a. External Nose. The external nose is the portion projecting from
the face. It is supported primarily by cartilages. It has a midline divider called the
nasal septum, which extends from the internal nose. Paired openings (nostrils) lead to
paired spaces (vestibules). Guard hairs in the nostrils filter inflowing air.
b. Nasal Chambers (Internal Nose). Behind each vestibule of the
external nose is a nasal chamber. The two nasal chambers together form the internal nose.
These chambers too are separated by the nasal septum.
(1) Mucoperiosteum. The walls of the nasal chambers are lined with a thick
mucous-type membrane known as the mucoperiosteum. It has a ciliated epithelial surface and
a rich blood supply, which provides warmth and moisture. At times, it may become quite
swollen.
CILIATED = provided with cilia (hairlike projections which move fluids to
the rear)
(2) Conchae. The lateral wall of each chamber has three scroll- like
extensions into the nasal chamber which help to increase the surface area exposed to the
inflowing air. These scroll-like extensions are known as conchae.
CONCHA (pronounced KON-kah) = sea shell
CONCHA (singular), CONCHAE (plural)
(3) Olfactory epithelium. The sense of smell is due to special nerve
endings located in the upper areas of the nasal chambers. The epithelium containing the
sensory endings is known as the olfactory epithelium.
(4) Paranasal sinuses. There are air "cells" or cavities in the
skull known as paranasal sinuses. The paranasal sinuses are connected with the nasal
chambers and are lined with the same ciliated mucoperiosteum. Thus, these sinuses are
extensions of the nasal chambers into the skull bones. For this reason, they are known as
paranasal sinuses.
c. Pharynx. The pharynx (FAIR-inks) is the common posterior space
for the respiratory and digestive systems.
(1) Nasopharynx. That portion of the pharynx specifically related to the
respiratory system is the nasopharynx. It is the portion of the pharynx above the soft
palate. The two posterior openings (nares) of the nasal chambers lead into the single
space of the nasopharynx. The auditory (eustachian) tubes also open into the nasopharynx.
The auditory tubes connect the nasopharynx with the middle ears (to equalize the pressure
between the outside and inside of the eardrum). Lying in the upper posterior wall of the
nasopharynx are the pharyngeal tonsils (adenoids). The soft palate floor of the
nasopharynx is a trapdoor which closes off the upper respiratory passageways during
swallowing.
(2) Oropharynx. The portion of the pharynx closely related to the
digestive system is the oropharynx. It is the portion of the pharynx below the soft palate
and above the upper edge of the epiglottis. (The epiglottis is the flap that prevents food
from entering the larynx (discussed below) during swallowing.)
(3) Laryngopharynx. That portion of the pharynx which is common to the
respiratory and digestive systems is the laryngopharynx. It is the portion of the pharynx
below the upper edge of the epiglottis. Thus, the digestive and respiratory systems lead
into it from above and lead off from it below.
Primary Content Providers: The U. S. Army, The
U.S. Navy
Ancillary Content and Online Version: David L. Heiserman
Publisher: SweetHaven Publishing Services
