Deep Back Muscles

Question 1

What are the deep intrinsic muscles?

Answer 1

Located under erector spinae, collectively known as transversospinales. Group of short muscles associated with transverse and spinous processes of vertebral column
Three major muscles: semispinalis, multifidus and rotatores

Question 2

Semispinalis

Answer 2

Most superficial of deep intrinsic muscles
Divided by superior attachments into thoracic, cervicis and capitis

Question 3

Semispinalis attachments

Answer 3

Originates from transverse process of C4-T10. Fibres ascend 4-6 vertebral segments, attaching to spinous processes of C2-T4 and to occipital bone of skull

Question 4

Innervation of semispinalis

Answer 4

Posterior rami of spinal nerves

Question 5

Actions of semispinalis

Answer 5

Extends and contralaterally rotates head and vertebral column

Question 6

Multifidus

Answer 6

Located underneath semispinalis muscle. Most developed in lumbar area

Question 7

Attachments of multifidus

Answer 7

Broad origin - arises from sacrum, posterior iliac spine, common tendinous origin of erector spinal, mammillary processes of lumbar vertebrae, transverse processes of T1-T3 and articular processes C4-C7.
Fibres ascend 2-4 vertebra, segments, attaching to vertebral spinous processes

Question 8

Innervation of multifidus

Answer 8

Posterior rami of spinal nerves

Question 9

Actions of multifidus

Answer 9

Stabilises vertebral column

Question 10

Rotatores

Answer 10

Deepest muscles of transversospinales group. Most prominent in thoracic region

Question 11

Rotatores attachments

Answer 11

Originates from vertebral transverse processes. Fibres ascend and attach to lamina and spinous processes of vertebrae above

Question 12

Actions of rotatores

Answer 12

Contributes to extension and rotation of vertebral column. Stabilises vertebrae and has a proprioceptive function

Question 13

Innervation of rotatores

Answer 13

Posterior rami of spinal nerves

Question 14

Minor deep intrinsic muscles

Answer 14

Interspinales, intertranversarii, levatores costarum

Question 15

Interspinales

Answer 15

Spans between adjacent spinous processes, stabilises vertebral column

Question 16

Intertranversarii

Answer 16

Spans between adjacent transverse processes, stabilises vertebral column

Question 17

Levatores costarum

Answer 17

Originates from transverse processes of C7-T11, attaches to rib immediately below
Elevates the ribs

Question 18

Why are the deep muscles described as intrinsic?

Answer 18

Develop embryonically in the back

Question 19

Superficial and intermediate muscles are described as

Answer 19

Extrinsic muscles (don’t embryonically develop in the back)

Question 20

Deep muscles covered by

Answer 20

Deep fascia

Question 21

Deep muscles divided into

Answer 21

3 layers: superficial, intermediate and deep

Question 22

Superficial deep muscles

Answer 22

Spinotransversales
2 muscles in this group: splenius capitis and splenius cervicis

Question 23

Splenius capitis attachments

Answer 23

Originates from lower aspect of ligamentum nuchae, and spinous process of C7-T3/4 vertebrae.
Fibres attach to mastoid process and occipital bone of skull

Question 24

Innervation of splenius capitis

Answer 24

Posterior rami of spinal nerves C3 and C4

Question 25

Actions of splenius capitis

Answer 25

Rotate head to the same side

Question 26

Splenius cervicis attachments

Answer 26

Originates from spinous process of T3-T6 vertebrae.
Fibres attach to transverse processes of C1-3/4

Question 27

Innervation of splenius cervicis

Answer 27

Posterior rami of lower cervical spinal nerves

Question 28

Actions of splenius cervicis

Answer 28

Rotate head to the same side

Question 29

2 splenius muscles act together to

Answer 29

Extend the head and neck

Question 30

Intermediate deep back muscles

Answer 30

3 - iliocostalis, longissimus, spinalis
Form a column - erector spinae

Question 31

Where is the erector spinae?

Answer 31

Posterolaterally to spinal column between vertebral spinous processes and costal angle of ribs

Question 32

Iliocostalis

Answer 32

Located laterally within erector spinae, associated with ribs, can be divided into 3 parts - lumborum, thoracic and cervicis

Question 33

Iliocostalis attachments

Answer 33

Arises from common tendinous origin, attaches to costal angle of ribs and cervical transverse processes

Question 34

Innervation of iliocostalis

Answer 34

Posterior rami of the spinal nerves

Question 35

Actions of iliocostalis

Answer 35

Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend vertebral column and head

Question 36

Longissimus

Answer 36

Situated between iliocostalis and spinalis
Largest of the three columns
Divided into 3 - thoracic, cervicis and capitis

Question 37

Longissimus attachment

Answer 37

Arises from common tendinous origin, attaches to lower ribs, the transverse processes of C2-T12 and mastoid processes of the skull

Question 38

Longissimus innervation

Answer 38

Posterior rami of spinal nerves

Question 39

Longissimus actions

Answer 39

Acts unilaterally to flex vertebral column. Acts bilaterally to extend the vertebral column and head

Question 40

Spinalis

Answer 40

Located medially within erector spinae
Smallest of 3 muscle columns
Divided into thoracic, cervicis and capitis (cervicis part is absent in some people)

Question 41

Spinalis attachments

Answer 41

Arise from common tendinous origin, attaches to spinous processes of C2, T1-T8 and occipital bone of skull

Question 42

Spinalis innervation

Answer 42

Posterior rami of spinal nerves

Question 43

Spinalis actions

Answer 43

Acts unilaterally to laterally flex the vertebral column. Acts bilaterally to extend the vertebral column and head