214 VISCERAL ANATOMY. 



Name the Arteries and Nerves of the Auricle. The 

 ARTERIES, are derived from the External Carotid. The 



Posterior Auricular, a main branch of the external carotid. 



Anterior Auricular, branch of the Temporal br. of the ext. carotid. 



Auricular, branch of the Occipital branch of the ext. carotid. 

 NERVES, are the 



Auriculus Magnus, from the cervical plexus. [See p. 133.] 



Posterior Auricular, from the facial nerve. 



Auricular, branch of the pneumogastric (also called Arnold's nerve). 



Auricula-temporal, branch of the inferior maxillary div. of the 5th. 



Describe the External Auditory Canal. It is an osseo-cartilagino'" 

 tube, about i% inch long, extending from the concha to the membrana tym- 

 pani, and curved irregularly in its course. The cartilaginous, or external por- 

 tion, is about ^ inch long, and deficient posteriorly and above, where it is 

 filled by strong fibrous tissue. The canal is lined with integument, having 

 numerous hair follicles, sebaceous and ceruminous glands. 



Sulcus Tympanicus, a groove at the bottom of the canal for the insertion 

 of the membrana tympani. It is interrupted above by the 



Segment of Rivinus, at the upper part of the sulcus tympanicus, each end 

 having an osseous spine, the Spina Tympanica Major and Minor. 



What are the Relations of the External Auditory Canal ? In front. 

 the articulation of the lower jaw; below and in front, the parotid gland-, 

 behind, the mastoid cells and the transverse sinus ; above, the mastoid cells 

 and the dura mater of the brain. 



Name its Vessels and Nerves. Its 

 Arteries, are branches of the Posterior and Deep Auricular. 

 Nerves, are chiefly derived from the Temporo-auricular Branch of the inferiol 



maxillary division of the 5th nerve. 



THE MEMBRANA TYMPANI. 



What is the Membrana Tympani? The Membrana Tympani, 01 

 Drumhead, is an oval, inelastic, semi-transparent membrane, about -^\^ inch 

 in thickness, situated obliquely at the bottom of the external auditory canal 

 which it separates from the cavity of the tympanum. Seen through the canal, 

 it is of a delicate blue-gray color, arched inwards, and presenting for consid- 

 eration the following points, viz. : A 



Tubercle, white in color at the upper border, made by the short process 



of the malleus. 



Stripe, also white, running downwards from the tubercle, and formed by 

 the handle of the malleus. 



