Muscles Intercostal Most Internal

The innermost intercostal muscles (m. intercostales intimi, pna, bna, jna) are a thin layer of muscle fibers located under the external intercostal muscles. They are attached to the lower edge of the rib and run obliquely upward and medially, attaching to the upper edge of the next rib.

The function of the innermost intercostal muscles is to lower the ribs when exhaling. By contracting, these muscles pull the lower rib down, which leads to a narrowing of the volume of the chest.

The innermost intercostal muscles, together with the external intercostal muscles, form the intercostal muscles, which participate in the act of breathing, changing the volume of the chest. The contraction of the internal and external intercostal muscles must be synchronous to ensure effective breathing.