Muscles of the back

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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
Superficial Extrinsic Back Muscles
  • 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
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
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

Intermediate Extrinsic Back Muscles
Serratus Posterior Superior
  • Nuchal ligament 
  • Spinous processes C7-T3
Superior borders of 2nd-5th ribs
Anterior rami T2-T5Elevate 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)

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
  • Laterally flex neck, ipsilateral rotation
  • 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
Intermediate Extrinsic Back Muscles (Erector Spinae)
  • 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

  • Laterally flex vertebral column

  • Extend vertebral column and head
When back is flexed:
  • Control movement via eccentric contraction

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 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
Deep Intrinsic back muscles (transversospinales)
SemispinalisTransverse 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
  • Extend head and cervical and thoracic regions 
  • Contralateral rotation
  • 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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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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