Deep Layers Of Intrinsic Back Muscles

Question 0

Origin of multifidus

Answer 0

Arises from posterior sacrum, posterior superior iliac spine of ilium, aponeurosis of erector Spinae, sarco-iliac ligaments, mammillary processes of lumbar vertebrae, transverse processes of thoracic vertebrae, articular processes of C4-C7

Question 1

Origin of semispinalis

Answer 1

Arises from transverse process of C4-T10 vertebrae

Question 2

Origin of rotatores

Brevis and longus

Answer 2

Arise from transverse processes of vertebrae, best developed in thoracic region.

Question 3

Insertion of semispinalis

Answer 3

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

Question 4

Insertion of multifidus

Answer 4

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

Question 5

Insertion of rotatores

Answer 5

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

Question 6

Nerve supply of semispinalis , multifidus , and rotatores

Answer 6

Posterior rami of spinal nerves

Question 7

Action of semispinalis

Answer 7

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

Question 8

Action of multifidus

Answer 8

Unilateral contraction, rotates to contralateral side

Stabilizes vertebrae during local movements of vertebral column

Question 9

Action rotatores

Answer 9

May function as organs of properioception

Possibly stabilize vertebrae and assist with local extension and rotatory movements of vertebral column