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The external abdominal obliques require you to do those sideways-turning sit-ups.
Origin
The rectus abdominis originates from the pubic symphysisCartilaginous joint connecting the two pubic bones at the midline. and the pubic crestRidge on superior surface of pubic body; attachment for abdominal muscles..
Insertion
The rectus abdominis extends upwards along the midline of the abdomen. It inserts into the xiphoid processSmall, cartilaginous tip at the inferior end of the sternum; often pointed. of the sternumFlat bone forming the center of the chest; anchor for ribs and clavicles. Appears as a vertical dagg and into the costal cartilages of the fifth, sixth, and seventh ribsCurved bones forming the rib cage; articulate with thoracic vertebrae and most with the sternum..
Actions
- Posture and Movement
- Trunk Flexion

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 superficialNear the surface of the body.. 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 deepAway from the surface of the body. to superficial: transverse abdominisCompressor Deepest abdominal layer; squeezes abdominal contents and stabilizes core., internal obliqueFlexor / Rotator Under external oblique; helps twist and compress abdomen., 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.
Identify More Muscles
Link to more Muscle Identification
Upper Arm Muscles
Forearm Muscles
Calf Muscles
Anterior Thigh Muscles
Posterior Thigh Muscles
Knee Structures
Chest Muscles
Back Muscles
Abdominal Muscles
Neck Muscles
Head Muscles
List of terms
- pubic symphysis
- pubic crest
- xiphoid process
- sternum
- ribs
- external oblique
- superficial
- deep
- transverse abdominis
- internal oblique