When do internal intercostal muscles contract

Some authors describe the muscle continuing over several ribs and intercostal spaces, as opposed to the internal and external intercostal muscles which only span each intercostal space 1. As their name indicates, they are internal to the internal and external intercostal muscles.

Variably, the muscles become continuous anteriorly with the tranversus thoracis muscles and posteriorly with the subcostal muscles. Muscular branches from the intercostal nerves of the respective intercostal space T1-T11 , which run with the intercostal vessels under the costal groove in between the internal and innermost intercostal muscles. Innermost intercostal muscle contraction causes reduction in volume of the thoracic cavity in the transverse dimension, expelling air from the lungs during expiration.

They are probably the weakest of the intercostal muscles. Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. Updating… Please wait. Unable to process the form. Check for errors and try again.

Thank you for updating your details. Log In. Sign Up. Become a Gold Supporter and see no ads. Log in Sign up. The muscles responsible for expiration are the abdominal muscles and internal intercostals plus some accessory muscles. Respiratory Muscles. Brent Cornell. Cell Introduction 2. Cell Structure 3. Membrane Structure 4. Membrane Transport 5. Origin of Cells 6. Cell Division 2: Molecular Biology 1.

Metabolic Molecules 2. Water 3. Protein 5. Enzymes 6. Cell Respiration 9. Photosynthesis 3: Genetics 1. Genes 2. Chromosomes 3. These muscles are found between the ribs, and there are two kinds: the internal and external intercostals. The internal intercostal muscles in the inside of the ribcase extend from the front of the ribs, and go around back, past the bend in the ribs.

The external intercostal muscles on the outside of the ribcase wrap around from the back of the rib almost to the end of the bony part of the rib in front. The image above is seen from the inside. The yellowish bones are the sternum in the centre and the ribs and clavicle at the very top. Between the ribs can be seen the internal intercostals.