The innermost intercostal muscle is a layer of
intercostal muscles
The intercostal muscles comprise many different groups of muscles that run between the ribs, and help form and move the chest wall. The intercostal muscles are mainly involved in the mechanical aspect of breathing by helping expand and shrink th ...
.
It may also be called the intima of the internal intercostal muscles.
It is the deepest muscular layer 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 ...
,
with
muscle fibres running vertically (in parallel with the
internal intercostal muscles).
It is present only in the middle of each
intercostal space
The intercostal space (ICS) is the anatomic space between two ribs (Lat. costa). Since there are 12 ribs on each side, there are 11 intercostal spaces, each numbered for the rib superior to it.
Structures in intercostal space
* several kind ...
, and often not present higher up the
rib cage
The rib cage or thoracic cage is an endoskeletal enclosure in the thorax of most vertebrates that comprises the ribs, vertebral column and sternum, which protect the vital organs of the thoracic cavity, such as the heart, lungs and great ve ...
.
It lies deep to the plane that contains the
intercostal nerves
The intercostal nerves are part of the somatic nervous system, and arise from the anterior rami of the thoracic spinal nerves from T1 to T11. The intercostal nerves are distributed chiefly to the thoracic pleura and abdominal peritoneum, and dif ...
and
intercostal vessels, and the
internal intercostal muscles.
The
diaphragm is continuous with the innermost intercostal muscle.
Additional images
File:Innermost intercostal muscles animation.gif, Innermost intercostal muscle (shown in red). Animation.
File:1114 Thorax zoom.png, A cutout of the thoracic wall showing the three layers of intercostal muscle - from the left wall.
References
External links
* - "Thoracic Wall: The Intercostal Nerve and Vessels"
* - "Transverse section of thorax."
*
Muscles of the torso
{{muscle-stub