4 SUPERFICIAL ANATOMY OF THE HEAD AND NECK. 



It commonly deviates a little to one side, more frequently the right, especially in 

 its hindmost part, as it descends over the upper portion of the occipital bone to its 

 termination. From the latter spot the lateral sinus runs outwards and forwards, 

 describing a slight curve with its convexity upwards, to the back of the ear on a 

 level with the upper margin of the external auditory meatus, and then turns down- 



Fig. 3. SIDE VIEW OF SKULL, SHOWING THE COURSE OF THE MIDDLE MENINGEAL ARTERY, LATERAL 

 SINUS, &c. (From a photograph by G. W. U. Waters.) f. (G. D. T.) 



The meningeal artery is represented in red and the lateral sinus in blue : the position of these was 

 ascertained by drilling holes from the interior of the skull. The shaded area above and behind the 

 external auditory meatus indicates the position of the epitympanic recess and mastoid antrum. The 

 broken line represents the inferior limit of the cerebral hemisphere as traced on the surface of the 

 skull, t f t indicate the points of intersection of vertical and horizontal lines respectively one inch, 

 one inch and a half, and two inches behind the external angular process of the frontal bone, and above 

 the upper border of the zygoma. 



wards, following a course directed to the tip of the mastoid process as far as a point 

 about 5 mm. beyond the level of the lower border of external auditory meatus. In 

 the first part of its course the sinus usually lies altogether above a line drawn 

 transversely from the external occipital protuberance to the centre of the opening of 

 the ear, and the highest part of its arch, where the sinus crosses the postero-inferior 



