Dalley, 10th Edition

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Muscles of Back

TABLE 2.7. DEEP LAYERS OF INTRINSIC BACK MUSCLES Muscle Inferior Attachment

Superior Attachment

Nerve Supply Main Action(s)

Major deep layer Transversospinalis

Extension

Transverse processes

Spinous processes of more superior vertebrae Semispinalis: thoracis, cervicis, capitis; bers run superomedially to occipital bone and spinous processes in tho racic and cervical regions, spanning 4–6 segments. Multi dus: thickest in lumbar region; bers pass obliquely superomedially to entire length of spinous processes, located 2–4 segments superior to proximal attachment. Rotatores: bers pass superomedi ally to attach to junction of lamina and transverse process or spinous process of vertebra immediately (brevis) or 2 segments (longus) superior to vertebra of attachment. Inferior surfaces of spinous processes of vertebra superior to vertebra of proximal attachment Transverse processes of adjacent vertebrae

Posterior rami of spinal nerves a

Semispinalis

Semispinalis: extends head and thoracic and cervical regions of vertebral column and rotates them contralater ally Multi dus: stabilizes vertebrae during local movements of ver tebral column

Semispinalis: arises from trans verse processes of C4–T12 vertebrae

2

Multi dus

Multi dus: arises from posterior sacrum, posterior superior iliac spine of the ilium, aponeurosis of erector spinae, sacroiliac liga ments, mammillary processes of lumbar vertebrae, transverse processes of T1–T3, articular processes of C4–C7 Rotatores: arises from transverse processes of vertebrae; best developed in thoracic region

Rotatores (brevis and longus)

Rotatores: stabilizes vertebrae and assist with local extension and rotatory movements of vertebral column; may function as organs of proprioception

Minor deep layer Interspinales

Posterior rami of spinal nerves

Aid in extension and rotation of vertebral column

Superior surfaces of spinous processes of cervical and lumbar vertebrae Transverse processes of cervical and lumbar vertebrae

Intertransversarii

Posterior and anterior rami of spinal nerves a Posterior rami of C8–T11 spinal nerves

Aid in lateral exion of verte bral column; acting bilaterally, stabilize vertebral column

Levatores costarum Pass inferolaterally and insert on rib between tubercle and angle Elevate ribs, assisting respira tion; assist with lateral exion of vertebral column a Most back muscles are innervated by posterior rami of spinal nerves, but a few are innervated by anterior rami. Intertransversarii of the cervical region are supplied by anterior rami. Tips of transverse processes of C7 and T1–T11 vertebrae

Cervical interspinales

Semispinalis capitis

Multifidus

Cervical intertransversarii

Spinalis cervicis

Rotatores

Multifidus

Transverso spinalis

Semispinalis

Intrinsic muscles

Spinalis

Erector spinae

Longissimus Iliocostalis

Rotatores

Levatores costarum

Serratus posterior inferior

Spinalis thoracis

Extrinsic muscles

Latissimus dorsi Copyright © 2027 Wolters Kluwer. Unauthorized reproduction of the article is prohibited.

Lumbar interspinales

Thoracic spinous process

Trapezius

Lumbar intertransversarii

(D) Transverse section

Multifidus

Key for A–D: Back muscles

Superficial extrinsic Intermediate extrinsic

Intermediate intrinsic (erector spinae) Deep intrinsic (transversospinales)

(A) Posterior view

(B) Posterior view

(C) Posterior view

FIGURE 2.37. Deep layers of intrinsic back muscles. A. The transversospinalis muscle group (major deep layer— purple ) is deep to the erector spinae ( pink —see D ). B. Deeper dissection showing the rotatores and multi dus. The levatores costarum muscles represent the intertransversarii muscles in the thoracic region. C. Minor deep layer: interspinales, intertransversarii, and levatores costarum. D. Schematic transverse section demonstrating relationships of the groups and individual extrinsic and intrinsic back muscles.