The subcostales (singular: subcostalis) (Infracostales) consist of muscular and
aponeurotic
An aponeurosis (; : aponeuroses) is a flattened tendon by which muscle attaches to bone or fascia. Aponeuroses exhibit an ordered arrangement of collagen fibres, thus attaining high tensile strength in a particular direction while being vulnerabl ...
fasciculi
Fascicle or ''fasciculus'' may refer to:
Anatomy and histology
* Muscle fascicle, a bundle of skeletal muscle fibers
* Nerve fascicle, a bundle of axons (nerve fibers)
** Superior longitudinal fasciculus
*** Arcuate fasciculus
** Gracile fasc ...
, which are usually well-developed only in the lower part of the
thorax
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 di ...
; each originates from the inner surface of one
rib
In vertebrate anatomy, ribs () are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the thoracic cavity, enabling the lungs to expand and thus facilitate breathing by expanding the ...
, and is inserted into the inner surface of the second or third rib below, near its angle.
Their fibers run in the same direction as those of the
intercostales interni
The internal intercostal muscles (intercostales interni) are a group of skeletal muscles located between the ribs. They are eleven in number on either side. They commence anteriorly at the sternum, in the intercostal spaces between the cartilages ...
.
Depresses the ribs to assist in expiration.
References
Muscles of the torso
{{muscle-stub