Intrinsic Back Muscles (Quiz 1) Flashcards
(44 cards)
What is the 1 muscle in the superficial layer of intrinsic back muscles?
splenius
What is the origin/proximal attachment of the splenius?
-nuchal ligament
-SP of C7-T6 vertebrae
What is the insertion/distal attachment for the splenius capitis?
-fibers run superolaterally to mastoid process of temporal b.
-lateral 3rd of superior nuchal line of occipital bone
What is the insertion/distal attachment for the splenius cervicis?
tubercles of TPs of C1-C3 or C4 vertebrae
What innervates the splenius?
posterior rami of spinal nerves
What are the actions of the splenius?
acting alone
-laterally flex neck
-rotate head to side of active muscles
acting together (splenius capitis and splenius cervicis)
-extend head and neck
What are the 3 muscles in the intermediate layer of the intrinsic back muscles?
Together they’re called “erector spinae”
1) iliocostalis
2) longissumus
3) spinalis
What do the erector spinae muscles do?
chief extensors of the vertebral column, generally act bilaterally
What are the origin/proximal attachments of the iliocostalis, longissumus, and spinalis (erector spinae muscles)?
theres a lottttttttt
-arises from a broad tendon from the posterior part of the iliac crest
-posterior surface of sacrum
-sacro-iliac ligaments
-sacral and inferior lumbar SP’s
-supraspinous ligament
What are the insertion/distal attachments of the iliocostalis?
-lumborum
-thoracis
-cervicis
these 3 fibers run superiorly to angles of lower ribs and cervical TP’s
What innervates the iliocostalis, longissumus, and spinalis (erector spinae muscles)?
posterior rami of spinal nerves
What are the main actions of the iliocostalis?
acting bilaterally
-extend vertebral column
-as back is flexed, control movement via eccentric contraction
acting unilaterally
-laterally flex vertebral column
What are the insertion/distal attachments of the longissumus?
-thoracis
-cervicis
-capitis
these 3 fibers run superiorly to ribs between tubercles and angles to TPs in thoracic and cervical regions, and to mastoid process of temporal bone
What are the actions of the longissumus?
acting bilaterally
-extend head
-as back is flexed, control movement via eccentric contraction
acting unilaterally
-laterally flex vertebral column
What are the insertion/distal attachments for the spinalis?
-thoracis
-cervicis
-capitis
these fibers run superiorly to SPs in the upper thoracic region and to cranium
What are the main actions of the spinalis?
acting bilaterally
-extend vertebral column and head
-as back is flexed, control movement via eccentric contraction
acting unilaterally
-laterally flex vertebral column
What are the 3 muscles of the deep layer of intrinsic back muscles?
together they are called transversospinalis
1) semispinalis
2) multifidus
3) rotatores (brevis and longus)
What are the 3 muscles of the minor deep layer of intrinsic back muscles?
1) interspinales
2) intertransversarii
3) levatores costorum
The transversospinalis muscles occupy what?
the lamina gutter
The transversospinalis muscles originate from _____ and attach to the __________________
TPs, SPs and lamina
What so the transversospinalis muscles do?
-relatively inactive in the stand easy position
-act as static postural muscles (fixators or steadiers) of vertebral column maintaining erect posture
What is the origin/inferior attachment of the semispinalis?
TPs of C4-T12 vertebrae
What is the insertion/superior attachment of the semispinalis?
SPs of more superior vertebrae
thoracis, cervicis, and capitis fibers run superomedially to occipital bone and SPs in thoracic and cervical regions, spanning 4-6 segments above
What innervates the semispinalis, multifidus, and rotatores?
posterior rami of spinal nerves (same as the erector spinae muscles)
