The semispinalis muscles are a group of three
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 belonging to the
transversospinales. These are the semispinalis capitis, the semispinalis cervicis and the semispinalis thoracis.
Location
The semispinalis capitis (''complexus'') is situated at the upper and back part of the
neck
The neck is the part of the body in many vertebrates that connects the head to the torso. It supports the weight of the head and protects the nerves that transmit sensory and motor information between the brain and the rest of the body. Addition ...
, deep to the
splenius muscles, and medial to the
longissimus cervicis and
longissimus capitis. It arises by a series of tendons from the tips of the
transverse processes of the upper six or seven
thoracic
The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen.
In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main ...
and the
seventh cervical vertebrae
In tetrapods, cervical vertebrae (: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In saurop ...
, and from the articular processes of the three cervical vertebrae above this (
C4-C6).
The tendons, uniting, form a broad muscle, which passes upward, and is inserted between the superior and inferior
nuchal lines of the
occipital bone
The occipital bone () is a neurocranium, cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone lies over the occipital lob ...
. It lies deep to the
trapezius muscle and can be palpated as a firm round muscle mass just lateral to the cervical spinous processes.
The semispinalis cervicis (or ''semispinalis colli''), arises by a series of tendinous and fleshy fibers from the transverse processes of the upper five or six
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 ...
, and is inserted into the cervical
spinous processes, from the axis to the fifth
cervical vertebrae
In tetrapods, cervical vertebrae (: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In saurop ...
inclusive. The semispinalis cervicis is thicker than the semispinalis thoracis. The fasciculus connected with 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 ...
is the largest, and is chiefly muscular in structure.
The semispinalis thoracis (or ''semispinalis dorsi'') muscle consists of thin, narrow, fleshy
fasciculi, interposed between
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 of considerable length. It arises by a series of small tendons from the
transverse processes of the sixth to the tenth
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 ...
, and is inserted, by tendons, into the
spinous processes of the upper four thoracic and lower two
cervical vertebrae
In tetrapods, cervical vertebrae (: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In saurop ...
.
The semispinalis muscles are innervated by the dorsal rami of the
cervical spinal nerves.
See also
*
List of muscles of the human body
Additional images
Image:Gray129.png, Occipital bone
The occipital bone () is a neurocranium, cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone lies over the occipital lob ...
. Outer surface.
Image:Gray187.png, Base of skull
The base of skull, also known as the cranial base or the cranial floor, is the most Anatomical terms of location#Superior and inferior, inferior area of the human skull, skull. It is composed of the endocranium and the lower parts of the Calvaria ...
. Inferior surface.
File:Slide1ccc.JPG, Semispinalis capitis muscle
File:Gray384.png, Section showing cervicis and fascia
References
External links
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Image at ithaca.edu*
*
{{Authority control
Muscles of the torso