DEVELOPMENT OF THE AURICLE IN THE HUMAN EMBRYO. 



121 



include all that part of the helix derived from the mandibular arch ; on the median 

 side of the cartilage corresponding to the articular fossae: eminentia articularis 

 superior, for eminentia fossa triangularis; and eminentia articularis inferior, for 

 eminentia conchse. 



It may be pointed out here that the two articular eminences (fig. 1) are con- 

 tinuous with each other anteriorly, and that together they constitute a relatively 

 rigid, bowl-shaped base from which the auricle is suspended. It is this part only 

 of the auricular cartilage that offers a contact surface suitable for its attachment 

 to the skull, and it may therefore be designated as the pars articularis. It is chiefly 

 the inferior eminence that contributes to the surface, although the anterior and lower 



Eminentia 



articularis 



superior 



Sulcus 

 plicae 

 principalis 



Eminentia 



articularis 



inferior 



Fossa articularis 

 superior 



Plica principalis 



Fossa artic.inf. 



Crus helicis 



Tragus 



Meatus acustext. 



na helicis 



Scapha-helix 

 Tuberculum 



Anthelix 

 Concha 



Antitragus 



Lobulus 



Figs. 1 and 2. Human adult auricle, illustrating terminology used in this paper. In figure 1 the auricular cartilage is 

 viewed from the median side, thus showing the two eminences which constitute its main area of contact with 

 the skull. In figure 2 can be seen the cavities (fossa; articulares) of these eminences and the plica principalis 

 projecting between them as a strengthening ridge. 



portions of the superior eminence also take part. The band-like fenestrated carti- 

 lage surrounding the external acoustic meatus likewise has a bony attachment, but 

 this is quite different in character from the pars articularis; it may be compared 

 rather to the tracheal rings, serving as a mechanism to prevent collapse of the 

 meatus. In structure and position it offers little if any support to the auricle. 



For the convenience of the reader I am appending a glossary containing the 

 principal terms met with in the literature dealing with the development of the 

 auricle. In some instances the author who introduced the term is mentioned. 



