498 



SEVENTH PAIR OF NERVES. PORTJO DURA. 



from the cavity by a fissure on the outside of the Eustachian 

 tube, to join the lingual branch of the fifth pair, as has been 

 already mentioned.* 



The Portio Dura, after passing out of the Foramen Stylo- 

 Mastoideum, is situated behind and within the parotid gland. 



Fig. 209.f 



* The late John Hunter believed that the chorda tympani is merely a con- 

 tinuation of the twig of the pterygoid branch which joins the portio dura above. 

 See Observations on certain parts of the Animal Economy, page 220. 



f The destribution of the facial nerve and the branches of the cervical 

 plexus. 1. The facial nerve, escaping from the stylo-mastoid foramen, and 

 crossing the ramus of the lower jaw ; the parotid gland has been removed in 

 order to see the nerve more distinctly. 2. The posterior auricular branch ; the 

 digastric and stylo-mastoid filaments are seen near the origin of this branch. 

 3. Temporal branches, communicating with (4) the branches of the frontal 

 nerve. 5. Facial branches, communicating with (6) the infra-orbital nerve. 

 7. Facial branches, communicating with (8) the mental nerve. 9. Cervico- 

 facial branches, communicating with (10) the superficialis colli nerve, and 

 forming a plexus (11) over the submaxillary gland. The distribution of the 

 branches of the facial in a radiated direction over the side of the face consti- 

 tutes the pes anserinus. 12. The auricularis magnus nerve, one of the ascend- 

 ing branches of the cervical plexus. 13. The occipitalis minor, ascending 

 along the posterior border of the sterno-mastqid muscle. 14. The superficial 

 and deep descending branches of the cervical plexus. 15. The spinal acces- 

 sory nerve, giving off a branch to the external surface of the trapezius muscle. 

 16. The occipitalis major nerve, the posterior branch of the second cervical nerve. 



