Colombia and Venezuela of Caribbean South America are sometimes included in this subregion.

The Caribbean is occasionally excluded from this subregion while Bermuda and The Guianas are infrequently included.

[4] On the west, the Middle American mainland comprises the tapering, isthmian tract of the American landmass between the southern Rocky Mountains in the southern United States and the northern tip of the Andes in Colombia,[5] separating the Pacific Ocean on the west and the Atlantic Ocean (viz.

[4] The region developed subaerially southward from North America as a complex volcanic arc-trench system during the Early Cretaceous period, eventually forming the land bridge during the Pliocene epoch when its southern end (at Panama) collided with South America through tectonic action.

In English, the term is uncommonly used as a synonym of the term Mesoamerica (or Meso-America),[5][7] which generally refers to an ancient culture region situated in Middle America extending roughly from central Mexico to northern Costa Rica.