Killian's dehiscence is seen in -
Between these two parts of inferior constrictor exists a potential gap called Killian's dehiscence.
It is also called the gateway to tear as perforation can occur at this site during esophagoscopy.
It is also the site for herniation of pharyngeal mucosa in case of the pharyngeal pouch.
Oropharynx
Nasopharynx
Cricopharynx
Vocal cords