[Embryogeny of facial, mastication, tongue, palate and neck muscles (author's transl)].

The mesenchymal origin muscular tissues entailing some difficulties in the knowledge of certain muscles embryogeny, two methods are therefore applied: the comparison of the ontogenesis data with those of comparative anatomy and the use as a guide of the functional motor unit with which the muscle combines. In resorting to these methods necessary precautions are precisely defined. The origins of the concerned muscles are, at first, situated among those of the whole musculature subjected to will, which are of two types "somitic" and "branchial". The realities lying under these two misleading terms are analysed. Then the usual data on each of the muscular groups embryogeny reviewed and compared, if necessary, with recent works. For the facial muscles a confusion results from the use of the term platysma both in comparative anatomy and in embryology, in pursuance of transposition, exact on that particular point, of the philogenic development of these muscles in ontogenesis. The development of these muscles comes in the scope of the extensive general character of the superficial hyoïd arch derivatives, and their topographic and functional particularities should be brought together with the disposition of the facial nerve nucleus and its arising fibres. Among the muscles in action in the mastication, a link appears between their precise role in this function and their embryogeny. For the neck muscles, the spinal nerve systematisation and the variations of the sterno-mastoïd muscle in mammals agree in assigning to this muscle an entire somitic origin lying exactly at the junction with the so-called branchial muscles. The somitic origin of the tongue muscles and the sharing between the somitic and branchial origins of those of the soft palate bring to light the place in the organism of these two anatomic structures. Then, the conjunction of muscles proceeding thus from two origins in these anatomic structures carries a particular signification in man by reason of the language.