External Oblique

Time To Read

1–2 minutes

Date Last Modified

Illustration of the rectus abdominis and external obliques, highlighting their anatomical relationships
Illustration of the rectus abdominis and external obliques, highlighting their anatomical relationships

The external abdominal obliques require you to do those sideways-turning sit-ups.

Origin

The rectus abdominis originates from the pubic symphysis and the pubic crest.

Insertion

The rectus abdominis extends upwards along the midline of the abdomen. It inserts into the xiphoid process of the sternum and into the costal cartilages of the fifth, sixth, and seventh ribs.

Actions

  • Posture and Movement
  • Trunk Flexion
The image shows a detailed anatomical model highlighting the external oblique muscle.
The image shows a detailed anatomical model highlighting the external oblique muscle.
Photography, text, and labels by Rob Swatski, Assistant Professor of Biology, Harrisburg Area Community College – York Campus, York, PA.

Deciphering Models

Muscle models are designed so that the right side of the model will have all muscles in place. You can only see what is superficial. On the left side of most models, certain elements are intentionally altered. I mean the model’s left side, not your left side. Some aponeuroses and even some superficial muscles are removed. This is the case with the abdominal muscles.

The abdominal muscles can be ordered from deep to superficial: transverse abdominis, internal oblique, rectus abdominis, external oblique. Think of them like aprons that you are putting on. The transverse abdominis is the apron with fibers running right to left across your squishy guts. This is also the muscle that, when cut in a C-section, refuses to go back to its prior state. There are three more aprons over the transverse abdominis. They include the internal oblique, the rectus abdominis, and the external oblique. This is their order from deep to superficial.

The muscles on the left side of a muscle model are removed. However, the transverse abdominis is still not visible without removing the front plate of the model. This is what you see in the picture below. That is the inside of the ribs and abdomen. This is usually the only way you can see the transverse abdominis in a muscle model.

List of terms