150 PRACTICAL ANATOMY. 



The lenticular or ciliary ganglion. 



\VIiere is tlic ciliary ganglion located, and how is it formed .' 



It lies between the external rectus muscle and the optic nerve on the outer 



side of the ophthalmic artery. It is the size of a pin's head. It has three 



roots : 



1 . A sensory root from the nasal nerve. 



2. A motor root from the motor oculi nerve. 



3. A sympathetic root from the cavernous sympathetic. 

 Hoiv do the nerves gain access to the orbit ? 



The optic nerve passes through the optic foramen ; all the others pass through 

 the sphenoidal fissure with the ophthalmic vein. 



Name all the structures seen on inspecting the eye of a patient. 



1. The palpebral fissure, a slit between the lids. 



2. The outer and inner canthi, the extremities of the fissure. 



3. The tarsal cartilages, the free margins of the lids. 



4. The cornea, behind, which is the iris. 



5. The pupil, surrounded by the iris.- 



6. The tendo oculi, or inner palpebral ligament. 



7. The lachrymal caruncle, just within the inner can thus. 



8. The superior palpebral fold when the eye is opened. 



9. The inferior palpebral fold when the eye is opened. 

 10. The palpebral and ocular conjunctivae. 



i i. The conjunctival cul-de-sac or fornix. 



1 2. The sclerotica, or white of the eye. 



13. The conjunctival sac. This is the space between the posterior surface of 

 the lid and the eyeball. It is completely covered by conjunctiva. 



A patient gets a cinder in his eye : What nerve or nerves report the pain to the 

 brain f 



The cornea and sclerotica are supplied by the ciliary nerves. The infra- 

 trochlear branch of the nasal nerve supplies the conjunctiva, the lachrymal sac, 

 and the caruncula lachrymalis. The lachrymal nerve sends conjunctival branches 

 to the upper lid. The palpebral branches of the superior maxillary send con- 

 junctival branches to the lower lid. While, then, a number of branches are con- 

 cerned locally, one nerve, the trigeminus or fifth, does terminal work for all, 

 since the lachrymal, nasal, superior maxillary, and the sensory root of the ciliary 

 ganglion are all derived from the fifth nerve. A reflex circuit is completed by 

 the seventh nerve, acting on the orbicularis palpebrarum to close the eye. 



Emissary Foramina and Their Veins. 



Define emissary foramina ami emissary veins. 



Emissary foramina derive their importance from the veins they transmit ; 

 emissary veins are both physiologically and pathologically important. The emis- 

 sary veins are connected centrally to the sinuses in the dura mater ; peripherally 

 they communicate with veins both deep and superficial. From a physiological 

 standpoint these veins regulate indirectly the arterial pressure in the brain, since, 

 in cases of cerebral engorgement, when the internal jugular veins are unable to 

 convey the required amount of blood in the dural sinuses from the brain, the 

 emissary veins deliver large quantities of this venous blood to the superficial or 

 to the deep veins with which they communicate peripherally. This action of the 

 emissary veins has been compared to a safety-valve in mechanics. From a 

 pathological standpoint these veins are conveyers of septic material from areas 

 accessible to the surgeon and physician, to regions beyond the reach of either. 

 Infection in the orbit, posterior nares, and scalp over the forehead reaches the 

 cavernous sinus via the angular and ophthalmic veins. Infection in the face, 

 nose, and teeth reaches the cavernous sinus via the Vesalian vein and pterygoid 



