Lower Back/Spine

Question 1

Iliocostalis Lumborum O/I, innervation, action

Answer 1

O: common origin of erector spinae muscles: spinous processes and supraspinous ligament of T11-L5, medial sacral crest, sarcotuberous ligament, posterior sacroiliac ligament, lateral sacral crest, posteromedial iliac crest

I: inferior borders and angles of the lower 6-9 ribs

Action: extend and laterally flex spine

Innervation: lateral branches of dorsal rami of nearby spinal nerves

Question 2

Iliocostalis cervicis O/I, innervation, action

Answer 2

O: angles of 3-6th ribs
I: posterior tubercles of transverse processes of C4-C6

Innvervation: dorsal rami of nearby spinal nerves

Action: extend and laterally flex spine

Question 3

Iliocostalis thoracis O/I, innervation, action

Answer 3

O: angles of lower 6 ribs
I: angles of ribs 1-6 and transverse process of C7

Innervation: lateral branches of dorsal rami of nearby spinal nerves

Action: extend and laterally flex spine

Question 4

Longissimus thoracis O/I innervation and action

Answer 4

O: common origin of erector spinae muscles: spinous processes and supraspinous ligament of T11-L5, medial sacral crest, sacrotuberous ligament, posterior sacroiliac ligament, lateral sacral crest, posteromedial iliac crest - transverse and accessory processes of all lumbar vertebrae

I: 3rd -12th ribs, all transverse processes of thoracic vertebrae

Innervation: lateral branches of dorsal rami of nearby spinal nerves

Action: extend and laterally flex spine

Question 5

Splenius capitis O/I, action, innervation

Answer 5

O: lower part of ligamentum nuchae and spinous processes of C7-T4
I: mastoid process of temporal bone and occipital bone below lateral part of superior nuchal line

Action: BILATERALLY - extend head, UNILATERALLY - laterally flex and rotate face to same side

Innervation: lateral branches of dorsal rami of midcervical spinal nerves (C3-C5)

Question 6

Splenius cervicis O/I, action, innervation

Answer 6

O: spinous processes of T3-T6
I: transverse processes of C1-C4

Action: BILATERALLY: extend neck UNILATERALLY: flex and rotate face to same side

Innervation: lateral branches of dorsal rami of lower cervical spinal nerves (C5-C7)

Question 7

Multifidus O/I, action, innervation

Answer 7

O: posterior sacrum, L1-5 mammillary processes, T1-12 transverse processes, C4-7 articular processes

I: spinous processes two to four segments above each origin point

Action: BILATERALLY - extend spine UNILATERALLY - extend, laterally flex, and rotate vertebral bodies to opposite side

Innervation: medial branches of dorsal rami of spinal nerves