BRANCHES OF THE FIFTH NERVE. 801 



in two bundles, connected with its superior and inferior angles ; the low r er bundle 

 is the larger. They run forward with the ciliary arteries in a wavy course, one 

 set above and the other below the optic nerve, and are joined by the long ciliary 

 nerves from the nasal. They pierce the sclerotic at the back part of the globe, pass 

 forward in delicate grooves on its inner surface, and are distributed to the ciliary 

 muscle, iris, and cornea. Tiedemann has described one small branch as penetrating 

 the optic nerve with the arteria centralis retinae. 







Superior Maxillary Nerve (Fig. 483). 



The Superior Maxillary, or second division of the fifth, is a sensory nerve. It 

 is intermediate, both in position and size, between the ophthalmic and inferior 

 maxillary. It commences at the middle of the Gasserian ganglion as a flattened 

 plexiform band, and passes forward through the foramen rotundum, where it 

 becomes more cylindrical in form and firmer in texture. It then crosses the 

 spheno-maxillary fossa, enters the orbit through the spheno-maxillary fissure, 

 traverses the infra-orbital canal in the floor of the orbit, and appears upon the face 

 at the infra-orbital foramen. 1 At its termination the nerve lies beneath the 

 Levator labii superioris muscle, and divides into a leash of branches, which spread 

 out upon the side of the nose, the lower eyelid, and upper lip, joining with filaments 

 of the facial nerve. 



Branches of Distribution. The branches of this nerve may be divided into four 

 groups : 1. Those given off in the cranium. 2. Those given off in the spheno- 

 maxillary fossa. 3. Those in the infra-orbital canal. 4. Those on the face. 



In the cranium . . . Meningeal. 



( Orbital or temporo-malar. 

 Spheno-maxillary fossa < Spheno-palatine. 



(^ Posterior superior dental. 



T f , . , f Middle superior dental. 



Infra-orbital canal < , , 



( Anterior superior dental. 



( Palpebral. 



On the face . . < Nasal. 



( Labial. 



The meningeal branch is given off directly after its origin from the Gasserian 

 ganglion, and supplies the dura mater, communicating with a meningeal branch 

 from the inferior maxillary nerve. 



The orbital or temporo-malar branch arises in the spheno-maxillary fossa, 

 enters the orbit by the spheno-maxillary fissure, and divides at the back of that 

 cavity into two branches, temporal and malar. 



The temporal branch runs in a groove along the outer wall of the orbit (in the 

 malar bone), receives a branch of communication from the lachrymal, and, 

 passing through a foramen in the malar bone, enters the temporal fossa. It 

 ascends between the bone and substance of the Temporal muscle, pierces this 

 muscle and the temporal fascia about an inch above the zygoma, and is distributed 

 to the integument covering the temple and side of the forehead, communicating 

 with the facial and auriculo-temporal branch of the inferior maxillary nerve. As 

 it pierces the temporal fascia it gives off a slender twig, which runs between the 

 two layers of the fascia to the outer angle of the orbit. 



The malar Branch passes along the external inferior angle of the orbit, emerges 

 upon the face through a foramen in the malar bone, and, perforating the Orbicu- 

 laris palpebrarum muscle, supplies the skin on the prominence of the cheek, and 

 is named subcutaneus malce. It joins with the facial and the palpebral branches 

 of the superior maxillary. 



The spheno-palatine branches, two in number, descend to the spheno-palatine 

 ganglion. 



1 After it enters the infra-orbital canal, the nerve is frequently called the infra-orbitui. 

 51 



