1 3 o PRACTICAL ANATOMY. 



connective tissue, called Meckel's fascia. The relation of the ganglion to the 

 internal carotid is of great importance in surgical operations on the ganglion. 



In figure 86 the artery will be seen behind the Gasserian ganglion, the third, 

 fourth, sixth, and ophthalmic division of the fifth nerve, and Meckel's fascia. In 

 other words, turn all these nerves aside and you will see the Gasserian ganglion 

 between two layers of subdural connective tissue called Meckel's fascia. The space 

 between these two layers of fascia is called Meckel's space. The space through 

 which the fifth nerve passes, between the tentorium and the superior border of 

 the petrosa, near the apex of the bone, is called the trigeminal notch. Turn the 

 Gasserian ganglion out of its bed and cut through the lower layer of Meckel's 

 fascia, and you will find the internal carotid. In operations for removal of the 

 Gasserian ganglion, this relation of the ganglion to the artery must be borne in 

 mind, since the only protection to the artery is a thin layer of Meckel's fascia. 



Find the superior maxillary division of the fifth nerve leaving by the foramen 

 rotundum in the greater iving of the sphenoid. 



The inferior maxillary division you will find leaving by the foramen ovale in 

 the greater wing of the sphenoid. 



Dissection and study of 



1. The Gasserian ganglion, its branches and relations. 



2. Meckel's fascia, anterior and posterior layers. 



3. The middle, or great, and the other meningeal arteries. 



4. The facial nerve, the seventh cranial in the petrosa. 



5. The tympanic cavity, the tympanum or middle ear. 



6. The petrosal stage of the internal carotid artery. 



7. The cavernous stage of the internal carotid artery. 

 Locate ike following anatomical structures : 



1. The middle meningeal groove and its artery. 



2. The superior border of the petrosa. 



3. The inferior border of the petrosa. 



4. The posterior surface of the petrosa. 



5. The anterior surface of the petrosa. 



6. The internal auditory meatus with the seventh and eighth nerves. 



7. The hiatus Fallopii and great petrosal nerve. 



8. The tegmen tympani or roof of the tympanum. 



9. The foramen lacerum medium. Sphenotic fissure. 



10. The foramen spinosum in the alar spine of sphenoid bone. 



1 1. The sphenoidal fissure in the sphenoid bone. 



12. The foramen ovale for third division of the fifth nerve. 



13. The foramen rotundum for the second division of the fifth nerve. 



14. The anterior, middle, and posterior clinoid processes. 

 Describe the middle meningeal artery. 



It is a branch of the first stage of the internal maxillary artery. External to 

 the cranium it lies behind the internal pterygoid muscle. It passes between the 

 two roots of origin of the auriculo-temporal nerve. It enters the cranium by the 

 foramen spinosum, in the great wing of the sphenoid bone, and ramifies between 

 the dura mater and the bone, both of which it supplies with blood. Its two 

 accompanying veins are tributary to the internal maxillary vein. The middle 

 meningeal artery divides in anterior and posterior branches which supply the 

 greater part of the bones of the cranium. (Fig. 81.) 



This vessel gives off the following minor branches : 



1 . Small branches to the Gasserian ganglion and its adjacent dura mater. 



2. A branch through the hiatus Fallopii to the seventh nerve and tympanum. 



3. Temporal branches perforating the bone to the temporal fossa. 



4. Orbital branches passing through the sphenoid fissure to the orbit. 



