On the Facial Musculature of Macacus Cyclopsis

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Anatomical observation wa s conducted on the facial musculature on each side of the face of 32 bodies (14 male,18 female) of Macacus cyclopsis (60 cases).
The following findings were obtained. The facial muscles of primates do not have defin i te muscle fascia such as other skeletal muscles. The evolution of these muscle is reported to be the greatest (Huber) and complicated (Supli van and Osgoo d) at the glabella, the supraorbital region and about the mouth. Similar findings were noted in Macacus cyclopsis. All of these facial muscles are supplied by branches from N. facialis.
1) M. orbicularis oculi This muscle may b e divided into Pars palpebralis, orbitalis, and peripheralis but the former two are unremarkable. Pars peripheralis is called M. malaris and if its Caput laterale has a bony attachment it should be called M. zygomaticus minor. The origin is by Caput mediale and Caput laterale but during its course, it interdigitates with the muscle fibers of M. levator labii sup. alaeque nasi and M. levator labii sup. to form a single muscular mass and runs to the upper lip.
2) M. depressor supercilii This is a part of the fibers from the medial region of M. orbicularis oculi. They intermesh with the muscle fibers of M. frontalis, M. procerus and M. corrugator supercilii at between the brows and it is difficult to separate them.
3) M. corrugator supe r cilii This muscle which should be considered a part of the deep fibers of M. orbicularis oculi interdigitates with the muscle fibers of M. depressor supercilii and M. frontalis.
4) M. procerus This is an unpaired muscle formed by the union of M. levator labii sup. alaeque nasi on each side. This muscle is ill-defined due to the interdigitation of muscle fibers.