Maxilla

“ Each outer maxilla is furnished with a pair of muscles, apparently a flexor and extensor; there is also a little muscle between the two maxillæ, I presume for the purpose of bringing them together. The outer and inner maxillæ generally stand close together, and in several genera a little way apart, from the mandibles; but there is no trace of any labrum or true lower lip, bounding the mandibles and orifice of the œsophagus. The outer and inner maxillæ and mandibles are not opposed in pairs to each other, but against the thickened inner fold of the labrum ”

“ 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. ”

“ A uniform arch necessitates uniformity of development between the arch of the maxilla and the arch of the teeth and a correct position of the individual teeth in their relation to each other. When there is inharmonious development between the jaws and the teeth, as may happen when one parent has a small maxilla with correspondingly small teeth, and the other a large one, with correspondingly large teeth, [Pg 250] if the child inherit the jaw of one and the teeth of the other, irregularities must follow. ”

“ The maxillary palpus properly so called, is a pretty long, jointed, commonly filiform process, the presence of which always distinguishes the maxillæ from the mandibles. The figure and proportion of the joints are very variable; the terminal joint especially exhibits a great variety of forms, which are of great service in distinguishing genera. The number of joints never exceeds six.
Closing the mouth on the underside is a piece which acts as an antagonist to the upper lip, and has therefore been named the under lip or labium. ”

“ Gurlt has named subjects presenting the total or partial absence of the inferior maxilla, agnathes or hemiagnathes. Simple atrophy of the inferior maxilla has been seen in man as well as in the lower animals, but is much less frequent than atrophy of the superior maxilla. Langenbeck reports the case of a young man who had the inferior maxilla so atrophied that in infancy it was impossible for him to take milk from the breast. He had also almost complete immobility of the jaws. Boullard reports a deformity of the visage, resulting in a deficiency of the condyles of the lower jaw. ”

“ Each maxilla is a long blade. The maxillæ, combined with the lower lip, constitute what, in popular language, is known as the tongue, the organ by means of which the food is conveyed to the mouth, or the nectar extracted from a flower. ”

“ The morbid rarefaction usually affects the whole skeleton more or less, yet in perhaps the majority of cases; the change is greatest in the bones of the face, and the resulting distortions are usually symmetrical on the two sides. It may show mainly in the maxilla, which is thickened to twice or even five times its normal thickness, it may show in rounded, general swelling of the nasal and superior maxillary bones and those around the orbit, or it may involve the turbinated bones, the vomer and even the cartilaginous nasal septum. ”

“ The palate bone is developed by one centre which is formed in what will be the vertical plate of that bone in the membrane, behind the centre or centres for the body of the maxilla and at a little later date (see E. Fawcett, Journ. Anat. and Phys. vol. 40, p. 400) .
The mandibular or Meckel's cartilage is continued up into the tympanum where it joins the proximal end of the cartilage of the second or hyoid arch, and it is from this junction (hyomandibular plate) that, according to H. Gadow, Anat. Anzeiger, Bd. 19, p. 396, the malleus and incus bones of the middle ear are developed (see Ear) . ”

“ In each of these processes cartilage is formed in the lower vertebrates, which in the case of the mandible (lower jaw) reaches to the mid-ventral line and forms what is known as Meckel's cartilage; but in the maxillary process the stage of chondrification is suppressed in man and other mammals, and the palato-quadrate cartilaginous bar which is so evident in embryo fishes and amphibians is not formed. It will thus be seen that both the maxillary and mandibular bars are derivatives of the first visceral arch. ”

“ 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. ”

“ The maxillary consists sometimes of one piece, sometimes of two or three. The principal membrane-bone of the mandible is the dentary (34) , to which is added the angular (36) and rarely a smaller one, the splenial or os operculare, which is situated at the inside of the articulary.
5. Cartilage-bones of the respiratory portion of the visceral skeleton of the skull.—With few exceptions all the ossifications of the hyoid and branchial arches, as described above (p. 58) , belong to this group. ”

“ The expanded portion of the maxillæ and frontals broader in front of the orbit. The protuberance which projects into the anteorbital notch much larger and the ridge on the maxilla which extends backward from it much higher. Distance from inner margin of maxillary foramen to tip of protuberance much more than one-half the distance between the maxillary foramina of the two sides. Rostrum deeper at the base. Inferior surface of pterygoids more or less convex, with a ridge (in adults) running diagonally across it. ”

“ Bill slender, depressed, nearly as long as head, its width at frontal antiæ very much greater than its depth at same point, and equal to about half the distance from nostril to tip of maxilla or less; culmen distinctly but not sharply ridged, straight for about basal half then more and more decurved terminally, the tip of maxilla minutely but distinctly uncinate ”

“ The actual piercing organs are the mandibles, while the upper lip or labrum forms a sucking tube. The maxillae are not piercing organs, and their function is to protect the mandibles and labrum and separate the hairs or feathers of the host. ”

