Innermost intercostal muscle

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Section of the thorax showing the arrangement of the intercostal muscles.

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Synonyms
Pronunciation
Carnegie stage
Days
Precursor
Gives rise to
Part of

The Innermost Intercostal Muscle (Musculus intercostalis intimus) is a layer of muscle between the ribs (intercostal) that is the deepest of the three layers of intercostal muscles.

Anatomy

The innermost intercostal muscles are found between the ribs and are the deepest layer of the intercostal muscles. They originate from the inferior border of the rib above and insert into the superior border of the rib below. The fibers of the innermost intercostal muscles run in the same direction as those of the internal intercostal muscles.

Section of the thorax showing the arrangement of the intercostal muscles.

Function

The primary function of the innermost intercostal muscles is to depress the ribs, which decreases the transverse dimensions of the thoracic cavity during forced expiration.

Clinical significance

Damage to the innermost intercostal muscles can result in difficulty breathing and pain during respiration.

See also

• Intercostal muscles
• Intercostal nerves
• Intercostal arteries