back muscles

O - Superior nuchal line, external occipital protuberance, ligamentum nuchae, spinous processes of CVII to TXII

I - Lateral one-third of clavicle, acromion, spine of scapula

In - Motor-accessory nerve [XI]; proprioception-C3 and C4

F - Assists in rotating the scapula during abduction of humerus above horizontal; upper fibers elevate, middle fibers adduct, and lower fibers depress scapula

O - Transverse processes of CI to CIV

I - Upper portion medial border of scapula

In - C3 to C4 and dorsal scapular nerve (C4, C5)

F - Elevates scapula

O - Spinous processes of TVII to LV and sacrum, iliac crest, ribs X to XII

I - Floor of intertubercular sulcus of humerus

In - Thoracodorsal nerve (C6 to C8)

F - Extends, adducts, and medially rotates humerus

O - Spinous processes of TII to TV

I - Medial border of scapula between spine and inferior angle

In - Dorsal scapular nerve (C4, C5)

F - Retracts (adducts) and elevates scapula

O - Lower portion of ligamentum nuchae, spinous processes of CVII and TI

I - Medial border of scapula at the spine of scapula

In - Dorsal scapular nerve (C4, C5)

F - Retracts (adducts) and elevates scapula

O - Spinous processes of TXI to LIII and supraspinous ligaments

I - Lower border of ribs IX to XII just lateral to their angles

In - Anterior rami of lower thoracic nerves (T9 to T12)

F - Depresses ribs IX to XII and may prevent lower ribs from being elevated when the diaphragm contracts

O - Lower portion of ligamentum nuchae, spinous processes of CVII to TIII and supraspinous ligaments

I - Upper border of ribs II to V just lateral to their angles

In - Anterior rami of upper thoracic nerves (T2 to T5)

F - Elevates ribs II to V

• Semispinalis - most superficial
• Multifidus - best developed in thoracic region
• Rotatores - deepest; best developed in thoracic region
• -Rotatores brevis - cross one vertebra
• -Rotatores longus - cross two vertebrae

• Iliocostalis - most lateral column
• Longissimus - intermediate column
• Spinalis - most medial column

• Splenius Capitis
• O -Lower ligamentum nuchae & spinous processes of C7-T4
• I -Occipital bone & mastoid process of temporal bone

• Splenius Cervicis
• O -Spinous processes of T3-T6
• I -Transverse processes of upper cervical vertebrae

• Levatores costarum - deep segmental muscle of back; attaches transverse processes of C7-T11 to ribs below & can elevate the ribs
• Interspinalis - connect adjacent spinous processes
• Intertransversarii - connect adjacent transverse processes