Fig. i6. Base of the Skull and Soft Parts after partial removal 



of the Bones. 



This complete fissure is constructed from eight dissections made after 

 hardening in formol and removing various parts of the Brain in successive 

 layers. After decalcifying the bones considerable portions were easily removed 

 by tlie knife. 



On the left side the part of tlie Occiput forming the Posterior Fossa 

 ivas removed, the Cavernous Sinus opened and the Gasserian Ganglion with 

 its three divisions dissected out. Tlie roof of tlie Orbit was removed and the 

 structures occupying the upper part of this cavity exposed to view. By cutting 

 away the Cribriform Plate of the Ethmoid, the Accessory Sinuses of the Nasal 

 Cavity were opened up — Mucous Membrane is coloured pink. 



On the right side a more extensive area of the base of the Skull 

 has been removed, only a few thin bars beeing left [Tympanic Cavity pink, 

 Membranous part of Meatus brown). In the lower part of the Orbital Cavity, 

 — the eye-ball having been cut across horizontally and supposed to be transparent, — 

 all the structures including the nerves and muscles are shew}i. 



The Nerves of the Special Senses are green (Optic Nerve light green ; 

 Auditory Nerx'e and apparatus, dark green). 



Sensory Nerves, yellow. Motor, dark blue (Veins being light blue), so 

 that the Motor Root of the Vth Nerve is definitely shewn. 



The Vagus Group IX, X, XI, being mixed nerves, are yellow, like the 

 sensory. Gassertan, Ciliary and Geniculate Ganglia are orange; on tlie left, 

 the air-cells of the Auditory apparatus, the Eustachtax Tube and the unusually 

 large Lateral Recess of the Sphenoidal Sinuses extending into the greater wings 

 of the Bone are projected upwards (pink). 



This figure — probably the first of this kind — gives, by shewing the vessels 

 and muscles under the base of the Skull in their natural position, an idea of the 

 Topography of this region unattainable from below because in this manner their 

 relations remain undisturbed b}' dissection. 



The figure shews the topographical relations of the 3 great organs of 

 special sense: e. g. E3'e, Ear and Nose, moreover, it gives a good view of the 

 course of the Nerves which have a primary intra- , and a subsequent extra- 

 cranial course. 



Lastly connections are exhibited which could scarcely be appreciated by 

 other methods. 



