20 DISSECTION OF THE HEAD. 



surface the fascia is in contact with the muscles already examined, and 

 with the superficial temporal vessels and nerves. 



An incision in the fascia, a little above the zygoma, will show it to con- 

 sist there of two layers, which are iixed to the edges of the upper border 

 of the zygomatic arch. Between the layers is some fatty tissue, with a 

 small branch of the superficial temporal artery, and a slender twig of the 

 orbital branch of the superior maxillary nerve with its artery. 



Dissection. The temporal fascia is now to be detached from the skull, 

 and to be thrown down to the zygomatic arch, in order that the origin of 

 the underlying temporal muscle may be examined. A soft areolar tissue 

 which lies beneath it near the zygoma is to be taken away. The difference 

 in thickness of parts of the fascia will be evident. 



The TEMPORAL MUSCLE is laid bare only in part. Wide and thin above, 

 it becomes narrower and thicker at the lower end. The muscle arises 

 from the temporal fascia, and from all the surface of the impression on the 

 side of the skull, which is named the temporal fossa. From this origin the 

 fibres descend, converging to a tendon, which is inserted into the under 

 surface and fore part of the coronoid process of the lower jaw. 



On the cutaneous surface is the temporal fascia, with the parts superfi- 

 cial to that membrane ; and concealed by the muscle are the deep tempo- 

 ral vessels and nerves which ramify in it. The insertion of the muscle 

 underneath the zygomatic arch will be afterwards followed. 



The temporal belongs to the group of masticatory muscles ; and its 

 action will be referred to with the description of the pterygoid region. 



Dissection. For the dissection of the vessels and nerves, let the fact 1 

 be now turned to the left side, and let an incision be carried along the 

 eyebrow and the zygomatic arch to a little behind the ear, so as to allow 

 the skin on the right half of the head to be reflected. The flap of skin 

 is to be raised from before backwards, but the subcutaneous fat should be 

 left till the nerves are found. 



Behind the ear the skin should be raised as on the other side, to un- 

 cover the posterior auricular vessels and nerve. 



Along the eyebrow seek the branches of vessels and nerves which come 

 from the orbit (fig. 2), viz., the supra-orbital vessels and nerve opposite 

 the middle, and the supra-trochlear nerve and frontal vessels near the 

 inner part of the orbit ; they lie at first beneath the occipito-frontalis, and 

 the muscular fibres must be cut through to find them. 



On the side of the head, in front of the ear, the superficial temporal 

 vessels and nerve are to be traced to the vertex ; and above the zygomatic 

 arch the branches of the facial which join an offset ( 10 ) of the superior 

 maxillary nerve, are to be sought. 



Behind the ear the posterior auricular vessels and nerve, and below it 

 branches from the great auricular nerve to the tip and back of the ear, are 

 to be found ; one or more offsets of the last should be followed to their 

 junction with the posterior auricular nerve. 



At the back of the head the ramifications of the occipital vessels, also 

 the large and small occipital nerves, should be denuded ; the former nerve 

 lies by the side of the artery, and the latter about midway between this 

 vessel and the ear. 



CUTANEOUS ARTERIES. The arteries of the scalp (fig. 2), are fur- 

 nished by the internal and external carotid trunks, and anastomose freely 

 over the side of the head. Only two small branches, the supra-orbital 



