• Primary function is postural
• Thick, dense CT fascia - Thoracolumbar fascia
• doesn't stretch well (lots of Type I collagen)
• When naming muscle groups, named for inferior attachment to superior attachment
• When describing muscle actions for the muscles of the trunk, the inferior attachment is fixed

• Fibers that run superior-lateral (spinous process to transverse process of skull) will rotate the vertebral column to the same side (V)
• Fibers that run superior-medial (transvers process to spinous process) will rotate the vertebral column to the opposite side (Λ)

• 3 muscles
• Spinalis (medial)
• Longissimus
• Iliocostalis (lateral)

• Between spinous processes lumbar region to spinous process of axis
• Capitis portion is considered part of the semispinalis muscle

• Between transverse processes lumbar region through cervical and tubercles of the ribs to mastoid process of the skull

• Posterior iliac crest and sacrum
• Ribs (all)
• Transverse processes mid-low cervical (C4-C6)

• I-V Joint
• Extension
• Sidebend (Iliocostalis & Longissimus)
• Rotation to the same side (Iliocostalis & Longissimus)
• Hip Joint
• Anterior Pelvic Tilt

Erector Spinae Muscles

Nerve Innervation

• Dorsal rami of spinal nerves

• Two muscles
• Splenius Cervicis (deep to capitis)
• Splenius Capitis
• V fiber orientation

• Spinous processes T3-T6 (inferior attachment)
• Transverse process C1-C3 (4) (superior attachment)

• Spinous processes C7-T3 (inferior attachment)
• Mastoid process and superior nuchal line of occiput (superior attachment)

• I-V Joint 
• Extension
• Sidebend 
• Rotation to the same side

Spinotransversae Muscles 

Nerve Innervation

• Dorsal rami of spinal nerves

• 4 Muscles
• Semispinalis
• Multifidus
• Long Rotators
• Short Rotators

• Cervical and Thoracic regions, attaches to the head
• Transverse processes T10-C4 ( inferior attachments)
• Spinous processes and Occipital bone C7- C2 (superior attachments)
• Cross an average of 4-8 vertebrae between inferior and suprior attachments

• All regions cervical - sacral, no attachment to the head
• PSIS and Transverse processes Sacrum-Low cervical (inferior attachments)
• Spinous processes L4-C2 (superior attachments)
• Cross an average of 2-4 vertebrae between inferior and superior attachments

• Transverse processes all vertebral levels (inferior atachments)
• Spinous processes all vertebral levels to C2 (superior attachments)
• Span 2 vertebrae

• Transverse processes all vertebral levels (inferior attachments)
• Spinous process all vertebral levels to C2 (superior attachments)
• Span 1 vertebrae

• I-V Joints
• Extension
• Sidebend (limited)
• Rotation to the Opposite side (generally poor)

Transverospinae Muscles

Nerve Innervation

• Dorsal rami of spinal nerves

• 4 Muscles
• Rectus Capitis Posterior Major
• Rectus Capitis Posterior Minor
• Obliquus Capitis Superior
• Obliquus Capitis Inferior

• Spinous process of Axis (C2)
• Occipital bone

• Posterior aspect Atlas (C1)
• Occipital bone

• Transverse process of Atlas (C1)
• Occipital bone

• Spinous process of Axis (C2)
• Transverse process of Atlas (C1)

• Cervical I-V Joints
• Extension
• Rectus Capitis Posterior Major (A-O and A-A joints)
• Rectus Capitis Posterior Minor and Obliquus Capitis Superior (A-O joint)
• Obliquus Capitis Inferior (A-A joint)
• Sidebend
• Obliquus Capitis Superior (A-O joint)
• Rectus Capitis Posterior Major & Minor (A-O joint)
• Rotation to the Same side
• Rectus Capitis Posterior Major and Obliquus Capitis Inferior (A-A joint)

Suboccipital Triangle Muscles 

Nerve Innervation

• Dorsal Ramus C1