. On the anatomy of vertebrates [electronic resource] . e platysma draws down the lower part of the face, or,by a slighter action, the lower lip: the c risorial slip tends toraise the angle of the mouth. Most of the muscles of the faceare attached at one part to bone, at another to skin or to some othermuscle. The skin of the human face is remarkable for its tenuity,flexibility, and abundant supply of vessels and nerves; its vascu-larity tinting the cheeks and lips : it is more adherent and thesubjacent cellular tissue is denser along the median line than atother parts. The 6 orbicularis oris,
. On the anatomy of vertebrates [electronic resource] . e platysma draws down the lower part of the face, or,by a slighter action, the lower lip: the c risorial slip tends toraise the angle of the mouth. Most of the muscles of the faceare attached at one part to bone, at another to skin or to some othermuscle. The skin of the human face is remarkable for its tenuity,flexibility, and abundant supply of vessels and nerves; its vascu-larity tinting the cheeks and lips : it is more adherent and thesubjacent cellular tissue is denser along the median line than atother parts. The 6 orbicularis oris, fig. 29, 0 0, has no attachment to bone. MUSCULAR SYSTEM OF MAMMALIA. 61 It consists of two semi-elliptic planes of muscular fibres whichsurround the mouth and interlace on either side with those ofthe c buccinator and other dilators of the oral orifice. The ex-ternal or peripheral surface adheres to the skin, the internal orposterior surface is covered by the mucous membrane of themouth. Acting as a whole it closes the mouth, bringing the lips 28 29. Superficial muscles of the head and neck. Muscles of the face. in contact and pressing them firmly together, but the upper andlower halves can act separately, or the fibres of one side maycontract while the others are quiescent, so that different parts ofthe lips may be moved by different portions of the muscle, whichmay be regulated or antagonised by the muscles which con-verge to the mouth. A pair of accessory strips to the orbi-cularis, e accessorii orbicularis superioris, rise from the alveolarborder of the premaxillary, and arching outward on each side arecontinuous at the angles of the mouth with the other musclesthere inserted. A second pair, 4 naso-labiales, descend from theseptum of the nose to the upper lip, but with an interval, cor-responding with the depression on the skin beneath that septum. 62 ANATOMY OF VERTEBRATES. The levator labii superioris, fig. 29, I, arises from the lowermargin of the orbit, and descends t
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