Intrinsic Back Muscles

Question 1

Intrinsic muscles of the back extend from what to what

Answer 1

Pelvis to skull

Question 2

What do the intrinsic muscles consist of?

Answer 2

-extensors and rotators of the head and vertebral column
-short segmental muscles

Question 3

Layers of thoracolumbar fascia

Answer 3

-posterior layer: thick and attached to SP of lumbar and sacral vertebrae

-middle layer: attached medially to TP of lumbar vertebrae and inter transverse ligaments, inferiorly attaches iliac crest and superiorly to lower border of rib 12

-anterior layer: quadratics lumboroum, TP lumbar vertebrae, attached to iliac crest and forms accurate ligament for attachment of diaphragm

Question 4

Splenius capitis OIIA

Answer 4

Origin: ligamentum nuchae and SP of C7 to T3

Insertion: mastoid process and superior unchallenged line

Innervation: posterior rami of middle cervical nerves

Action: together (extend the neck), individually (rotate head)

Question 5

Splenius cervicis OIIA

Answer 5

Origin: SP of T3 to T6

Insertion: TP of C1 to C3

Innervation: posterior rami lower cervical n’s

Action: together (extend neck), individually (rotate head)

Question 6

Where are the erector spinae muscles located between?

Answer 6

SP and angle of ribs

Question 7

Erector spinae muscles function, unilateral contraction, bilateral contraction

Answer 7

-primary extensors of vertebral column
-uni: bend the vertebral column laterally
-bi: straighten back, returning it to upright position from flexed position

Question 8

What are the 3 major subgroups of transvesospinales muscles?

Answer 8

Semispinalis, multifidus, rotatores

Question 9

Semispinalis (located, spans between)

Answer 9

-most superficial transversospinales
-being in lower thoracic region and end in occipital bone
-span between 4 and 6 vertebrae

Question 10

Multifidus (spans from, between)

Answer 10

-deep to semispinalis
-length of vertebral column
-from TP to SP
-span between 2 and 4 vertebrae

Question 11

Rotatores (characteristics, length of)

Answer 11

-smallest and deepest
-length of vertebral column
-long rotatores (cross 2 vertebrae), short rotatores (attach to adjacent vertebrae)

Question 12

Function of transvesospinales muscles

Answer 12

-bilateral contraction: extend vertebral column, similar to erector spinae group
-one side contraction: pull SP toward TP, rotate the trunk

Question 13

What are the 2 groups of segmental muscles

Answer 13

1st group: Levator costarum

2nd: interspinales, intertrasversarii

Question 14

Function of Levator costarum

Answer 14

Elevate the ribs

Question 15

Function of interspinales and intertrasversarii

Answer 15

Stabilize vertebrae during movements of vertebral column