Closure Mechanisms

Three anatomical factors maintain the integrity of the gastroe-sophageal junction (Fig. 2.21):

1. The functional (and anatomical) lower esophageal sphincter

2. The diaphragmatic hiatus

3. The valvular element of gastric anatomy (angle of His)

Esophagus

Endoscopy is excellent for evaluating the morphology of this region. A functional evaluation is often subject to a degree of uncertainty and especially to differences of interpretation by different examiners.

The endoscopist identifies and evaluates the sphincter itself, the diaphragmatic hiatus, and the transitional region between the squamous epithelium of the esophagus and the columnar epithelium of the stomach, which are separated by a visible junction called the Z-line.

Stratum circulare

Sphincter zone

Esophagus

Stratum circulare

Sphincter zone

Phrenicoesopha-geal ligament

Diaphragm Z-line

Fig. 2.20 Sphincter zone of the terminal esophagus

Phrenicoesopha-geal ligament

Diaphragm Z-line

Fig. 2.20 Sphincter zone of the terminal esophagus

Esophagus

Diaphragm

Central Gastric tendon fundus

Esophagus

Diaphragm

Central Gastric tendon fundus

Angle of His, cardiac notch

Oblique fibers

Crura of the diaphragm

Fig. 2.21 Anatomical closure mechanisms about the gastroesophageal junction. The stomach has been slightly separated from the diaphragm for clarity

Crura of the diaphragm

Angle of His, cardiac notch

Oblique fibers

Fig. 2.21 Anatomical closure mechanisms about the gastroesophageal junction. The stomach has been slightly separated from the diaphragm for clarity

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