CRANIUM. 737 



tal to the two parietal bones (Jig. 373, ft), external and internal surfaces of the skull 



The lambdoidal (<>) consists of two diverging itself. 



lines formed by the articulation of the posterior For this purpose the external surface may 



border of the two parietals with the superior be divided into four regions : the superior, the 



half of the occipital; and extends from the inferior, and the two lateral, 



superior to the lateral angles of that bone. The superior region extends from the nasal 



The Kdgiltul is the line of union between the process of the frontal bone to the occipital 



parietals themselves, and runs longitudinally protuberance, and is bounded on each side 



from the superior part of the larnbdoidal to by the linea temporalis; a curved line, which, 



the centre of the coronal suture. On each side commencing at the external angular process 



of the skull is the squnmous suture (Jig. 373, of the frontal bone, passes backwards, traverses 



<) ; it has none of the serrated characters of the parietal below its protuberance, and is re- 



the other sutures, but is an arched line ex- ceived on the extreme point of the root of the 



tending from the great wing of the sphenoid zygomatic process of the temporal bone. To 



to the mastoid process of the temporal bone, proceed from before to behind, there are, on 



and traversing so much of the border of its the median line, the nasal process and the 



squamous process as embraces the parietal rough notch for the articulation of the nasal 



bone. bones ; the nasal protuberance ; the glabella 



The squamous suture and the lambdoidal bounded laterally by the frontal processes ; the 



suture are connected by a short transverse line line indicating the junction of the two foetal 



formed by the articulation of the mastoid angle portions of the frontal bone ; the centre of the 



of the parietal bone with the mastoid process coronal suture; the whole length of the sa- 



of the temporal, and which is called udditu- gittal suture, with the foramen parietale on 



incut inn nutura: s^nnwoste (Jig. 373, g). From each side of it; the superior angle of the 



the lateral angle of the occipital bone to its occipital bone; a part of the occipital bone 



jugular process, that is, from the termination itself; and, lastly, the occipital protuberance, 



of the lambdoidal suture (where it is joined by Laterally, and on each side, there are the 



the before-mentioned supplement of the squa- frontal process, the superciliary ridge, the 



mous suture) to the jugular foramen, there is depression between them, and the supra-or- 



a line formed by the posterior border of the bitary foramen ; the frontal protuberance ; the 



mastoid process and the occipital bone termed coronal suture ; the parietal protuberance ; the 



(idditumcntuin sutura: latnbdoidatis. lambdoidal suture; and so much of the side 



The transverse frontal suture (fg. 373, a) of the occipital bone as is above the transverse 



is situated transversely, but forms several ridge. 



angles in its course. It extends from one The inferior region extends from the pos- 



external angular process of the frontal bone to terior part of the nasal process to the occipital 



the other; commencing at either angle, after protuberance, and is circumscribed by a line, 



uniting that angle to the malar bone, it enters continuous with the extremities of the supe- 



the orbit, and unites the frontal bone to the rior curved ridge of the occipital bone, and 



great wing and to the small wing of the sphe- passing on the outside of the mastoid and in 



noid ; it then passes out of the other side of the direction of the zygomatic process of the 



the orbit, joining the same bone to the eth- temporal bone, to the crest which is on the 



moid, lachrymal, nasal process of the superior temporal process of the great wing of the sphe- 



maxillary and nasal bones themselves ; enters noid. The facts to be here noticed are nu- 



the orbit of the opposite side and retires from merous, and, to facilitate their enumeration, 



it, articulating the frontal to bones analogous this region may be divided into three parts, 



to those in the other orbit. one anterior to the pterygoid processes of the 



Other sutures are occasionally enumerated, sphenoid bone, one posterior to the articu- 



such as the sphenoidalj which entirely sur- lating processes of the occipital bone, and a 



rounds the sphenoid bone; and the ethmoidal y middle one between these two. 



which bounds the cribriform plate of the eth- The anterior division contributes to form the 



moid bone. Both of these, so far as they nose and the orbits. For the first, there may 



deserve the name of sutures, are comprehended be observed on the median line, the nasal 



in the transverse frontal suture. lamella of the ethmoid bone, articulated, in 



The articulations of the temporal with the front, to the nasal process of the frontal, and, 



occipital, sphenoid, and parietal bones have behind, to the crest in front of the body of the 



been designated as the petro-occipital, petro- sphenoid. On the same line, but below and 



sphenoidal, spheno-temporal, and spheno-pari- behind this, is the azygos process, and inferior 



etal sutures; but, with the exception of the part of the body of the sphenoid, with the 



last, (which is squamous, and truly a part of channels to form, with the vomer, the palatine 



that suture,) they are not sutures. canals. On either side of the nasal lamella is 



It ought further to be remarked that, while the slit for the ethtnoidal nerve and vessels ; 



the bones of the calvaria are much thinner the cribriform plate and its foramina; and the 



than those of the base, they are comparatively space which assists to form the nares. More 



thicker in their borders to allow of that serra- laterally, and still passing from before back- 



tion from which the term suture is derived. wards, is the internal angular process of the 



To study, in combination with each other, frontal bone, to unite with the lachrymal ; the 



the facts enumerated in the foregoing descrip- cellular mass of the ethmoid, with its turbi- 



tion, it is necessary to take a survey of the nated processes on one of its sides, ami the 



