Intrinsic Back Muscles Flashcards
Splenius origin
arises from nuchal ligament and spinous processes of C7-T6 vertebrae
splenius capitis insertion
fibers run superolaterally to mastoid process of temporal bone and lateral third of superior nuchal line of occipital bone
splenius cervicis insertion
tubercles of transverse processes of C1-C3 or C4 vertebrae
splenius innervation
posterior rami of spinal nerves
splenius action
acting alone: laterally flex neck and rotate head to side of active muscles
acting together: extend head and neck
superficial layer of intrinsic back muscles
splenius capitis and splenius cervicis
intermediate layer of intrinsic back muscles (erector spinae)
iliocostalis, longissimus, spinalis
Iliocostalis origin
arises by broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral and inferior lumbar spinous processes and supraspinous ligament
longissimus origin
arises by broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral and inferior lumbar spinous processes and supraspinous ligament
spinalis origin
arises by broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral and inferior lumbar spinous processes and supraspinous ligament
iliocostalis insertion
fibers run superiorly to angles of lower ribs and cervical transverse processes
iliocostalis made up of
lumborum, thoracis, and cervicis
longissimus insertion
fibers run superiorly to ribs between tubercles and angles to transverse processes in thoracic and cervical regions and to mastoid process of temporal bone
longissimus made up of
thoracis, cervicis and capitis
spinalis insertion
fibers run superioly to spinous processes in upper thoracic region and to cranium
spinalis made up of
thoracis, cervicis, and capitis
iliocostalis innervation
posterior rami of spinal nerves
longissimus innervation
posterior rami of spinal nerves
spinalis innervation
posterior rami of spinal nerves
iliocostalis, longissimus, spinalis action
acting bilaterally: extend vertebral column and head, as back is flexed, control movement by gradually lengthening their fibers
acting unilaterally: laterally flex vertebral columns
deep layer of intrinsic back muscles (transversospinales)
semispinalis (thoracis, cervicis, and capitis)
multifidus
rotatores (brevis and longus)
semispinalis origin
arises from transverse processes of C4- T10 vertebrae
semispinalis insertion
fibers run superomedially to occipital bone and spinous processes in upper thoracic and cervical regions, spanning four to six segments
semispinalis innervation
posterior rami of spinal nerves
semispinalis action
extends head and thoracic and cervical regions of vertebral column and rotate them contralaterally
multifidus origin
arises from posterior sacrum, posterior superior iliac spine of ilium, aponeurosis of erector spinae, sacro-iliac ligaments, mammillary processes of lumbar vertebrae, transverse processes of thoracic vertebrae, and articular processes of C4-C7
multifidus insertion
thickest in lumbar region, fibers pass obliquely superomedially to entire length of spinous processes of vertebrae located two to four segments superior to origin
multifidus innervation
posterior rami of spinal nerves
multifidus action
unilateral contraction rotates to contralateral side. stabilizes vertebrae during local movements of vertebral column
rotatores origin
arise from transverse processes of vertebrae, are best developed in thoracic region
rotatores insertion
fibers pass superomedially to attach to junction of lamina and transverse process or spinous process of vertebra immediately (brevis) or two segments (longus) superior to vertebra of origin
rotatores innervation
posterior rami of spinal nerves
rotatores action
may function as organs of proprioception, possibly stabilize vertebrae and assist with local extensor and rotatory movements of vertebral column
