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
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.