Archive for the ‘Freezermas’ Category

Freezermas continues! Today we have a treat for you. Lots of detailed anatomy! This post comes from my team’s dissections of an ostrich last week (~3-7 February 2014), which I’ve been tweeting about as part of a larger project called the Open Ostrich.

However, before I go further, it’s as important as ever to note this:

Stomach-Churning Rating: 9/10: bloody pictures of a dissection of a large ostrich follow. Head to toes, it gets messy. Just be glad it wasn’t rotten; I was glad. Not Safe For Lunch!

If the introductory picture below gets the butterflies a-fluttering in your tummy, turn back now! It gets messier. There are tamer pics in my earlier Naked Ostriches post (still, a rating of 6/10 or so for stomach-churning-ness there).

All photo credits  (used with permission) on this post go to palaeoartist Bob Nicholls (please check out his website!), who got to attend and get hands-on experience in extant dinosaur anatomy with my team and Writtle College lecturer Nieky VanVeggel (more from Nieky soon)!

Research Fellow Jeff Rankin, myself and technician/MRes student Kyle Chadwick get to work.

Research Fellow Jeff Rankin, myself and technician/MRes student Kyle Chadwick get to work, removing a wing.

This is a male ostrich, 71.3 kg in body mass, that had gone lame in one foot last summer and, for welfare reasons, we had to put down for a local farmer, then we got the body to study. We took advantage of a bad situation; the animal was better off being humanely put down.

The number for today is 6; six posts left in Freezermas. But I had no idea I’d have a hard time finding a song involving 6, from a concept album. Yet 6 three times over is Slayer’s numerus operandi, and so… The concept album for today is Slayer’s  1986 thematic opus “Reign in Blood” (a pivotal album for speed/death metal). The most appropriate track here is the plodding, pounding, brooding, then savagely furious “Postmortem“, which leads (literally and figuratively, in thunderous fashion) to the madness of the title track, after Tom Araya barks the final verse:

“The waves of blood are rushing near, pounding at the walls of lies

Turning off my sanity, reaching back into my mind

Non-rising body from the grave showing new reality

What I am, what I want, I’m only after death”

I’m not going to try to reword those morbid lyrics into something humorous and fitting the ostrich theme of this post. I’ll stick with a serious tone for now. I like to take these opportunities to provoke thought about the duality of a situation like this. It’s grim stuff; dark and bloody and saturated with our own inner fears of mortality and our disgust at what normally is politely concealed behind the integumentary system’s viscoelastic walls of keratin and collagen.

But it’s also profoundly beautiful stuff– anatomy, even in a gory state like this, has a mesmerizing impact: how intricately the varied parts fit together with each other and with their roles in their environment, or even the richness of hues and multifarous patterns that pervade the dissected form, or the surprising variations within an individual that tell you stories about its life, health or growth. Every dissection is a new journey for an anatomist.

OK I’ve given you enough time to gird yourself; into the Open Ostrich we go! The remainder is a photo-blog exploration of ostrich gross anatomy, from our detailed postmortem.


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Seven dead old limbs
Seven science wins
Seven icy forms beheld
And our trip begins

Seven anat’my jokes
Seven bloody posts
Seven are our sci-comm fires
Seven frozen choirs…

(props to Iron Maiden’s “Moonchild” opening lyrics, from the iconic “Seventh Son of a Seventh Son” concept album, of lofty, epic, frozen, anatomy-bearing motifs)

7th Son

So we come full circle to another Freezermas, another foolhardy attempt to honour Charles Darwin (his birthday is Weds 12th Feb) with seven blog posts in seven days!

There will be mysterious morphology! Expositions of new projects and a new paper! Detailed dissections showing amazing anatomy! Silly songs and other nonsense! So much more that I have no idea about at this writing but will surely come to me! (there is an amorphous plan)

Last year I invoked the 7 days of Freezermas song, but this year the songcraft has changed. Christmas is so 2013! Time for a 1970smodern approach! We’re doing hard rock/heavy metal concept album songs and motifs each day. I started off with one above. Future posts will try to stick to a theme of songs/albums featuring numbers, counting down from seven. Because we all know that Darwin loved to rock. But let’s get on with the real rockin’: the freezer-based anatomical science!

