Muscles of the back

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Muscles of the back

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Anatomy of the ascending spinal cord pathways

Anatomy of the descending spinal cord pathways

Anatomy of the suboccipital region

Anatomy of the vertebral canal

Bones of the vertebral column

Joints of the vertebral column

Muscles of the back

Vessels and nerves of the vertebral column

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Anatomy clinical correlates: Bones, joints and muscles of the back

Anatomy clinical correlates: Spinal cord pathways

Anatomy clinical correlates: Vertebral canal

Notes

Anatomy of Muscles of the Back

Figure 1: Superficial Extrinsic back muscles. A. Superficial subgroup. B. Deep subgroup (trapezius and latissimus dorsi removed).

Figure 2: A. Superficial intrinsic back muscles. B. Intermediate intrinsic back muscles.

Figure 3: A. Intermediate intrinsic back muscles. B. Deep intrinsic back muscles (transversospinales).

Figure 4: Semispinalis (deep intrinsic back muscles).

Figure 5: Dorsal scapular artery and nerve. Dorsal scapular artery as: A. the deep branch of the transverse cervical artery or B. a direct branch from the subclavian artery

MUSCLE TABLE

Muscle	Origin	Insertion	Innervation	Action
Superficial Extrinsic Back Muscles
Trapezius	Medial third of superior nuchal line External occipital protuberance Nuchal ligament Spinous processes of C7-T12	Lateral 1/3 of clavicle Acromion & spine of the scapula	Motor: Spinal accessory nerve (CN XI) Sensory: Anterior Rami C3-C4	Desc. part: elevation of scapula Middle part: retraction of scapula Asc. part: depression of scapula (lowering shoulder) Asc. + desc.: upward rotation of scapula
Latissimus Dorsi	Iliac crest Thoracolumbar fascia Inferior six thoracic vertebrae Inferior three or four ribs	Floor of intertubercular groove of the humerus	Thoracodorsal nerve (C6, C7, C8)	Extends, adducts and medially rotates the humerus
Rhomboid Major	Spinous processes of T2-T5 vertebrae	Medial border of scapula inferior to spine of scapula	Dorsal Scapular nerve (C4, C5)	Retraction and downward rotation of scapula Assist the serratus anterior in holding the scapula against the thoracic wall
Rhomboid Minor	Nuchal ligament Spinous processes of C7 & T1 vertebrae	Medial border of scapula at spine of scapula	Dorsal Scapular nerve (C4, C5)
Levator Scapulae	Posterior tubercles of the transverse processes C1-C4	Medial border of the scapula (superior to the spine of the scapula)	Dorsal Scapular nerve (C4-C5) Anterior rami C3-C4	Elevates scapula Fixes scapula (resists downward force) Downward rotation of scapula

Muscle	Origin	Insertion	Innervation	Action
Intermediate Extrinsic Back Muscles
Serratus Posterior Superior	Nuchal ligament Spinous processes C7-T3	Superior borders of 2nd-5th ribs	Anterior rami T2-T5	Elevate superior ribs during inspiration
Serratus Posterior Inferior	Spinous processes T11-L2	Inferior borders of 9th-12th ribs	Anterior rami T9-T12	Proprioception Depress(es) inferior ribs (controversial)

Muscle	Origin	Insertion	Innervation	Action
Superficial Extrinsic Back Muscles
Splenius Capitis	Nuchal ligament Spinous processes of C7-T4	Mastoid process of the temporal bone Lateral 1/3 of superior nuchal line of the occipital bone	Posterior rami of the middle cervical spinal nerves	Unilaterally: Laterally flex neck, ipsilateral rotation Bilaterally: Extend head and neck
Splenius Cervicis	Spinous processes of T3-T6	Posterior tubercles of the transverse processes of C1-C3	Posterior rami of the lower cervical spinal nerves

Muscle	Origin	Insertion	Innervation	Action
Intermediate Extrinsic Back Muscles (Erector Spinae)
Iliocostalis	Broad tendon that attaches to: Posterior part of the iliac crest Posterior surface of the sacrum Sacroiliac ligaments Sacral and inferior lumbar spinous processes Supraspinous ligament	Iliocostalis cervicis Transverse processes of cervical vertebrae Iliocostalis thoracis: Angles of lower ribs Iliocostalis lumborum: Transverse processes of lumbar vertebrae	Posterior rami of spinal nerves	Unilaterally: Laterally flex vertebral column Bilaterally: Extend vertebral column and head When back is flexed: Control movement via eccentric contraction
Longissimus		Longissimus Capitis: Mastoid process of temporal bone Longissimus Cervicis: Transverse processes of cervical vertebrae Longissimus Thoracis: Ribs between tubercles and angles Transverse processes of thoracic vertebrae
Spinalis		Spinalis capitis:* Occipital bone Spinalis Cervicis:* Spinous processes in cervical region Spinalis Thoracis: Spinous processes in upper thoracic region *variable, may be absent or fused with other muscles

Muscle	Origin	Insertion	Innervation	Action
Deep Intrinsic back muscles (transversospinales)
Semispinalis	Transverse processes of C4-T12	Occipital bone Semispinalis: thoracis, cervicis, capitis: fibers run superomedially to occipital bone and spinous processes in thoracic and cervical regions, spanning 4–6 segments	Posterior rami of spinal nerves	Bilaterally: Extend head and cervical and thoracic regions Unilaterally: Contralateral rotation
Multifidus	Posterior sacrum Posterior superior iliac spine of the ilium Aponeurosis of the erector spinae Mammillary processes of the lumbar vertebrae, Transverse processes of the thoracic vertebrae Articular processes of C4 to C7	Spinous processes located 2 to 4 segments superior to their origin		Stabilize vertebrae during local movements of the vertebral column
Rotatores (Brevis and longus)	Transverse processes	Lamina/spinous process of process 1 (brevis) to 2 (longus) segments above origin		Contralateral rotation of the vertebral column Stabilize vertebrae Assist with extension Proprioception

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Back Muscles

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Transcript

Content Reviewers

Viviana Popa, MD,David Clay, MSc, BSc

Contributors

Kaylee Neff,Elizabeth Nixon-Shapiro, MSMI, CMI,Patricia Nguyen, MScBMC

Here at Osmosis, we support each other - we’ve got each other’s backs. And it turns out, our backs support all of us! Let’s look at the muscles of the back that help maintain our posture and also provide movements of the trunk and upper limb.

The muscles of the back are divided into two major groups: the extrinsic back muscles and the intrinsic back muscles. The extrinsic back muscles include the superficial back muscles, which produce and control upper limb movements, and the intermediate back muscles, which are thought to be involved in respiratory movements.

The superficial extrinsic back muscles include the trapezius, latissimus dorsi, levator scapulae, and the two rhomboids - rhomboid major and rhomboid minor.

All these muscles are posterior axioappendicular muscles, which connect the axial skeleton, primarily the vertebral column, to the superior appendicular skeleton, specifically the pectoral girdle and the humerus.

The posterior axioappendicular group is divided into two subgroups. The first subgroup consists of two superficial muscles: the trapezius and latissimus dorsi.

The trapezius is a large triangular muscle that covers the posterior aspect of the neck and the superior half of the back. There are two trapezius muscles in the back, which when seen together, look like a trapezium.

Proximally, the trapezius originates on the medial third of the superior nuchal line, the external occipital protuberance, the nuchal ligament, and the spinous processes of the C7 to T12 vertebrae.

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Muscles of the back

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Muscles of the back

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Anatomy of Muscles of the Back

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