title: An anatomical study of the orbital floor in relation to the infraorbital groove: implications of predisposition to orbital floor fracture site.
abstract: OBJECTIVE
  To examine the anatomy of the orbital floor in relation to the infraorbital groove.
  
  
  METHODS
  Twenty-two Japanese cadavers aged 86.9 ± 6.0 years at death were used. We examined whether the bony overhang on the infraorbital nerve extending laterally was connected to the segment medial to the infraorbital groove. The bone thicknesses at 1, 2, and 3 mm anterior to the junction between the infraorbital groove and the inferior orbital fissure were measured along the groove. We examined the angle between the infraorbital groove and the orbital floor, both at the medial and lateral margins, at the thinnest point in the above three measurement points. We used the measurement values examined in the left orbits to prevent doubling the number of the orbits.
  
  
  RESULTS
  The bony overhang was not connected to the medial segment in 19 (86.4 %) orbits. The thickness at the thinnest point was thinner in the medial portion (1.02 ± 1.20 mm) than in the lateral portion (2.60 ± 1.82 mm; p = 0.001). The angle between the medial margin and the orbital floor was obtuse (156.5° ± 12.3°), compared with that of the lateral margin (104.0° ± 17.0°; p < 0.001).
  
  
  CONCLUSIONS
  The results of this study imply that the medial portion has an anatomical weakness and few supportive structures. Although these findings were obtained only from Japanese cadavers, there may be associated with frequent occurrences of an orbital floor fracture just medial to the infraorbital groove.
authors: Department of Oculoplastic, Orbital & Lacrimal Surgery, Aichi Medical University Hospital, 1-1, Yazakokarimata, Nagakute, Aichi, 480-1195, Japan.
authors: Yasuhiro
authors: Y
authors: Takahashi
authors: Department of Anatomy, Aichi Medical University, 1-1, Yazakokarimata, Nagakute, Aichi, 480-1195, Japan.
authors: Takashi
authors: T
authors: Nakano
authors: Department of Plastic & Reconstructive Surgery, Wakayama Medical University, 811-1, Kimiidera, Wakayama, 641-8509, Japan.
authors: Hidetaka
authors: H
authors: Miyazaki
authors: Department of Oculoplastic, Orbital & Lacrimal Surgery, Aichi Medical University Hospital, 1-1, Yazakokarimata, Nagakute, Aichi, 480-1195, Japan. cosme@d1.dion.ne.jp.
authors: Hirohiko
authors: H
authors: Kakizaki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D059925:Anatomic Landmarks; D002102:Cadaver; D005260:Female; D015775:Fractures, Stress / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D008297:Male; D009915:Orbit / Q000033:anatomy & histology*; D009917:Orbital Fractures / Q000175:diagnosis* / Q000209:etiology; D012307:Risk Factors; D013312:Stress, Physiological
keywords: Angle; Bony overhang; Infraorbital groove; Orbital floor fracture; Thickness