b. Mouth. Air can also enter the lungs by way of the mouth, but the mouth does
not as efficiently moisten, warm, or remove foreign particles from the air.
(1) Nasopharynx. The nasopharynx, one of the three parts of the
pharynx, is located directly behind the nasal cavities. The nasopharynx connects the
pharynx with the posterior nares (openings between the nasal cavities and the
nasopharynx) and the eustachian tubes (which connect the tympanic cavities of the ear
with the nasopharynx). The nasopharynx is the part of the pharynx, which lies above
the soft palate.
(2) Oropharynx. The oropharynx is the part of the pharynx lying between
the soft palate and the upper edge of the epiglottis.
(3) Laryngopharynx. The laryngopharynx, which opens into the trachea and
esophagus, is the part of the pharynx, which lies below the upper edge of the epiglottis.
d. Larynx. The larynx, or "voice box," is termed the "Adam's apple" and is
prominent in the male. The larynx is located in front of the pharynx and above the
beginning of the trachea. The framework of the larynx is entirely cartilaginous and
consists mainly of the thyroid and cricoid cartilages.
(1) Glottis. The larynx contains the vocal cords which produce the voice.
Sound is produced by the exhalation of air. The space that is present between the
vocal cords is known as the rima glottidis, or simply the glottis. During ordinary
breathing the part of the glottis between the vocal cords is relatively wide and triangular,
the apex of the triangle being in front.
(2) Epiglottis. The epiglottis is a leaf shaped piece of fibroelastic cartilage
that lies behind the tongue. Its free, rounded end projects upwards behind the back of
the tongue. Its slender, stemlike lower end is attached by a ligament to the upper part
of the thyroid cartilage. The epiglottis helps to close off the trachea during swallowing.
e. Trachea. The trachea, or windpipe, is a smooth tube, which transports the air
to the lungs. Embedded in this tube are cartilaginous rings, which are closed anteriorly,
and open posteriorly. These semicircles are about threefourths inch in diameter, and
serve the function of keeping the trachea open at all times. The rings are open
posteriorly (but connected by smooth muscle and connective tissue) to facilitate
swallowing in the adjacent esophagus. The trachea begins at the lower border of the
larynx, and passes behind the sternum into the thorax. The tube is lined by a mucous
f. Bronchi. As the trachea continues downward into the thoracic cavity, it
bifurcates into two bronchi, the right bronchus and the left bronchus. An inflammation of
the mucous lining of the bronchi is termed bronchitis.