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choana vs naris
The distinction between the terms naris, internal naris, external naris,
choana, and others was one that I've had to sort out for my own
research, and also as a member of the International Committee on Avian
Anatomical Nomenclature. My conviction is that anatomists, as much as
possible, should adopt the established terminologies codified in the
various nomina: Nomina Anatomica (NA: humans), Nomina Anatomica
Veterinaria (NAV: domesticated mammals), and Nomina Anatomica Avium
(NAA: extant dinosaurs). The NAA is most relevant to us.
I've used the osteological terms naris and choana for the rostral and
caudal apertures, respectively, of the nasal cavity. My usage is not
entirely consistent with the nomina, which has become an issue for me
"Naris" is Latin for nostril, that is, the soft-tissue structure (skin,
neurovasculature, musculature, etc.) immediately surrounding the
external opening of the nasal cavity. All of the nomina use the term
naris in this sense. This is inconsistent with the sense used by
paleontologists (myself included) who use "naris" for the bony hole.
The nomina all use "bony nasal aperture" (NAV, NAA) or "piriform
aperture" (NA) for the bony hole.
"Choana" is a latinization deriving from the Greek xoanh funnel. All of
the nomina use this term for the opening between the nasal cavity and
pharynx. In fact, all of the nomina use "choana" for both the opening
in the skull and the fleshed-out head. The reason for this is that
"choana" technically refers to the opening, not the rim of the opening,
so it doesn't matter if the choanal margin under consideration is
osseous or mucosal. Occasionally in human anatomy you'll see reference
to "nasopharyngeal meatus" for the rim enclosing the choana, again
regardless of whether the rim is bone or mucous membrane. If you're
having trouble relating, an analogous and more familiar situation is
with the pupil and iris.
Note that none of the nomina use "internal naris" or "external naris."
Adopting "choana" was, for me, a no-brainer---I just bought into the
convention. "Naris" was a harder decision, and I opted for the
"traditional" paleo usage in my previous research where it wasn't that
critical. Now that I'm working on reconstructing the narial soft
tissues of dinosaurs, this becomes a problem, because now I'm also
interested in the "naris"---i.e., nostril---in the sense used by the
nomina, as well as the "apertura nasi ossea" (gaak!).
Nobody said it would be easy?
Lawrence M. Witmer, PhD, Assistant Professor of Anatomy
Department of Biomedical Sciences, Grosvenor 114
Ohio University College of Osteopathic Medicine
Athens, Ohio 45701 USA
Phone: 740 593 9489; Fax: 740 593 1730
email: email@example.com OR firstname.lastname@example.org