The Powerhouse. Core Muscle Review: The External and Internal Obliques

Photos Courtesy of The Muscle System Pro III
(from left to right fig 1-4)


This is the second article in a series about the powerhouse “core muscle review”. Anatomically these muscles work together to maintain balance and stability in the core. The external and internal obliques act as a bridge between the upper torso (rib-cage) and hips. This is a major point that I repeat over and over again in class. The powerhouse connects upper to lower and provides stability from which the limbs move freely. First starts the thought, then the breath, then engagement of the core, then the movement.

The first structure to look at is in figure 1. This is the broad flat tendon in front of the torso called the Abdominal Aponerouses  (an aponerouses is a “broad flat tendon). An important characteristics of this structure is that it is a “common” tendon for multiple muscles. It is thick and strong and has layers of fascia creating a strong connector. Both the externals and internals find their way to this structure.

External Obliques (figure 1)

(Visualization) Imagine you have your favorite jacket on or vest. We’ll start on your left side. reach your left hand up towards the outside upper edge of your rib cage. Move your hand downward in medially towards your belly button and hips. This is the direction of the fibers of the external obliques.The external obliques originate at the outer surfaces of the 5th to the twelfth rib and insert along the linea alba the pubic crest the anterior iliac spine and iliac crest. Movements that occur are rotation of the torso to the opposite side and side bending on the same side.

Internal Obliques (figure 2)

(Visualization) Imagine you are about to reach into your left pant pocket with your right hand. Continue upward and inward towards the ribs and mid-line to demonstrate the fiber direction of the internal obliques. The internals originate around towards the thoracolumbar aponerouses, anterior iliac crest and inguinal ligament just above the pubic bone.  Movements that occur are rotation of the trunk to the same side and side bending to the same side.

I talk about these muscles in a singular view but it is important to keep in mind that they all work together. Especially in Pilates. Some muscle support and stabilize while others move. It certainly is exciting to think about ! Also both muscles wrap around to the back and act as a girdle or corset to provide lift, protect our organs and are the “front” part of the core muscle group. By the way, our “love handles” are composed of the obliques. Do you want a tight waist? Work your Pilates.

Next muscles in the series” Hamstrings” Stay Tuned !

Written by
Scott Miller
Certified Pilates Instructor
Licensed Massage Practitioner
Massage Educator


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