Upper mandible

“ The mandibles are entirely covered with skin, of which the subcutaneous tissue is wanting, the cutis condensed, and the cuticle in large irregular longitudinal plates, leaving the surface somewhat rough and scaly. The crest-like excrescence on the ridge of the upper mandible is not formed of bone, nor otherwise connected with the osseous surface, which is smooth and continuous beneath it, than by being placed upon it, like any other part of the skin, and when softened by immersion in a liquid may be bent a little to either side. ”

“ The lengthened beak could be compensated for by (A) migration of the anterior end of the jugal bar toward the rostral tip of the bill and away from the fronto-nasal hinge with a simultaneous enlargement of the adductor muscles of the lower mandible, or [Pg 535] (B) enlargement of the one muscle that functions simultaneously as an efficient retractor of the upper mandible and adductor of the lower mandible, namely M. pseudotemporalis profundus. ”

“ The upper mandible is convex, a little inclining at the point, with no notch: but the edges are a little protuberant at the base below the nostrils, the lower one being flat at the sides, and having an angle on the lower side. The general colour of the plumage on the upper parts, the throat, and neck, is a heavy olive brown shading off at the ends of the quills into dusky, except in some of the primaries, the ends of which are of a lighter brown, and the lower parts of a brownish yellow. ”

“ Lower mandible straight, the dorsal line at the base sloping upwards, at one-third of the length of the bill bulging, then straightish and slightly ascending, the tip narrower than that of the upper mandible, the sides at the base sloping upwards, and having a shallow groove, towards the end becoming perpendicular. ”

“ Body large and heavy; upper mandible depressed, narrower and higher at base, broader and flattened toward the end, composed of a median bar, continuing the whole length of the bill and terminating in a strongly hooked nail, and of two lateral portions each separated from the median bar by a very narrow groove, in the basal part of which the small nostril opens; lower mandible thin, of two flexible arches supporting a large pouch of naked membrane. ”

“ Bill short, robust, conical, acute; upper mandible straight in the dorsal outline, angular, and encroaching a little on the forehead, broader than the lower, acute and inflected on the edges; lower mandible also inflected at the edges; the gap-line deflected at the base. Head rather large, neck short, body full. ”

“ In consequence of this direction they tend by their contraction to pull the pterygoid plates and posterior parts of the maxilla away from the sagittal plane of the head, and thus to secure the normal width of the posterior nares. It is these muscles which bring about the lateral movements of the mandible, causing the lower teeth to move laterally and sagittally across the upper, the food being in this way far more effectually ground than by a mere vertical pressure of the teeth against one another. ”

“ Maxillary bone without pronounced vertical depth in part supporting cheek teeth, its inferior border only slightly lower than inferior border of premaxillary and alveolar lips of molariform teeth consequently approximately level with, or slightly below, alveolar lip of upper incisor; squamosal without lateral expansion, therefore, meatal tube of auditory bulla separated from zygomatic process of squamosal by deep, well-developed postglenoid notch; angular part of mandible below alveolar level of mandibular cheek teeth ”

“ The ethmoid ends in the ethmo-turbinal (e.t.) ; the nasal, the naso-turbinal (n.t.) ; and the maxilla, the maxillo-turbinal (m.t.) . In the anterior corner of the orbit there is a bone, the lachrymal (lc. Figure 1) , which is hidden by the maxilla in the side view of the skull.
Section 91. The lower jaw (mandible) is one continuous bone in the mammal. Three incisors bite against the three of the upper jaw. Then comes a canine, four premolars, and three molars, the first of which is blade-like (sectorial tooth) , and bites against the similar sectorial tooth (last premolar) of the upper jaw. ”

“ The palpi are of moderate size. The mandibles have from three to five main teeth, the number sometimes varying even in the same species: the lower teeth are either plainly double laterally, or very obscurely double, or to all appearance quite single: a rather large lower portion of the mandible is finely pectinated. The maxillæ are always notched under the two or three large upper spines: the notch bears some fine spines: beneath the notch there are some large spines, and at the inferior angle some smaller ones. ”

“ The mandible is composed of several bones as in reptiles. The os articulare bears on its inner side the inner mandibular process which serves for the insertion of part of the digastric muscle or opener of the mouth; another portion of this muscle is attached to the os angulare, which frequently forms a posterior mandibular process. The greater part of the under-jaw is formed by the right and left dentaries, which in all recent birds are fused together in front. Supra-angular and coronoid splint-bones serve for the insertion of part of the temporal or masseter muscle. ”

“ The mandible is usually as long as the skull and is slender. It is composed of 6 elements so far as known (465) ; these are the articular, the surangular, the angular, the coronoid, the dentary, and the splenial. Other elements may be present, but the anatomy of this portion of the animals is not very completely known. The bones are sculptured and cut by lateral-line canals (458) in a few forms. Whether the articular operated on an osseous or cartilaginous quadrate is unknown, though certain specimens seem to indicate an osseous condition for that element. ”

“ The mandibles are straight for a greater part of their length, but the upper one is much hooked at the point, and very sharp, and the cutting edges of both mandibles are in all their length beset with short, but strong and sharp teeth inclining backward. ”

