What are Paraspinal Muscles or Deep Muscles or Intrinsic Muscles of back?
These
are deep or intrinsic back muscles. These muscles form a prominent mass on each
side of the spinal column extending from base of the skull to the sacrum. These
muscles consists of many separate, overlapping muscles of different lengths,
attached to the spinous or transverse processes of different vertebrae.
Together, these muscles act to maintain the posture and control the movements
of vertebral column like backward bend.
The
deep back muscles are grouped according to their relationship to the surface.
Superficial
layer (of deep back muscles)
Splenius
muscles
- thick and flat muscles of the neck,
- lie on the side and on more aspect of neck,
- arise from the midline and extend superolaterally to the cervical vertebra (slpenius cervicis) and skull (splenius capitis)
Intermediate layer
of deep back muscles
Erector
spinae
- Lies in a groove on each side of vertebral column
- Chief extensor (backward bend) of vertebral column
- Divides into three column
Iliocostalis –
lateral column
Longissimus – intermediate
column
Spinalis –
medial column
Each
column is divided regionally into three parts according to its superior
attachments (e.g. iliocostalis lumborum, iliocostalis thoracis and
iliocostalis cervicis; thoracis, cervicis and capitis in case of longissimus and
spinalis)
Arises
through a broad tendon from the posterior part of iliac crest, posterior aspect
of sacrum and the sacroiliac ligaments, and sacral and inferior lumbar spinous
processes
Deep
layer of intrinsic back muscles
Transversosinal
muscle group
- Obliquely disposed deep to the erector spinae
- Arises from transverse processes of vertebrae and pass to the spinous processes of more superior vertebrae
- Three types
The
multifidus is deeper
The rotators are the deepest
The rotators are the deepest
Minor
deep layer of intrinsic back muscles
Interspinales,
intertransversarii and levatores costarum are poorly developed in the thoracic
region
REFERENCES:
Following resources are used while preparing this post (readers are strongly recommended to go through them for more details):
K. L. Moore's Clinically Oriented Anatomy
R. Snell's Clinical Anatomy