(3) The sense of smell is due to special nerve endings located in the upper
areas of the nasal chambers. The epithelium containing the sensory ending is known
as the olfactory epithelium.
(4) There are air "cells" or cavities in the skull called paranasal sinuses.
The paranasal sinuses are connected with 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 is the common posterior space for the respiratory and
(1) The 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. This allows the pressure
between the outside and inside of the eardrum to be equalized. Lying in the upper
posterior wall of the nasopharynx are the pharyngeal tonsils (adenoids). The soft palate
floor of the nasopharynx is a trapdoor that closes off the upper respiratory passageways
(2) 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 when a person swallows.
(3) The portion of the pharynx that is common to both the respiratory system
and the digestive system 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.
The larynx, also called the Adam's apple or voice box, connects the pharynx with
the trachea. The larynx is located in the anterior neck region and has a box-like shape
(figure 1-3). The larynx of the male becomes larger and heavier during puberty and
causes the voice to deepen. The adult male's larynx tends to be located lower in the
neck. In the female, the larynx remains higher and smaller.
a. The larynx has a vestibule ("entrance hallway") that can be covered over by
the epiglottis. The glottis itself is the hole between the vocal cords. Through the glottis,
air passes from the vestibule into the main chamber of the larynx (below the cords) and
then into the trachea. The skeleton of the larynx is made up of a series of cartilages.