Serratus posterior inferior muscle

The serratus posterior inferior muscle, also known as the posterior serratus muscle, is a muscle of the human body.

Structure

The muscle is situated at the junction of the thoracic and lumbar regions. 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.

Passing obliquely upward and lateralward, it becomes fleshy, and divides into four flat digitations. These 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 thoracolumbar fascia, and aponeurosis of the latissimus dorsi muscle.

Function

The serratus posterior inferior draws the lower ribs backward and downward to assist in rotation and extension of the trunk. This movement of the ribs may also contribute to inhalation and forced expiration of air from the lungs.

Additional images

See also

• Serratus anterior muscle
• Serratus posterior superior muscle

References

This article incorporates text in the public domain from page 404 of the 20th edition of Gray's Anatomy (1918)

External links

• Anatomy figure: 01:05-04 at Human Anatomy Online, SUNY Downstate Medical Center - "Intermediate layer of the extrinsic muscles of the back, deep muscles."
• Cross section image: pembody/body8a—Plastination Laboratory at the Medical University of Vienna

1. Serratus posterior superior muscle
2. Serratus anterior muscle
3. Serratus posterior
4. Thoracolumbar fascia
5. Levator scapulae muscle
6. Serratus
7. Trapezius
8. Abdominal external oblique muscle
9. Muscles of respiration
10. List of skeletal muscles of the human body
11. Iliocostalis
12. Subscapularis muscle
13. Epaxial and hypaxial muscles
14. Scapula
15. Human back
16. Rib cage
17. Glossary of medicine
18. Brachial plexus
19. Outline of human anatomy
20. Shoulder joint