliquus capitis superior: Innervation

posterior ramus of C1

obliquus capitis inferior: Attachments

SP of C2 (axis) to Tp of C1 (atlas)

obliquus capitis inferior: Action

rotate head to ipsilateral side

obliquus capitis inferior: Innervation

posterior ramus of C1