Tympanum 95 



A foreign body in the ear may be detected by the speculum, and 

 perhaps extracted by appropriate forceps. If a stream of tepid water can 

 be got behind it, but obviously not otherwise, it may be washed out by 

 prolonged syringing, the stream being directed along the roof. A fine 

 stream is better than a full one, as it is more likely to pass behind the 

 foreign body. A large nozzle should not be used, lest, obstructing the 

 outflow, it produce so much tension as even to burst the membrana. 

 Rough syringing is always dangerous. 



If the parts be much swollen the attempt at extraction should be 

 delayed until they have quieted down ; the foreign body may quietly 

 lie at the bottom of the meatus for months or years and cause no harm. 

 Possibly a hair-pin bent at the closed end, may happily bring it out, 

 but no rough efforts should be made, lest the membrane be torn. If 

 the case be urgent, the cartilaginous part of the meatus may be cut 

 half across from behind the concha, flat with the surface of the head, 

 when, the pinna being turned forwards, the body is found well within 

 reach. 



If insects have entered the meatus, warm oil should be poured in. 



Supplies. The arteries of the meatus come from the posterior 

 auricular, internal maxillary, and superficial temporal. The veins run 

 to the external jugular, and the lymphatics to the glands near the 

 angle of the jaw. 



The nerves come from the auriculo-temporal (p. 63), the great 

 auricular, and from the auricular branch of the pneumogastric. It is 

 owing to the presence of the last-named nerve that the introduction of 

 a speculum, or the presence of a plug of wax, sometimes sets up a 

 cough known as an ' ear-cougli ' (see p. 69), which may be accounted 

 for by the fact that the pneumogastric or the auriculo-temporal nerve 

 conveys an impression to the grey matter of the medulla which is to 

 the effect that some annoyance exists in the larynx for which the 

 usual remedy is a cough. It is a sort of physiological equivalent of a 

 * printer's error.' The information conveyed by nerves is not invariably 

 true to the letter, and some have a worse character for veracity than 

 others notably the obturator (p. 359) and the vesical nerves (p. 411). 



Sometimes irritation of the auricular branch of the pneumogastric, 

 as by a plug of wax or by a foreign body, causes faintness, nausea, or 

 reflex vomiting, which entirely ceases on the cause being removed. 



The tympanum is a minute cavity situated between the external 

 and the internal ear. Its outer limit are the membrana, and an osseous 

 surface upon which are the apertures of entrance and exit of the 

 chorda tympani (p. 66). Its inner wall is the bony partition which 

 separates it from the internal ear. The roof is formed by a thin plate 

 of bone separating it from the middle cranial fossa, and its floor 

 is another thin plate which shuts it off from the jugular fossa. In 

 front of it ascends the internal carotid artery, and at that aspect also 

 enter two tubes, the upper one transmitting the tensor tympani, and 



