41)4 



THE ARTERIES 



between the bone and dura mater, supplying both structures. It at first ascends for 

 a short distance in a groove on the greater wing of the sphenoid, and then divides 

 into two l)ranches. an anterior and a posterior. 



The anterior branch i)asses upwards, in the groove on the greater wing of the 

 sphenoid, on to the parietal bone at its anterior and inferior angle; at this spot the 

 groove becomes deepened and often bridged over by a thin plate of bone, being 

 converted for a quarter to half an inch or more into a distinct canal. The situation 

 of the artery is here indicated on the exterior of the skull by a spot an inch and a 

 half l:)ehind, and al)out an inch above, the external angular process of the orbit. 

 The anterior liranch is continued along the anterior border of the parietal bone 

 nearl}^ as far as the superior longitudinal sinus, and gives off in its course, 1)ut 

 especially posteriorly, large l)ranches which raniif}^ in an upward and backward 

 direction in grooves on the parietal l)one (fig. 337). 



The posterior branch passes backwards over the squamous portion of the 

 temporal bone; and thence on to the parietal bone, behind the anterior branch. 



Fig. 337. — The Middle Meningeal Artery within the Skill. 



BREGMA 



This l)ranch and its collaterals extend upwards as far as the longitudinal sinus, and 

 l)ackwards as far as the lateral sinus. 



In addition to its terminal anterior, and terminal posterior In'anches, the middle 

 meningeal gives off: — (a) Gasserian branches to the Gasserian ganglion and 

 Meckel's space, (b) A petrosal branch, which enters the hiatus Fallo}ui in com- 

 l)anv with the large superficial i)etrosal ncn-ve and anastomoses with the terminal 

 ]»ranch of the stylo-mastoid artery, (c) A tympanic branch, Avhich enters the 

 canal for the tensor tympani, and supplies that muscle, {d) An orbital or 

 lachrymal branch, ^vhicll enters the orbit at the outermost part of the sphenoidal 

 fissure, or sometimes through a minute foramen, just external to that fissure, and 

 anastomoses with the lachrymal branch of the ophthalmic. {<') Anastomotic or 

 perforating branches which pierce the greater wing of the s])henoid bone, and 

 anastomose with the deep temjioral arteries. 



(4) The mandibular (inferior dental) artery (fig. 330). arising from the 

 internal maxillary as it lies brtweeii the sjilieno-mandibular ligament and neck of 

 the jaw, courses downwards to the mandibular foramen, which it enters in company 



