Deep Back Flashcards
What structure do the intrinsic back muscles primarily work on?
Axial Skeleton
What muscles are the superficial intrinsic back muscles?
Splenius capitis and cervicis
What nerve innervates the intrinsic back muscles?
Regional Dorsal Primary Rami
What is the origin, insertion, and action of the splenius capitis?
Origin - Spinous processes of C7-T6 and nuchal ligament
Insertion - Mastoid process
Unilateral Action - Laterally flex and rotate head ipsilaterally
Bilateral Action - Extend head and neck
What is the origin, insertion, and action of the splenius cervicis?
Origin - Spinous processes of C7 - T6 and nuchal ligament
Insertion - Transverse processes of C1-C3
Unilateral Action - Laterally flex and rotate head ipsilaterally
Bilateral Action - Extend head and neck
What ways can the intrinsic back muscles act?
Can act unilaterally or bilaterally.
Bilateral action of all is extension of the vertebral column and/or head and neck depending on attachments
What muscles are intermediate intrinsic back muscles?
Erector Spinae - Iliocostalis, Longissimus, and Spinalis
What are characteristics of the erector spinae muscles?
- All share an origin, insertions differ
- Fibers run superolaterally
- All share a unilateral action - laterally flex vertebral column ipsilaterally
- Bilateral action - extend vertebral column, head, and neck
What common origins do the erector spinae muscles share?
Iliac crest, Sacrum, Lumbar spinous processes, and supraspinous ligament
What is the origin and insertion of iliocostalis? How is it divided?
Origin - Iliac crest, Sacrum, Lumbar spinous processes, and supraspinous ligament
Insertion - Angle of ribs and cervical transverse processes
3 parts - depend on attachments
1. Lumborum - lower rib
2. Thoracis - upper ribs
3. Cervicis - Cervical transverse processes
What is the origin and insertion of longissimus? How is it divided?
Origin - Iliac crest, Sacrum, Lumbar spinous processes, and supraspinous ligament
Insertion - Ribs between tubercles and angles, transverse processes of thoracic and cervical vertebrae, mastoid process
3 parts - depend on attachments
1. Thoracis - transverse processes of thoracic vertebrae
2. Cervicis - Transverse processes of cervical vertebrae
3. Capitis - mastoid process
What is the origin and insertion of spinalis? How is it divided?
Origin - Iliac crest, Sacrum, Lumbar spinous processes, and supraspinous ligament
Insertion - Spinous processes of superior thoracic and cervical vertebrae, occipital bone
3 parts - depending on attachments
1. thoracis - spinous processes of thoracic vertebrae
2. cervicis - spinous processes of cervical vertebrae
3. capitis - indistinct; usually blends with the semispinalis capitis
What muscles are deep instrinsic back muscles?
- Transversospinalis group
- semispinalis capitis
- semispinalis cervicis
- semispinalis thoracis (poorly developed)
- multifidus
- rotatores longi
- rotatores brevi
What are characteristics of the transversospinalis group?
All share a unilateral action - rotate axial skeleton contralaterally
Fibers run superomedially from transverse to spinous processes
What is the origin, insertion, and unilateral action of the semispinalis capitis?
Origin - Transverse processes of thoracic and lower cervical vertebrae
Insertion - Occipital bone
Action - Rotates head and neck contralaterally
What is the origin, insertion, and unilateral action of the semispinalis cervicis?
Origin - Transverse processes of thoracic and lower cervical vertebrae
Insertion - Spinous processes of thoracic and cervical vertebrae. Terminate at spinous of C2 and span 4-6 vertebral segments
Action - Rotate head and neck contralaterally
What is the origin, insertion, and action of the multifidus muscle?
Origin - Sacrum, ilium, mammillary processes of lumbar vertebrae
Insertion - Spinous processes of thoracic and lumbar vertebrae. Span 2-4 vertebral segments. Best developed in lumbar, but present in thoracic and cervical
Action - Stabilization of vertebrae during locomotion
What is the origin, insertion, and action of the rotatores longi?
Origin - Transverse processes
Insertion - Spinous process or lamina. Span 2 vertebral segments
Action - Assists in stabilization and rotation of vertebrae
What is the origin, insertion, and action of the rotatores breves?
Origin - Transverse processes
Insertion - Spinous process or lamina. Attaches to the vertebra immediately superior
What are the deep accessory muscles and what do they do?
Deep accessory muscles assist other muscles in extension, rotation, lateral flexion, and stabilization of vertebral column.
- Interspinalis - assist in extension
- Intertransversarii - assist in lateral flexion, stabilization
- Levatores costarum - elevate ribs and assist in respiration, assist in lateral flexion
How do the intrinsic back muscles develop?
Derived from myotomes. Myotomes divide into dorsal and ventral mass. The dorsal mass or epimere becomes intrinsic back muscle and the ventral mass or hypomere because hypaxial muscles
What muscles are suboccipital muscles?
- Rectus capitis posterior major
- Rectus capitis posterior minor
- Obliquus capitis inferior
- Obliquus capitis superior
What are the characteristics and actions of the suboccipital muscles?
Inferior to external occipital protuberance
Innervated by the suboccipital nerve
Assist in rotation and extension of the head, maintenance of posture, and proprioception
What is the origin, insertion, and action of the rectus capitis posterior major?
Origin - Spinous process of C2
Insertion - Inferior nuchal line of occipital bone
Action - Extension and ipsilateral rotation of head
