Ans. b. Stapedius tendon (Ref: Dhingra 5/e p6)'Facial recess or the posterior sinus is a depression in the posterior wall lateral to the pyramid. It is bounded medially by the vertical part of Vllth nerve, laterally by the chorda tympani and above, by the fossa incudis. Surgically, facial recess is important, as direct access can be made through this into middle ear without disturbing posterior canal wall.'- Dhingra 5/e p6. Boundaries of Facial RecessMedially* Vertical part of Vllth nerveQLaterally* Chorda tympaniQAbove* Fossa incudisQ