Larynx

The nasopharynx contains the three conchae of the nasal cavity. The top of this structure

includes the adenoids or “pharyngeal tonsils” This is a lymphoid nodule like the tonsils we have

already talked about and contain lymphocytes that have the capacity to destroy pathogens that

come in through the nose. These, like the oropharyngeal tonsils, are larger in children and

smaller in adults, sometimes disappearing completely in adults.

Other structures of the nasopharynx are the uvula (a teardrop-shaped structure hanging from

the soft palate) and the soft palate. These structures will move upward during swallowing in

order to keep food from entering the nasal cavity during the act of swallowing. There is also the

Eustachian tube, which connects the nasopharynx to the middle ear cavity.

The oropharynx is used for both air and food passage. The front of it is the boundary of the oral

cavity and is referred to as the “fauces,” while the upper border is the nasopharynx. The

epithelium anteriorly changes from ciliated pseudostratified columnar epithelium to stratified

squamous epithelium. There are two separate sets of tonsils in this area: the palatine tonsils

(on either side of the fauces) and the lingual tonsils, located at the base of the tongue.

The laryngopharynx is the lowermost aspect of the pharynx and is located behind the larynx. It

is used for digestion and respiration. The anterior part (front part) of the laryngopharynx opens

into the larynx. The posterior part (back part) opens into the esophagus.

LARYNX

The larynx is made from cartilage. It connects the pharynx to the trachea, sending in just the

right amount of air per breath. There are several separate cartilaginous structures that make

up the larynx. The thyroid cartilage is located in the front (anteriorly); the epiglottis is above the

vocal cords, and the cricoid cartilage is below the cords. The thyroid cartilage is the “Adam’s

apple” and is more prominent in men. It is the largest cartilage of the larynx. There are three

smaller cartilages that are paired. These are the cuneiforms, the corniculates, and the arytenoid

cartilages. Figure 96 shows what the structures of the larynx look like:

The epiglottis is the piece of cartilage that covers the trachea during swallowing. The glottis is

made of the true vocal cords, which are white, membranous folds that are attached to the

thyroid and arytenoid cartilages. The vestibular folds are the false vocal cords, which are folded

segments of mucous membrane. The true cords will oscillate and separate in order to produce

noise of different pitches.

The upper part of the larynx is continuous with the laryngopharynx and thus is lined with

stratified squamous epithelium. It gradually develops respiratory epithelium, which is ciliated

and contains goblet cells that produce mucus that traps the debris and potential pathogens as

they enter the trachea. In this case, the cilia beat in one direction in order to push mucus

upward toward the laryngopharynx, where it can be coughed out or swallowed.