Deep (Intrinsic) Back Muscles

Question 1

Splenius capitis (superficial layer)

Answer 1

O: nuchal ligament, spinous process of C7-T4
I: mastoid process of temporal bone and lateral third of superior nuchal line
A: bilaterally- extends head; unilaterally- laterally bends and rotates face to same side
I: middle cranial nerves

Question 2

Splenius cervicis (superficial layer)

Answer 2

O: spinous processes of T3-T6
I: transverse processes C1-C3
A: bilaterally- extends towards neck; unilaterally- laterally bends and rotates face to same side
I: lower cervical nerve

Question 3

Erector spinae (intermediate layer)

Answer 3

O: posterior sacrum, iliac crest, sacrospinous ligament, supraspinous ligament, and spinous process of lower lumbar and sacral vertebrae
I: Iliocostalis= angles of lower ribs and cervical transverse processes; Longissimus= between tubercles and angles of ribs, transverse processes of thoracic and cervical vertebrae, and mastoid process; Spinalis= spinous processes of upper thoracic and midcervical vertebrae
A: extends and laterally bends vertebral column and head
I: respective spinal nerves

Question 4

Semispinalis (intermediate layer)

Answer 4

O: transverse processes of C4-T12
I: spinous process of cervical and thoracic regions
A: extends the head, neck, and thorax and rotates them to opposite side
I:respective spinal nerves

Question 5

Multifidi

Answer 5

O: sacrum, ilium, and transverse processes T1-T12 and articular processes of C4-C7
I: spinous processes of vertebrae above, spanning one or two segments
A: stabilizes spine
I: respective spinal region

Question 6

Rotatores (intermediate layer)

Answer 6

O: transverse process
I: lamina and transverse processes or spine above, spanning one or two segments
A: stabilizes, extends, and rotate spine
I: respective spinal region

Question 7

Rectus capitis posterior major

Answer 7

O: spine of axis
I: lateral inferior nuchal line
A: extends head and rotates to the same side
I: C1

Question 7

Rectus capitis posterior major

Answer 7

O: spine of axis
I: lateral inferior nuchal line
A: extends head and rotates to the same side
I: C1

Question 8

Rectus capitis posterior minor

Answer 8

O: tubercle of posterior arch of atlas
I: median inferior nuchal line
A: extends head
I: C1

Question 9

Obliquus capitis superior

Answer 9

O: transverse process of atlas
I: occipital bone
A: extends head and bends it laterally
I: C1

Question 10

Obliquus capitis inferior

Answer 10

O: spine of axis
I: atlas transverse process
A: rotates atlas to turn face to same side
I: C1