388 



MOTORES OCTJLOr.UM ABDTJCENTES. 





Fig. 128* 



tinuations upwards of the anterior columns of the spinal cord, or 

 motor tract, and that these fasciculi are prolonged onwards through 

 the pons Varolii and crura cerebri into the ganglia of the hemi- 

 spheres. Now, the three motor nerves arise from the cerebral por- 

 tion of the motor tract at different points of its course. 



3d pair, MOTORES OCULORUM. The motor oculi nerve arises from 

 the inner side of the crus cerebri, near to the pons Varoli, and passes 



forward between the posterior 

 cerebral and superior cerebellar 

 artery. It pierces the dura 

 mater immediately in front of 

 the posterior clinoid process; 

 descends obliquely along the ex- 

 ternal wall of the cavernous 

 sinus; and divides into two 

 branches which enter the orbit 

 between the two heads of the 

 external rectus muscle. The 

 superior branch ascends, and 

 supplies the superior rectus and 

 levator palpebrse. The inferior 

 sends a branch beneath the optic 

 nerve to the internal rectus, 

 another to the inferior rectus, 

 and a long branch to the in- 

 ferior oblique muscle. From 

 the latter a short thick branch 

 is given off to the ciliary gan- 

 glion, forming its inferior root. 



The fibres of origin of this 



nerve may be traced into the gray substance of the crus cerebri,f 

 into the motor tractj and as far as the superior fibres of the crus 

 cerebri. In the cavernous sinus it receives one or two fila- 



* The anatomy of the side of the neck, showing the nerves of the tongue. 1 . A frag- 

 ment of the temporal bone containing the meatus auditorius externus, mastoid, and 

 styloid process. 2. The stylo-hyoid muscle. 3. The stylo-glossus. 4. The slylo- 

 pharyngeus. 5. The tangue. 6. The hyo-glossus muscle ; its two portions. 7. The 

 genio-hyo-glossus muscle. 8. The genio-hyoideus ; they both arise from the inner sur- 

 face of the syrnphysis of the lower jaw. 9. The sterno-hyoid muscle. 10. The sterno- 

 thyroid. 11. The thyro-hyoid, upon whicli the hyoid branch of the lingual nerve is 

 seen ramifying. 12. The omo-hyoid crossing the common carotid artery (13), and in- 

 ternal jugular vein (14). 15. The external carotid giving off its branches. 16. The 

 internal carotid. 17. The gustatory nerve giving off a branch to the submaxillary 

 ganglion (18), and communicating a little further on with the hypoglossal nerve. 19. 

 The submaxillary, or Wharton's duct, passing forwards to the sublingual gland. 20. 

 The glosso-pharyngeal nerve. 21. The hypoglossal nerve curving around the occipital 

 artery. 22. The dcscendens noni nerve, forming a loop witli (23) the communicans 

 noni, which is seen to be arising by filaments from the upper cervical nerves. 24. The 

 pneumogastric nerve, emerging from between the internal jugular vein and common 

 carotid artery, and entering the chest. 25. The facial nerve, emerging from the stylo- 

 mastoid foramen, and crossing the external carotid artery. 



t Mayo. t Solly. Grainger. 



