The spinalis is a portion of the
erector spinae, a bundle of
muscle
Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...
s and
tendon
A tendon or sinew is a tough band of fibrous connective tissue, dense fibrous connective tissue that connects skeletal muscle, muscle to bone. It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tensi ...
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 si ...
, is scarcely separable as a distinct muscle. It is situated at the medial side of the
longissimus dorsi
The longissimus () 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.
Structure
Longissimus th ...
, and is intimately blended with it; it arises by three or four tendons from the
spinous processes
Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...
of the first two
lumbar
In tetrapod anatomy, lumbar is an adjective that means of or pertaining to the abdominal segment of the torso, between the diaphragm (anatomy), diaphragm and the sacrum.
Naming and location
The lumbar region is sometimes referred to as the lowe ...
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 vertebra (anatomy), vertebrae of intermediate size between the ce ...
: 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, 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 p ...
, the
spinous process
Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...
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 (: axes) may refer to:
Mathematics
*A specific line (often a directed line) that plays an important role in some contexts. In particular:
** Coordinate axis of a coordinate system
*** ''x''-axis, ''y''-axis, ''z''-axis, common names ...
, 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.
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 late ...
*
Longissimus
*
Semispinalis muscle
References
External links
* - "Intrinsic muscles of the back."
Dissection at ithaca.edu
{{Authority control
Muscles of the torso