VH Dissector: Deep Back Muscles
VH Dissector: Deep Back Muscles
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The deep back muscles are long strap-like muscles with various subdivisions. They span multiple segments to one spinal segment and play a major role in spinal mobility/stability. All of these muscles are innervated by the corresponding dorsal rami. As you study these muscles you are only responsible to know the origin, insertion for the suboccipital group. For the rest of the groups, you need to have a general understanding of the origins and insertions (e.g. - the splenius cervicis originates from upper thoracic spinous processes to the transverse processes mid and upper cervical spine).
The Suboccipital Group
The Suboccipital Group
Add the rectus capitis posterior minor
Refer to your assigned textbook for the Origin, Insertion, Innervation, Action, and Blood supply.
Rotate - the cadaver to visualize this muscle.
Add the rectus capitis posterior major
Refer to your assigned textbook for the Origin, Insertion, Innervation, Action, and Blood supply.
Rotate - the cadaver to visualize this muscle.
Add the obliquus capitis superior
Refer to your assigned textbook for the Origin, Insertion, Innervation, Action, and Blood supply.
Rotate - the cadaver to visualize this muscle.
Add the obliquus capitis inferior
Refer to your assigned textbook for the Origin, Insertion, Innervation, Action, and Blood supply.
Rotate - the cadaver to visualize this muscle.
The Segmental Back Muscles
The Segmental Back Muscles
These muscles are the smallest of the deep back muscles.
Add the intertransversarii group connect transverse processes, respectively in the cervical and lumbar spine.
Rotate - the cadaver to visualize this muscle.
Add the interspinales group connect spinous processes respectively in the cervical and lumbar spine.
Rotate - the cadaver to visualize this muscle.
The Transversospinales Muscles
The Transversospinales Muscles
Add the rotatores group which help with segmental rotation of the spine. This group is best developed in the thoracic region spanning 1 segment (brevis) or 2 segments (longus). VH dissector shows the rotatores in the lumbar region, however they are not as well defined and in the literature are more often the deepeset layer of the multifidi.
Rotate - the cadaver to visualize this muscle.
Add the multifidus which span 2-4 segments running from the sacrum and ilium to the C4-C7 articular processes. Note the difference in the overall size of the multifidus in the lumbosacral region compared to the thoracic and cervical regions.
Rotate - the cadaver to visualize this muscle.
Add the semispinalis group capitis, cervicic, thoracis.
Rotate - the cadaver to visualize this muscle.
The Erector Spinae Muscles
The Erector Spinae Muscles
Add the spinalis group. The thoracis component of this muscle group is the only part shown. The capitis and cervicis often blend with the fibers of the semispinalis and ligamentum nuchae
Rotate - the cadaver to visualize this muscle.
Add the longissimus group is the longest portion of the erector spinae, with a thoracis, cervicis, and capitis parts and sits between the spinalis group and iliocostalis.
Rotate - the cadaver to visualize this muscle.
Add the iliocostalis group is the most lateral group, with a lumborum, thoracis, and cervicis parts running along the ribs from the ilium through the thoracic spine to the transverse processes in the cervical spine.
The Spinotransversales Muscles
The Spinotransversales Muscles
Add the splenius group, which runs along the nuchal ligament and upper 6 thoracic vertebrae out to the transverse processes of C1-C4 vertebrae and the mastoid process in the cervicis and capitis parts respectively.
The members of the deep back muscles function as follows:
The members of the deep back muscles function as follows:
When working in equilibrium, they stiffen the spine so we can stand erect.
When working unilaterally, they cause the spine to rotate in the ipsilateral direction for the Spinotransversalis muscles, and the contralateral direction for the Transversospinalis muscles.
When all are contracting, they cause the spine to hyperextend posteriorly.
Cross Section of lumbar spine at L3 vertebral level.
Cross Section of lumbar spine at L3 vertebral level.
Now study some of the muscles indicated above by viewing them on cross-section in the image below, and then go to the VH Dissector model at Step 15 and add in the Cross Sections Panel. Put your mouse on the sagital cross-section and move this cross section up or down to change the transverse cross-section view and study how a muscles shape and position changes and how it is oriented to the surrounding structures. From this point you can use the highlighter tool and look at other muscles in relation to the superficial back muscles.
Fig: Transverse plane cross-section cut of a cadaver at the L3 vertebral level. Note all the structures indicated. Which superficial back muscle is not present in this picture at this level?
Credits:
Credits:
VH Dissector steps modified for Drexel Dissector byHaviva Goldman, PhD, Noel Goodstadt, DPT and Sophie Geagan (MD student) from original website activity created by Jeffrey Fahl, MD, Kyle Petersen, PhD, Richard Drake, PhD, Alesha Petitt, MA, Claira Ralston, MS and Kim Price, MA and modified by Jeffrey Fahl, MD, Michael Smith, PhD, Albany Medical College.
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