Today we’ll ease you in to Freezermas: The Concept Album, like the acoustic intro of Moonchild did, with some simple Mystery CT Anatomy…

(insert guitar solo here while you mentally prepare yourself)

Stomach-Churning Rating: 2/10; simple CT scan of a body.

Mystery Anatomy 2014: same rules as before; remember that the scoreboard has been reset.

Identify the animal in the CT scout/pilot image below, as specifically as you can. 

Today’s special rule: Your answer must be in the form of a lyric (at least 2 lines) from a song by Queen (Google some if you’re unfamiliar– but how?).

Why Queen? One should never question Queen; not a little or a lot.

Difficulty: Is this the real life? Is this just fantasy?

You will probably want to click to emgiganticate the image below.

Mystery CT 11

Don’t let this one drive you Stone Cold Crazy! I know you’re feeling Under Pressure; just Tie Your Mother Down and play The Game.

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…a daily picture of anatomy! And today the pictures are a mysteryyyyyyy! ♫

Welcome back againagain, and again (gasp, pant)– and again (exhausted howl)… and… aaaaaagaiiiiin… to Freezermas

This is the end. I’ve worked hard all week to bring you all-new content for Freezermas, and on the Seventh Day I get drunk rest— and make you do the work! Off into the hoary wilderness you go, seeking answers to eternal trivial mysteries.

Seven mystery photos of museum specimens today, each from a different museum (or other institution whose role it is to display critters, in 2/7 cases) and animal! I’ve visited all these facilities and taken these photos myself. Which specimens can you identify, and (ultra difficult) can you identify the institution it’s from?

Stomach-Churning Rating: 2/10. Super tame.

You had some impromptu practice on day 2. Very well, then. This session counts for points. If you want a recap of points, see last Mystery Dissection.

But because the pictures are small and numerous (refer to them by number 1-7, please), the points/correct answer are simplified: 2 pts for correct answer, and maybe 1 bonus pt for something clever but incorrect, 0 pts here just for shooting the breeze (“Superhuman effort isn’t worth a damn unless it achieves results.”–Ernest Shackleton), plus 1 pt extra credit if you correctly ID the museum/institution. Being first does not matter here. Just being correct. With 7 mysteries, you can freeze up a lot of points here! But…

Difficulty: Cropping. Lots of cropping. And therefore quite pixellated if you zoom in much; don’t even bother clicking to embigitate. However, there may or may not be themes between some pictures, or critical clues. They are identifiable.

Off you venture, brave Freezerinos! Wear multiple layers.

1) Freezermas7-1 2) Freezermas7-2

3) Freezermas7-3

4) Freezermas7-4 

5)Freezermas7-5 6)Freezermas7-6


But wait– there is a mystery eighth specimen, which even I am not completely sure what it is! No points for figuring it out, but mucho respect!



Happy Freezermas! One last time– sing it: “On the seventh day of Freezermas, this blo-og gave to me: one tibiotarsustwo silly Darwinsthree muscle layersfour gory heartsfive doggie models, six mangled pangl’ins a-aaaaaaand seven specimens that are mysteries!” ♪

I hope you enjoyed Freezermas. Let’s hope we’re all thawed out in time for the next one.

CLUES/ANSWERS: Click these thumbnails to embigrinate them if you need help–

snapperpareiasaurs frogfish  Sclerocephalus  Suedinosauroidaardvarks

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…a daily picture of anatomy! And today it is five pictures; zza-zza-zee! ♫

Welcome back againagain, (gasp, pant) and again to Freezermas

I’m letting the dogs out today. Science gone barking mad! Hopefully my puns will not screw the pooch.

Stomach-Churning Rating: 4/10; a dog cadaver’s leg (not messy), then just tame digital images of anatomy.

I am working with Rich Ellis, a former MSc student at Univ. Colorado (see his cool new paper here!), for a fun new collaboration this year. He was awarded a prestigious Whitaker Foundation scholarship to do this research, which focuses on how different animals stand up from a squatting position, with the legs about as bent as they can be.

