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Position of the serratus posterior inferior (shown in red). Animation.
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Close up. The muscle arises from the vertebrae T11 through L2 and inserted into lower border of the 9th through 12th ribs.
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Lumbar triangle
Serratus posterior inferior muscle | |
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Details | |
Origin | Vertebrae: Spinous processes of T11 - L2 |
Insertion | The inferior borders of the 9th through 12th ribs |
Artery | Intercostal arteries |
Nerve | Intercostal nerves T9 through T12 |
Actions | Depress the lower ribs 9-12, aiding in expiration |
Identifiers | |
Latin | musculus serratus posterior inferior |
TA98 | A04.3.01.010 |
TA2 | 2235 |
FMA | 13402 |
Anatomical terms of muscle |
The serratus posterior inferior muscle, also known as the posterior serratus muscle,[ citation needed] is a muscle of the human body.
The muscle is situated at the junction of the thoracic and lumbar regions. [1] It has 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 vertebrae. [1]
Passing obliquely upward and lateralward, it becomes fleshy, and divides into four flat digitations. [1] These are inserted into the inferior borders of the lower four ribs, a little beyond their angles. [1]
The thin aponeurosis of origin is intimately blended with the thoracolumbar fascia, and aponeurosis of the latissimus dorsi muscle.[ citation needed]
The serratus posterior inferior draws the lower ribs backward and downward to assist in rotation and extension of the trunk. [1] This movement of the ribs may also contribute to inhalation and forced expiration of air from the lungs. [2]
This article incorporates text in the public domain from page 404 of the 20th edition of Gray's Anatomy (1918)