Veterinary Anatomy: Directions and Body Plans
Hello one and all, welcome to my first revision blog post! I really like writing things out in order to remember them, so writing a blog post about lectures with lots to learn makes a lot of sense to me. Plus, anatomy is fascinating, who wouldn't want to know this?
We had lecture one of our VAP (veterinary anatomy and physiology) module today, which ran through the weird and wonderful terminology that vets use when talking about anatomy. We couldn't do it like human anatomy though, so everything I knew because of mum is completely useless (unless you're talking about the eye, that gets a bit weird!) I should also just preface this with the fact that I'm a first year student who has had all of one lecture on anatomy - please don't assume this is a reliable source to quote on national news. Anyway, onto the weird and wonderful world of anatomy...
The very basic 'directions' involve looking at an animal side on. As you can see by the lovely diagram I've made (why didn't I take graphics A-Level??) there are some really fancy terms here. But basically: dorsal means towards the back, whereas ventral means towards the belly. Caudal means towards the arse, whereas cranial means towards the head (fairly obvious there!) The bit where it gets weird is the head, because you can't exactly say the head is 'cranial' because you'd essentially be saying 'the head is towards the head' which makes no sense. So instead, we use 'rostral', which means we refer to the head region in general.
Unfortunately, like all good things, these terms don't apply once you've gone past the 'knee' (it's not called a knee, but that part was a bit complicated for first years apparently so we're waiting to learn that bit). So instead, we have 'dorsal', which means towards the front of a leg for both the fore and hind limbs, but we then have 'palmar' and 'plantar'. Palmar means towards the back of the forelimb, and plantar means towards the back of the hind limb. No, I don't know why they don't use the same thing like they do with dorsal, it doesn't make sense to me either.
Again, these terms don't apply to embryos either. Which makes sense to be fair: embryos don't really have much of a head or bum. So instead, we use 'cephallic' (I keep thinking this means towards the bum for obvious reasons, so I'm having to train my brain) and 'caudal'. (the diagram below says dorsal, I don't know why I've done that, feel free to ignore it.)
Next up we've got this beautiful sheep to demonstrate the idea of 'planes'. You've got to do a bit of imagining here, and pretend he's facing head on towards us instead of the awkward angle he's chosen. It was the only image with a creative commons license, give me a break.
Anyway, the medial plane refers to splitting the animal straight down the middle (again, imagine it was going straight down the head and body), and the sagittal plane means a plane that's parallel but slightly off centre.
We also have the 'axis' which means splitting the animal down its limb between the third and fourth digits (like Mr Spock on the left here, which I think's a pretty good way of remembering it). Unfortunately this doesn't work for horses (screw them and their massive hoof).
As a result of the axis line, we then have the terms 'axial' and 'abaxial', which basically mean something on the axis, or something to the left or right of the axis plane.
Finally, we've got 'proximal' and 'distal' on the limbs, which essentially just mean towards the top and bottom of the limb. Sadly, veterinary anatomists seem to dislike it when you use normal terms to refer to things, so it means we get these random words of direction that absolutely no sane person ever uses in casual conversation. Actually, if I ever get an owner that refers to a problem with the distal end of their dog's limb, I might actually think the world's ending!
There are other planes too, as evidenced by my beautiful dog on the right. There's the dorsal plane which runs straight across the middle (easy to remember as you'll recall from earlier that 'dorsal' means towards the back), and then the transverse plane which is perpendicular. In terms of the cat on the left, those lines refer to superficial (which is not really where I've put the line because it just means under the skins surface or there abouts) and deep (profundus), which apparently is just a fancy way of saying 'really far under'. Honeslty I reckon I could save these anatomists some time by simplifying the way they talk.
Here's where it gets confusing. Because oh look, humans, the very species I went into veterinary medicine to avoid having to treat have appeared! Except, they're very annoying any use weird words that we don't use in vet med, but actually seem to make more sense than the ones we do use. We get our own back by nicking 'anterior' and 'posterior' off them though, and we use it to refer to the eye. Posterior in this sense means towards the back, towards the retina, and anterior means towards the front, or the iris.
The mouth is just whacky, but really we never use these terms as vets. Unless you're an equine dentist or something equally as niche in the dental world. If you look at my rather hasty diagram, the blue semi circle represents the jaw, and the black square a tooth.
If we're referring to the back of the mouth we say distal, and the front is mesial. Towards the tongue it's lingual, and towards the outside of the jaw it's vestibular, or buccal, which for those of you who did A-Level biology will remember from a fish's buccal cavity. If you're talking about the tooth's surface, it's the occlusal surface.
And finally, just because I thought it was interesting. These are the regions of a dog. The thorax contains the heart, lungs, and the blue line between that and the abdomen represents the diaphragm - side note, we did a dissection of a fetal pig and saw this in real life, and it's a lot thinner than you might think.
In the abdomen we have a million things packed together. There's the tiny strip of spleen that looks like nothing but is incredibly long in pigs, the large and small intestines including the secum that joins them, the bladder, liver, kidneys, and stomach. There's also other bits in other places, but those are the main bits.
And that's everything we learned in our first lecture! It was so much information chucked at us and this is hardly the beginning, but I do feel like I've gotten better with them now that I've done diagrams and written a blog post! I'm moving on to doing a post about some histology stuff we've done after this, and scheduling that for later in the week, so hopefully these become useful for revision and updating you with what we do in lectures!
Random footnote I felt like adding: fetal pigs are encase in two membranes in the uterus, one's red and one's transparent. They also have soft bits on their hooves known as 'hoof slippers' so that they don't damage the membranes whilst in utero!