MUSCULATURE • DICCIONARIO INGLES.COM • Definition of Musculature

... considered. Swallowing may be involuntary or voluntary. The constrictors are anatomically not considered part of esophagus proper. When the constrictors voluntarily deliver the bolus past the cricopharyngeal fold, the involuntary or peristaltic contractions of the esophageal mural musculature carry the bolus on downward. There is no sphincter at the cardiac end of the esophagus. The site of spasmodic stenosis in the lower third, the so-called cardiospasm, was first demonstrated by the author to be located at the hiatus esophageus and the spasmodic contractions are of the ...

— Bronchoscopy and Esophagoscopy - A Manual of Peroral Endoscopy and Laryngeal Surgery • Chevalier Jackson