We want to know how animals do this standing up movement, because it is in some ways a very demanding activity. Very flexed/bent limb joints mean that the muscles (and some tendons) are stretched about as far as they ever will be. So this places them at disadvantageous lengths (and leverage, or mechanical advantage) for producing force. We know almost nothing about how any animal, even humans, does this-– how close to their limits of length are their muscles? Which muscles are closest? Does this change in animals with different numbers of legs, postures, anatomy, size, etc? Such fundamental questions are totally unaddressed. It’s an exciting area to blaze a new trail in, as Rich is doing. So far, we’ve worked with quail, humans, and now greyhounds; in the past I did some simple studies with horses and elephants, too. Jeff Rankin from my team and other collaborators have also worked on six species of birds, of varying sizes, to see how their squat-stand mechanics change.  Thus we’ve covered a wide diversity of animals, and now we’re learning from that diversity. “Diversity enables discovery,” one of my former PhD mentors Prof. Bob Full always says. Too true.

Greyhounds are interesting because they are medium-sized, long-legged, quadrupedal, quite erect in posture, and very specialized for fast running. Fast runners tend to have big muscles with fairly short fibres. Short fibres are bad for moving the joints through very large ranges of motion. So how does a greyhound stand up? Obviously they can do it, but they might have some interesting strategies for doing so- the demands for large joint motion may require a compromise with the demands for fast running. Or maybe the two demands actually can both be optimized without conflict. We don’t know. But we’re going to find out, and then we’ll see how greyhounds compare with other animals.

To find out, we first have to measure some dogs standing up. We’ve done that for about 8 greyhounds. Here is an example of a cooperative pooch:

Those harmless experiments, if you follow me on Twitter, were live-tweeted under the hashtag #StandSpotStand… I dropped the ball there and didn’t continue the tweeting long after data collection, but we got the point across– it’s fun science addressing useful questions. Anyway, the experiments went well, thanks to cooperative pooches like the one above, and Rich has analyzed most of the data.

Now the next step involves the cadaver of a dog. We could anaesthetize our subjects and do this next procedure to obtain subject-specific anatomy. But it really wouldn’t be ethically justified (and if I were an owner I wouldn’t allow it either!) and so we don’t. A greyhound is a greyhound as far as we’re concerned; they’ll be more like each other than either is like a quail or a human. Individual variation is a whole other subject, and there are published data on this that we can compare with.

We get a dead dog’s leg — we don’t kill them; we get cadavers and re-use them:

Greyhound hindlimb for CT

We study the hindlimb because birds and humans don’t use their forelimbs much to stand up normally, so this makes comparisons simpler. We’re collecting forelimb data, though, as we work with quadrupeds, for a rainy day.

We then CT scan the leg, getting a stack of slices like this– see what you can identify here:

It’s not so clear in these images, but I was impressed to see that the muscles showed up very clearly with this leg. That was doggone cool! Perhaps some combination of formalin preservation, fresh condition, and freezing made the CT images clearer than I am used to. Anyway, this turned out to be a treat for our research, as follows.

We then use commercial software (we like Mimics; others use Amira or other packages) to “segment” (make digital representations in 3D) the CT scan data into 3D anatomy, partitioning the greyscale CT images into coloured individual objects– two views of one part of the thigh are shown below.

What can you identify as different colours here? There are lots of clues in the images (click to embiggen):

Hindlimb segmentation of greyhound

And here is what the whole thigh looks like when you switch to the 3D imaging view:

Quite fetching image, eh?!

The next steps after we finish the limb segmentation are to apply the experimental data we observed for greyhounds of comparable size by importing the model and those data into biomechanics software (SIMM/OpenSim). We’ve done about 40 models like this for various species. I detailed this procedure for an elephant here.

Then, at long last, science will know how a greyhound stands up! Wahoo! Waise the woof! Stay tuned as we hound you with more progress on this research-as-it-happens. Rich just finished the above thigh model this week, and the rest of the leg will be done soon.

Many thanks to Rich Ellis for providing images used here. And thank you for persevering my puns; they will now be cur tailed.

Happy Freezermas! Sing it: “On the fifth day of Freezermas, this blo-og gave to me: one tibiotarsus, two silly Darwins, three muscle layers, four gory hearts, a-and five stages modelling a doggie!” ♪

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…a daily picture of anatomy! And today it is four pictures; da-da-dee! ♫

Welcome back again, again to Freezermas! 

