Intercostal muscle
Intercostal muscle | |
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Intercostal muscles highlighted in dark red. | |
Details | |
Origin | ribs 1-11 |
Insertion | ribs 2-12 |
Artery | intercostal arteries |
Nerve | intercostal nerves |
Actions | Elevation or Depression of the Ribs |
Identifiers | |
Latin | Musculi intercostales |
MeSH | A02.633.567.900.500 |
FMA | 13354 |
Intercostal muscles are several 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. These muscles help expand and shrink the size of the chest cavity to facilitate breathing.
Structure
There are three principal layers;
- External intercostal muscles aid in quiet and forced inhalation. They originate on ribs 1-11 and have their insertion on ribs 2-12. The external intercostals are responsible for the elevation of the ribs and bending them more open, thus expanding the transverse dimensions of the thoracic cavity.
- Internal intercostal muscles aid in forced expiration (quiet expiration is a passive process). They originate on ribs 2-12 and have their insertions on ribs 1-11. The internal intercostals are responsible for the depression of the ribs and bending them inward, thus decreasing the transverse dimensions of the thoracic cavity.
- Innermost intercostal muscle, the deep layers of the internal intercostal muscles which are separated from them by a neurovascular bundle. This in turn is composed of:
- Transversus thoracis muscle
- Sternocostal muscle
- Subcostalis muscle
Innervation
Both the external and internal muscles are innervated by the intercostal nerves (the ventral rami of thoracic spinal nerves), are supplied by the intercostal arteries, and are drained by the intercostal veins. Their fibers run in opposite directions.
Function
The scalene muscles, which also move the chest wall and have a function in inhalation, are also intercostal muscles, just not one of the three principal layers.
See also
This article uses anatomical terminology; for an overview, see Anatomical terminology.
- Thoracic diaphragm, another muscle importantly involved in breathing action.
- Exhalation
External links
Wikimedia Commons has media related to Intercostal muscle. |
- -294977459 at GPnotebook
- Anatomy figure: 18:03-03 at Human Anatomy Online, SUNY Downstate Medical Center
- UCC
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This article is issued from Wikipedia - version of the Sunday, January 10, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.