<prompt> The lymphatic drainage of pyriform fossa is to:upper deep cervical nodesPrelaryngeal nodePara pharyngeal nodesMediastinal nodes  <response>: Pyriform sinus drains into jugular chain and then to deep cervical group of lymph nodes. Post cricoid region drains into para pharyngeal and paratracheal group of lymph nodes. Posterior pharyngeal wall drains into para pharyngeal lymph nodes and finally to deep cervical lymph nodes. Ref Tuli 1e,p 231,232. 