Dan has taught college Nutrition and Anatomy courses for over 5 years. He has a B.S. in Exercise Physiology from Furman University and a M.S. in Dietetics & Nutrition from Florida International University. He is a Registered Dietitian (RD) and a Certified Exercise Physiologist (EP-C)
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.
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.
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.|
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 is the muscle that is located at the front of the abdomen; it is most often referred to as the ''abs.'' The action of this muscle pulls the rib cage and the pelvic bone towards the middle of the abdomen, just like the movement when a person performs a sit-up or crunch.
The rectus abdominis originates from the pubic crest and pubic symphysis, which are both located at the front/middle of the pelvic bone. From these locations, the rectus abdominis muscle extends directly upward and inserts on the costal cartilages of the fifth through seventh ribs and the xiphoid process of the sternum (breastplate). The costal cartilage is the extension at the front end of each rib that is made up of connective tissues, while the xiphoid process is a piece of cartilage that extends off the bottom of the sternum.
So next time you're watching TV late at night and see an infomercial for an ab machine, be sure to remember that the true name of the abs is rectus abdominis.
Medical Disclaimer: The information on this site is for your information only and is not a substitute for professional medical advice.
To unlock this lesson you must be a Study.com Member.
Create your account
Register to view this lesson
Unlock Your Education
See for yourself why 30 million people use Study.com
Become a Study.com member and start learning now.Become a Member
Already a member? Log InBack