CoGHiLL, Cranial Nen'cs of Amblystonia. 221 



laterally of the twig just described to the skin over the 

 temporalis muscle mesially. 



In the immediate vicinity of the optic nerve several twigs 

 arise which may be considered together as the tJiird branch (0. 

 p. V. 7) of the ophthalmicus profundus. ■ They may be describ- 

 ed regardless of their order of branching, as follows: Tzvig "^" 

 passes to a position mesial of the r. ophthalmicus superficialis 

 VII and then cephalad to the skin over the anterior part of the 

 cranium. Twig "i?" is distributed to the skin immediately dor- 

 sally and anteriorly of the eye. Txvig "C" penetrates the fourth 

 nerve on the mesial side of the m. levator bulbi, then penetrates 

 the muscle also and goes to the skin of the immediate vicinity 

 of the dorsal margin of the muscle. It sends fibers mesiad, 

 also, to the skin, in the vicinity of the r. ophthalmicus super- 

 ficialis VII. Txvig "i?" sends fibers to the immediate vicinity 

 of the upper eyelid and then passes across the r. ophthalmicus 

 superficialis VII to the skin in the region of that nerve. 



In one specimen a large twig from the third branch of the 

 ophthalmicus profundus penetrates the roof of the nasal capsule 

 and anastomoses with a twig of the mesial terminal branch of 

 the nerve. The resulting nerve passes again through the 

 cartilage to the skin over the capsule. 



It should be emphasized that there is great variation in the 

 manner in which the twigs described above arise from the main 

 nerve or from one another. They may arise as two or more 

 distinct nerves, a part of one fusing with a part of the other and 

 then branching again in an indefinite manner. Their point of 

 origin from the main nerve is also variable, and in consequence 

 of this the general direction of the twigs is in no way constant. 

 The area innervated, however, by all collectively seems constant, 

 i. e. the skin of the infra-orbital region, and for a variable dis- 

 tance cephalad and caudad of this region. 



The terminal branches, also, of the r. ophthalmicus pro- 

 fundus vary in their manner of origin from the main nerve. The 

 three may arise simultaneously, or the ventral branch may arise 

 from the lateral branch. I have observed no case in which the 

 ventral arises from the mesial branch. The ventral branch is 



