Ii62 A MANUAL OF ANATOMY 



municates freely with the pterygoid plexus of veins through the 

 spheno-maxillary fissure, and that plexus sometimes represents its 

 mode of termination. 



Structures passing through the Sphenoidal Fissure. — ^These struc- 

 tures are as follows : 



1. The third nerve. 



2. The fourth nerve. 



3. The nasal, lachrymal, 



and frontal nerves. 



4. The sixth nerve. 



5. The sympathetic root of 



the ciliary ganglion. 



6. The two ophthalmic veins. 



7. The orbital branch of the 



middle meningeal artery. 



8. The recurrent branch of the 



lachrymal artery, 

 g. A process of the dura mater. 



The lachrymal, frontal, and fourth nerves enter the orbit above 

 the external rectus muscle, in the order named from without 

 inwards. 



The third nerve, the nasal nerve, and the sixth nerve enter the 

 orbit between the two heads of the external rectus muscle, the third 



, Small Wing of Sphenoid 

 Lachrymal Nerve . 



Frontal Nerve --"\^. ^n^^^^V^^- Optic Nerve 



Fourth Nerve... 



Upper Division of Third Nerve 



Nasal Ner\e. 



Lower Division of Third Nerve 



Sixth Nerve 



Ophthalmic Vein 



Fig. 474. — Diagram of the Left Sphenoidal Fissure, showing the 

 Transmitted Structures (Posterior View). 



nerve having previously broken up into two divisions ; and the two 

 ophthalmic veins leave the orbit between the two heads of the 

 external rectus. The order of parts between the two heads of the 

 external rectus, from above downwards, is as follows : 



1. The superior division of the third nerve. 



2. The nasal nerve. 



3. The inferior division of the third nerve. 



4. The sixth nerve. 



5. The ophthalmic veins (or vein). 



The sympathetic root of the ciliary ganglion passes through the 

 sphenoidal fissure independently, or along with the nasal nerve, or 

 sometimes with the third nerve. 