Today I’m shimmying down your interwebz with a late delivery. I’ve promised before to show how we clean up our nasty gooey skeletons to preserve them for future research to use. This is the intended final destination of all critters that are tenants of my freezers– the freezer is just a lovely holiday home, but bony heaven is the end result. I’ve accumulated a little museum of the bones of exotic animals I’ve studied, using these cleaned specimens. Here is how I do that preservation– there are four basic steps, and I’ll show them in four photos.

Stomach-Churning Rating: 8/10; first just dry bones, but then some gooey bones and by the end we ratchet it up to bloody organs.

Step 1) We get the deceased animal from various zoos and other EU sources, CT/MRI scan it, and dissect it. That’s what most of this blog focuses on, so I won’t show that. But I will show the end result, and then how I get to that:


Those are some elephant and rhino bones, some of which you saw on the 2nd day of Freezermas. Elephant bones are super greasy; it’s almost impossible to get rid of that brown grease visible in this photo (upper LH side) without making the bones brittle and over-bleached. The bones of the whiter white rhino on the right show what I’m usually aiming for. How do I get this done? Well, here’s an example for an elephant shank:

Cookin' up elephant shank

I take the elephant shank and make soup.  (above) An Asian elephant’s patella, tibia and fibula were dissected, frozen for many years (queued up for cleaning; much freezer burn occurred on this specimen— it was jerky-fied), and then thawed. I put large specimens in this Rose cooker unit, which is a big ham cooker with a heater unit at the bottom. My baby, a Rapidaire MKV 5-ham unit is shown; oooh, ahhh!

The Rose cooker is filled up with tap water and been set it at around 60-90C. Then I let it cook away! A brothy soup develops, and sometimes it smells rather nice (my favourite aroma is giraffe leg). Sometimes… it’s not so nice. We check it every few hours to top up the water and remove stray tissue, and then change the water every day or so.

An elephant shank like this will take 2-3 days of cooking, longer if only switched on during work hours. The key thing is not to let it cook dry, which happened once with a faulty Rose cooker that did not do its normal auto-shutoff when the water ran low… showing up to work to encounter some fire trucks and unhappy college Health & Safety rep is not a good way to start your day, trust me!

This step is only slightly different for smaller (<30cm) specimens. Rather than the Rose cooker, we use the lovingly named “Croc Crock”, which isn’t visually impressive but you can see it here. As the name indicates, we’ve mainly used it for small crocodiles, and it is a crock pot. (a helpful thing is to add some detergent to the water for these small specimens; then bleaching isn’t so necessary)

Step 2) Then I empty out the water through the bottom spout, do the very nasty job of cleaning out the fat and other tissue that has accumulated (think 20 gallons of goo), hose off the bone, and set it in a ~10% bleach solution for at least a day, or up to a week or so for an elephant bone. Once it’s cleared up, I leave it out to dry (for big elephant bones, copious amounts of grease may be emerging for a few weeks). And then…

Elephant shank bones

Step 3) I varnish the dry bones with a clear varnish, and let them dry. Here is how that elephant shank turned out. Pretty good! Finally, they get to join their friends:

The bone shelves

Step 4) The prepared bones are labelled, given a number/name that I file in a world class comprehensive electronic database (cough, get on that John, cough!), and they become part of my humble mini-museum, shown above. Voila! The chef’s job is finished. Let science be served!

Happy Freezermas! Sing it: “On the fourth day of Freezermas, this blo-og gave to me: one tibiotarsus, two Darwin pictures, three muscle layers, a-a-and four steps of bone cookery!” ♪

Oh it’s Valentine’s day, so, err, have a heart today. Have four, actually!

giraffe heart - 1 white-rhino-heart-Perez Windfall-ele 054


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…a daily picture of anatomy! And today it is three pictures, scoob-a-dee!

Welcome back again to Freezermas! 

