REGIONS AND MUSCLES OF THE CRANIUM. 



740 



sessing the same properties as the periosteum 

 in other parts of the body, is, in a practical 

 point of view, not the least interesting structure 

 which is to be found in this region. It is 

 largely supplied with blood, more especially 

 in early life. We have already noticed its 

 adhesion to the super] acent aponeurosis ; it 

 adheres to the bone by cellular membrane, and 

 is easily raised from it by dissection in all 

 points except where there are sutures. This 

 membrane is not unfrequently the seat of peri- 

 ostitis and of nodes. 



II. Temporo-parietal region. The lateral 

 boundary of the occipito-frontal region consti- 

 tutes the superior limit of this region, and a 

 line drawn from the external angular process of 

 the os frontis backwards and a little down- 

 wards along the zygoma to the mastoid process 

 of the temporal bone, limits it inferiorly. 



The integument and subcutaneous cellular 

 membrane of this region differ but little from 

 the same structures in the occipito-frontal re- 

 gion. The former is finer and not so thick as 

 in the middle and posterior parts of the last- 

 named region. The hairs are oblique, some 

 directed forwards, others backwards towards 

 the occiput, and others downwards overlap- 

 ping the ears. Here the hairs first begin to 

 grow grey, whence the denomination tempora 

 has been applied to these regions, grey hairs 

 marking the inroads of time. The skin of this 

 region, however, is naturally bald for a consi- 

 derable portion in front of the ear, and for the 

 distance of about an inch immediately behind 

 and above it. 



The subcutaneous cellular tissue is very 

 loose in front of the ear, but behind it in the 

 vicinity of the mastoid process, it is more 

 dense, and hence the scalp is much less move- 

 able over that process, and immediately be- 

 hind the ear. The epicranial aponeurosis is 

 confounded with this subcutaneous tissue in 

 the superior part of this region. 



Temporal fascia. Subjacent to the cellular 

 expansion is a fibrous membrane of consider- 

 able strength, which stretches from the zygoma 

 below to the curved line above and behind 

 which limits the temporal fossa on the frontal, 

 parietal, and temporal bones. It is very thick 

 and strong, composed of white interlacing fi- 

 bres, firmly attached to the points of bone 

 referred to, and giving attachment by the 

 greater part of its deep surface to the fibres of 

 the temporal muscle. In front and below, 

 however, for a short space, some adipose cel- 

 lular membrane intervenes between the muscle 

 and the fascia. Along the margin of the zy- 

 goma, especially in front, the fascia is divisible 

 into two laminae, which pass down, one in- 

 ternal, the other external to the bone, and 

 become incorporated with periosteum : by their 

 separation above the zygoma they leave a tri- 

 angular space which is in general filled with 

 cellular tissue more or less adipose. 



Muscles. Some fibres of the occipito- 

 frontalis extend more or less into this region, 

 according to the state of developement of the 

 muscle. Here too we find the three auricular 

 muscles immediately subjacent to the subcu- 



taneous cellular tissue. (See EAR.) Under the 

 temporal fascia and adhering to its deep surface 

 is the fleshy portion of the temporal muscle, 

 attached to almost the whole of the fossa. 

 Behind, the mastoid process is enveloped by 

 the tendinous insertion of the sterno-mastoid 

 muscle. 



Nerves. The nerves of this region are very 

 numerous. The subcutaneous ones are derived 

 from the portio dura and the superficial tem- 

 poral or auricular of the fifth, and posteriorly 

 from the mastoid and digastric branches of the 

 portio dura, as well as some from the ascending 

 branches of the cervical plexus. The deep- 

 seated nerves in the temporal fossa are the deep 

 temporals from the inferior maxillary, and the 

 temporal filament of the orbitar branch of the 

 superior maxillary. 



Arteries. The superficial arteries are nu- 

 merous and important. They are derived from 

 the trunk of the superficial temporal, which 

 enters this region by passing over the zygoma 

 in front of the tragus, crossed over by the 

 anterior auris muscle. After it has passed the 

 zygoma it inclines forwards, and is a little more 

 distant from the ear than when on the zygoma. 

 In all this course it may be felt distinctly, 

 although it is pretty firmly bound down by the 

 subcutaneous tissue and epicranial aponeurosis, 

 which are here conjoined. A little more than an 

 inch above the zygoma it divides, and we trace 

 its anterior branch forwards towards the frontal 

 region, which it enters and anastomoses with 

 the supra-orbital. The posterior branch passes 

 upwards and backwards, winding over the ear, 

 and anastomoses with ramifications from the 

 occipital artery. It is in one or other of these 

 branches that arteriotomy is generally performed, 

 in preference to opening the trunk of the artery. 

 The middle branch of the temporal artery pierces 

 the fascia, and enters the substance of the tem- 

 poral muscle, anastomosing with the deep 

 temporals. The posterior part of this region is 

 supplied from branches of the occipital and 

 posterior auris. 



Veins. Veins accompany almost all the 

 arteries : there are none worthy of any special 

 notice. 



Lymphatics. These vessels likewise accom- 

 pany the arteries, and enter the ganglions in 

 the neighbourhood of the ear, and those of the 

 neck. 



Pericranium. The pericranium does not 

 differ from that of the occipito-frontal region, 

 except perhaps in firmer adhesion to the squa- 

 mous portion of the temporal bone. It 

 affords insertion to the fibres of the temporal 

 muscle. This region presents more surgical 

 interest than the former one; it is more fre- 

 quently the seat of operation (arteriotomy, and 

 in its posterior part, that of opening the mastoid 

 cells); and in consequence of the number of its 

 arteries and nerves, and the great strength of 

 the temporal fascia, wounds in this region are 

 of a more dangerous kind. Fractures here are 

 also liable to be complicated with a wound of 

 the middle meniugeal artery, part of the course 

 of which corresponds to this region. 



( R. B. Todd.) 



