Understanding the Anatomy The hypopharynx is a part of the throat. It is basically the lower throat. The hypopharynx is behind the voice box, below the oropharynx and just above the esophagus. It extends from the hyoid bone down to the uppermost muscle of the esophagus, which is called the cricopharyngeus muscle. There are three different parts of the hypopharynx:
  • Posterior pharyngeal wall:This is the back wall of the pharynx, from the level of the hyoid bone down to the esophagus. The wall is made up of constrictor muscles, and it basically sits on the tissue covering the vertebrae (spinal bones).
  • Pyriform sinuses on each side:There is one pyriform sinus on each side of the larynx. Each one is like an upside-down pyramid, with the tip pointing into the esophagus. This is the most common subsite for hypopharyngeal cancer.
  • Post-cricoid area:This is the part of the throat just behind the cricoid cartilage. It opens directly into the esophagus. This is the least common subsite of hypopharyngeal cancer.