“ The superior maxillary is one-third deeper and much more prominent than the Indian’s. The inferior maxillary is of uncommon prominence, depth, and power, far exceeding that of the Indian. The mouth is narrow and long, more dog-shaped than the Indian’s. The foramen magnum or aperture at base of skull, where the spinal cord enters the head, is peculiarly small. The condyloid processes are full, oblong, flat on the working surfaces, and at such an angle as to set the head upward and back more than any race we know to-day on this continent. ”

“ To this cranium probably belongs a detached portion of the left side of the facial region (No. 5) , in a similar state of preservation and slightly smaller than the maxilla (No. 4) . The suture between the frontal and the maxilla still persists, while the oral border is preserved farther forward than in the last-mentioned specimen, showing a fragment of the much-reduced premaxilla united with the maxilla by a jagged suture.
The third imperfect occiput is about as large as the immature specimen No. ”

“ The face is drawn out into a long rostrum, formed of the maxillae and premaxillae surrounding the vomer and the mesethmoid cartilage. The maxillae are specially large, and extend backwards so as to partially overlap the frontals. The nasals are always small, and the anterior nares open upwards between the cranium and rostrum. The periotics are loosely connected with the other bones of the skull and the tympanics are commonly large and dense. The mandible has hardly any coronoid process, and the condyles are at its posterior end. ”

“ When the skin and subcutaneous adipose membrane are removed by careful dissection from the cervical region, certain structures are exposed, which, even in the undissected neck, projected on the superficies, and are the unerring guides to the localities of the blood-vessels and nerves, &c. In Plate 4, the top of the sternum, 6; the clavicle, 7; the “Pomum Adami,” 1; the lower maxilla at V; the hyoid bone, Z; the sterno-cleido-mastoid muscle, B; and the clavicular portion of the trapezius muscle, 8; will readily be felt or otherwise recognised through the skin, &c. ”

“ The articulation of the inferior maxillary, or lower jaw bone, with the zygomatic process of the temporal bone, in flesh-eating animals, is such as to permit the direct or cutting motion, but prevent the lateral or grinding, which latter is the principal motion in man and other plant-eating creatures. ”

“ The upper jaw is constituted of a long and slender stylet, the situation of which nearly corresponds with that of the intermaxillary, while the maxillary is wanting, unless we assume that the two bones are confounded. ”

“ This form of appendage is well seen in the swimmerets (17, Fig. 229) of the abdominal region; further forwards the appendages become walking legs (9-13, Fig. 229) ; next come three pairs which combine the characters of legs and jaws, and are called maxillipedes (8, Fig. 229) ; then are the true jaws—two pairs of maxillae, and one pair of biting and crushing mandibles; and lastly, in front of the jaws, two pairs of feelers (ant. 2 and ant. 1) . ”

“ In some cases, when the space between the palatine plates of the superior maxillary bone is wide, it may be necessary, by mechanical contrivance, fitting on metallic apparatus possessing a strong spring, to approximate the bones before attempting to unite the lip. The cases must be very rare, where the soft parts cannot be otherwise brought together: when they can be united, their equable and continued pressure will have the effect of gradually approximating the hard parts. ”

“ The massive intermaxillary bone had its posterior margin of an angular form, and into the notch thus formed there was wedged the anterior end of a long strip of plates, which expanded as they approached the occipital part of the cranium, and terminated in three irregular plates that may represent the place of the parietal and occipital bones. ”

“ 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 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 skin of the forehead is without hair, is well nourished, and has little adipose tissue underlying it, facts that make it especially useful for these operations. The skin surface he turns into the mouth cavity, while the outer or raw surface is covered with a pedunculated skin flap taken from the region of the intramaxillary region. ”

“ In a well-marked case the hands and feet are greatly enlarged, but not otherwise deformed, and the normal functions are not disturbed. The hypertrophy involves all the tissues, giving a curious spade-like appearance to the hands. The feet are similarly enlarged, although the big toe may be relatively much larger. The nails also become broad and large. The face increases in volume and becomes elongated, in consequence of the hypertrophy of the superior and inferior maxillary bones. The latter often projects beyond the upper teeth. The teeth become separated, and the soft parts increase in size. ”

“ Myriads of micro-scopical workers will plow the skeleton, cleaning away the last impurities clinging to the framework, undoing the marvelous articulations, scraping away the cement which holds the vertebræ together. Some day the lower jaw will loosen, falling toward the abdominal cavity, leaving the upper jaw bone, the teeth of which knew the splendor of smiles and the caress of kisses. Some other day, the skull, as the pivot on which it rests comes apart, will fall in turn and mingle with the dust of the ribs and the little bones of the feet which mark the rhythm of an undulating walk. ”

“ Their ultimate branching takes a very wide range: the inner filaments obliquely cross the clavicular origin of the sterno-mastoid; the outer, the anterior fibres of the trapezius; the middle ones, the clavicle itself; and are distributed, in their respective regions, to the integuments of the scapula, shoulder, chest, and sternum.
The branch from the portio dura, which enters the neck, is the lower division of its cervico-facial part. From near the angle of the jaw, where it traverses the fascia, it passes toward the hyoid bone, and supplies the platysma from its deeper side. ”