Intrinsic (Deep) Back Muscles Flashcards
all of the intrinsic back muscles are innervated by _____
dorsal rami
how do the intrinsic back muscles maintain posture/balance?
- resist gravity
- stabilize the vertebral column
- extend, ABD/ADD (lateral flex/extend), and rotate the vertebral column
the intrinsic back muscles can unilaterally _____ and bilaterally _____
ABD/ADD, rotate; extend
what is unique about the intrinsic back muscles?
they are staggered
what muscles are in the superficial layer of deep back muscles?
- the splenius is the only one, but it has 2 parts: capitis and cervicis
- capitis attaches superiorly at the mastoid process, so it can act on the atlantoaxial and atlanto-occipital joints
- cervicis attaches superiorly at the cervical vertebrae, so it acts on the cervical region
name the muscles of the erector spinae group (intermediate layer of deep back muscles)
- iliocostalis
- longissimus
- spinalis
on what regions does the iliocostalis act?
lumbar, thoracic, cervical (limited to lower cervical)
on what regions does the longissimus act?
thoracic, cervical, capitis
on what regions does the spinalis act?
thoracic, cervical, capitis
the spinalis cannot ____ as much as the other erector spinae muscles
- ABD/ADD
- It is so close to the midline that it can’t do this action very much
name the muscles of the transversospinalis group (deep layer of deep back muscles)
- semispinalis
- multifidus
- rotatores
on what regions does the semispinalis act?
thoracic, cervical, capitis
on what regions does the multifidus act?
lumbar - it is the bulk of the muscle in the lumbar region.. when you think of this muscle, think of the lumbar region
rotatores actions
mostly unilateral rotation (thoracic), little unilateral ABD/ADD (sup lumbar)
what is the difference between rotatores brevis and longus?
rotatores brevis cross 1 intervertebral joint; rotatores longus cross 2 intervertebral joints
