Retro pharyngeal space extends up to which of the following level?
Base of skull to C6 vertebra
Base of skull to bifurcation of trachea
Base of skull to the level of diaphragm
Base of skull to cricoid cartilage
(Refer: P. L. Dhingra’s Diseases of Ear, Nose and Throat & Head and Neck Surgery, 6th edition, pg no: 265)