Which of the following is TRUE about Zenker's diveiculum?

Zenker's diveicula are mucosal outpouchings occurring through the triangular bare area (Killian's triangle) between the upper oblique fibres (also known as thyropharyngeus muscle) and lower horizontal fibres (also known as cricopharyngeus muscle) of the inferior constrictor muscle. Zenker's diveicula are rarely seen below 30 years of age, most patients are over 50 years of age. Dysphagia is the most common symptom. Other common symptoms include regurgitation of digested food specially when the patients is in the recumbent position, swelling of the neck, gurgling noise after eating, halitosis and foul metallic taste in the mouth. It is a pulsion diveiculum i.e caused by an increased intraluminal pressure in the esophagus (secondary to abnormal motility of esophagus) which push the mucosa and submucosa through the muscular defect. It is not a true diveicula as it does not contain all layers of esophageal wall. Other type of diveicula are traction diveicula in which the inflamed or scarred peribronchial and mediastinal lymph nodes pull the full thickness of the wall of esophagus out, creating a true diveicula. Ref: Bailey & Love 25/e, Page 1040; CSDT 13/e, Page 432; Mangiots 11/e, chapter 8.