Postnatal development of the subarcuate fossa and subarcuate canaliculus-a computed tomographic study.

Purpose: The subarcuate fossa (SF) is an anatomical structure situated on posterior wall of the petrous part of the temporal bone. In older children and adults, SF is a shallow depression and the subarcuate canaliculus starts within it. Awareness of postnatal changing morphology of this region is important especially for otosurgeon. The aim of this paper is to characterize both SF and SC by means of anatomical and radiological methods.

Methods: The study was carried out on CT scans of 101 children, aged 1-60 months. Length of the pyramid (PL), the distance between the anterior semicircular canal (ASC) and the pyramidal apex (PLM), the outer diameter of ASC (ASCD), width under ASC (SFWM), the distance between the fundus of SF and ASC (SFLL), the maximal width of SF lateral to ASC (SFWL), the distance between the fundus of SF and posterior surface of the pyramid (SFL) were measured.

Results: Average value of all measured distances: PL 52.14 ± 6.32 mm and PLM 25.73 ± 3.47 mm (raised with age); ASCD 8.63 ± 0.67 mm; SFWM 0.95 ± 1.24 mm; SFLL 1.07 ± 1.63 mm; SFWL 0.76 ± 1.19 mm; SFL 3.60 ± 2.50 mm.

Conclusions: Petrous part of the temporal bone grows with age up to 5 years old, whereas ASC does not. SF diminishes with age: lateral to ASC is well developed in newborns and infants (up to first year), rapidly diminishes in children aged 1-2 years and is totally absent in children > 2 years. SF medial to ASC is constant and diminishes with age. In children older than 3 years morphology of SF is similar to adult.