58 



THE OSTEOLOGY AND MYOLOGY 



tection of the brain; the rest forms the roof of the nasal, and the inner wall of ilie orbital, 

 cavities. The point of greatest constriction of the brain-case is in the frontal l)one, just in 

 advance of the overlapping of the ])order of the parietal. The greatest width of the cranial 

 part of the bone is much narrower than the nasal part ; its depth is equally as much less. 

 While the cranial cavity of the bone will barely admit the tip of one's forefinger, the uasal 

 will contain nearly the whole of the first segment of the thumb ; the former is nearly cylin- 

 drical ; the latter represents the frustra of two cones ]»laced end to end ; the strait between 

 the cranial and nasal cavities is perfectly circular. The coronal suture, never o])literated, 

 may be either directly transverse, or obliquely placed, inclining forward from above down- 

 ward ; it has no notches, or other notable irregularities along its course. The coronal, and all 

 the other sutures around the frontal are strictly squamous ; the several bones (parietal, orbi- 

 to-sphenoid, maxillary, palatal, lachrymal and nasal) all overlap the frontal, except for about 

 half of the fronto-palatine suture, when the reverse takes place. The outer lower margins 

 of the bone are very irregular in their course, but in general terms, may be said to be direct 

 from the lower corner of the coronal suture through part of the palatal, and thence to extend 

 obli({ucly upward and forward to the point of greatest anterior extension, between which 

 point and its fellow there is a very deep notch for the reception of the nasals, usually ex- 

 tending quite to the supra-orbital protuberance. The anterior part of the surface of the 

 frontal is perfectly smooth, and nearly flat in every direction ; it is bounded in front by the 

 naso-frontal, and at the side by the fronto-lachrymal, suture. Behind, it is separated from 

 the orbital and temporal surfaces by two prominent ridges, which, arising from the supra- 

 orbital prominence, rapidly approximate as they proceed backward, meeting each other on 

 the median line, uniting, and running backward as the frontal portion of the sagittal crest. 

 The part of the frontal forming the temporal fossa3 is irregularly concave ; the orbital part is 

 smooth, plane, and vertical; the two are separated by a slight ridge running from the supra- 

 orbital })rotuberance to the sphenoid. 



The Interior of the frontal is perfectly smooth for its cerebral portion, the surface being 

 only marked with two slight depressions for the rhinencephalon ; the walls of the nasal 

 cham])er, on the other hand, are irregular, and marked in various ways. A strong ridge de- 

 pends from the median line, marking the junction of the vertical ethmoidal plate, and dividing 

 the interior into lateral moieties. The superior portion of the surface of each is hol- 

 lowed for the reception of the upper turbinal convolutions ; the lower portion (inner surface 

 of orbital plate of frontal) is marked by several (four or five) longitudiiuil, horizontal lines, 

 nearly parallel with each other, corresponding with the middle convolutions of the turbinate 

 bones. There are a few other irregularities, not necessary to particularize, which, like those 

 just described, relate to the convolutions of the spongy bones. 



The nasals remain distinct from each other, and from the surrounding bones with 

 which they are suturally connected. Thev are long and narrow, nearlv straiirht, in 

 mutual apposition along the median line. The anterior half is narrowly linear, the posterior 

 has a lateral expansion ; so that the fronto- and maxillo-nasal sutures enclose a diamond- 

 shaped space upon the lower forehead ; the naso-intermaxillary takes the place of the naso- 

 maxillary suture for the anterior third of the bone. These sutures are squamous, the nasal 

 overlapping the maxillary and intermaxillary. The superior surface of the nasals is smooth 

 and nearly plane ; the inferior aspect of the conjoined bones is a half-cylinder. The nasals 



