ANATOMY. 



221 



plate the human cranium in its external aspect. 

 Even in this view, the united bones we have de- 

 scribed are divided into the cranium, or skull, and 

 face. The adult cranium is, in general, spherical, 

 but there is a great variety in skulls as well as 

 in heads. The superior part of the skull is arched, 

 and in some this arch is greater than in others ; 

 anteriorly, it is more or less flattened, posteriorly, 

 more or less rounded, but always considerably more 

 convex than on the interior part, and at the sides 

 the cranium is flattened. There are a great num- 

 ber of processes and depressions on the outer sur- 

 face, so as to render it very irregular in its appear- 

 ance. 



Upon viewing the external superior part of a 

 skull, several zigzag lines are observable, called 

 sutures; that which extends from one temple across 

 over the head to the other temple is termed the cor- 

 onal suture, (No. 2. fig. 1.) which unites the frontal 

 to the parietal bones ; another suture proceeds from 

 one ear upwards across to the other, and is called 

 the occipital, or lambdoidal suture ; it unites the oc- 

 cipital bone to the two parietal, (No. 3. fig. 2.) ; and 

 the suture which extends upon the crown of the 

 head from the lambdoidal to the coronal, is called 

 the sagittal. These are sometimes termed the 

 true sutures, to distinguish them from two spurious 

 or squamous, which are found on each side of the 

 cranium, (No. 4. fig. 1.) extending from the temple 

 backwards in the form of an arch, and uniting part 

 of the temporal bone to the parietal. Besides these 

 two sutures, two other portions are to be noticed, 

 the one belonging to the lambdoidal and the other 

 to the squamous suture, being in fact continua- 

 tions of them, and are called additamentums to those 

 sutures. The triangular shaped bones sometimes 

 observed in the course of some of the sutures, are 

 the Ossa Wormiana, or triquetra, or triangularia, 

 already described. 



The sutures are all more strongly marked on 

 the external surface of the cranium, and their 

 formation appears to be the effect of the parti- 

 cujar manner in which the bones of the cranium 

 ossify. Towards old age, bony matter is often 

 deposited between the bones, so as to cause their 

 disappearance, and sometimes, though seldom, at a 

 very early peroid of life ; and skulls have been met 

 with in which the true sutures were obliterated 

 at the age of twenty-eight, and likewise cases in 

 which the sagittal and coronal sutures were 

 likewise entirely obliterated in children of eight 

 years old (Plate LII. Ency. figs. 1. 2. 3. for 

 sutures). 



The partitioning of the cranium into so many 

 pieces, seems to be designed to facilitate the os- 

 sification after birth, and likewise to accelerate 

 and render less difficult that event both to mo- 

 ther and child, as well as to prevent the spread- 

 ing of fractures from one bone to another. There 

 are, too, besides the sutures we have enumerated, 

 several prominences upon the upper surface of the 

 cranium, two on the frontal bone, one immedi- 

 ately over each eye, between it and the suture, 

 one in the middle of each parietal bone, one in 

 the middle of the occipital, pointing out the cen- 

 tre of ossification in these different bones. 



The bones composing the upper part of the skull 

 are composed of an external and internal table, 

 which are of a compact structure, and of a spongy 

 intervening substance, called the meditullium 

 or diploe, already noticed when describing the 

 structure of bones. The skull has been divided 



into the upper part now named, which is some, 

 times called the calvaria, and the basis. The cal- 

 varia comprehends all that portion situated ante- 

 riorly about an inch above the nose, laterally 

 above the semicircular ridge of the parietal bones, 

 and posteriorly about an inch above the occipital 

 tubercle. It is this part (the calvaria) which is 

 sawed off to examine the brain after death, and 

 the operation of trepanning may be performed on 

 any part of the calvaria, avoiding, if possible, those 

 parts which lie over the sinuses of the dura mater. 

 The calvaria is sometimes very thick, but it is not 

 always clear whether this thickness be the effect 

 of disease or not, but it has sometimes been, and 

 perhaps justly considered, as one of the consequences 

 of rheumatic inflammation. The calvaria is very 

 subject to spongy venereal exostosis and caries, 

 and one kind is peculiar to it, viz. the honeycomb 

 caries, which consists in the total destruction 

 here and there of one or both tables, so as to con- 

 vey, though very imperfectly, the resemblance of 

 the cells of a honeycomb. The compiler of this 

 article, more than thirty years ago, when acting as 

 assistant to the late Mr Taunton, surgeon to the 

 City and Finsbury dispensaries, attended a patient 

 of the former of these institutions, in which the 

 greater part of the frontal bone was entirely de- 

 stroyed by caries, from syphilis. The patient, a 

 female, about twenty-eight years of age, recovered, 

 and nature supplied new bony matter as a cover- 

 ing to the exposed brain. 



Diastasis, or separation, and often the absorp- 

 tion of the bones of the calvaria, are frequently 

 the consequences of an accumulation of water 

 within the skull. Upon the internal surface of the 

 upper part of the cranium there are a number of 

 grooves in an arborescent form, made by the spinous 

 artery of the dura mater, and the sutures are seen 

 here in the form of a line not dove-tailed, and the 

 whole surface appears more polished than the ex- 

 ternal. The internal surface of the basis of the 

 cranium is divided naturally into eight considerable 

 depressions, adapted to the lobes of the brain and 

 cerebellum. Our limits forbid a particular notice 

 of these cavities, with the different foramina and 

 processes in the internal part of the skull, which, 

 however, are all wonderfully contrived for the dis- 

 charge of the respective offices they are destined 

 to perform in the animal economy. 



The Fatal Cranium. From the facts already 

 stated in our description of the separate bones, it 

 will be found that the bones of the skull of a 

 foetus at birth, are far more numerous than those 

 of an adult, for many of the processes of the latter 

 are epiphesis in the former, a difference which has 

 already been explained in a previous section of this 

 article. Thus, for example, the occipital bone 

 consists of four portions, and the sphenoid of three, 

 and so of several other bones. There are no 

 sutures in the cranium of the foetus. The parietal 

 and frontal bones do not coalesce until the third 

 year, so that before that period there is an ob- 

 vious interstice, commonly called the mould, or open 

 of the head, technically the fontanel, or fons 

 pulsatilis. There is also a lesser space occasion- 

 ally between the occipital and parietal bones, 

 termed the posterior fontanel. These spaces be- 

 tween the bones are filled up by the dura mater, 

 and the external integuments, so that during birth 

 the size of the head may be lessened, for at that 

 time the bones of the head upon the superior part 

 are not only pressed nearer to each other, but they 



