746 



REGIONS AND MUSCLES OF THE CRANIUM. 



of the diploe so as to effect their obliteration ; 

 but when it is of a more vivid character, the 

 opposite effect of softening (the precursor of 

 ulceration) takes place, and both the outer and 

 inner tables are rendered friable. This fre- 

 quently occurs to a great extent in the mastoidal 

 cells, especially in children ; and as, in them, 

 the posterior portion of the meatus auditorius 

 internus possesses an unclosed fissure, the dis- 

 charge which is consequent on the destruction 

 of the cells is allowed an exit, before the mem- 

 brana tympani is destroyed ; although that, as 

 well as the whole of the internal ear, is fre- 

 quently involved in the ravages of the disease 

 then, however, having passed into another ter- 

 mination of osteitis, viz. ulceration. 



Adhesion can take place only where the cra- 

 nium has experienced a lesion from a mechani- 

 cal cause; and it is altogether prevented if the 

 solution of continuity be great. The edges of a 

 wound, produced by a cutting instrument 

 penetrating more or less perpendicularly to the 

 surface of the bone, do not approximate; but 

 they are united by an interposing callus as in 

 the case of a common fracture, and the line 

 formed by it is always visible in the same 

 way as the cicatrix which persists after the ad- 

 hesion of soft parts. When a piece of the 

 outer plate is elevated by a cutting instrument 

 passing very obliquely to the surface of the bone, 

 and the scalp is not detached, it will, on being 

 immediately re-applied, unite with the surface 

 from which it has been raised ; and, if it be 

 altogether removed, the reparation will be 

 effected in the same way as in other parts, viz. 

 by the granulation and cicatrization of the cut 

 surface. 



When there is loss of substance of the entire 

 thickness of the bone, whether that loss be pro- 

 duced by mechanical or pathological causes, 

 granulations spring up from the dura mater; 

 the edge of the opening becomes very thin; 

 the surface cicatrizes and produces the appear- 

 ance of a dense fibrous membrane, the circum- 

 ference of which is attached to the margin of the 

 hole and the adjacent pericranium. 



Caries, which is analogous to ulceration of 

 the soft parts, and is, in fact, an ulcerative ab- 

 sorption of bone, attacks the cranium in com- 

 mon with the rest of the osseous system ; but it 

 always first appears on one of the two tables, 

 and not on the diploe, although ultimately the 

 entire thickness is, in some cases, involved. 

 Indeed, when it commences on the inner table, 

 it is only by the extension of the ulcerative pro- 

 cess through the substance of the bone, that 

 the suppurative collection can be emancipated. 



In this affection the pericranium is sometimes 

 enormously thickened and almost inseparably 

 attached to the rough biscuit-like surface of the 

 bone beneath. In other cases, especially in 

 those in which the ulcerative process has been 

 provoked by mercury, it is in irregular patches; 

 the pericranium is unattached and the denuded 

 surface is of a dark colour. 



Necrosis, or mortification of the bone, is of 

 frequent occurrence ; but not in the way usually 

 implied by that term. Whether it be the sub- 

 stance of the bone, or merely its outer lamina 



which is deprived of its vitality, the reparation 

 is not by a fresh deposition of bone, nor is 

 it coeval with the separation of the necrosed 

 part, as in the long bones ; but it is a subse- 

 quent action (such as has been already pointed 

 out) which is established to supply the loss. 

 Considerable portions of the frontal and parietal 

 bones may thus be thrown off and the deficiency 

 provided for by the granulations of either the 

 subjacent diploe or the dura mater. 



Medullary sarcoma sometimes manifests 

 itself in the cranium. It appears to commence 

 in the diploe by a deposition of tuberculous 

 matter, which softens, and which in that state 

 may be mistaken for pus; the inorganic ele- 

 ment is withdrawn ; the accumulation con- 

 tinues and advances towards both tables, which 

 in turn submit to the same change of structure; 

 and, ultimately, a tumour is formed, the capsule 

 of which is constituted, on the one side by the 

 pericranium, and, on the other, by the dura 

 mater. In this tumour the knife detects spiculae 

 of bone interspersed throughout its substance, 

 and the edge of the opening which is left in the 

 skull after maceration, is studded with irregular 

 projecting points. 



For the Bibliography, see OSSEOUS SYSTEM. 

 ( J. Malyn.) 



CRANIUM, REGIONS AND MUSCLES 

 OF THE, (Surgical Anatomy.) If a line be 

 drawn on the skull from the external angular 

 process of the frontal bone, backwards along 

 the rough line on that and the parietal bone, 

 which indicates the attachment of the temporal 

 fascia, be continued downwards and backwards 

 parallel and a little external to the occipito- 

 mastoid suture, and then be carried forwards 

 along the inferior surface of the occipital bone to 

 end just behind the foramen jugale, and a little 

 internal to the stylo-mastoid foramen, this 

 line, with another similar one on the other side, 

 will include an oblong region which has very 

 natural limits both before and behind. Ante- 

 riorly this region is limited on each side by the 

 anterior margins of the roof of the orbit, in 

 the centre by the line of articulation of the 

 frontal bone with the nasal and superior maxil- 

 lary, posteriorly by the superior curved line of 

 the occipital bone, and on each side by the 

 mastoid process. To this oblong region may 

 be appropriately given the designation occipito- 

 frontal region. 



The line which thus limits laterally the region 

 just named circumscribes another region which 

 occupies nearly the whole lateral surface of the 

 cranium, and which is called the temporo- 

 purietal region. This region passes into the 

 base of the cranium, and may be limited below 

 and within by a line from the styloid process 

 external to the glenoid cavity, as far as the 

 spheno-maxillary fissure.* 



* Bland in makes five cranial regions occipito- 

 frontal, temporal, auricular, mastoid, and the region 

 of the base of the cranium : the last is quite out 

 of the reach of the surgeon, and therefore is 

 excluded from consideration in the present article. 

 Velpeau has three regions, the frontal, temporo- 



