Toads in the Hole

Embryology: Bane of My Existence (With Apologies to Those Who Are Expecting)

Six weeks have passed since I began medical school, and as far as I can tell, I my grades bob along in the lofty and seldom-visited heights of the 95s. I’m usually more of an A-/B+ man, squeaking by in that exciting and shadowy world where every exam question could stand between me and an A. I also like to bomb the first test, as I can think of no greater spur to keep one’s head in the books than the sharp and pointy prospect of a thirty-point hill that needs climbing.

None of that sort of thing for me, however, as I’ve studied effectively and tested well thus far. It’s still early, however, and my mounting hatred for embryology could, with the high-pitched squeal of rapidly escaping gas, bring my bobbing grades down to a more familiar level.

What’s so hard about embryology? To begin with, the whole field is about an animal that is undergoing change. Every little bit and bob oozes and morphs into something completely different. And let’s emphasize that “animal” thing. The textbooks, the professor, and the diabolical geniuses at Shell Oil all seem to feel the need to emphasize the alienness of the developing fetus. It’s this whole other critter with not one, or two, but at least three different names for every piece of its anatomy as it grows. Where you or I have the usual assortment of protuberances, notches, and foramen, it sports an endless litany of plates, streaks, grooves, pores, pits, buds, cups, membranes, and pouches.

In grown-ups, most of the structures have names that make sense. Apparently in the olden days the trend was to name things after people rather than what they do or where they are. Nowadays the muscle stretching from the styloid process to the hyoid bone is called the “stylohyoid muscle”, not the “melio-elliptical band of Norman”, as it was formerly known. Some these structures, however, are still with us. Those of us who are not on the Atkins diet receive nourishment to the brain through a network of arteries that, if examined from the right angle, look exactly like a winged devil-boy with eight arms. Rather than call this structure “the arterial network of the brain” or even “the bloody devil boy who lives in all our heads” we call it the Circle of Willis.

In embryology, there are a lot more Circles of Willises than stylohyoid muscles. The initial opening in the head which becomes the mouth is not named “the proto-mouth area” or “primitive pie-hole”, it is the stomodeum. Oh, well, I just looked it up, and stomodeum actually does mean “primitive pie-hole” in Greek, so maybe that was a bad example.

Another irritating thing about embryology is how useful it’s supposed to be: A great way to remember that cranial nerve VII is the nerve for muscles of facial expression, is to know that both the nerve and the muscles develop out of the fetus’ second branchial arch! My, that is easy! In order to remember one relationship, I can go out and memorize another! Much simpler than thinking, “Hmm, cranial nerve VII is called the facial nerve. I bet its muscles are… well, not the tongue or the ear….” (The branchial arches, by the by, are so named because “branchy” means “kind of like a gill” in Greek, and the arches are like the gills of fish. Which, in one swell foop emphasizes the alienness of the subject and provides a hard-to-memorize name for a structure that swiftly disappears.)

It’s an important subject, as 6% of Americans are eventually diagnosed with a birth defect. And our fertility rates are dropping, so it might be handy to know how babies get made in case we, you know, have to someday actually make them. So I’ll keep on plugging away at it and cram into my head the “superior sulcus terminales” (Greek for “The line between passing and failing.”)