“ The reconstructed skull contains teeth which are large and in the incisor region (i.e. in front) are much curved downwards in the direction of their length. But this, though probably correct, is yet a matter of inference, for only a couple of teeth (the second premolars of the left side) were found in situ. And so far no detailed description of these teeth has appeared. The mandible is of extraordinary dimensions; very widely separated ‘ascending rami’ converge to the massive body of the jaw. The sigmoid notch is almost as shallow as in the Mauer jaw. The chin is retreating or absent. ”

“ For years the workmen had been instructed to keep a sharp lookout for human remains. The jaw had evidently drifted down with the river sands and had become separated from the skull, but it remained in perfect preservation. The author's description may first be quoted. (36) The mandible shows a combination of features never before found in any fossil or recent man. The protrusion of the lower jaw just below the front teeth which gives shape to the human chin is entirely lacking. ”

“ The upper jaw bone is the most complex of all the bones of the face. Looking at its central part or body we are first of all struck with the cavity in it—the antrum of Highmore. Now, if you take a hundred bones, you will not be able to find two antra exactly alike, but they will differ in size, in shape, in depth, in width, and in size of their angles and inclination of each of their walls. And all these peculiarities influence the countenance, and must, therefore, be studied before you can hope to be successful in replacing the lost dental organs. ”

“ The articulation of the mandible to the quadrate-bone is such as to allow of a very considerable amount of lateral play, and, by a particular arrangement of the muscles which move the former, it comes to pass that so soon as the bird opens its mouth the point of the mandible is brought immediately opposite to that of the maxilla (which itself is movable vertically) , instead of crossing or overlapping it—the usual position when the mouth is closed. ”

“ From the coronoid process, the height diminishes with a tolerably rapid sweep (but not so rapid as in Iguanodon) , and the broken end, 2⋅5 inches from the articular surface, is only 0⋅5 inch high. The mandibular teeth are completely hidden.
The centrum of a vertebra (fig. 1, c) , which lies on the outer side of the ramus of the mandible, is 0⋅6 inch long, and the exposed articular end, which is very slightly concave, is 0⋅45 inch high by 0⋅4 inch wide. ”

“ The nasals themselves are slender, and reach the posterior likewise long and narrow prolongations of the premaxillaries.
Gavialis.–The snout is extremely long and slender. The mandibular symphysis is so long that it comprises a great portion of the splenial bones, and extends backwards almost to the level of the last teeth and to the palatal foramina. The nasal {452}bones are very short, and are separated from the premaxillaries by the long suture of the maxillaries. About twenty-eight upper and twenty-five lower teeth on each side. ”

“ In old males the length of face is much greater than one-half, and the front of the upper jaw is stuck out considerably. But in all there is a swelling of the upper jaw-bone, just in front of the orbit and on each side of the nose-bones, which sometimes is vast and at others turned into a ridge. ”

“ The fore-limbs are only half the size of the hind-limbs. The neck consists of about ten vertebrae, mostly with long and {424}pointed ribs. Tail long with well-developed chevrons. The skull is long and pointed, composed of thin bones, which have lost most of the sutures; with large lateral, temporal, and pre-orbital, but without supratemporal, foramina. Premaxillae, maxillae, and mandible with numerous slender and rather long, conical, alveolar teeth. ”

“ The last tooth of the under-jaw is also liable to produce a similar hemicrania, when it begins to decay. When a tooth in the upper-jaw is the cause of the headach, a slighter pain is sometimes perceived on the cheek-bone. And when a tooth in the lower-jaw is the cause of headach, a pain sometimes affects the tendons of the muscles of the neck, which are attached near the jaws. ”

“ Fractures of the jaw commonly heal from the fourteenth to the twenty-first day.
“In luxations of the jaw (Chapter XII) the bone is always displaced forward; but sometimes only on one side, and sometimes on both sides. When the dislocation is only on one side, the chin and the whole jaw are found deviated toward the part opposite to the luxation; and the similar teeth of the two dental arches do not correspond; but instead under the upper incisors will be found the canine tooth of the dislocated89 part. If, however, the luxation is bilateral, the chin inclines and projects forward ”

“ The points to be specially noted in the maxilla are the thinness of the outer alveolar wall as compared with the inner, the prominence of the canine socket, and the cancellous character of the bone in the region of the third molar. In the mandible the outer alveolar border will be seen to be thinner than the inner, with the exception of that portion in the region of the{13}
Fig. ”

“ Now, as I observed just now, there are several tall, athletic young men about, and also there are several men who have lost teeth. But now I saw that this tall and athletic young man had lost exactly two teeth—one from the lower jaw, just to the left of the centre, and another from the upper jaw, further still toward the left! Trivialities, pointing in the same direction, became important considerations. More, his teeth were irregular throughout, and, as nearly as I could remember it, looked remarkably like this little plaster mould of mine. ”

“ The results of fractures of the mandible were, in so far as my experience went, remarkably good, as deformity was seldom considerable. The absence of obliquity and the effect of primary local shock were no doubt favourable elements, little primary displacement from muscular action occurring. [Pg 309]
Wounds of the cheek healed readily, and the same was noticeable of the lips. Wounds of the tongue healed with remarkable rapidity when of the simple perforating type, often with little or no swelling or evidence of contusion. At the end of a few days it was often difficult to localise them. ”