262 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



some small lightly staining fibres. These are for the most 

 part handed over to the lower nerve, and collect at its 

 outer side. Finally they pass over into the ciliary 

 ganglion and hence form the radix brevis (fig. 26, rx. b.) 

 of that ganglion. 



The upper division of the oculomotor (r.s.) passes into 

 the Rectus superior muscle of the eye. Its small fibres 

 are distributed to the smaller fibres of its muscle. 



The lower division soon after leaving the ciliary 

 ganglion, to which it has been closely opposed, passes 

 sharply downwards and forwards accompanied at first by 

 the ramus ciliaris brevis from the ciliary ganglion (fig. 26, 

 ciL b.). It splits into three almost equal branches, which 

 soon take up the following positions in the vertical plane, 

 and are as below : — 



(a) Dorsal branch (r. it.). To rectus internus. Passes 

 upwards and inwards and reaches the ventral surface of 

 the lower or right optic nerve. It subsequently breaks up 

 in its muscle between and below the two optic nerves. 



(b) Intermediate branch (r. if.). To rectus inferior. 

 Divides into three principal twigs which enter their 

 muscle in the order shown in the figure. 



(c) Yentral branch (o.i.). To obliquus inferior. 

 Descends and crosses the palatinus vii. internally and for 

 some distance lies just below and internal to it. It then 

 rises, crosses the palatine again, and now lies to the inner 

 side of the rectus inferior. From this point it courses 

 almost straight forwards at the right side of the 

 parasphenoid and ethmoid cartilage, and finally splits up 

 to enter its muscle in the way shown in the figure. 



As regards now the left side, it may be noted at once 

 that the distribution of the eye muscle nerves, except 

 those coursing far forwards like the patheticus and the 

 branch of the third to the inferior oblique, is not much 



