Internal abdominal oblique muscle

Last update: May 25th, 2023

The internal 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
Origin	Anterior two thirds of the iliac crest; Thoracolumbar fascia
Insertion	Inferior margins of the ribs 10-12; Linea alba; Pubic crest
Innervation	Intercostal nerves 6-11; Subcostal nerve (T12)
Functions	Flexion 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

Origin and insertion

The internal oblique muscle originates 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.

Origin and insertion of the internal abdominal oblique

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 flexion of the trunk and increasing intraabdominal pressure.

First image in animation of a figure with a flexed vertebral column

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Flexion of the trunk

Unilateral contraction contributes to the lateral flexion and rotation of the trunk.

First 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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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

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.