122 



DEVELOPMENT OF THE AURICLE IN THE HUMAN EMBRYO. 



GLOSSARY. 



Anteron [Boas]. By macerating the cartilage of the 

 auricle and auditory canal the whole system can 

 be unrolled into a flat plate. When this is done 

 the plate presents, along its anterior and posterior 

 margins, and particularly in its proximal half, 

 a series of incisures which divide the contour 

 into a corresponding series of processes. The 

 processes along the anterior margin are designated 

 anteron 1, anteron 2, etc., numbering from the 

 base of the cartilage. The processes along the 

 posterior margin are designated posteron 1, etc. 

 In the typical mammalian ear, anteron 5 cor- 

 responds to the spina helicis, posteron 4 to the 

 tragus, and posteron 5 to the antitragus. 



Anthelix. The rounded brim of the concha, from 

 which the secondary part of the auricle flares out 

 as the scapha-helix. (See fig. 2.) 



Antitragus. The thickened ventral rim of the concha, 

 situated between the incisura intertragica and the 

 anthelix. Apparently a part of the closure 

 mechanism. 



Cartilago-scutiformis, or cartilago-scutularis. See 

 Scutulum. 



Cauda helicis. (1) Term applied to the terminal 

 process of the cartilage of the helix, which is 

 separated from the concha] cartilage by a cleft 

 (fissura antitragico-helicina). His designated that 

 part of it forming the skeletal part of the lobule 

 as lingula auricula. (2) The term applied by 

 His to the fold found in the embryo, extending 

 from the third auricular hillock, directly posterior 

 to the fourth and fifth hillocks. According to 

 that author, the adult helix is derived from it. 



Cavitas conchas. See Concha. 



Colliculi branchiales externi [Moldenhauer]. The name 

 originally given to the hillocks that appear in the 

 embryo on the first and second branchial arches. 



Concha. The shell-shaped primary part of the auricle 

 immediately surrounding the meatus. As pre- 

 viously used, the term included only the cymba 

 conchas and the cavitas conchas. In this paper 

 I have extended the term to include also what has 

 been known as the fossa triangularis. The 

 contour of the concha thus is outlined by the 

 tragus, incisura intertragica, antitragus, anthelix, 

 and crus helicis. 



Crista inferior anthelicis [Schwalbe]. Used syn- 

 onymously with crus inferius anthelicis or plica 

 principalis. 



Crus helicis. Formerly restricted to the horizontal 

 portion of the helix, forming a transverse ridge in 

 the floor of the concha. In this paper the term is 

 extended to include all that part of the helix 

 derived from the mandibular arch. (See fig. 2.) 

 It constitutes the lateral free edge of the pars 

 articularis concha?, differing in structure and 

 development from the remainder of the helix. 



Crus inferius anthelicis. Fold in the auricular car- 

 tilage extending forward from the anthelix and 

 separating the fossa triangularis from the cymba 

 concha?. Equivalent to plica principalis, which 

 is a better term. 



Crus superius anthelicis. Ridge limiting the upper 

 border of the fossa triangularis (fossa articularis 

 superior). In using the term concha to include 

 this fossa, the crus superius anthelicis becomes 

 merely the upper end of the anthelix itself. 



Crus supertragicum [His]. A process sometimes ex- 

 tending forward from the crus helicis to the 

 region just above the tragus. Also called anti- 

 tragicum [Gradenigo]. 



Cymba conchas. See Concha. 



Darwin's tubercle. See Tuberculum auricula:. 



Eminentia articularis inferior. See Eminentia articula- 

 ris superior. Formerly known as eminentia concha;. 



Eminentia articularis superior. Same as eminentia 

 fossa? triangularis. The pars articularis of the 

 concha, as viewed from the median side, presents 

 two eminences which constitute the chief area of 

 contact of the auricle with the skull. In this 

 paper these are designated, respectively, eminentia 

 articularis superior and eminentia articularis inferior. 

 (See fig. 1.) The groove between them is the 

 sulcus corresponding to the plica principalis. 



Fissura antitragico-helicina. Cleft separating carti- 

 laginous cauda helicis from conchal cartilage. 



Fossa angularis [His]. Name applied to the first 

 branchial cleft when modified by the formation of 

 the auricular hillocks, five of which form a plump 

 ring around it. 



Fossa articularis inferior. Same as cymba concha;. 

 See Fossa articularis superior. 



Fossa articularis superior. Same as fossa triangularis. 

 When the pars articularis concha? is viewed from 

 the lateral side, its floor presents two fossa? 

 (superior and inferior) separated by the plica 

 principalis. (See fig. 2.) 



Fossa concha? [Hammar]. Essentially the same as 

 fossa angularis. 



Fossa intercruralis. Same as fossa triangularis, or, 

 as used in this paper, fossa articularis superior. 



Fossa scaphoidea. See Scapha. 



Fossa triquetra. Same as fossa triangularis, or, as 

 used in this paper, fossa articularis superior. 



Free ear-fold, or freien Ohrfalte [Schwalbe]. The ridge 

 representing first appearance of definitive auricle. 

 Same as helix hyoidalis [Gradenigo], cauda helicis 

 [His], or primitive scapha [Henneberg]. 



Helix. In adult man the rolled-in margin of the auricle, 

 when viewed as a whole from the lateral side, 

 resembles in outline a coiled spring and on this 

 account it was termed helix. Included under it are 

 parts that are quite different, both embryologically 

 and structurally. Furthermore, it is not appli- 

 cable to the auricle of other animals. If the term 

 scapha be used for all of the auricle peripheral to the 

 anthelix, and the term helix used for the rolled 

 edge of the scapha, where this occurs, the difficult)' 

 is then largely removed. It is so used in this 

 paper, and under scapha-helix will be designated 

 only those parts of the secondary auricle derived 

 from the hyoid arch. The crus helicis is a different 

 structure. The lobulus auricula? is a part of the 

 secondary auricle and bears a similar relation to 

 the concha as does the scapha. (See fig. 2.) 



Helix ascendens [Schwalbe). The anterior portion 

 of the helix which is derived from the third auric- 

 ular hillock of the mandibular arch. Partially 

 synonymous with crus helicis, as used by me. 



Helix hyoidalis [Gradenigo]. That portion of the helix 

 derived from the hyoidal arch, from a fold pos- 

 terior to the fourth, fifth, and sixth auricular 

 hillocks. Same as cauda helicis [His] and helix 

 posterior [Schwalbe]. 



