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)
One of the best parts of a birthday is getting to blow out the candles on a birthday cake. Think about the last time you did this, you probably took a big breath in and then blew the air out of your mouth very forcefully in order to blow out all of the flames. Did you know that your internal oblique muscle helped you do this?
The internal oblique muscle is a muscle that is found at each side of the body, just lateral to the abdomen. The word 'oblique' means 'diagonal' or 'slanted', which is a reference to the slanted direction that the muscle fibers of this muscle run up the sides of the body.
Origin of the Internal Oblique
The internal oblique originates from three different locations, which are described by the following chart.
|Point of Origin||Description|
|Iliac crest||The top, outer rim of the ilium.|
|Inguinal ligament||The diagonal band of connected tissue at the front of the pubic bone.|
|Thoracolumbar fascia||The membrane of connective tissue located at the back of the thoracic and abdominal cavities.|
Insertion of the Internal Oblique
The internal oblique inserts onto the costal cartilages of the eighth through twelfth ribs and the linea alba. Costal cartilage is the section of cartilage that extends from front ends of the ribs, and the linea alba (Latin for 'white line') is a band of connective tissue that runs up the middle of the abdomen.
Action of the Internal Oblique
There are several different actions of the internal oblique muscles, which are described in the following chart.
|Action of the Internal Oblique||Description|
|Flexion of the trunk||Bending the trunk forward, such as when you bend over to pick something up off the ground.|
|Lateral rotation of the trunk||Turning the trunk to either side, such as when you turn around to look at someone behind you.|
|Lateral flexion of the trunk||Bending the trunk to either side, such as when you perform side bends|
Additionally, the internal oblique assists with forced exhalation, such as when you blow out birthday candles. When the internal oblique contracts, it helps push the air out of the lungs, helping to create a more powerful and forceful exhale.
The internal oblique muscle is a diagonal muscle that is found at each side of the body, just lateral to the abdomen. This muscle has several different points of origin, which include:
- Iliac crest: the top, outer rim of the ilium
- Inguinal ligament: a diagonal band of connected tissue at the front of the pubic bone
- Thoracolumbar fascia: a membrane of connective tissue located at the back of the thoracic and abdominal cavities
From these points of origin, the internal oblique runs diagonally up the side of the body and inserts onto the costal cartilage of the eighth through twelfth ribs and the linea alba. The costal cartilage are the sections of cartilage that extend from the front ends of the ribs, and the linea alba is a band of connective tissue that runs up the middle of the abdomen.
The internal oblique has several different actions, including:
- Flexion of the trunk: bending the trunk forward
- Lateral rotation of the trunk: turning the trunk to either side
- Lateral flexion of the trunk: bending the trunk to either side
- Assistance in forced exhalation: helps to compress the lungs to aide in exhalation
Medical Disclaimer: The information on this site is for your information only and is not a substitute for professional medical advice.
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