THE EXTERNAL EAR 123 



The annular cartilage is a ring which encircles the auditory 

 process, and, as already stated, it is itself telescoped within the base 

 of the conchal cartilage. The lining membrane of the ear is 

 continued over the inner aspect of the annular cartilage on to that 

 of the concha. In addition to the continuity of this membrane, 

 the cartilages are maintained in connection by elastic fibres which 

 pass from one to the other. 



The scuti^orm cartilage is a thin somewhat triangular plate, which 

 lies on the outer aspect of the temporal muscle, in front of the 

 conchal base. It is attached to the concha by muscles. 



The Muscles. — Numerous little muscles are attached to the 

 conchal cartilage, and by their contraction these muscles enable the 

 animal to direct the opening of the trumpet forwards, outwards or 

 backwards at will. 



The parotido-auricularis runs from the cartilage to the outer surface 

 of the parotid gland and enables the animal to incline the ear 

 downwards and outwards. 



The three cervico-auriculares muscles run from the poll to the 

 cartilage, and these during contraction direct the opening first 

 outwards, and then backwards, meanwhile drawing the ear toward 

 the poll. 



The parieto - auriculares {externus and internus) connect the 

 cartilage with the parietal or sagittal crest, and enable the animal to 

 prick the ear, and restore it to its erect position after its having been 

 depressed by the parotido-auricularis. 



The zygomatico-auricularis muscle runs from the zygomatic process 

 to the scutiform and the concha, and assists in pricking the ear. 



The scuio-auriculares {externus and internus) connect the outer and 

 inner surfaces of the scutiform cartilage with the base of the concha. 



The mastoido-auricularis is a short muscle running from the auditory 

 process to the base of the concha. It assists in telescoping the latter 

 on the annular cartilage. 



