PRACTICAL CONSIDERATIONS : THE SCALP. 491 



mistaken diagnosis of fracture of the skull ; (7) lipomata are rare, as in the only 

 layer in which fat is found its abnormal growth is resisted by the density of the 

 surrounding connective tissue. 



Baldness affects especially the area of the scalp which directly overlies the 

 occipito-frontal aponeurosis. It is attributed (Elliott) largely to the lack of muscular 

 fibres in this region, so that the skin is not ", exercised" and the lymph-current is 

 made to depend chiefly on gravity. The density of the superficial fascia connecting 

 the skin and the aponeurosis allies it with that of the palmar and plantar regions, in 

 both of which similarly dense fascia is found and hair is absent. 



Dermoids are common over the anterior fontanelle and the occipital protuber- 

 ance because the early contact of the skin and dura mater continues longest in these 

 regions. ' ' Should the skin be imperfectly separated, or a portion remain persist- 

 ently adherent to the dura mater, it would act precisely as a tumor germ and give 

 rise to a dermoid cyst" (Sutton). 



Wens are also common on account of the presence of large numbers of seba- 

 ceous glands. In removing such growths, if the dissection is carried close to the 

 sac, the subaponeurotic layer will not be opened and all danger, even in case of 

 infection, will be minimized. 



So-called ' ' horns' ' are found here with relative frequency by reason of the 

 number of sebaceous glands. 



Emphysema of the scalp may occur as a complication of fractures involving the 

 pharynx, the frontal sinuses, or the ethmoid or nasal bones. The air infiltrates 

 either the subaponeurotic or subcutaneous cellular tissue. 



Pneicmatocele of the frontal region is very rare, but has occurred in a few cases 

 as a result of a communication between the nasal cavity and bony defects in the 

 anterior wall of the frontal sinuses. The swelHng is soft, elastic, and resonant, and is 

 made more tense by forced expiration, less so by pressure. The entrance and escape 

 of air may be heard on auscultation. The air is always beneath the pericranium. 



Syphilis, tuberculosis, carcinoma, and sarcoma may affect the scalp primarily, 

 and are mentioned in the order of frequency of occurrence. 



Cirsoid aneurism is especially frequent upon the scalp. 



The Temporal Region. — Here the skin is thinner and less intimately adherent 

 to the subcutaneous fascia than in the occipito-frontal region ; that fascia also is 

 somewhat less closely connected to the aponeurosis beneath. Hemorrhage between 

 these layers is therefore more easily controlled by the usual process of picking up 

 and tying the vessel, the walls of which will be found freer from attachments to the 

 bundles of fascia. 



The fascia over the temporal muscle itself is of such strength and thickness that 

 abscesses beneath it rarely point above the zygoma, but are directed into the pterygo- 

 maxillary region and thence into the pharynx or into the neck, or along the anterior 

 temporal muscular fibres to the coronoid process and thence into the mouth. 

 Abscesses above it have no special anatomical peculiarities. 



The fat in the temporal fossa is abundant, and is found in the subcutaneous 

 fascia, between the two layers of the temporal fascia, and directly upon the muscle 

 itself. The disappearance of this fat in diseases attended by emaciation causes the 

 characteristic unnatural prominence of the zygoma and apparent deepening of the 

 temporal fossae. 



The temporal muscle should be considered with the pterygoids in their relation 

 to fracture of the ramus and coronoid process (pages 245, 493), to dislocation of 

 the inferior maxilla (pages 246, 493), and to resection of that bone. 



The pericranium of this region is thinner and more adherent than that of the 

 occipito-frontal region, and the subpericranial connective tissue is absent ; hence 

 subperiosteal abscess or haematoma is practically unknown. 



The region may be invaded by tumors originating in the orbit and spreading 

 through the spheno-maxillary fissure or through the thin orbital process of the 

 malar bone. 



Trephining and other operations in this region are so closely related to intra- 

 cranial diseases and middle-ear disease that they will be considered in that relation 

 (page 1509). 



