Choana

Choana
Lateral wall of nasal cavity.
Dissection of the muscles of the palate from behind. (Choanae visible at center top.)
Details
Identifiers
Latinchoana
TA98A02.1.00.096
TA2501
FMA76585
Anatomical terminology
The choanae (internal nostrils) of a cat, indicated by the dashed lines and bounded by the vomer (blue gray) and the palatine bone (orange)

The choanae (sg.: choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the pharynx, in humans and other mammals (as well as crocodilians and most skinks). They are considered one of the most important synapomorphies of tetrapodomorphs, that allowed the passage from water to land.[1]

In animals with secondary palates, they allow breathing when the mouth is closed.[2] In tetrapods without secondary palates their function relates primarily to olfaction (sense of smell).

The choanae are separated in two by the vomer.

  1. ^ Clack, Jennifer (2012). Gaining Ground: The Origin and Evolution of Tetrapods. Indiana University Press. p. 74. ISBN 978-0-253-35675-8. Retrieved 5 August 2015.
  2. ^ Janvier, Philippe (2004) "Wandering nostrils". Nature, 432 (7013): 23–24. doi:10.1038/432023a