14 SURGICAL ANATOMY OF 



in front at the root of the nose, and is to be carried back- 

 wards to the occipital tuberosity ; a second at right angles 

 to it across the scalp from ear to ear. Care must be taken 

 that the depth of the first incisions extends no farther 

 than the hair-bulbs. The flaps so formed are next to be 

 very carefully reflected forwards and backwards. 



The integument is tolerably thick, smooth, and some- 

 what uneven in surface. It is very rich in sebaceous fol- 

 licles, and these, by the inspissation of their contents and 

 closure of their excretory ducts, constitute the encysted 

 tumors or wens so often met with in this region. It is 

 highly vascular, and is frequently the seat of aneurisms 

 by anastomosis, erectile tumors, &c., and has immediately 

 subjacent a dense lamellated cellular tissue, containing a 

 little nodulated fat and the hair-bulbs, adhering firmly 

 to the underlying tendinous expansion of the occipito- 

 frontalis muscle or epicranial aponeurosis. This apon- 

 eurosis is extremely thin over the vertex of the cranium, 

 but very thick in the temporal region, and freely mova- 

 ble. Effusions of blood may take place either above or 

 below this structure in the loose areolar tissue separating 

 it from the pericranium. Thus a " black eye " can be 

 produced by a blow on the back of the head, by the 

 gravitation of the blood downwards and forwards into 

 the loose subcutaneous tissue of the forehead and eyelids. 

 In phlegmonous erysipelas of the scalp the pus burrows 

 under this aponeurosis, so that free incisions down to the 

 bone and counter-openings are necessary. Beneath this 

 cellular layer is the pericranium or external periosteum, 

 which is much stronger in the child than in the adult; 

 it is frequently the seat of periostitis and of nodes. 



The arteries supplying this region are in front, the 

 supra-orbital, the frontal, and the superficial temporal, 



