| Serratus posterior inferior muscle | |
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| Muscles connecting the upper extremity to the vertebral column. (Serratus posterior inferior labeled at center right.) | |
| Gray's | subject #117 404 |
| Origin | vertebrae T11 - L3 |
| Insertion | the inferior borders of the 9th through 12th ribs |
| Artery | intercostal arteries |
| Nerve | intercostal nerves T9 through T12 |
| Actions | depress the lower ribs, aiding in expiration |
The Serratus posterior inferior muscle (or posterior serratus) is a muscle of the human body.
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Origin and insertion
The muscle lies at the junction of the thoracic and lumbar regions. It arises from the vertebrae T11 through L2 and runs superolaterally to attach to the lower border of the 9th through 12th ribs.
It is situated at the junction of the thoracic and lumbar regions: it is of an irregularly quadrilateral form, broader than the serratus posterior superior muscle, and separated from it by a wide interval.
It arises by a thin aponeurosis from the spinous processes of the lower two thoracic and upper two or three lumbar vertebræ, and from the supraspinal ligament.
Passing obliquely upward and lateralward, it becomes fleshy, and divides into four flat digitations, which are inserted into the inferior borders of the lower four ribs, a little beyond their angles.
The thin aponeurosis of origin is intimately blended with the lumbodorsal fascia, and aponeurosis of the Latissimus dorsi.
Function
Serratus Posterior Inferior draws the lower ribs backward and downward to assist in rotation and extension of the trunk. This movement of the ribs also contributes to forced expiration of air from the lungs.
See also
External links
- LUC spi
- SUNY Figs 01:05-04 - "Intermediate layer of the extrinsic muscles of the back, deep muscles."
- Cross section at UV pembody/body8a
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.
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