i568 A MANUAL OF ANATOMY 



in view the third, fourth, ophthalmic, superior maxillary, and sixth nerves, as 

 well as the cavernous sympathetic plexus. Anteriorly the sinus will be found 

 to receive its blood from the orbit through means of the ophthalmic vein or 

 veins. It is connected with its fellow of the opposite side by two venous 

 channels, namely, the anterior and posterior intercavernous sinuses (so-called 

 circular sinus) , lying in front of and behind the pituitary body. The cavernous 

 sinus is to be shown dividing posteriorly into the superior and inferior petrosal 

 sinuses. The superior petrosal sinus is to be followed along the superior- 

 border of the pars petrosa to the point where it opens into the lateral sinus, 

 and the inferior petrosal sinus is to be laid open between the pars petrosa 

 and the basilar process of the occipital bone as far as the antero-internal 

 compartment of the jugular foramen, through which it passes independently. 

 The transverse or basilar sinus is represented by several veins arranged in a 

 plexiform manner, and lying over the basilar process of the occipital bone. 

 It forms a connection between the right and left inferior petrosal sinuses. 



The cranial nerves are next to receive attention, as they make their exit 

 from the cranial cavity. The olfactory lobes have been removed along with 

 the brain, and the olfactory filaments traverse the foramina in the cribriform 

 plate of the ethmoid bone. Lying upon each half of this plate there is the 

 nasal nerve, accompanied by the anterior ethmoidal artery, both lying beneath 

 the dura mater, and passing forwards and inwards towards the fore part of 

 the side of the crista galli, where they disappear through the nasal slit. The 

 optic nerve will be found at the optic foramen, where it has the internal 

 carotid artery directly behind it. The third, fourth, ophthalmic, superior 

 maxillary, and sixth nerves are to be met with in close relation to the cavernous 

 sinus. The first four of these nerves will be found in relation to the outer 

 wall of the sinus, and the sixth nerve in close contact with the outer wall of 

 the cavernous part of the internal carotid artery within the sinus. The 

 dissection of the cavernous sympathetic plexus, in close relation to the artery, 

 requires considerable care, and the artery itself, with its branches, is to be 

 shown. 



The Gasserian ganglion on the large sensory root of the fifth nerve is to be 

 carefully displayed, the small motor root of the nerve lying underneath the 

 ganglion. The locality of the ganglion is the Gasserian depression on the 

 superior surface of the pars petrosa near the apex. From the ganglion the 

 ophthalmic nerve is to be followed forwards to the outer wall of the cavernous 

 sinus, the superior maxillary nerve forwards to the foramen rotundum, and 

 the inferior maxillary nerve, along with the motor root of the fifth nerve, 

 downwards to the foramen ovale. At the entrance to the meatus auditorius 

 internus will be found the seventh and eighth nerves, with the internal 

 auditory artery. At the jugular foramen will be found the ninth, tenth, 

 and eleventh nerves, as well as the lateral and inferior petrosal sinuses, and 

 the relative position of the structures at this foramen should receive careful 

 attention. The twelfth nerve will be met with at the anterior condylar 

 foramen, and it is to be noted that it pierces the dura mater in two bundles. 



The various structures passing through the foramen magnum must be- 

 mastered. 



The different meningeal arteries will be found fully described in the text. 

 The sphenoidal fissure and the transmitted structures should be postponed 

 until the dissection of the orbit is being overtaken. 



The pituitary body is now to receive attention. It will be found in the 

 pituitary fossa or sella turcica of the sphenoid bone, where it is largely covered 

 by the fold of dura mater called the diaphragma sellae. If in favourable 

 condition, it should be carefully removed, and studied according to the de- 

 scription given of it in the text. 



The interior of the skull, having been carefully cleaned, is now to be pro- 

 tected by placing upon the interior of the base pieces of cotton-wool, soaked 

 in preservative fluid. Thereafter the calvaria is to be replaced, or, if it is 

 not now available for use, the saturated cotton-wool is to be protected from 

 evaporation by the usual means familiar to all. 



Side of the Neck. — The subject being now placed with its face upwards. 



