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