376 LABORATORY MANUAL OF HUMAN ANATOMY 



sharp scissors, going right around the cornea in this way. All 

 the soft parts may now be stripped off the sclera back as far as 

 the N. opticus. Take two eyes, hardened in formalin, and divide 

 one by a sagittal section into a medial and a lateral half, and the 

 other by a coronal section through the equator into an anterior 

 and a posterior half. With a sharp razor this can be easily 

 accomplished in formalinized eyes without freezing. 

 Ascertain the exact meaning of the following terms : 



(a) Anterior pole (polus anterior}. 



(b) Posterior pole (polus posterior}. 



(c) Equator (aequator}. 



(d) Meridians (meridiani}. 



(e) External axis of eyeball (axis oculi externa}. 



(f) Internal axis of eyeball (axis oculi interna}. 



(g) Optic axis (axis optica). 

 (h) Line of vision (linea visus}. 



And of the two embryological terms : 



(i) Ophthalmic vesicle (vesicula ophthalmica} . 

 (j) Ophthalmic cup (caliculus ophthalmicus} . 



Note that the eyeball possesses the following: 



(a) Fibrous tunic (tunica fibrosa oculi}. 



(aa) Cornea. 



(aft) Sclera. 

 (6) Vascular tunic (tunica vasculosa oculi}. 



(ba} Chorioid coat (chorioidea} . 



(bb) Ciliary body (corpus ciliare}. 



(be} Iris (iris}. 



(c} Pigment layer (stratum pigmenti}. 

 (d) True nervous portion of eye (retina}. 



(e} Anterior and posterior chambers (camera oculi anterior, posterior}, 

 (f} Vitreous body (corpus vitreum}. 

 (g} Crystalline lens (lens crystallina}. 

 (h} Ciliary zonule (zonula ciliaris [Zinni]}. 



Fibrous Coat of Eye (Tunica fibrosa oculi). 



Make an incision with a very sharp knife through the sclera 

 of an eyeball at the equator ; let the knife cut only as far as the 

 black chorioidea, then lay it aside. Catch the edge of the sclera 

 in forceps, and with sharp fine scissors cut through the sclera 

 all the way around the eyeball, along the line of the equator. 

 Raise the anterior and posterior segments of the sclera from 

 the subjacent parts. In turning the anterior half forward, over- 

 come the resistance met near the margin of the cornea, due to 

 the attachment of the M. ciliaris to the deep surface of the sclera, 



