title: Subannular tube insertion: anatomical considerations.
abstract: OBJECTIVE
  To assess the distance between the bony groove created during subannular tubes placement and the chorda tympani, and examine the depth of the hypotympanum and retrotympanum.
  
  
  METHODS
  Grooves drilled in cadaver temporal bones at two levels were imaged to measure: the distance between the chorda tympani nerve and the tympanic sulcus, and the depth of the hypotympanum and the retrotympanum relative to the annulus.
  
  
  RESULTS
  The chorda tympani was between 0 and 5 mm from the groove cut across the annulus. The hypotympanum average depth was 2 mm (0.44-6.40 mm) and the retrotympanum average depth was 1 mm (0-2.53 mm).
  
  
  CONCLUSIONS
  Grooves drilled across the tympanic sulcus should be placed at a point 20 per cent of the height of the tympanic membrane or lower; this will ensure least risk of injury to the chorda tympani nerve. The depth of the hypotympanum and retrotympanum dictates that the posteroinferior part of a subannular tube flange should be approximately 2 × 1 mm.
authors.affiliation: ORLHNS Department,Christchurch Public Hospital,New Zealand.
authors.forename: A K
authors.initials: AK
authors.lastname: Guidera
authors.affiliation: Department of Plastic Surgery,Hutt Hospital,Wellington,New Zealand.
authors.forename: L
authors.initials: L
authors.lastname: Benoiton
authors.affiliation: Emergency Department,Middlemore Hospital,Auckland,New Zealand.
authors.forename: L
authors.initials: L
authors.lastname: McManus
authors.affiliation: Department of Surgical Sciences,Dunedin School of Medicine,University of Otago,New Zealand.
authors.forename: P J D
authors.initials: PJ
authors.lastname: Dawes
mesh_terms: D002102:Cadaver; D018424:Cholesteatoma, Middle Ear / Q000473:pathology; D002814:Chorda Tympani Nerve / Q000033:anatomy & histology; D006801:Humans; D007440:Intubation / Q000379:methods*; D008876:Middle Ear Ventilation / Q000379:methods*; D010034:Otitis Media with Effusion / Q000473:pathology; D013701:Temporal Bone / Q000033:anatomy & histology*; D014057:Tomography, X-Ray Computed; D014432:Tympanic Membrane / Q000033:anatomy & histology
keywords: Anatomy; Chorda Tympani Nerve; Middle Ear Ventilation; Otitis Media