For the previous days of Freezermas we first had 1 picture, then 2, now guess how many we have today? Right, we’ve settled into a groove and have three (plus one silly one). Today is fresh beefy anatomy day! No focus on bones, but on soft tissues– however, once again, I’m representin’ bird legs! And this time, no mystery things to identify; sorry. But if you want to muscle in on some myology, today is the day for you. I will unwrap the thigh of an ostrich and consider the major muscles that power rapid running in this biped, and how they illuminate the evolution of bipedal motion along the line of descent to birds. For more ostrich escapades, see this old post. And we’re off!

Stomach-Churning Rating: 7/10; plenty of fresh, red, meaty meat from ostrich leg muscles.

Ostrich thigh muscles 1

Here you are looking at a right hindlimb of an ostrich, in side/lateral view. To help orient yourself, the hip lies deep in the middle of the image and the knee is the rounded bump near the bottom right corner, with the shank angling sharply back toward the bottom left.

I’ve labelled six muscles in yellow. As usual for sauropsid (bird/reptile) pelvic limb muscles, they have sensible names that reflect their attachments. They don’t have so many silly old mammalian names like pectineus or latissimus, which tell you rather little about the muscles themselves. We can thank 19th century anatomists like two of my anatomist heroes, Hans Gadow and Alfred Romer (who refined Gadow’s earlier work and made it more popular among English-speakers and palaeontologists), for that enlightened nomenclature.

The six muscles seen above are the IC (iliotibialis cranialis), IL (iliotibialis lateralis), “AMB2?” (one of the ambiens muscles– correctly identified; ignore the ?), ITC (iliotrochantericus caudalis), CFP (caudofemoralis pars pelvica) and FCLP (a mouthful to say: flexor cruris lateralis pars pelvica). The ambiens is the one oddly, non-anatomically named muscle, and has nothing to do with helping you sleep (pssst– wake up! Muscles are exciting!), but everything to do with the state of total awesomeness, which is what “ambiens” means. Maybe. Or I am making shit up.

Amazed ostrich

The IC, IL and AMB2 are parts of the triceps femoris group (discussed in my 1st Freeezermas post), or for mammal fans the quadriceps. The IC and AMB are in front of the hip so they flex it (move the thigh forward; protract it); the IL is right around the hip so it can flex or extend the hip (protract/retract the femur); all three of these can extend (straighten) the knee joint to varying degrees. The IC is fairly typical for a bird except for its size, and helps to quickly swing the leg through the air between steps. Some birds have multiple parts of the IL, but ostriches and many others have simplified it to one major mass; regardless, it is a major muscle used to support the weight of the body.

The AMB2 is a remarkable muscle unique to ostriches; it can also be called the dorsal ambiens muscle. Typical birds just have a single head of the AMB sitting on the preacetabular (pubic) tubercle, so in front of and below the hip. It has a crazy tendon that snakes past the knee (in some birds, perforating/grooving the patella) into the lower leg muscles and may be able to even pull on the toes. But ostriches, for some reason, added a second head of this muscle that was shifted way up onto the front of the pelvis (the ilium; dorsal bladelike bone). Crocodilians also have a 2nd ambiens muscle but in a different position, and almost certainly as an example of convergent evolution. The function of the ambiens is mysterious, but this muscle has featured prominently in avian systematics/taxonomy, evolution (invoked as a key muscle used in perching) and more.

These muscles of the triceps femoris group are easily identifiable in crocodiles and other reptiles because they are remarkably similar in their attachments. The main changes these muscles experienced during the evolution of bipedalism, dinosaurs and later birds are simply proportional– they got bigger, with stronger, larger attachments on the pelvis and the front of the knee (the CC/LC, if you remember from Freezermas day 1).

The ITC is a muscle that is very dear to me. I’ve written a lot about it, and I love saying the name “Iliotrochantericus caudalis”- it is musical to me. For mammal fans, think gluteal muscles (medial gluteal in particular). It is a huge, pennate muscle (short and strongly angled muscle fibres in a “sandwich” with a tendinous sheet between the two layers of fibres). It has a short, broad tendon that wraps around the trochanteric crest (a structure on the upper front end of the femur with a history that goes wayyyy back into dinosaurs; long story!) to insert in a scarred depression. The ITC seems to mainly rotate the femur around its long axis to help support the body. I could go on and on about this muscle, which is part of the enigmatic “deep dorsal” thigh muscle group — the homologies of this group among land vertebrates are still controversial and confusing. But I will spare you the on-and-on. Incidentally, the ITC  is the “oyster” in birds that is the best cut of meat. And in ostriches it makes a massive steak.

