94 The /:<rr 



Beneath the skin are ligamentous and muscular slips, some of 

 which connect the pinna with the side of the head. The skin of the 

 pinna and of the meatus contains many sebaceous glands by which 

 the wax is secreted for lubricating the canal and for preventing the 

 entrance of insects. Sometimes it is secreted in excess, and forms at 

 last a plug which blocks the canal and causes deafness. 



As the result of violence, blood may be extravasated beneath the 

 skin of the pinna, forming hamatoma auris, or the cartilage of the ear 

 may be crumped up and permanently disfigured. Both these con- 

 ditions may be found in vigorous and forward foot-ball players. 



Passing down the meatus, the skin becomes gradually thinner, and 

 is at last blended with the periosteum. It forms also the outer layer 

 of the membrana tympani. 



Supply of tne pinna. The arteries are derived from the posterior 

 auricular and the superficial temporal. The veins take a correspond- 

 ing course. 



The nerves. The great auricular, from the second and third 

 cervical, supplies the lobule and the back of the pinna, the lesser 

 occipital also gives twigs to the occipital aspect of the pinna, as does 

 also the auricular branch of the pneumogastric. The auriculo- 

 temporal branch of the fifth supplies the outer aspect of the pinna. 

 The posterior auricular and temporal branches of the facial supply the 

 intrinsic muscles of the pinna. (It is noted elsewhere (p. 64) that pains 

 in the neighbourhood of the ear may be due to a lesion of the fifth 

 neive, and (p. 145) that pain at the back of the pinna may be the result 

 of cervical caries ) 



Muscles of the external ear. The attollens, fan-shaped, arises 

 from the aponeurosis of the occipito-frontalis, and is inserted into the 

 front of the helix. The most anterior fibres of this muscle constitute 

 the attrahens. The retrahens passes from the mastoid process forwards 

 to the back of the concha. 



Though the contemporary human anatomist hardly considers these 

 as muscles of expression, the suggestive fact, nevertheless, remains that 

 the facial nerve still supplies them : the retrahens by the posterior 

 auricular, and the attollens and attrahens by filaments from the 

 temporal division. The attollens may also receive a supply from the 

 lesser occipital nerve. 



The external auditory meatus is an osseo-cartilaginous canal 

 about \\ in. long, and is directed forwards and inwards. At the bottom 

 of the concha its greatest diameter is vertical, but near the membrane it 

 is transverse ; the narrowest part is about the middle. It is developed 

 by the outgrowth of the tympanic bone (p. 12). 



To make a thorough inspection of the canal, the pinna should be 

 drawn backwards, upwards, and a little outwards, the tragus being tilted 

 forwards. In the young child the meatus is extremely short ; the bony 

 wall is a subsequent development. 



