CRAMIM AM) SCALP 



10S5 



hairs and selmceous glands is of much more importance than ajtpears at lir-^t. 

 Thus the rooting of the former is so firm that in the ease of young women tlie 

 whole scalp may he torn off hy mticliincry. Tlie sebaceous glands have also 

 grave importance. If in removing them the aponeurosis hcncath is pricked or the 

 wound hecomes foul, fatal suppuration in the ' chmgerous area' Iteneath may 

 follow. (2) The subcutaneous fat is arranged much as in tlie ))alm. viz. t<^»ugh 

 fatty pellets are enclosed in lil)n)us jtartitions, dipping from the skin to tlie third 

 layer, and thus tying the three layers together. (8j The occipito-frontalis and 

 its aponeurosis have heen fully deserihed elsewhere (jtage 427). (4) The sub- 

 aponeurotic layer of connective tissue. The characters of this layer are ipiite 

 opposed to those of the layer of connective tissue above the aponeurosis. It is 

 loose, delicate, and fatless. From these result the free mobility of the scalp, the 

 fact that it can he torn away, and (most important of all) the facility with which 

 inflammatory jiroducts can s))read in this layer. Tiie perils of pus ])ent up hen; 

 are extreme, viz. sloughing of the scalp, or necrosis of tin- hones, hlood-poisoning, 

 and meningitis, from miscliief travelling along the emissary and di})loic veins 

 (fig. fiHo). The continuity of the different scalp layers hy bands of connective 

 tissue passing from the skin to the occipito-frontalis, and thence along vesseL-^, 



Via. fiO:?. — Section TiiKor(;ii thk Scalp, Skt-i-l. and Dika Matkr. (Tillaii.x.j 



Skin and superficial 

 fascia with 



HAR BlLtS ASO SEBACEOUS 



GLANDS 

 Fat pelleta 



Ocoipito-frontalia 

 aponeurOBlB 



Subaponeurotic con- 

 nective tiB8ue 



Pericranium 

 Subpericranial con- 

 nective tissue 



SKULL: DIPLOIC TISSUE 



Dura mater 

 Skull cavity 



emissarv and others, into the venous sinuses, or by the di)>loic veins within the 

 skull, will aeeount fur seal|) inflammation reaching the meninges. 



Of the vessels of the scalp, the arteries are peculiar in their jmsition. Thus 

 they lie superficial to the deep fascia, which is here rei)resented l>y the aponeumsis 

 (fig. ()<)3). From this position arises the fact that a large flap of seal], may be sep- 

 arated without })erishing. as it carries its own blood-vessels. From the densitv of 

 the layer in which the vessels run they cannot retract and are <litlicult t<» seize, 

 haemorrhage thus being free. Finally, from their position over closely adjacent 

 bone. ill-ai>i)lied pressure may easily lead to sloughing. 



The emissary veins. — These are communications between the sinuses witliin. 

 and the veins outside the cranium. Most of tliem are temporary, corresponding 

 to the chief period of growth of the brain. Thus in early life, when the develop- 

 ment of the brain has to be very rapid, owing to the api>roaching closure nf its vixnv, 

 a free escape of blood is mostC.ssential. especially in children, with their su<lden 

 explosions of laughter and passionate crying. 



1. Vein throu'jh the foramen ca'cum, between the" anterior extremity of the 

 superior longitu<linal sinus and the nasal mui-ous membrane. The value of this 

 temporary outlet is well seen in the timely ]irofuse ej.istaxis of children. (Hher 

 more perinanent connnunicati«»ns between the skull cavity and nasal mucous nu-ni- 



