The mandibular fossa ( glenoid fossa ) is bounded, in front, by the articular tubercle; behind, by the tympanic part of the bone, which separates it from the external acoustic meatus; it is divided into two parts by a narrow slit, the petrotympanic fissure ( Glaserian fissure ).
12.
:: The old edition of Gray's Anatomy available at bartleby . com says here that the distance along the ear canal ( external acoustic meatus ) from the bottom of the tragus ( the little flap you can press on to " close " your ears ) to the eardrum, about 4 cm ( 40 mm ).
