Instrinsic Muscles of the Back

Question 1

List the Superficial Layer of Intrinsic Back Muscles

Answer 1

Splenius Capitis

Spelnius Cervicis

Question 2

List the Intermediate Layer of Intrinsic Back Muscles (erector spinae)

Answer 2

Illiocostalis
Longissimus
Spinalis

Question 3

List the Deep Layer of Intrinsic Back Muscles (transversospinales)

Answer 3

Semispinalis (thoracic, cervicis, and capitis)
Multifidus
Rotatores (brevis and longus)

Question 4

List the Minor Deep Layer of Intrinsic Back Muscles

Answer 4

Interspinales
Intertransversarii
Levatores Costarum

Question 5

Splenius Capitis - Origin

Splenius Cervicis

Answer 5

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

Question 6

Splenius Capitis - Insertion

Splenius Cervicis

Answer 6

Splenius Capitis: Fibers run superolaterally to mastoid process of temporal bone and lateral third of superior nuchal line of occipital bone

Splenius cervicis: tubercles of transverse processes C-C3 or C4 vertebrae

Question 7

Splenius Capitis - Innervation

Spelnius Cervicis

Answer 7

Posterior rami of spinal nerves

Question 8

Splenius Capitis - Action(s)

Splenius Cervicis

Answer 8

Acting alone: laterally flexes neck and rotates head to side of active muscles

Acting together: extend head and neck

Question 9

Erector Spinae - Origin
Illiocostalis
Longissimus
Spinalis

Answer 9

Arise by broad tendon from posterior part of iliac crest
Posterior surface of sacrum
Sacro-iliac liaments
Sacral and inferior lumbar spinous processes and supraspinous ligament

Question 10

Erector Spinae - Insertion
Illiocostalis
Longissimus
Spinalis

Answer 10

Iliocostalis – fibers run superiorly to angles of lower ribs and cervical processes
Longissimus – fibers run superiorly to ribs between tubercles and angels to transverse processes in thoracic and cervical regions and to mastoid process of temporal bone
Spinalis – fibers run superiorly to spinous processes in upper thoracic region and to cranium

Question 11

Erector Spinae - Innervation
Illiocostalis
Longissimus
Spinalis

Answer 11

Posterior rami of spinal nerves

Question 12

Erector Spinae - Action(s)
Illiocostalis
Longissimus
Spinalis

Answer 12

Acting bilaterally: extend vertebral column and head; as back is flexed, control movement by gradually lengthening their fibers

Acting unilaterally: laterally flex vertebral column

Question 13

Semispinalis - Origin

thoracis, cervicis, and capitis

Answer 13

Arises form transverse processes of C4-T10 vertebrae

Question 14

Semispinalis - Insertion

thoracis, cervicis, and capitis

Answer 14

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

Question 15

Semispinalis - Innervation

thoracis, cervicis, and capitis

Answer 15

Posterior rami of spinal nerves

Question 16

Semispinalis - Action(s)

thoracis, cervicis, and capitis

Answer 16

Extends head and thoracic and cervical regions of the vertebral column and rotates them contralaterally

Question 17

Multifidus - Origin

Answer 17

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

Question 18

Multifidus - Insertion

Answer 18

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 19

Multifidus - Innervation

Answer 19

Posterior rami of spinal nerves

Question 20

Multifidus - Action(s)

Answer 20

Unilateral contraction rotates to contralateral side; stabilizes vertebrae during local movements of vertebral column

Question 21

Rotatores - Origin

brevis and longus

Answer 21

Arise form transverse processes of vertebrae; are best developed in thoracic region

Question 22

Rotatores - Insertion

brevis and longus

Answer 22

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

Question 23

Rotatores - Innervation

brevis and longus

Answer 23

Posterior rami of spinal nerves

Question 24

Rotatores - Action(s)

brevis and longus

Answer 24

May function as organs of proprioception; possibly stabilize vertebrae and assist with local extension and rotary movements of vertebral column

Question 25

Interspinales - Origin

Answer 25

Superior surfaces of spinous processes of cervical and lumbar vertebrae

Question 26

Interspinales - Insertion

Answer 26

Inferior surfaces of spinous processes or vertebrae superior to vertebrae of origin

Question 27

Interspinales - Innervation

Answer 27

Posterior rami and spinal nerves

Question 28

Interspinales - Action(s)

Answer 28

Aid in extension and rotation of vertebral column

Question 29

Intertransversarii - Origin

Answer 29

Transverse processes of cervical and lumbar vertebrae

Question 30

Intertransversarii - Insertion

Answer 30

Transverse processes of adjacent vertebrae

Question 31

Intertransversarii - Innervation

Answer 31

Posterior and anterior rami and spinal nerves

Question 32

Intertransversarii - Action(s)

Answer 32

Aid in lateral flexion of vertebral column; acting bilaterally, stabilize vertebral column

Question 33

Levatores Costarum - Origin

Answer 33

Tips of the transverse processes of C7 and T1-T11

Question 34

Levatores Costarum - Insertion

Answer 34

Pass inferiorly and insert on rib between its tubercle and angle

Question 35

Levatores Costarum - Innervation

Answer 35

Posterior rami of C8-T11 spinal nerves

Question 36

Levatores Costarum - Action(s)

Answer 36

Elevates ribs, assisting respiration; assist with lateral flexion of vertebral column