THE OPHTHALMIC ^sERYE. 5G5 



The nerve next pierces the orbicularis palpebrarum and occipito-frontalis 

 muscles, furnishing twigs to these muscles and the corrugator supercilii, 

 and after ascending on the forehead, ramifies in the integument. 



J). The sujyraorbifal Iranch (external frontal) passes through the 

 supraorbital notch to the forehead, and ends in muscular, cutaneous, 

 and pericranial branches ; while in the notch it distributes paljmhral 

 filaments to the upper eyelid. 



The muscvlar branches referred to are comparatively small, and supply the 

 corrugator of the eyebrow, the occipito-frontalis. and the orbicular muscle of 

 the eyelids, joining the facial nerve in the last muscle. The ctdanrons hrancJws, 

 among which two (outer and inner) may be noticed as the principal, are placed 

 at first beneath the occipito-frontalis. The outer one. the larger, perforates the 

 tendinous expansion of the muscle, and ramifies in the scalp as far back as the 

 lambdoidal suture. The inner branch reaches the surface sooner than the pre- 

 ceding nerve, and ends in the integument over the parietal bone. The jhricmnial 

 hraitches arise from the cutaneous nerve beneath the muscle, and end in the i:)eri- 

 cranium covering the frontal and parietal bones. 



Fi?. 33G. 



Fig. 336. — Nervks of the Or- 

 bit FROM THE Outer Side 

 (from Sappey after HirschfeUl 

 and Leveille). % 

 The external rectus muscle has 



been divided and turned down : 1, 



tlie optic nerve ; 2, the trunk o 



the third nerve ; 3, its iippei 



division i^assing into the levator 



palpehije and superior rectus ; 4, 



its long lower branch to the in- 

 ferior oblique muscle; 5, the 



sixlli or abducent nerve joined 



by twigs from the sympathetic ; 



6, the Gasserian ganglion ; 7, 



ophthalmic nerve ; 8, its nasal 



branch ; 9, the ophthalmic gang- 

 lion ; 10, its short or motor root; 



11, long sensory root from the nasal nerve ; 12, sympathetic twig from the carotid 



plexus ; 13, cihary nerves passing into the eyeball ; 14, frontal branch of the ophthalmic 



nerve. 



Nasal branch. — The nasal branch (oculo-nasalis), separating from its 

 parent trunk in the wall of the cavernous sinus, enters the orbit between 

 the heads of the outer rectus. It then inclines inwards over the optic 

 nerve, beneath the elevator of the upper eyelid and the superior rectus 

 muscle, to the inner wall of the orbit, through which it passes by the 

 anterior internal orbital foramen. In this oblique course across the 

 orbit it furnishes a single filament to the ophthalmic ganglion, two or 

 three (long ciliary) directly to the eyeball ; and, at the inner side of the 

 cavity, a considerable branch (infratrochlear), which issues from the 

 orbit at the fore part. 



On leaving the orbit the nasal nerve is directed transversely inwards 

 to the upper surface of the cribriform plate of the ethmoid bone, and 

 passing forwards in a groove at its outer edge, within the cranium, 

 descends by a special aperture, close to the crista galli at the fore part 

 of the plate, to the roof of the nasal fossa, where it divides into two 

 branches, one of which (external or superficial nasal) reaches the integu- 

 ment of the side of the nose, and the other (ramus septi) ramifies in the 

 pituitary membrane. 



