anatomy: oiai

[muscle]

origin

iliocostalis

broad tendon (from posterior iliac crest, sacrum, sacroiliac ligaments, spinous process of sacral + inferior lumbar vertebrae)

[muscle]

insertion

iliocostalis
lumborum: inferior border of angle of ribs (6-12)
thoracis: all ribs
cervicis: ribs 1-6 and posterior tubercles (c4-c6)

[muscle]

action

iliocostalis

• lateral flexion of head + vertebral column (ipsilateral)

• extend head + trunk (bilateral)

[muscle]

innervation

iliocostalis

dorsal rami (cervical, thoracic, lumbar spinal nerves)

[muscle]

origin

longissimus
broad tendon (from posterior iliac crest, sacrum, sacroiliac ligaments, spinous processes of sacrum/inferior lumbar vertebrae)

cervicis and capitis: transverse processes at lower levels

[muscle]

insertion

longissimus
thoracis:

• tips of transverse processes (t1-t12)

• inferior border of ribs (9-10)

cervicis:

• superior thoracic to cervical transverse processes

capitis

• with l. cervicis

• mastoid process

[muscle]

action

longissimus

• extend head and trunk (bilateral)

• lateral flexion of head and vertebral column (ipsilateral)

• rotate head to same side (l. capitis)

[muscle]

innervation

longissimus

dorsal rami (cervical, thoracic, lumbar spinal nerves)

[muscle]

origin

spinalis

broad tendon (from spinous processes)

[muscle]

insertion

spinalis

thoracis: tips of thoracic spinous processes

cervicis: ligamentum nuchae to axis

[muscle]

action

spinalis

extend head and vertebral column

[muscle]

innervation

spinalis

dorsal rami (cervical, thoracic, and lumbar spinal nerves)

[muscle]

origin

semispinalis

thoracis: transverse processes superomedially (t6-t10)

cervicis: transverse processes superomedially (t1-t6)

capitis:

• articular process (c7)

• transverse processes (t1-t6)

[muscle]

insertion

semispinalis

• spinous processes (t1-t4), (c2-c5), (c6-c7)

• inferior to superior nuchal line

[muscle]

action

semispinalis

thoracis and cervicis: extend vertebral column

capitis:

• extend head (bilaterally)

• rotate head + trunk to opposite side (unilaterally)

[muscle]

innervation

semispinalis

dorsal rami (cervical, thoracic, lumbar spinal nerves)

[muscle]

origin

multifidus

• laminae/mamillary processes (c2-s4)

• absent in thoracic region

[muscle]

insertion

multifidus

• spinous processes (superomedially 2-4 vertebrae)

[muscle]

action

multifidus

• lateral flexion of vertebral column and opposite rotation (unilateral)

• extend trunk and stabilize vertebral column (bilateral)

[muscle]

innervation

multifidus

dorsal rami (cervical, thoracic, lumbar spinal nerves)

[muscle]

origin

rotatores

• transverse processes of vertebral column

[muscle]

insertion

rotatores

• superomedially to spinous process

• brevis = next

• longus = 2nd

[muscle]

action

rotatores

• rotate superior vertebrae (contralateral)

• stabilize superior vertebrae (bilateral)

[muscle]

innervation

rotatores

• dorsal rami (cervical, thoracic, lumbar spinal nerves)

[muscle]

origin

splenius

cervicis:

• spinous processes (t3-t6)

capitis

• spinous processes (c7-t4)

• ligamentum nuchae

[muscle]

insertion

splenius

cervicis:

• transverse processes (c2-c5)

capitis

• superior nuchal line (lateral part)

• mastoid process

[muscle]

action

splenius

• extend cervical region (bilateral)

• lateral flexion + rotation (unilateral)

[muscle]

innervation

splenius
cervicis

• dorsal rami (c4-c8)

capitis

• dorsal rami (c3-c5)