340 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM 



cavernous sinus, being the lowest of the nerves. It receives 

 filaments from the cavernous plexus, and gives off filament a 

 to the third and sixth, and sometimes to the fourth nerve, 

 and a recurrent branch running in the tentorium with the 

 fourth. Finally, it divides into the frontal, lacrymal, and 

 nasal nerves, which pass through the sphenoidal fissure into 

 the orbit. 



The lacrymal, the smallest, runs with the lacrymal artery 

 above the external rectus muscle to the gland, which it supplies, 

 as well as the conjunctiva, communicating with the superior 

 maxillary nerve. It then pierces the palpebral ligament to 

 end in the upper lid, joining branches of the facial. 



The frontal, the largest branch, enters the orbit through 

 the widest part of the sphenoidal fissure, just below the peri- 

 osteum, and divides about the middle of the orbit into the 

 supratrochlear and supraorbital nerves. The former runs in 

 over the pulley of the superior oblique, and leaves the orbit 

 between it and the supraorbital foramen. It then ascends 

 beneath the muscles and ends in the skin of the forehead. It 

 communicates in the orbit with the infratrochlear nerve. 

 The frontal nerve continues as the supraorbital, which passes 

 through the supraorbital foramen, supplies the upper lid, and 

 divides into an inner and an outer branch. These ascend on 

 the forehead and supply the pericranium and skin, the outer 

 reaching nearly to the lambdoid suturs. 



The nasal enters the orbit between the two divisions of the 

 third nerve, and between the heads of the external rectus, 

 and then crosses over the optic nerve and runs to the anterior 

 ethmoidal foramen. In the orbit it gives off a hraneh to the 

 ophthalmic ganglion, one loin/ eilidri/ to the eyeball, and an 

 in/ratrochlecvr branch. It then reenters the cranial cavity 

 through the anterior ethmoidal canal. In the cranium it 

 runs in a groove on the cribriform plate, and through a slit 

 on the side of the crista galli into the nose, where it gives 

 off an external and an internal branch. The latter supplies 

 the mucous membrane of the septum, and the external the 

 outer wall of the nasal fossa. The nerve then runs in the 

 groove on the nasal bone to end as the (Ulterior branch in the 

 integument of the tip of the m>se, joining facial branches. 



The ophthalmic ganglion is found at the back of the orbit, 

 between the optic nerve and the external rectus. It has three 



