The Human Respiratory System - Computational Fluid and Particle Dynamics in the Human Respiratory System - page 22

Fig. 2.4 Structure of the internal nasal cavity. The turbinates are also referred to as concha because
of its resemblance to a conch shell
of the nose are two openings called the nostrils ( anterior nares , sing. naris ) and
are separated by nasal septum cartilage ( columna ). The nostrils are a portal for air
and particulates to enter the nasal cavity. Its shape can be very elliptical to circular
varying between people from different ethnicity and race.
Air enters the nasal cavity through the nostrils, which opens with a slight dilation
into an enclosed area called the vestibule. It is enclosed by the greater alar cartilage
and extends as a small recess toward the apex of the nose. The two nostril openings
and consequently the two vestibules leading to two nasal chambers or cavities are
separated by the septum. The anterior septum is primarily made of cartilage ( hyaline
cartilage ) but posteriorly is composed of the vomer bone and the perpendicular plate
of the ethmoid bone. It is a common occurrence for the septum to be deviated and in
severe cases this can lead to nasal dysfunction requiring surgical procedures. The top
of the nasal cavity is divided from the anterior cranial cavity by the cribiform plate
of the ethmoid bone and the sphenoid bone. The cribriform plate is perforated with
many small openings that allow the olfactory nerve branches that are responsible for
the sense of smell to extend through to the brain. The lateral walls abut on either side
with the maxillary bones, and the floor of the nasal cavity is separated from the top
of the mouth by the palatal bones.
From the vestibule the air passes through a constricted cross-sectional area which
has been termed the anterior nasal valve, before entering the main nasal passage.
In each cavity there are three passageways (superior, middle, and inferior meati;
singular, meatus ) within the main nasal passage, formed by three corresponding
curled bony plates that project medially into the main passage way from the septum
wall, called the superior, middle and inferior nasal turbinates or conchae (so-called as
they are shaped like a conch seashell, Fig. 2.4 ). At the posterior end of the main nasal