The CFP also has a cool evolutionary history. It runs from the back of the pelvis to the middle of the femur, closely adjoined to the caudal head of the muscle (CFC), which is more vestigial. In birds the CFP is usually not a large muscle, but in other sauropsids/reptiles it can be fairly hefty, although almost never as hefty as its more famous counterpart the caudofemoralis longus (= CFC in birds). Probably any dinosaur specialist is familiar with its origin and its insertion: respectively, the “brevis fossa” on the back of the ilium; a big shelf of bone; and the fourth trochanter of the femur; a crest of bone that is reduced to a scar/tubercle in birds. Much like its tail-based counterpart, the CFP became progressively reduced closer and closer to birds. This is related to a reduction in the amount of movement of the femur/thigh during locomotion, as birds shortened their tails and shifted their balance forward, as Steve Gatesy showed in a classic 1990 paper. Hopefully there will be more about this subject in a future paper from my team…

The FCLP is another muscle that didn’t change much, except by getting larger as we trace its evolution from early reptiles to birds. It is a “hamstring” muscle that is an important power source during locomotion in birds like the ostrich, because it retracts the lower limb (flexes the knee; hence flexor cruris in its name) as well as the femur/thigh (extends the hip). Your semitendinosus muscle is a good comparison to it. Indeed, these two differently named muscles are homologous– our very distant tetrapod ancestor had the same single muscle, and its descendants didn’t change it that much on our lineage or on the avian/reptile one.

Ostrich thigh muscles 3

I’ve reflected the IL muscle out of the way so we can see the second layer of muscles underneath it. Now we see two more muscles of the thigh, and large ones at that– the FMTL (femorotibialis lateralis) and ILFB (iliofibularis).

The FMTL simply is a part of the triceps femoris group that only comes from the femur and hence only, but due to its large size powerfully, straightens the knee. Unlike the other muscles in this group, it has no action about the hip joint. It is very similar to your vastus lateralis muscle: its fleshy origin dominates the surface of the femur (thigh bone). There are two other parts of that muscle, hidden in this figure, much like our vastus group has multiple parts. Again, this is a muscle that enlarged on the lineage leading to modern birds.

And that evolutionary enlargement applies, too, to the ILFB, whose prominent insertion I discussed on day 1 of Freezermas. This huge “biceps” muscle (it is single-headed unlike in humans, so the name “biceps” does not apply well) is the most powerful of the “hamstring”-type muscles that extend the hip and flex the knee. Therefore it is important for the “knee-driven” locomotion of birds. And hence the ILFB enlarged during avian evolution– which is very evident from changes of both its bony origin on the back of the pelvis/ilium and its insertion on the fibula.

Ostrich thigh muscles 2

Here, for the terminus of today’s trio of struthious tributes and tribulations, I’ve moved the ILFB  out of the way so you can see the various inner/medial layer of thigh muscles. Some of the former muscles are more exposed now, and we can see three new ones: the FCM (flexor cruris medialis), PIFM+(PIF)L (the tongue-twisting puboischiofemoralis medialis et lateralis), and tiny ISF (ischiofemoralis).

The FCM (~mammalian semitendinosus) is merely another, smaller part of the FCLP’s “hamstring” group, and its thin tendon blends with that of the FCLP, so it very much works with that muscle in locomotion, and has a similar evolutionary history.

The PIFM+L are “adductors”, but in birds they don’t really do any adduction (drawing the legs inwards) because they are right behind, rather than below or inside, the hip. They act as hip extensors/retractors of the femur, and probably aid more in holding the femur steady (“postural muscles”) than playing a major role in producing power for locomotion like the ILFB/hamstring group does. In earlier reptiles, they were much more important, for preventing the legs from splaying too far away from the body.

