The spinalis is a portion of the
erector spinae, a bundle of
muscles and
tendon
A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...
s, located nearest to the spine. It is divided into three parts: Spinalis dorsi, spinalis cervicis, and spinalis capitis.
Spinalis dorsi
Spinalis dorsi, the medial continuation of the
sacrospinalis
The erector spinae ( ) or spinal erectors is a set of muscles that straighten and rotate the back. The spinal erectors work together with the glutes (gluteus maximus, gluteus medius and gluteus minimus) to maintain stable posture standing or sitt ...
, is scarcely separable as a distinct muscle. It is situated at the medial side of the
longissimus dorsi
The longissimus ( la, the longest one) is the muscle lateral to the semispinalis muscles. It is the longest subdivision of the erector spinae muscles that extends forward into the transverse processes of the posterior cervical vertebrae.
Structu ...
, and is intimately blended with it; it arises by three or four tendons from the
spinous processes
The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...
of the first two
lumbar and the last two
thoracic vertebrae
In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical ...
: these, uniting, form a small muscle which is inserted by separate tendons into the spinous processes of the upper thoracic vertebrae, the number varying from four to eight.
It is intimately united with the
semispinalis dorsi
The semispinalis muscles are a group of three muscles belonging to the transversospinales. These are the semispinalis capitis, the semispinalis cervicis and the semispinalis thoracis.
The semispinalis capitis (''complexus'') is situated at the ...
, situated beneath it.
Spinalis cervicis
Spinalis cervicis, or spinalis colli, is an inconstant muscle, which arises from the lower part of the
nuchal ligament
The nuchal ligament is a ligament at the back of the neck that is continuous with the supraspinous ligament.
Structure
The nuchal ligament extends from the external occipital protuberance on the skull and median nuchal line to the spinous proc ...
, the
spinous process
The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...
of the seventh cervical, and sometimes from the spinous processes of the first and
second thoracic vertebrae, and is inserted into the spinous process of the
axis
An axis (plural ''axes'') is an imaginary line around which an object rotates or is symmetrical. Axis may also refer to:
Mathematics
* Axis of rotation: see rotation around a fixed axis
* Axis (mathematics), a designator for a Cartesian-coordinat ...
, and occasionally into the spinous processes of the two cervical vertebrae below it.
Spinalis capitis
Spinalis capitis (biventer cervicis) is usually inseparably connected with the
semispinalis capitis
The semispinalis muscles are a group of three muscles belonging to the transversospinales. These are the semispinalis capitis, the semispinalis cervicis and the semispinalis thoracis.
The semispinalis capitis (''complexus'') is situated at the ...
.
Spinalis capitis is not well characterized in modern anatomy textbooks and atlases, and is often
omitted from anatomical illustration. However, it can be identified as fibers that extend from the spinous processes of TV1 and CV7 to the cranium, often blending with semispinalis capitis
See also
*
Iliocostalis
Iliocostalis muscle is the muscle immediately lateral to the longissimus that is the nearest to the furrow that separates the epaxial muscles from the hypaxial. It lies very deep to the fleshy portion of the serratus posterior muscle. It latera ...
*
Longissimus
The longissimus ( la, the longest one) is the muscle lateral to the semispinalis muscles. It is the longest subdivision of the erector spinae muscles that extends forward into the transverse processes of the posterior cervical vertebrae.
Structu ...
*
Semispinalis muscle
The semispinalis muscles are a group of three muscles belonging to the transversospinales. These are the semispinalis capitis, the semispinalis cervicis and the semispinalis thoracis.
The semispinalis capitis (''complexus'') is situated at the u ...
References
External links
* - "Intrinsic muscles of the back."
Dissection at ithaca.edu
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Muscles of the torso