THE INFRA-ORBITAL TRUNK. l8l 



division separates first. It corresponds in part to the r. 

 buccalis, but it contains only a portion of the buccalis 

 fibres and it carries other fibres also not belonging to that 

 nerve, viz., general cutaneous and motor. The middle 

 division contains more fine than coarse fibres and is the 

 proper r. mandibularis V. The dorsal division contains 

 coarse and fine fibres in about equal proportions and cor- 

 responds to the r. maxillaris plus a portion of the r. 

 buccalis and a communis element. 



After this division has begun, but while the dorsal and 

 middle divisions are still in contact, a small branch {w. j) 

 is given off from the dorsal one. It contains only coarse 

 fibres and goes around the outer (lateral) side of the 

 middle division but around the inner and ventral side of 

 the ventral one. It runs over the dorsal edge of the m. 

 adductor mandibulae to the skin. It now sends about half 

 of its fibres into the substance of this muscle. These are 

 very coarse and apparently branch freely within the mus- 

 cle, for the number here is greater than the number which 

 enters the muscle. They are undoubtedly motor fibres. 

 The remaining fibres run a short distance downward be- 

 tween the m. adductor mandibulae and the skin and in this 

 position cross (apparently without anastomosis) one of the 

 ventrally directed twigs of the second branch of the infra- 

 orbital trunk, the latter twig being outside. They then 

 supply the nth organ of the infra-orbital line, which is a 

 naked papilla. 



J. — T/ie Ventral Division. 



This assemblage of fibres turns outward under the eye 

 and over the m. adductor mandibulae. Here it gives off 

 its first branch of coarse fibres (the fourth infra-orbital 

 branch), which curves laterally around the m. adductor 



