Middle Ear Anatomy  : 

   # 3 parts : i) mesotympanum (6mm) ii) epitympanum ( a/k/a attic  2mm ) iii) hypotympanum (4mm) 

   # Bone which covers the attic is called Scutum. 

   # 6 walls of middle ear : 

                        i) Roof = Tegmen tympani , above the 

   roof lies the dura of temporal bone

                         ii) Floor = below the floor lies Jugular bulb ( dilatation of lateral sinus ) 

                        iii) Anterior wall = 2 opening : a)  for tensor tympani muscle ( supplied by mandibular division of Trigeminal Nerve )  

                                    b)  for Eustachean tube 

                        iv) Posterior wall :  It has a projection called Pyramid . From Pyramid Stapedius muscle comes out which is attached to Stapes . Stapedius is supplied by Facial nerve .

                        v) Medial wall : Behind the medial wall lies the inner ear . This wall has 2 projection of inner ear :  

                                 a) Promontory = projection of basal turns of cochlea 

                                b) Lateral semicircular canal bulge 

                        Medial wall has 2 windows also : 

                      a) Oval window : covered by foot plate of stapes

                      b) Round window : covered by round   window membrane  

                      vi) Lateral wall : Tympanic membrane . 2 bony spicules in middle ear 

               a) Subiculum : separates oval wind from round                                                   window 

              b) Ponticulus : runs from promontory to pyramid   

NOTE : 5th and 6th nerve are related to apex of petrous part of temporal bone . So in petrositis ( Gradenigo's syndrome ) there is retro orbital  pain due to 5th nerve involvement  and diplopia due to 6th nerve involvement .

  Middle Ear cleft : 5 parts : i) Eustachian tube ii) Middle ear iii) aditus iv) antrum v) other cells