888 NEUROLOGY 



The supratrochlear nerve (n. supratrochlearis) , the smaller of the two, passes 

 above the pulley of the Obliquus superior, and gives off a descending filament, to 

 join the infratrochlear branch of the nasociliary nerve. It then escapes from the 

 orbit between the pulley of the Obliquus superior and the supraorbital foramen, 

 curves up on to the forehead close to the bone, ascends beneath the Corrugator 

 and Frontalis, and dividing into branches which pierce these muscles, it supplies 

 the skin of the lower part of the forehead close to the middle line and sends 

 filaments to the conjunctiva and skin of the upper eyelid. 



The supraorbital nerve (n. supraorbitalis) passes through the supraorbital foramen, 

 and gives off, in this situation, palpebral filaments to the upper eyelid. It then 

 ascends upon the forehead, and ends in two branches, a medial and a lateral, 

 which supply the integument of the scalp, reaching nearly as far back as the lamb- 

 doidal suture; they are at first situated beneath the Frontalis, the medial branch 

 perforating the muscle, the lateral branch the galea aponeurotica. Both branches 

 supply small twigs to the pericranium. 



The Nasociliary Nerve (n. nasociliaris; nasal nerve} is intermediate in size between 

 the frontal and lacrimal, and is more deeply placed. It enters the orbit between 

 the two heads of the Rectus lateralis, and between the superior and inferior rami 

 of the oculomotor nerve. It passes across the optic nerve and runs obliquely 

 beneath the Rectus superior and Obliquus superior, to the medial wall of the orbital 

 cavity. Here it passes through the anterior ethmoidal foramen, and, entering 

 the cavity of the cranium, traverses a shallow groove on the lateral margin of the 

 front part of the cribriform plate of the ethmoid bone, and runs down, through 

 a slit at the side of the crista galli, into the nasal cavity. It supplies internal 

 nasal branches to the mucous membrane of the front part of the septum and lateral 

 wall of the nasal cavity. Finally, it emerges, as the external nasal branch, between 

 the lower border of the nasal bone and the lateral nasal cartilage, and, passing 

 down beneath the Nasalis muscle, supplies the skin of the ala and apex of the nose. 



The nasociliary nerve gives off the following branches, viz.: the long root of the 

 ciliary ganglion, the long ciliary, and the ethmoidal nerves. 



The long root of the ciliary ganglion (radix longa ganglii ciliaris] usually arises 

 from the nasociliary between the two heads of the Rectus lateralis. It passes 

 forward on the lateral side of the optic nerve, and enters the postero-superior angle 

 of the ciliary ganglion; it is sometimes joined by a filament from the cavernous 

 plexus of the sympathetic, or from the superior ramus of the trochlear nerve. 



The long ciliary nerves (nn. ciliares longi), two or three in number, are given off 

 from the nasociliary, as it crosses the optic nerve. They accompany the short 

 ciliary nerves from the ciliary ganglion, pierce the posterior part of the sclera, 

 and running forward between it and the choroid, are distributed to the iris and 

 cornea. The long ciliary nerves are supposed to contain sympathetic fibers from 

 the superior cervical ganglion to the Dilator pupillse muscle. 



The infratrochlear nerve (n. infratrochlearis) is given off from the nasociliary 

 just before it enters the anterior ethmoidal foramen. It runs forward along the 

 upper border of the Rectus medialis, and is joined, near the pulley of the Obliquus 

 superior, by a filament from the supratrochlear nerve. It then passes to the 

 medial angle of the eye, and supplies the skin of the eyelids and side of the nose, 

 the conjunctiva, lacrimal sac, and caruncula lacrimalis. 



The ethmoidal branches (nn. ethmoidales) supply the ethmoidal cells; the posterior 

 branch leaves the orbital cavity through the posterior ethmoidal foramen and gives 

 some filaments to the sphenoidal sinus. 



The Ciliary Ganglion (ophthalmic or lenticular ganglion) (Figs. 775, 777). The 

 ciliary ganglion is a small, sympathetic ganglion, of a reddish-gray color, and about 

 the size of a pin's head; it is situated at the back part of the orbit, in some loose 

 fat between the optic nerve and the Rectus lateralis muscle, lying generally on the 

 lateral side of the ophthalmic artery. 



