For those who have not seen it (and are not squeamish about a horse being dissected), the Inside Nature's Giants series did a spectacular episode some time ago on the racehorse. This is indeed a very insightful, scientific look into what makes the modern domestic horse (not just racehorses) the extreme biomechanical machines they are. Fascinating.
I did several equine necropsies in school. Two were on freshly euthanized horses (terminal illness and irrecoverable lameness), and one was a freeze dried specimen (admittedly not nearly as interesting as the freshly deceased ones). I also dissected many (I quite literally forget how many) speciments of legs, hearts, lungs, etc in our anatomy lecture. Suffice it to say, anatomy was my favorite class. Ever.
It helps to know that the horse is dead and gone, and not feeling any pain. I have no problem grabbing a knife and jumping in, as horrible as that might sound to other horse enthusiasts. I even assisted the local hunt one day, in taking apart a pony that had recently come to the end and been donated and euthanized (via gunshot) for the hounds to feed from. I happened to be there waiting on someone, the staff needed a hand, and what the hell...give me the knife and step aside. I'll take that front leg off at the scapula in about ten swipes. Here you go, Fido.
(THAT SOUNDS HORRIFIC I KNOW... but it is kind of fun.)
Bottom line, if you can handle it, watch this video. It's fascinating. Like, I wish I was there helping kind of fascinating. It gives you a great look at the unique anatomy and structures of the horse's body, and how they perform. It gives you a great appreciation for the horse's strength, and the fine line they walk between that strength and fragility.