October 25, 2013 7:33 pm

The Doctor: a voyage inside the middle ear

‘Just below the umbo, a reliable little dazzle of light appears when you shine the otoscope in’

Before I started medicine, I shared with romantic fiction the belief that the body is studded with places too poetic and special for anyone to have named them – the hollow above her fragile collarbone; the dimple behind her lovely knee; the dip above his manly lips etc. With anatomy lessons came the discovery that everything has been labelled. The supraclavicular fossa; the popliteal fossa; the philtrum: there is no fold or knobble too minor for categorisation.

It is still possible to be surprised, though. The first time I looked into someone’s ear – holding the otoscope in one shaky hand – there was a registrar whispering into my ear. It was not romantic. “Can you see the tympanic membrane?” I nodded. I had no idea what I was looking at. “Now, can you see the umbo?”

I eventually learnt my way around the ear’s strange names. But it can still be difficult to explain ear problems to patients. I think it’s harder to understand what’s going on if you can’t see it for yourself. There is confusion about the distinction between the outer and the middle ear, for example, perhaps because it’s difficult to visualise the anatomy. The outer ear is everything you can see, plus the ear canal – the bit you poke into with a paperclip before going to the doctor and denying you’ve done any such thing. The canal is lined with some of the thinnest skin in the body. An infection affecting just this skin is called otitis externa, or swimmer’s ear. It can be extremely painful, and you may get a discharge, as the inflamed tissues lining the canal slough off debris; the swelling and discharge can also cause temporary deafness. But as a diagnosis I’ve found it lacks popularity, and among some patients, credibility. “It’s inside, I’m telling you! It’s not just the tube bit! It’s deeper than I can reach!”

If you continue along the ear canal for about an inch, you arrive at a dead end: the ear drum. The tympanic membrane is a translucent disc of skin which separates the outer ear from the middle ear, normally forming a perfect seal. Through the otoscope it looks like a piece of clingfilm stretched over a bowl of leftovers. Looming palely behind the membrane is a spindly bone like a chicken leg which hangs down from about the 12 o’clock position. This is the handle of the malleus, the first of the three tiny bones of the middle ear.

It is attached to the inside of the drum, and pulls it in a little, making the outer surface slightly concave. The most concave point, which is attached to the tip of the malleus, is called the umbo.

Just below the umbo – at five o’clock in the right ear and seven o’clock in the left ear, for precisionists – a reliable little dazzle of light appears when you shine the otoscope in. This is called, imaginatively, “the cone of light”. If there’s anything nasty going on in the middle ear, such as an infection, this light reflex may disappear as the drum bulges or reddens and loses its reflectivity.

If enough pus accumulates in the middle ear it can tear the drum and leak out, producing an instant sensation of relief (you can also break your tympanic membrane in other ways – an ambitious cotton bud, a blow to the head, deep-sea diving). A perforation looks like a ragged dark hole in the clingfilm; if it is big enough, the bones of the middle ear may suddenly be nakedly visible, gleaming white in the murk. Like all things made of skin, the tympanic membrane can often heal itself. This is usually all you need to do with a perforation, the registrar explained. “Leave it to mend. It’s not like a broken heart.”

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Sophie Harrison is a hospital doctor in South Yorkshire

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