DISSECTION OF THE HEAD AND NECK 381 



(n) Greater arterial circle (circulus arteriosus major), 

 (o) Lesser arterial circle (circulus arteriosus minor). 



What is the pupillary membrane (membrana pupillaris) of foetal 

 life? 



The ciliary nerves and ciliary arteries and the Vv. vorticosae 

 should now be reviewed. (See pp. 277-281.) Examine espe- 

 cially, at the back part of the eye, between the chorioid and the 

 sclera, the passage of the Vv. vorticosae into the sclera; cut 

 through these and observe the Aa. ciliares posteriores breves 

 coming from the sclera to the chorioid. 



Layer of Pigment (Stratum pigment!) . 



In an eyeball which has had its sclera and cornea removed 

 and is under water, remove the chorioidea piecemeal, so as to 

 expose the stratum pigmenti and the retina. Note that the 

 stratum pigmenti is divisible into three parts : 



(a) Pigment layer of retina (stratum pigmenti retinae). 



(b) Pigment layer of ciliary body (stratum pigmenti corporis ciliaris). 



(c) Pigment layer of iris (stratum pigmenti iridis). 



Retina. 



In this study the following : 



(a) Optic part of retina (pars optica retinae). 



(aa) Serrated edge (ora serrata). 



(b) Ciliary part of retina (pars ciliaris retinae). 



(c) Papilla of optic nerve (papilla N. optici). 



(d) Excavation of papilla of optic nerve (excavatio papillae N. optici). 



(e) Yellow spot (macula lutea). 



Present in man, but not in the ox or sheep. 

 (/) Central fovea (fovea centralis). 

 (g) Blood-vessels of the retina (vasa sanguinea retinae). (Fig. 184.) 



The blood-vessels of the retina may now be studied. The 

 student should sometime control this study by an examination 

 of the eye-ground of a living person through the ophthalmoscope. 

 Note 



(a) Superior arteriole [venule] of temporal retina (arteriola [venula] 



temporalis retinae superior). 



(b) Inferior arteriole [venule] of temporal retina (arteriola [venula] 



temporalis retinae inferior). 



(c) Superior arteriole [venule] of nasal retina (arteriola [venula] nasalis 



retinae superior). 



(d) Inferior arteriole [venule] of nasal retina (arteriola [venula] nasalis 



retinae inferior). 



