Internal abdominal oblique muscle

Author: Kevin Kuschel MD

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The image descriptioninternal abdominal oblique is part of the anterolateral abdominal muscles, a group that also includes the transversus abdominis, external abdominal oblique, rectus abdominis, and pyramidalis muscles.

This paired muscle is situated between the rectus abdominis and transversus abdominis muscles and plays a role in the flexion and rotation of the trunk.

Internal abdominal oblique muscle
OriginAnterior two thirds of the iliac crest;
Thoracolumbar fascia
InsertionInferior margins of the ribs 10-12;
Linea alba;
Pubic crest
InnervationIntercostal nerves 6-11;
Subcostal nerve (T12)
FunctionsFlexion of the trunk;
Lateral flexion of the trunk;
Rotation of the trunk.
Internal oblique muscle with labels: Deltoid, latissimus dorsi, external oblique, biceps brachii, abdominal aponeurosis, pectoralis major, serratus anterior
Internal oblique muscle with labels: Pectoralis minor, latissimus dorsi, external oblique, biceps brachii, rectus abdominis, serratus anterior, Linea alba
Internal oblique muscle with labels: External intercostals, internal intercostals, serratus anterior, external oblique, linea alba, rectus abdominis
Internal oblique muscle with labels: external oblique, linea alba, internal oblique, abdominal aponeurosis
Internal oblique muscle with labels: external oblique, linea alba, internal oblique, transversus abdominis, abdominal aponeurosis
Internal Oblique labeled and highlighted
Location and relations of the internal abdominal oblique muscle
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Origin and insertion

The internal oblique muscle image descriptionoriginates from the anterior two-thirds of the iliac crest and the thoracolumbar fascia. Its fibers diverge over the side of the trunk and insert along the structures of the midline, including the inferior margins of ribs 10-12, the linea alba, and the pubic crest.

Internal Oblique labeled and highlighted
Origin and insertion of the internal abdominal oblique
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Innervation

The internal abdominal oblique is innervated by intercostal nerves 6-11 and the subcostal nerve.

Functions

Bilateral contraction of the internal oblique muscle aids in the image descriptionflexion of the trunk and increasing intraabdominal pressure.

First image in animation of a figure with a flexed vertebral column
Second image in animation of a figure with a flexed vertebral column
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Fourth image in animation of a figure with a flexed vertebral column
Flexion of the trunk

Unilateral contraction contributes to the image descriptionlateral flexion and image descriptionrotation of the trunk.

First image in animation of a figure with lateral flexion
Second image in animation of a figure with lateral flexion
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Lateral flexion of the trunk

Learn this topic even more efficiently with this trunk wall muscle anatomy reference chart. 

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Second image in animation of a figure with a rotated vertebral column
Third image in animation of a figure with a rotated vertebral column
Fourth image in animation of a figure with a rotated vertebral column
Rotation of the trunk

An Overview of the Internal Oblique Muscle

Muscles That Act On Abdominal Wall

1b Test yourself on internal oblique muscle with answers shown:Deltoid, pectoralis major, latissimis dorsi, serratus anterior, biceps brachii, external oblique, linea alba, rectus abdominis, abdominal aponeurosis
Test yourself on internal oblique muscle with answers hidden
Test yourself on internal oblique muscle with answers shown:Pectoralis major, latissimis dorsi, serratus anterior, biceps brachii, external oblique, linea alba, rectus abdominis, abdominal aponeurosis
Test yourself on internal oblique muscle with answers shown:Pectoralis minor, latissimis dorsi, serratus anterior, biceps brachii, external oblique, linea alba, rectus abdominis, abdominal aponeurosis
Test yourself on internal oblique muscle with answers shown: :External intercostals, internal intercostals, serratus anterior, external oblique, linea alba, rectus abdominis, abdominal aponeurosis
Test yourself on internal oblique muscle with answers shown:External intercostals, internal intercostals, external oblique, linea alba, rectus abdominis, abdominal aponeurosis
Test yourself on internal oblique muscle with answers shown: Internal intercostals, external oblique, linea alba, rectus abdominis, abdominal aponeurosis
Test yourself on internal oblique muscle with answers shown: external oblique, linea alba, rectus abdominis, abdominal aponeurosis
Test yourself on internal oblique muscle with answers shown: external oblique, linea alba, abdominal aponeurosis
Test yourself on internal oblique muscle with answers shown: external oblique, linea alba, internal oblique, abdominal aponeurosis
Internal Oblique with labels: Insertion and Origin
Test yourself while observing the internal oblique muscle anatomy
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References

  • Open Anatomy. (n.d.). TA2 Viewer. Retrieved April 5, 2023, from https://ta2viewer.openanatomy.org/
  • Betts, J. G., Young, K. A., Wise, J. A., Johnson, E., Poe, B., & Kruse, D. H. (2022). Anatomy and Physiology (2nd ed.). OpenStax. https://openstax.org/details/books/anatomy-and-physiology-2e
  • Palastanga, N., & Soames, R. (2012). Anatomy of Human Movement (6th ed.). Edinburgh, Scotland: Churchill Livingstone.
  • Moore, K. L. (2018). Clinically Oriented Anatomy (8th ed.). Philadelphia, PA: Wolters Kluwer.
  • Drake, R. L., Vogl, A. W., & Mitchell, A. W. M. (2015). Gray’s Anatomy for Students (3rd ed.). Edinburgh, Scotland: Churchill Livingstone.