The innermost intercostal muscle is a layer of intercostal muscles. It may also be called the intima of the internal intercostal muscles. It is the deepest muscular layer of the thorax, with muscle fibres running vertically (in parallel with the internal intercostal muscles).
This refers to the deepest muscular layer in the thorax, which is also known as the innermost intercostal muscle or the intima of the internal intercostal muscles. The vertical muscle fibers in this layer are aligned with those of the internal intercostal muscles within the thoracic cavity.