The ISF is usually quite a large muscle in birds, but ostriches and some other ratites have reduced it to a thin slip of muscle– often mistaken for other muscles (indeed, like a few other muscles I’ve described here, modern anatomists still get confused by this muscle– an otherwise superb recent description by Gangl et al., among others, mis-identifies this and some other muscles— an error an upcoming paper from my group will rectify). Normally the ISF sits atop a bone-free window on the outer surface of the pelvis, the ilio-ischiadic fenestra (literally a window in Latin) in birds; in ostriches it has moved more onto the ischium. In contrast, in other sauropsids it lies inside the pelvis, so during its evolution it became more lateral, but the insertion on the upper femur was maintained. It is a weak rotator and extensor of the hip, especially in ostriches in which its role is probably proportionately puny.

And there you have read a healthy chunk of my 2001 PhD thesis, condensed into less jargonious language. You might now know almost half of the key muscles of the avian hind limb. If you made it this far, you are one awesome anatomical enthusiast. If you eat meat, apply this lesson to the next chicken thigh you consume, to consumate this enthusiasm.

A broader point I’d like to make here is that anatomy is best conveyed not only along with the functional narrative (How does anatomy work?) but also the evolutionary tale (Where did anatomy come from and What were the consequences of its changes? Why did it change?). This takes it away from dry memorization of terms and locations, and carries it into the realm of explaining why nature is the way it is, and how every organism’s biology has a richly detailed and complex background. This style portrays nature as much more like that tangled bank that Darwin so enchantingly envisioned. I’ve tried to do that justice here, using this one ostrich whom we affectionately called Twinkletoes, or Twinkie, when we dissected it back in 2002.

Happy Freezermas! Sing it: “On the third day of Freezermas, this blo-og gave to me: one tibiotarsus, two silly pictures, a-and three muscle layers from Twinkie!”

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…a daily picture of anatomy! And today it is two pictures, tra-la-lee!

Welcome back to Freezermas! And HAPPY DARWIN DAY! Last year our whole lab got involved in DD2012, but this blog was just a twinkling in my keyboard back then. This year it was a more mellow, somber occasion for DD2013. But Heinrich Mallison of the dinosaurpalaeo blog took part, and took photos (all credits go to him), and the result kicked ass and took names. Bring it on!

Darwin amidst the bones

Here is Darwin amidst a selection of greatest hits from my bone collection; post-freezer denizens. How many can you identify? Have a go in the comments below. A few should be quite familiar to blog followers… More about these bones later this week. Incidentally, Darwin is standing on a Kistler forceplate. So biomechanics afficionados can geek out about this, too.

An offering to The Master

And here I am hamming it up again. Give it a rest, John! But ’tis merely a humble offering to The Master. I’m sure he’d appreciate it. Any guesses what it is?

Happy Freezermas! Sing it: “On the second day of Freezermas, this blo-og gave to me: one tibiotarsus, a-and two silly pictures with Chucky D!”

(don’t know the song? Try this version)

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…a daily picture of anatomy!

Welcome to Freezermas! In the dead of winter, the WIJF blog jumps down your internet to deliver mind-warming science, and images, and evolution! To celebrate Charles Darwin’s birthday (204th = tomorrow Feb 12, 2013), I’m bringing you one Anatomy Vignette each day this week (we’ll see if I can manage the weekend or not)! Let’s do this!

Stomach-Churning Rating: 2/10; just bones; one picture of them, and then a lot of discussion of muscle anatomy but no pictures of it.


The above image comes from one of my old, somewhat obscure anatomy papers (link to pdf here), from 2003. It’s possibly the first figure I made, entirely by myself, that I’m sort of proud of. It doesn’t totally suck compared with some of my other attempts. I did the stippled line drawing on the left, and on the right is one of my first usages of a digital photo in a paper (digital cameras were finally up to the task around that time; I used my new Nikon Coolpix 900, if memory serves). It was a greatly improved figure over what I’d submitted for this paper originally, which was a rushed, half-baked manuscript for a SICB conference symposium on tendons. I’ll never forget one of the peer reviews of the manuscript, which said something like “the text of this paper is a joy to behold, but the figures are a horror.” They were right, and luckily the images in the paper I submitted changed a lot in revision. (I’m still embarrassed by the incident, though!)

