BONES OF TIIE Fece.—The bones of the face comprise all those of the skull which do not contribute to form the cavity for the brain; they inclose, either by themselves or in con junction with the adjacent bones of the cranium, 1. the organs of three senses, viz. sight, smelling, and taste; 2. the organs of mastica tion and the orifices of the respiratory and digestive canals ; 3. they give attachment to most of the muscles of expression.
The face is divided into the upper or the fixed, and the lower or the moveable jaw, both of which are provided with teeth. The lower jaw is a single and symmetrical bone; the upper jaw, though formed of thirteen bones, consists principally of two, viz. the ossa maxillaria superiora, to which the others may be considered as additions, being attached to them immoveably, and forming altogether one large, irregular, and symmetrical piece, which constitutes the upper jaw.
Of the fourteen bones which contribute to the face, two only arc single or median ; the others are double, and form six pairs, viz. 2 ossa maxilla superioris ; 2 ossa polati ; 2 assa nasi ; 2 ossa make ; 2 assa lachrymalia ; 2 ossa turbinate inferiora. The two single bones are, the vomer and the us maxilla in seriaris.
the superior maxillary bones, (assa max il laria superiora ; Germ. die Obern Kinnbacken beine oder Oberkiefer.) These bones, situated in the middle and front of the face, are of a very irregular figure; they are united below along the median line, and form together, the greater part of the upper jaw. Each has four surJimes, viz. 1. a or anterior ; 2. a posterior or zygomatie ; 3. an internal or naso palatine; 4. a superior or orbiter. The borders are three; 1. an anterior or naso-maxillary; 2. a posterior or pterygoid ; 3. an inferior or alveolar.
The surface presents from before backwards, 1. the fossa myrtiformis, a depres sion situated above the incisor teeth, which gives attachment to the depressor !Ail superi oris : 2. the canine ridge, which corresponds to the socket of the canine tooth, and which sepa rates the myrtiform from, 3. the canine (or the infra-orbitar) fossa, which gives attachment to the levator anguli oris, and at the upper part of which is seen the Infra-orbitar foramen, giving exit to the vessels and nerves of the same name ; 4. the molar ridge, a semicircular crest which descends vertically from the malar pro cess to the alveolar border of the bone, and divides its facial from its zygomatic surface, which is prominent behind, where it forms the maxillary tuberosity, most conspicuous before the exit of the last molar tooth, which in the child is lodged within it. On this surface are
several small holes, (posterior dental fora mina) which are the orifices of canals for the posterior and superior dental vessels and nerves.
From the upper and front part of the ante rior surface of the bone a long vertical process (the nasal process) ascends between the nasal and lachrymal bones to be united with the frontal; its external surface is rough, presenting small irregular holes, which transmit vessels to the cancellous interior of the bone and to the nose, and giving attachment to the levator labii superioris alTque nasi muscle. The internal sur face of this process is marked with some minute grooves and holes for vessels, and, tracing it from below upwards, by a transverse ridge or crest (the inferior turbinated ridge) for the lower spongy bone ; above this by a depres sion corresponding to the middle meatus; next by a crest (the superior turbinated ridge) for the upper spongy bone of the ethmoid ; and above this by a surface which receives and completes some of the anterior ethmoid cells. The nasal process has three borders: 1. an anterior, thin and inclined from above downwards and forwards; above, it is cut obliquely from the internal towards the external surface of the bone, and below in the contrary direction, so that this edge of the nasal process and the corresponding border of the nasal bone with which it is united, mutu ally overlap each other. 2. A posterior border, or surface, thick and divided into two margins by a deep vertical groove (the lachrymo-nasal canal) which contributes to lodge the lachrymal sac above, and the nasal duct below. The direction of the lachrymo-nasal canal is curved from above downwards and outwards ; so that its convexity looks forwards and inwards, and its concavity in the contrary direction. The inner margin of this groove is thin, and is united above to the anterior border of the os unguis, and below to the inferior spongy bone. The outer margin is bounded and gives attach ment to the tendon and to some of the fibres of the orbicularis palpebrarum; it commonly ter minates below in a little tubercle (the lachrymal tubercle). 3. The upper border of the nasal process, which is short, thick, and irregular, is articulated with the internal angular process of the frontal bone.