1154 A MANUAL OF ANATOMY 



Branches of the Ophthalmic Division of the Fifth Nerve. — ^The 



ophthalmic nerve, having left the outer wall of the cavernous sinus, 

 and before arriving at the sphenoidal fissure, gives ofi the nasal 

 nerve, and then divides into the frontal and lachrymal nerves. 



The frontal nerve, of large size, enters the orbit through the 

 sphenoidal fissure above the muscles. In this situation it has the 

 lachrymal nerve external to, and on the same plane with, it, and 

 the fourth nerve internal to it, but on a slightly higher plane. It 

 then passes forwards on the upper surface of the levator palpebrae 

 superioris, underneath the periosteum of the roof of the orbit, and 

 before arriving at the supra-orbital margin it divides into two 

 branches, supra-orbital and supratrochlear. 



Fig. 469. — Scheme of the Distribution of the Third, Fourth, and 

 Sixth Cranial Nerves (Flower). 



U.D. Upper Division i L.P.S. Levator^Palpebrae Superioris 



f R.Int. Rectus Internus 

 Third Nerve; L.D. Lower Division < R.Inf. Rectus Inferior 



I, O.I. Obliquus Inferior 

 C.G. Ciliary Ganglion 

 M.R. Motor Root 



S.R. Sensory Root (from Nasal Nerve) 

 Sy.R. Sympathetic Root 

 S.C. Short Ciliary Nerves 



Fourth Nerve — O.S. Obliquus Superior 



Sixth Nerve — R.E. Rectus Externus 



The supra-orbital nerve, which in size and direction is the con- { 

 tinuation of the frontal, passes forwards to the supra-orbital notch, | 

 or foramen, through which it emerges in company with the supra- 

 orbital artery. On the forehead it divides into two branches, 

 outer and inner, which have been already described (seep. 1067;. 

 Sometimes this division takes place within the orbit, and in these 

 cases the inner branch emerges through the frontal notch. 



The supratrochlear nerve, of small size, passes forwards and in- 

 wards to the trochlea or pulley of the superior oblique muscle, 

 above which it emerges on to the forehead, where it has been 

 previously described (see p. 1067). Before leaving the orbit it gives 

 off a small twig, which passes downwards, close to the pulley of the 

 superior oblique, to form a loop with the infratrochlear branch of 

 the nasal nerve. 



