[Gross anatomy and microstructure of the orbicularis muscle and philtral contour].

In order to improve the reconstruction of orbicularis oris muscle and philtral contour and the effect of repair in the cleft lip, orbicularis oris muscle was dissected on three adult cadavers and two newborns with normal lip. Histological studies of seven newborn cadavers were made with sections in transverse, sagittal and coronal planes and stained with masson's trichrome technique. The results are as follows. The orbicularis oris muscle consists of two layers: deep and superficial. The muscular fibers of deep layer originate from the buccinator, its upper and lower fibers horizontally and respectively enter the upper lip and lower lip, while the middle fibers are decussated on the corner of the mouth. The marginal part of the orbicularis oris muscle curls upon itself forming vermilion. The superficial layer originates from the muscles of facial expression, consists of an upper and lower bundle. The lower bundle derives its fibers from depressor anguli muscle and inserts in the skin of the philtral ridges. The upper bundle attaches to the anterior nasal spine. The levator labii superioris mingles with the rim of orbicularis oris, insert into the vermilion border, forming labial arch and peak. There are longitudinally running fibers in the philtral ridges. In the sagittal section of the philtral groove, it was seen that a few of vertical muscle running from the part marginalis of the orbicularis oris and inserting into the lower skin of philtral groove. In the horizontal section of upper lip, muscular bundles from the lateral incisor bone inserting into ipsilateral and contralateral philtral ridges were seen.