| Muscles Acting On The Back |
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Origin |
Insertion |
Innervation |
Action |
| Trapezius |
Superior nuchal line, external occipital protuberance, ligamentum nuchae, spinous processes of C7 – T12 |
Lateral 1/3 of clavicle, acromion, spine of scapula |
For motor – accessory nerve. For proprioception – C3 – C4 |
Assists in rotating the scapula during abduction of humerus above horizontal. The upper fibres elevate, middle fibres adduct, & lower finres depress the scapula |
| Latissimus dorsi |
Spinous processes of T7 – L5 & sacrum, iliac crest, ribs 10 - 12 |
Intertubercular sulcus of humerus |
Thoracodorsal nerve (C6 – C8) |
Extends, adducts & medially rotates humerus |
| Levator scapulae |
Transverse processes of C1 – C4 |
Upper portion of medial border of scapula |
C3 – C4 & dorsal scapular nerve (C4 – C5) |
Elevates scapula |
| Rhomboid major |
Spinous processes of T2 – T5 |
Medial border of scapula between spine & inferior angle |
Dorsal scapular nerve (C4 – C5) |
Retracts & elevates the scapula |
| Rhomboid minor |
Lower portion of ligamentum nuchae, spinous processes of C7 – T1 |
Medial border of scapula at the spine of scapula |
Dorsal scapular nerve (C4 – C5) |
Retracts & elevates scapula |
| Splenius capitis |
Lower half of ligamentum nuchae, spinous processes of C7 – T4 |
Mastoid process, skull below lateral 1/3 of superior nuchal line |
Posterior rami middle cervical nerves |
Bilaterally – draw head backwards, extending the neck. Unilaterally – draw & rotate head to one side |
| ERECTOR SPINAE: |
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| Iliocostalis lumborum |
Sacrum, spinous processes of lumbar & lower 2 thoracic vertebrae & supraspinous ligaments, & iliac crest |
Angles of lower 6 or 7 ribs |
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| Iliocostalis thoracis |
Angles of lower 6 ribs |
Angles of the upper 6 ribs & transverse process of C7 |
| Iliocostalis cervicis |
Angles of ribs 3 to 6 |
Transverse processes of C4 – C6 |
| Longissimus thoracis |
Blends with iliocostalis in lumbar region & is attached to transverse processes of lumbar vertebrae |
Transverse processes of all thoracic vertebrae & just lateral to the tubercles of the lower 9 or 10 ribs |
| Longissimus cervicis |
Transverse processes of upper 4 or 5 thoracic vertebrae |
Transverse processes of C2 – C6 |
| Longissimus capitis |
Transverse processes of upper 4 or 5 thoracic vertebrae & articular processes of lower 3 or 4 cervical vertebrae |
Posterior margin of the mastoid process |
| Spinalis thoracis |
Spinous processes of T10/11 – L2 |
Spinous processes of T1 – T8 |
| Spinalis cervicis |
Lower part of ligamentum nuchae & spinous process of C7 |
Spinous process of C2 (axis) |
| Spinalis capitis |
Usually blends with semispinalis capitis |
With semispinalis capitis |
| Quadratus lumborum |
Transverse process of L5 vertebra, iliolumbar ligament & iliac crest |
Transverse process of L1 to L4 vertebrae, & inferior border to rib 12 |
Anterior rami of T12 & L1 – L4 |
Depress & stabilise rib 12 & some lateral flexion of the trunk |
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| Ligaments Acting On The Back |
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| Ligament |
Attachment |
Attachment |
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| Anterior longitudinal ligament |
Base of the skull |
Anterior surface of the sacrum |
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| Posterior longitudinal ligament |
Runs on the posterior surface of the vertebral bodies, lining the anterior surface of the vertebral canal |
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| Ligamenta flava |
Posterior surface of the lamina on the vertebra below |
Anterior surface of the lamina of the vertebra above to resist separation of the laminae in flexion, & extension to the anatomical position |
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| Supraspinous ligament |
Connects & passes along the tips of the vertebral spinous processes from C7 to Sacrum |
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| Ligamentum nuchae |
Base is attached from the skull, apex is attached from the tip of the spinous process of C7, the deep side attached from posterior tubercle of C1 & the spinous processes of the other cervical vertebrae |
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| Interspinous ligaments |
Base of apex of each spinous process |
Blend with the supraspinous ligament posteriorly, & the ligament flava anteriorly on each side |
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