Intrinsic Back Muscles

Question 1

Splenius origin

Answer 1

arises from nuchal ligament and spinous processes of C7-T6 vertebrae

Question 2

splenius capitis insertion

Answer 2

fibers run superolaterally to mastoid process of temporal bone and lateral third of superior nuchal line of occipital bone

Question 3

splenius cervicis insertion

Answer 3

tubercles of transverse processes of C1-C3 or C4 vertebrae

Question 4

splenius innervation

Answer 4

posterior rami of spinal nerves

Question 5

splenius action

Answer 5

acting alone: laterally flex neck and rotate head to side of active muscles
acting together: extend head and neck

Question 6

superficial layer of intrinsic back muscles

Answer 6

splenius capitis and splenius cervicis

Question 7

intermediate layer of intrinsic back muscles (erector spinae)

Answer 7

iliocostalis, longissimus, spinalis

Question 8

Iliocostalis origin

Answer 8

arises by broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral and inferior lumbar spinous processes and supraspinous ligament

Question 9

longissimus origin

Answer 9

arises by broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral and inferior lumbar spinous processes and supraspinous ligament

Question 10

spinalis origin

Answer 10

arises by broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral and inferior lumbar spinous processes and supraspinous ligament

Question 11

iliocostalis insertion

Answer 11

fibers run superiorly to angles of lower ribs and cervical transverse processes

Question 12

iliocostalis made up of

Answer 12

lumborum, thoracis, and cervicis

Question 13

longissimus insertion

Answer 13

fibers run superiorly to ribs between tubercles and angles to transverse processes in thoracic and cervical regions and to mastoid process of temporal bone

Question 14

longissimus made up of

Answer 14

thoracis, cervicis and capitis

Question 15

spinalis insertion

Answer 15

fibers run superioly to spinous processes in upper thoracic region and to cranium

Question 16

spinalis made up of

Answer 16

thoracis, cervicis, and capitis

Question 17

iliocostalis innervation

Answer 17

posterior rami of spinal nerves

Question 18

longissimus innervation

Answer 18

posterior rami of spinal nerves

Question 19

spinalis innervation

Answer 19

posterior rami of spinal nerves

Question 20

iliocostalis, longissimus, spinalis action

Answer 20

acting bilaterally: extend vertebral column and head, as back is flexed, control movement by gradually lengthening their fibers
acting unilaterally: laterally flex vertebral columns

Question 21

deep layer of intrinsic back muscles (transversospinales)

Answer 21

semispinalis (thoracis, cervicis, and capitis)
multifidus
rotatores (brevis and longus)

Question 22

semispinalis origin

Answer 22

arises from transverse processes of C4- T10 vertebrae

Question 23

semispinalis insertion

Answer 23

fibers run superomedially to occipital bone and spinous processes in upper thoracic and cervical regions, spanning four to six segments

Question 24

semispinalis innervation

Answer 24

posterior rami of spinal nerves

Question 25

semispinalis action

Answer 25

extends head and thoracic and cervical regions of vertebral column and rotate them contralaterally

Question 26

multifidus origin

Answer 26

arises from posterior sacrum, posterior superior iliac spine of ilium, aponeurosis of erector spinae, sacro-iliac ligaments, mammillary processes of lumbar vertebrae, transverse processes of thoracic vertebrae, and articular processes of C4-C7

Question 27

multifidus insertion

Answer 27

thickest in lumbar region, fibers pass obliquely superomedially to entire length of spinous processes of vertebrae located two to four segments superior to origin

Question 28

multifidus innervation

Answer 28

posterior rami of spinal nerves

Question 29

multifidus action

Answer 29

unilateral contraction rotates to contralateral side. stabilizes vertebrae during local movements of vertebral column

Question 30

rotatores origin

Answer 30

arise from transverse processes of vertebrae, are best developed in thoracic region

Question 31

rotatores insertion

Answer 31

fibers pass superomedially to attach to junction of lamina and transverse process or spinous process of vertebra immediately (brevis) or two segments (longus) superior to vertebra of origin

Question 32

rotatores innervation

Answer 32

posterior rami of spinal nerves

Question 33

rotatores action

Answer 33

may function as organs of proprioception, possibly stabilize vertebrae and assist with local extensor and rotatory movements of vertebral column