Anyway, the picture is of  the lower hind limb of two theropod dinosaurs: (a,c) an adult Tyrannosaurus rex, and (b,d) a wild turkey (Meleagris) from my personal collections of dissected-then-skeletonized animals (this turkey became a biomechanical model in a 2004 paper of mine, too!).  In both cases we’re looking at a right hind limb; in (a) and (b) from a caudal/posterior/rear view, and in (c) and (d) from a lateral/side-on/profile view.

If you’re having trouble visualizing these bones in the real animal, check this T. rex skeleton in rear and side views and try to find these bones. You can do it! You might also want to look back at my paroxysmic outburst of love for knee joint anatomy.

The thicker long bone is the tibia (your main shank bone; or in a lamb shank, chicken drumstick, etc); the thinner outer bone is the fibula. Together with some smaller bones, for brevity we can call them the tibiotarsus — but only in theropod dinosaurs, or you will anger the freezer gods.

The labels show some cool anatomical features, as follows:

CC” the cranial cnemial crest of the tibia (a projection of bone unique to the knees of birds);

CF” the crista fibularis; or fibular crest; of the tibia (more about this below);

FT” the fibular tubercle (insertion of the big hamstring/biceps muscle M. iliofibularis);

LC” the lateral cnemial crest of the tibia (a big arching swath of bone that both birds and non-avian theropods like Tyrannosaurus have; the CC is just pasted on top of this in birds); and

MF” which denotes a muscle fossa (depression) on the inner surface of the upper end of the fibula, which presumably housed a muscle (M. popliteus) binding the fibula to the tibia in earlier dinosaurs, but is vestigial in birds.

The CF, or fibular crest, is a feature that only theropod dinosaurs, among reptiles, develop like this. It evolved early in their history and thus was passed on to birds with other ancient features like hollow bones and bipedalism. It binds the fibula closely appressed to the tibia, making those bones act more like a single functional unit –and sometimes they even fuse together. The CF also transmits forces from the whopping big M. iliofibularis muscle’s insertion (the FT label) across the puny fibula onto the robust tibia. The MF once held a muscle that also helped keep those two bones together, but additionally it could have contracted to move them relative to each other a little bit, as in other living animals (many mammals and reptiles have a big M. popliteus and/or M. interosse[o]us). So these features all have a common functional, anatomical and evolutionary (and developmental; different story for evo-devo fans) relationship. By binding the fibula and tibia together, these structures helped early bipeds (the first theropods and kin) support themselves on one leg at a time during standing and moving, and also helped begin to reduce the limbs to lighten them for easier, faster swinging. So we can think of these features as specializations that helped theropod dinosaurs, and ultimately birds, get established as bipedal animals.

The CC and LC have a similar story to tell; for one, they are muscle attachments, again mainly for thigh muscles. And again, the LC dates back to early theropods (and some other dinosaurs had a version of it; usually smaller). These crests serve mainly as insertions for the “quadriceps” (in human/mammal terms) or triceps (in reptile/bird terms) muscle group’s major tendon, spanning from the pelvis/femur across the thigh and knee to this region. In birds, we call this structure of insertion the patellar tendon or (less appropriately) ligament. But dinosaurs had no patella, ever, so the triceps femoris tendon would be the proper technical term. Regardless, that crest (LC, and later LC too) helped the attached muscles to straighten the knee joint or support body weight during standing/moving, by giving them better leverage. So it would have been important for early bipeds, too, like the CF, MF and other features above. Your cnemial crest (tibial tuberosity) is pathetic by comparison. Don’t even look at it. Droop your knees in primate shame!

Bumps and squiggles on bones might seem puny details just for anatomists to study and describe in long, tedious monographs, but each is part of the great story of evolution, and each has a story to tell that fits into that story. Back in Darwin’s day, some of the world’s greatest scientists of the age (Richard Owen and Thomas Huxley being but two spectacular examples) pored over these seemingly innocuous features, and so they became part of nascent evolutionary theory even then. This week, I’ll be celebrating a lot of those details, which I still feel are important today, and the stories they help to tell.

Happy Freezermas! Sing it: “On the first day of Freezermas, this blo-og gave to me: a tibiotarsus with a CF and FT!”

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