welcome to a board vitals question answered sponsored by med cram comm the
question is what is the last ossification center to fuse in the elbow
answer choices are capitellum lateral epicondyle medial epicondyle trochlea
or E all the Crenn on now a lot of you may have put down choice B but actually
it's a different answer and I'll explain that now a number of you are probably
familiar with the mnemonic cryto and that is the order here C R I T o e and
what these are are ossification centers in the elbow and this order of cryto
is the order that these ossification centers actually form in fact the ages
at which they form are thus one five seven ten ten and eleven years of age so
I'd like to draw your attention to this picture over here on the right which is
actually the right elbow for instance so we're looking at the right elbow end on
there for this side is lateral this side is medial this is the radius and this is
the owner obviously this is the humerus okay so what this means is that these
ossification centers are actually forming but notice that the question is
not asking the order in which they form but the order in which they fuse and
this will be very important the capitellum is the first one to form and
that is at age one so where is the capitellum it is actually in this area
right here and you'll see an island forming just off the coast of the
humerus it'll eventually fuse but it forms before it fuses so that is see the
next one that forms after C is going to be the radial head which is at age five
that one is going to form in this area here
again it's going to be floating out in the middle of nowhere on the x-ray but
it's actually going to fuse later now the next two ossification centers
are extremely important the internal and the trochlear and the reason why is
because of this order notice that the next one that forms is the internal
which we will see out here and it is free-floating again because it is
free-floating it can be a vault the key is is that it hasn't fused as yet it's
the last one to fuse after it is formed there's another one that forms called
the trochlear that's in this area and it again starts off as an island but then
it eventually shows up now this is the key point here if you see a troll clear
island or you see an ossification center here which is in the T area because of
the fact that the T is showing up there has to absolutely be an internal one if
you do not see the eye ossification Center in other words if you do not see
the medial epicondyle ossification center it has been evolved and it's gone
it forms before the trochlear but it fuses at the end and therefore it is at
risk for being avulsed so if you see a T there must have been an eye before it
and if you do not see an eye then it must have been involved and you need to
look for that fusion that has been involved okay so I before T the next one
is o which is in this area we're looking through the humerus that's at the back
it's the next one to form and then finally at the very end is the external
lateral epicondyle which again forms as a Island and then fuses II it's only at
that time because at the very end you have the fusion of the eye and now you
don't have to worry about being fused okay so let's go back to our question
what is the last ossification Center to fuse in the
bow is actually see the medial epicondyle and it is because it's the
last one to fuse that you've got to look for to make sure it's still there
because it could be avulsed and if you see the T without seeing the eye then
you have to be worried about an avulsion so the moral of this story is you've got
to read very carefully what the question is and not assume what the question is
asking sometimes when you study very hard and
you have all of these mnemonics down you know and can almost anticipate what
they're going to ask don't read into the question read the question and make sure
you're answering the right question and thanks for joining us