EXERCISE 18

ENDOSCOPIC ENDOMEATAL DISSECTION OF COCHLEAR AQUEDUCT

STEP A
COCHLEACTOMY…Cochleactomy is the initial step of the dissection
C..Basal turn of cochlea OW..Oval window


STEP B..EXPOSURE OF COCHLEAR AQUEDUCT
After cochleactomy the aqueduct is completely exposed.T he duct connects the scala tympani to the subarachnoid space in pyramidal fossa. It is very thin duct admits the hair only
1..Internal auditory canal 2..Cochlear aqueduct 3..Pyramidal fossa 4 .Jugular bulb


STEP B1
THE INNER OPENING OF COCHLEAR AQUEDUCT IN SCALA TYMPANI
The inner opening of duct is present inside the round window membrane behind the posterior part of CRISTA SEMILUNARIS
1..The inner opening of cochlear aqueduct 2.. vertical crest 3..crista semilunaris 4..Scala tympani 5..Scala vestibuli 6..Area of rwm attachment


STEP C
COCHLEAR AQUEDUCT AND INTERNAL AUDITORY CANAL
Cochlear aqueduct after coming out from scala tympani it runs below the internal auditoty canal parallel to its floor to enter the pyramidal fossa to open into subarachnoid space. Transmeatally once the sac is removed the pyramidal lip of the petrous bone (pyramidal fossa border) is seen
1..Cochlear aqueduct 2..Transmeatal exposure of IAC 3..Internal carotid artery