Rectus Abdominis Muscle: Action, Origin & Insertion

Instructor: Dan Washmuth

Dan has taught college Nutrition, Anatomy, Physiology, and Sports Nutrition courses and has a master's degree in Dietetics & Nutrition.

The rectus abdominis muscle is the muscle located at the front of the abdomen that is most often called the 'abs' or the 'six-pack.' Get ready to learn all about this muscle, including its action, origin, and insertion!

The Muscle of Late Night Infomercials

Have you ever stayed up late at night watching TV? If you have, there is a good chance that you've seen a late night infomercial trying to sell some sort of workout equipment or machine that promises to give you perfect-looking abs (you are probably picturing the infomercial right now in your head, filled with muscular people in tight leotards). These infomercials are filled with the empty promise that you will quickly get a ''six-pack'' set of abs, a muscle that has the scientific name of rectus abdominis.


The rectus abdominis is the muscle located at the front of the abdomen and is most often referred to as the abs.
rectus abdominis


Action of Rectus Abdominis

The rectus abdominis causes the rib cage and pelvis to tilt inward towards the abdomen. Think about those late night infomercials and the movements of the people who use these workout machines. Most of the time, these machines involve a crunch, which is the movement of compressing your abdomen by tilting your rib cage, pelvis or both. These movements are caused by the rectus abdominis muscle.


The rectus abdominis tilts the rib cage and pelvic bone towards the middle of the abdomen, such as when a person is performing an abdominal crunch.
crunch

Origin of the Rectus Abdominis

The rectus abdominis muscle originates from two different locations in the pelvis. The following chart describes these points of origin.

Point of Origin Description
Pubic crest The pubic crest is located at the front, middle of the pelvic bone.
Pubic symphysis The pubic symphysis is the cartilage that makes up the mid-line of the front of the pelvic bone.


The rectus abdominis originates from the pubic crest and the pubic symphysis, both of which are located at the front, middle of the pelvic bone.
pelvic bone


Insertion of the Rectus Abdominis

The rectus abdominis muscle also has multiple locations of insertion. The following charts describes these points of insertion.

Point of Insertion Description
Costal cartilage of the fifth through seventh ribs The costal cartilage are sections of connective tissues that extend from the front ends of the ribs. There are 12 total ribs on each side of the rib cage, and the rectus abdominis inserts onto the fifth through seventh ribs.
Xiphoid process The xiphoid process is a small piece of cartilage that extends off the bottom part of the sternum (breastplate). This location is very close to where you press on the chest when performing CPR.


The rectus abdominis muscle inserts onto the costal cartilage of the fifth through seventh ribs. The costal cartilage is shown in this picture as the gray extensions at the front ends of the ribs.
costal cartilage

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