portion of a nail that is under the surface of the skin at the proximal end of the nail large, air-filled space in the skull above and behind the nose that helps conduct air in and out of the body as ...portion of a nail that is under the surface of the skin at the proximal end of the nail large, air-filled space in the skull above and behind the nose that helps conduct air in and out of the body as part of the upper respiratory tract role of a species in its ecosystem that includes all the ways the species interacts with the biotic and abiotic factors of the ecosystem
