Cool Vetmed facts

Last week I learned 2 things that are so amazing, I'm STILL having trouble wrapping my mind around them.

Fascinating fact #1 - the forelimb of most of our pets (horses, dogs, cats etc.) is not attached to the body by a joint - it is held in place by muscles.

I guess I technically knew this, but I probably memorized joints and muscles without every REALLY internalizing this fact or really KNOWING it (the difference between traditional curriculum and this new style - at least for my learning style).  I haven't been able to get this concept out of my mind and I've been bringing it up in casual conversation because I find it so fascinating. 

Dogs in Motion - my new favorite book that happens to be a book recommended in this block for dog locomotion, gaits, and associated anatomy - does an especially good job of helping the reader visualize how the scapula is suspended against the body, but as I have the book out on loan to my mom, here's some images from the 'net and another one of my text books, Textbook of Veterinary Anatomy.

See links below to check out the books mentioned in the post.

*I will be doing a review of dogs in motion - it's not just a text book, it's not just a coffee table book.  Somehow art and science came together in a way to create a book I can't put down and can't get out of my mind.  Well worth every cent.  

The figure below is the front of a dog, looking into the rib cage with the front legs on either side.
Figure 2-54 Muscular suspension of the thorax between the forelimbs (dog). 1, Scapula; 2, humerus; 3, radius and ulna; 4, sternum; 5, pectoralis profundus (ascendens); 6, serratus ventralis; 7, trapezius; 8, rhomboideus.


(Dyce et al, K. M.. Textbook of Veterinary Anatomy, 4th Edition. W.B. Saunders Company, 122009.).


Do you see that??????? The forelimb is just hanging there!!!!!!  It's the same in horses too!!!!!  AMAZING.

On to amazing fact #2.

Horses' hind legs are are structured (with tendons and ligaments) in such a way that the stifle (equivalent to our knee) HAS to move in concert with the hock!  If the stifle flexes, the hock must flex to and vice versa.

I think this is why beginners have a hard time picking up hind feet - the mechanics of the hind leg feel strange and stiff.  Unlike the front leg where it's relatively simple to ask the horses' "knee" (carpus joint) to flex to have access to the hoof, the hind leg has to go through all sorts of contortions to show the hoof while still following the "rules" that hock and stifle must flex and extend together.





This figure is fig 24-15 from the same Textbook of Veterinary Anatomy demonstrating the "stay apparatus" (that handy little locking patella thingy that allows horses to nap standing up).  If you look really carefully at all those little lines, you will see that the stifle (the joint next to number "1") and the hock/tarsus (joint next to number "10") are tethered together so that the if one flexes (makes the angle of the joint smaller) the other one as to flex.  Look specifically at the line numbered "7" and the group of lines that run from the back of the top bone (the femur) down behind the hock.  Some of them even move past the pastern and attach in the hoof!  Thus even some movements of the hoof are coordinated with the joints above!  No wonder manipulating that hind leg can feel really weird!