THE TRIGEMINAL NERVE 1237 



media) is a tiny filament which arises from the cavernous plexus and runs forward to 

 enter, either alone or with the sensory root, the upper posterior angle of the ganglion. 

 Branches. — These are the short ciliary nerves (nn. ciliares breves). They 

 number from four to six and by division are increased to twelve or twenty before 

 reaching the eyeball (Fig. 1058). They arise as t'wo fasciculi from the upper and 

 lower anterior angles of the ganglion and pass forward above and below the optic 

 nerve. The lower set is the more numerous and on its way forward is joined by the 

 long ciliary nerves from the nasal, with which one or more of its constituent branches 

 usually fuse. After piercing the sclerotic coat in two groups, one below and the 

 other above the entrance of the optic nerve, they pass forward in grooves on the 

 inner surface of the sclerotic to supply the choroid, iris, ciliary muscle and cornea. 



The short ciliary nerves include three sets of fibres : ( i ) Sympathetic fibres destined for 

 the walls of the blood-vessels and the radial (dilator) muscle of the iris ; these are links in the 

 chain made up of (a) white rami communicantes from the upper thoracic spinal nerves to the 

 cervical gangliated cord, and (d) the axones of neurones within the sympathetic ganglia. (2) 

 Fibres supplying the ciliary muscle and the circular (sphincter) muscle of the iris, which, while 

 in a sense the continuations of the oculomotor nerves, are immediately the axones of the stellate 

 sympathetic neurones within the ciliary ganglion. (3) Trigeminal fibres which transmit sensory 

 impulses from the interior of the eyeball, in conjunction with the long ciliary nerves. 



Variations. — The motor root occasionally bifurcates before it reaches the ganglion. As 

 noted above, the sensory and sympathetic roots frequently form a common trunk of entrance 

 into the ganglion. Occasionally the ganglion is very small, due possibly to the scattering of its 

 constituent neurones among the nerves connected with it (Quain). Additional roots have been 

 described as coming from the superior division of the oculomotor, from the trochlear, from the 

 lachrymal, from the abducent and from the spheno-palatine ganglion. Absence of the sensory 

 root has been noted, the deficiency possibly being corrected by the long ciliary nerves convey- 

 ing sensory fibres directly from the nasal to their destination, instead of these fibres passing 

 through the ganglion. The sympathetic root may be multiple, a condition held by some to be 

 normal, some of the fibres accompanying the oculomotor nerve. 



II. The Maxillary Nerve ox superior maxillary nerve {w. maxillaris) is purely 

 sensory and is intermediate in size between the ophthalmic and mandibular divisions 

 of the trigeminus. It supplies the cheek, the anterior portion of the temporal region, 

 the lower eyelid, the side of the nose, the upper lip, the upper teeth, and the mucous 

 membrane of the nose, naso-pharynx, maxillary antrum, posterior ethmoidal cells, 

 soft palate, tonsil and roof of the mouth. Arising from the middle of the anterior 

 convex border of the Gasserian ganglion, it passes forward beneath the dura mater in 

 the middle cranial fossa, lying below the cavernous sinus (Fig. 1053). The nerve 

 leaves the cranium through the foramen rotundum, traverses the spheno-maxillary 

 fossa and enters the orbital cavity by means of the spheno-maxillary fissure. It 

 occupies and then parallels the floor of the orbit in the infraorbital groove and canal, 

 finally emerging on the face by passing through the infraorbital foramen. Here it 

 breaks up fanlike into three terminal groups of branches (Fig. 1060). 



Branches and Distribution. — Branches are given of^ from the maxillary 

 nerve in the cranium, in the spheno-maxillary fossa, in the infraorbital canal and 

 on the face. These are : within the cranium, ( i ) the recurrent ; within the 

 spheno-maxillary fossa, (2) the spheno-palatine, (3.) the posterior siiperior 

 dental ■A.nA (4) the teviporo-malar ; in the infraorbital canal, (5) the middle 

 supericr dental and (6) the anterior superior dental; on the face (7) the 

 iyiferior palpebral , (8) the lateral ?iasal and (9) the superior labial. The last 

 three are terminal branches. 



1. The recurrent branch (n. meningeus) is given off before the maxillary nerve 

 passes through the foramen rotundum. It supphes the dura mater in the middle 

 cranial fossa. 



2. The two or three spheno-palatine branches (nn. sphenopalatini) (Fig. 

 1 061) arise in the spheno-maxillary fossa. They are short and thick and pass directly 

 downward to the upper margin of the spheno-palatine ganglion, whose sensory root 

 they supply. Only a small part of their fibres actually traverse the ganglion, the 

 much larger part passing lateral to or in front of the ganglion, to be continued 



