872 



ORGANS OF SPECIAL SEXSE 



aureiii, luive been described on i»age 431. The sjjecial intrinsic muscles are six in 

 nunil)er. They are ditiicult to display, and sometimes appear to be absent. 



Helicis major is a narrow slip Avliich arises from the spine of the helix and 

 passes upwards along the rim of the helix to near its summit. 



Helicis minor is an oblique fasciculus overh'ing the commencement of the 

 helix. 



The tragicus consists of nearly vertical fibres lying over the outer surface of 

 the tragus. 



The antitragicus arises from the outer surface of the antitragus to pass to the 

 caudate process. 



The transversus auris consists of mixed muscular and tendinous fibres which 

 with the following lies on the cranial aspect of the pinna, and traverses the hollow 

 formed between the bulging of the concha and the convexity corresponding to the 

 groove of the helix. 



The obliquus auris crosses the hollow between the concha and fossa of the 

 antihelix. 



Fig. 



495. — External and Interxal Surface of the Cartilage of the Right 

 Pinna and its Muscf.ES, etc. 



Helicis major 



Obliquus 



Helicis minor 



Fibrous band 



completing fore —7 



part of meatus 



PROCESSUS 



CAUDATUS y 



Transversus 



Antitragicus 



Tragicus Spine Fissure of Santorini 



of Helix 



Vessels. — The arteries are the posterior auricular from the external carotid, 

 and the anterior auricular from the temporal. 



The veins enter the posterior auricular and temporal veins. 



Nerves. — The inner surface of the pinna is supplied by three cutaneous nerves, 

 the great auricular, the small occipital and the auricular branch of tlie vagus. The 

 great auricular sui)})lies the lower three-quarters, with the exception of a small 

 ])()rtion near the meatus which, together with the back of the meatus, is supplietl 

 by the auricular branch of the vagus. The small occipital supplies the upi)er 

 fourth. Occasionally the great occipital sends a branch to the uppermost part 

 of the inner surface. The upper two-thirds of the outer surface receive their 

 cutaneous suppl}^ from the auriculo-temporal nerve, and the lower third is supplied 

 by the great auricular. The intrinsic muscles on the inner surface are supplied 

 by the posterior auricular liranch of the facial and those on the outer surface 

 by the tcni])or;il brnncb of the same nerve. 



The External Auditory Meatus is al)out an incli long (25 mm. ). It com- 

 mences at the bottom of the conclia, and passes inwards and a little forwards to 

 end at the membrana tymi)ani. It is narrowest at its centre. Near its orifice it 

 is oval from above downwards, but at its termination it is somewhat l)roader from 



