You may not know where your external obliques are, and you may not realize all that they do. However, if you have ever had low back pain, a pot belly, difficulty bending to the side, or difficulty twisting, you will want to keep reading. The external obliques are a major anterior supportive muscle for your spine, and they help hold all your organs inside your body. Plus, they help you bend to the side and rotate your spine.
Here’s more about this often ignored, multi-tasking abdominal muscle.
The external oblique originates on the external surfaces and bottom edges of the lower eight ribs. If you’re looking at a picture, you can see how the muscle’s origin is on the surface and lower edges of the ribs.
According to Flash Anatomy Muscles Flash Cards, the insertion for the external obliques is on the “linea alba by means of the broad abdominal aponeurosis from ribs to crest of pubis, inguinal ligament, and the anterior half of the iliac crest along the outer lip.” Remember, the linea alba is the line that runs down the middle of your rectus abdominis, turning your three-pack into a six-pack.
Aponeurosis is a new word for us. Basically, it is a fibrous tissue that takes the place of a tendon. It works similarly to a tendon, but they’re not the same thing. You may remember that tendons attach muscles to bones. That’s what this aponeurosis does, connecting the external oblique to the crest of the pubis. However, it also connects the external oblique to the linea alba.
Don’t forget that the external oblique also inserts on the inguinal ligament and the anterior half of the iliac crest. If you put your fingertips on the front of your pelvis and trace down about half way, this is where the external oblique insertion starts. As your fingertips move toward your pubis, you are tracing your external oblique insertion.
My Pilates instructor, Tracy Maxfield, taught me the obliques this way: To trace the external obliques, your hands start on the front of your rib cage. They slide down toward your pubis. That zone is X-rated. Thus, you get “X-ternal obliques.”
According to Flash Anatomy Muscles Flash Cards, the function of the external obliques is as follows:
“Acting unilaterally, rotates the trunk to the opposite side, and flexes it laterally on the side of muscle contraction. If rotation is only activity, the opposite internal oblique is synergist. Acting bilaterally, flexes the trunk anteriorly, supports and compresses the abdominal viscera, giving anterior support to the spinal column. Gives anterior stabilization to pelvis, decreasing lordosis. Assists in forced expiration.”
Whew! That’s a lot of work. So, when just one of the external obliques is firing, the working muscle will rotate the trunk to the opposite side. It will also bend to the side in the direction of the working muscle.
When both external obliques work, the torso bends forward. The external obliques also provide structural support. Sure, the spine is supported, especially the low back, but the external obliques also help hold the other abdominal muscles in their places.
Thus, it stands to reason that, if the external obliques are weak or injured, you can hurt your lumbar spine (low back). Without the muscle tone and stability of the external obliques, your personal contents shift. This places strain on your low back.
Imagine for a moment that your ribs and hips form a cylinder to contain your internal organs. Your transverse abdominis, or transversus, is the first muscle trying to keep your organs in that cylinder. However, it’s a very thin layer. It needs additional help.
This is where the external obliques come into play. They are the additional force to help keep your organs inside the cylinder.
Now, let’s say that your external obliques are weak or injured. They will not be supportive. With your spine closing the space in your back and your ribs and hips coming close to closing the space in the sides, there is only one area of weakness–your front.
When you have weak abdominals, your organs tend to spill forward out of your cylinder. This creates a pull on your low back. It’s kind of crazy to think about, but this is one common cause of low back injuries.
Restoring or Maintaining Health
In order to increase strength and recover from injury in your external obliques, you need to correctly perform rotation and side flexion exercises. As you rotate one direction, you will stretch the external oblique that you are rotating toward. (Remember, your right external oblique rotates you to the left. Therefore, as you rotate to the left, it will be your left external oblique stretching.)
Some excellent Pilates exercises that involve rotation are: Spinal rotation, Spine twist, Saw, Obliques roll back, and Obliques. When both external obliques fire, your torso comes toward your pelvis. Because of this, a case can be made that Roll up, Ab prep, The Hundred, Spine stretch forward, and other flexion exercises also strengthen your external obliques. In these scenarios, the external obliques would be secondary movers, though.
Yoga also offers many twists that could strengthen the external obliques. Some examples are: Simple seated twist, Revolved triangle pose, Revolved side angle pose, Ardha Matsyendrasana, Marichyasana C, and Revolved head to knee pose.
I consulted The Concise Book of Muscles by Chris Jarmey. Recently, the book was revised and is in its third edition.
Also, I consulted my Flash Anatomy Muscles Flash Cards. If you really enjoy anatomy and want a tool to help you locate specific muscles correctly, I highly recommend these flash cards. I turn to them any time a client comes in with pain.
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What are your favorite exercises for your external obliques? Let us know in the comments below.
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