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SECTION D: ESOPHAGUS

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Chapter 42

Esophageal Anatomy and Physiology and

Gastroesophageal Reflux Disease

Daniel S. Oh and Steven R. DeMeester

Key Points

1 The esophagus can be considered to have distinct anatomical locations in the neck, chest, and

abdomen with distinct physiologic and pathophysiologic considerations.

2 The esophageal wall is composed of three distinct layers – the mucosa, submucosa, and muscularis

propria. The mucosa is separated from the submucosa by the muscularis mucosae. Tumors lying

within the mucosal layer may be managed endoscopically.

3 The mucosal lining of the esophagus is squamous mucosa at birth. Repeated injury of the esophageal

squamous mucosa with reflux may lead to metaplastic change to columnar mucosa such as cardiac

mucosa, oxyntocardiac mucosa, or cardiac mucosa with intestinal metaplasia (goblet cells).

4 Barrett esophagus is defined as having both an endoscopic columnar segment and a microscopic

finding of cardiac mucosa with goblet cells or intestinal metaplasia.

5 During a swallow, the peristaltic wave begins in the upper esophageal sphincter. The lower

esophageal sphincter relaxes at the initiation of the swallow and remains relaxed until the peristaltic

wave progresses down the esophageal body and through the lower sphincter.

6 The lower esophageal sphincter retains its competence as a barrier to gastric contents by three

factors: its length, its resting pressure, and its position.

7 The function of the esophagus can be evaluated by endoscopy, radiology (fluoroscopy), and

manometry. Measurement of acid exposure in the esophagus can be performed with ambulatory pH

monitoring.

8 The endoscopist should note three critical landmarks during an EGD: the squamocolumnar junction

(SCJ), the gastroesophageal junction (GEJ), and the crura or hiatus.

9 Preoperative functional assessment of the esophagus and lower esophageal sphincter are mandatory

when considering antireflux surgery to tailor the operation to the appropriate circumstances of the

patient.

10 Ambulatory pH monitoring remains the gold standard for documenting gastroesophageal reflux and

should be used to confirm the diagnosis of GERD.

ESOPHAGEAL ANATOMY AND FUNCTION

The esophagus is a muscular tube that starts as the continuation of the pharynx with the upper

esophageal sphincter (UES) or cricopharyngeus and ends with the lower esophageal sphincter at the

fundus of the stomach (Fig. 42-1). Knowledge of the anatomy of the esophagus and its relationship with

other organs and structures is essential for the surgeon to evaluate the location of lesions seen by

endoscopy, barium swallow study, or computed tomography (CT); to interpret esophageal function

studies; and to safely expose the esophagus during surgery.

Cervical Esophagus

The cervical portion of the esophagus is approximately 3 to 5 cm long. It starts below the

cricopharyngeus muscle and appears as a continuation of the inferior constrictor muscle of the pharynx.

A space between the right and left inferior constrictor muscles posteriorly just above the

cricopharyngeus muscle is an area of natural weakening and referred to as Killian triangle, the site

where a Zenker diverticulum develops (Fig. 42-2). The beginning of the cervical esophagus is marked

by the level of C6, and the end by the lower border of T1. The cervical esophagus curves slightly to the

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left as it descends. Anteriorly, it abuts the trachea and larynx and can be dissected off both organs.

Posteriorly, the cervical esophagus lies on the vertebral bodies in a prevertebral or retroesophageal

space. This space is continuous with the retropharyngeal space superiorly and the posterior mediastinum

inferiorly, which is the primary route of descending mediastinitis from oropharyngeal infections.

Laterally, the omohyoid muscle crosses the cervical esophagus obliquely, and it is usually necessary to

divide this to expose that portion of the esophagus. The carotid sheaths lie laterally, and the lobes of the

thyroid and the strap muscles lie anteriorly. The recurrent laryngeal nerves lie in the grooves between

the esophagus and the trachea. The right recurrent nerve runs a more lateral and oblique course to

reach the groove and is more prone to anatomic variation. Although the surgical approach to the

cervical esophagus may be from either side of the neck through an incision along the medial border of

the sternocleidomastoid muscle, the left-sided approach is preferred to avoid injury to the more variable

course of the right recurrent nerve.

Thoracic Esophagus

The thoracic portion of the esophagus is approximately 18 to 20 cm long (Fig. 42-1) and starts at the

thoracic inlet. In the upper portion of the thorax, it is closely related to the posterior membranous wall

of the trachea. This close relationship is responsible for the early spread of cancer of the upper

esophagus into the trachea, and it may limit the surgeon’s ability to resect such a tumor. Above the

level of the tracheal bifurcation, the esophagus courses to the right of the aortic arch and the descending

aorta and then deviates to the left, passing behind the tracheal bifurcation and the left main bronchus.

In the lower portion of the thorax, the esophagus remains deviated to the left and passes anteriorly

through the diaphragmatic hiatus. There are three natural areas of constriction in the thoracic

esophagus: the cricopharyngeus or UES, the bronchoaortic constriction as it crosses behind the aortic

arch and left mainstem bronchus, and the lower esophageal sphincter.

Figure 42-1. Anatomy of the esophagus.

Unlike the remainder of the gastrointestinal tract, the esophagus does not have a serosal layer and its

strength is derived from its mucosa. The thoracic esophagus is covered only by parietal pleura, making

this portion the weakest and the most common site of perforation in Boerhaave syndrome, usually on

the left side where there is a lack of support from adjacent structures.

The azygos vein is closely related to the right of the esophagus as it ascends from the abdomen and

then arches from its paraspinal position over esophagus and the right main bronchus to enter the

superior vena cava.

The thoracic duct ascends behind and to the right of the distal thoracic esophagus between the azygos

vein and aorta. At approximately the level of T5, it passes alongside the aorta and ascends on the left

side of the esophagus to enter behind the junction of the left internal jugular and subclavian veins. Due

to the possibility of disrupting the thoracic duct during its course across the mediastinum during an

esophagectomy, ligation of the duct is generally performed low in the chest where it comes through the

aortic hiatus.

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