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1. Right Main Bronchus

The right main bronchus is shorter, wider, and more vertical than the

left. It divides into three lobar bronchi and 10 segmental bronchi: three

in the superior lobe, two in the middle lobe, and five in the inferior lobe.

2. Left Main Bronchus

The left main bronchus divides into two lobar bronchi and eight seg-

mental bronchi: four in the superior lobe and four in the inferior lobe.

Anatomic variations may be present.

C. Alimentary Tract

1. Hypopharynx

The hypopharynx begins at the level of the hyoid bone. It is divided into

the pyriform sinuses, the postcricoid region, and the posterior pharyn-

geal wall.

2. Esophagus

In adults the esophagus starts at the level of the cricopharyngeus or the

upper esophageal sphincter, and ends at the lower esophageal sphinc-

ter. It is approximately 22 centimeters (cm) long and has three points of

anatomic constriction: (1) the cricopharyngeal sphincter (16 cm from

incisors), (2) the left main stem bronchus (27 cm from the incisiors),

and (3) the gastroesophageal junction (38 cm from the incisors). The

cricopharyngeal sphincter is the narrowest point and is at highest risk of

injury or perforation.

3. Stomach

The stomach is divided into the cardia, fundus, body, and pylorus. The

cardiac notch is the acute angle between the intra-abdominal esopha-

gus and the gastric fundus.

II. Foreign Bodies

Although the incidence of aerodigestive foreign bodies has remained

stable, its recognition and safety in removal have increased dramati-

cally. The majority of foreign bodies are esophageal in both children and

adults. Airway foreign bodies are more likely to occur in children. A

higher incidence is found in children due to lack of molars, less con-

trolled coordination of swallowing, immaturity in laryngeal elevation

and glottic closure, and their tendency to explore their environment by

putting things in their mouth.