Roidevahelihas

Roidevahelihas is a term used in a limited set of Finnish-language sources to describe a proposed group of muscles associated with the rib cage. The term does not appear in standard anatomical nomenclature and is not widely recognized in medical textbooks. In most references it is encountered as a descriptive label rather than a formally defined muscle group.

The coinage seems to combine elements related to ribs (roide or rib) and a form of "auxiliary muscle" (vahelihas), but exact roots vary by source. Because there is no consistent definition, the precise location and function attributed to roidevahelihas differ between texts. Some uses describe it as an accessory mechanism for rib stabilization during respiration, while others treat it as a speculative or fictional construct.

In mainstream anatomy, breathing is driven primarily by the diaphragm and intercostal muscles; additional muscles such as the sternocleidomastoid, scalene, and serratus anterior can assist during heavy breathing. The roidevahelihas, as described in non-authoritative sources, is not part of this recognized framework. The term is more commonly encountered in educational glossaries, hobbyist discussions, or fictional contexts.

See also: Intercostal muscles, Diaphragm, Respiratory muscles.