Endoscopic frontal recess anatomy directed by the drainage pathways using the connecting plates as landmarks

Purpose To investigate the anatomical features of frontal recess (FR) drainage, and the classification of FR cells and frontal sinus (FS). Methods Fifty sides from 30 adult cadaver heads were examined. FR cells and FS along the drainage pathways were dissected under 0° and 70° endoscopic views using unique connecting structures between the uncinate process and the ethmoid bulla as landmarks. Results Connecting plates between the uncinate process and the ethmoid bulla were discovered and termed medial suprainfundibular plate (MSIP), which were observed on each cadaver head, and lateral suprainfundibular plate (LSIP) on 92% (46/50) sides. Separated by MSIP, two drainage pathways were identified and named medial pathways of the FR (MPFR) medial to the MSIP and the lateral pathways of the FR (LPFR) in the lateral side. Different drainage pathways of the FS were confirmed, in which drained into the MPFR in 37 and into the LPFR in 13 of the cadaver sides. Conclusions MSIP is the critical landmark for the recognition of MPFR, LPFR, and the classification of FR cells. The FR resection along LPFR and MPFR facilitated excellent exposure of FS.