Funtabulously Frivolous Friday Five 064

OK folks, you’d better really savour this week’s edition of the FFFF.

Why? You ask. Adding, that it goes without saying and that you savour every funtab-filled morsel of frivolousness that we throw up for you every blessed Friday.

Well, because life is currently well and truly in the TOO fast lane, and FFFF is going to go on another little hiatus until things calm down a bit… sometime in November most likely…

Right… time to lock and load — here are five of the best.

Questions

Q1. A patient with a cranial nerve palsy is walking around with his head tilted to the right. Why is he doing this? Which cranial nerve is affected and on which side?

  • Left trochlear nerve palsy (cranial nerve IV).
  • The patient is unable to intort his LEFT eye (i.e. he can’t look down when the eye is adducted, which occurs when he looks to the right).
  • To maintain binocular vision patients with cranial nerve IV palsies tend to tilt their heads to the opposite side to the lesion, so that they do not have to intort the affected eye.

Q2. What is synkinesis?

  • Synkinesis refers to involuntary muscle movements that accompany voluntary ones because of the ‘mis-wiring’ of nerves.
  • Synkinesis may be congenital or acquired. Proposed mechanisms include aberrant nerve regeneration, interneuronal ephaptic transmission, and nuclear hyperexcitability.
  • Below is a video showing synkinesis following a Bell’s palsy. When the patient blinks, the right side of his mouth also moves. The opposite can also occur — involuntary blinking when the patient smiles.

  • The Marcus Gunn jaw winking phenomenon is a congenital synkinesis associated with ptosis. It is also known as trigemino-oculomotor synkinesis and involves the 5th and 3rd cranial nerves. Cranial nerve V triggers pterygoid muscle contraction which opens the jaw, and is associated with pathological stimulation of the oculomotor nerve branch to levator palpebrae superioris which elevates the eyelid on the same side. As the video below shows, when the jaw opens, the ptosed (droopy) eyelid is raised.

Q3. If there are turkey vultures circling overhead and you are not dead, what should you suspect?

  • A nearby gas leak.
  • Some carrion-feeding birds have well developed senses of smell. The turkey vulture is attracted to the deathly stink of mercaptans and other chemicals emanating from dead and decaying bodies.
  • Similar chemicals are emitted from leaking gas pipes. In the 1930s, California gas company repair crews would watch for circling turkey vultures to help detect gas leaks [read more here].

Q4. When people kiss, which way do they generally tilt their heads?

  • To the right.
  • A 2003 study that observed 124 couples kissing in various locations in various countries found that couples were twice as likely to tilt their heads to the right. This study was published in Nature would you believe (see this Nature News article).
  • Güntürkün, O. Adult persistence of head-turning asymmetry. Nature421, 711, (2003). PMID: 12610611

Q5. How accurate are the references listed in articles published in major medical journals?

  • It depends on the journal, but in 2005 it ranged from 4.1% (New Eng J Med) to a whopping 40.3% (Lancet).
From www.thelancet.com (click image for source)
  • Of course, the study this data is from had to be published in the Lancet, and it was (though I haven’t checked its references yet…):
  • Siebers R, Holt S. Accuracy of references in five leading medical journals. Lancet. 2000 Oct 21;356(9239):1445. PMID: 11052618.

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