Hello anatomy colleagues this is Dr Alsup and in this video we will be
identifying the pertinent osteology for the forearm, wrist, and hand session.
Hopefully we are becoming quite familiar with this image of the distal humerus the anterior distal
humerus as we keep bringing it up and adding structures as we go through these sessions. Today
I want to focus on the epicondyles right now which both are located just superior or proximal to the
articular region right here with the capitulum and the trochlea which we've identified before.
The epicondyles are sites for attachment so you'll have both ligaments and tendons attaching there.
The medial epicondyle which is this one right here is the most prominent and it will project the most
it's projecting medially so it's often hard to miss and will be on the same side as the trochlea.
The ulnar collateral ligament will attach here supporting the elbow region but also importantly
most of those superficial muscles of the anterior or flexor compartment of the forearm will have
their proximal attachment here that's why it's so large. One other thing to note the ulnar nerve
will travel just posterior to this region to the medial epicondyle so when you hit your "funny bone"
I put that in quotes you're really kind of pinging your ulnar nerve in this general area.
The lateral epicondyle is on the same side as the capitulum so it's going to be more lateral.
It's certainly less robust than what you have on the medial epicondyle but nonetheless projects
some laterally and is on that same plane as the medial epicondyle. The radial collateral ligament
of the elbow attaches here but more importantly the common extensor tendon of some of the muscles
in the posterior or extensor compartment of the forearm will attach on the lateral epicondyle.
With repetitive use of those muscles this can lead to kind of micro tears in the
common extensor tendon or it even can cause little tears in the periosteum
that surrounds the actual bone of the lateral epicondyle so causing pain in this area this
is referred to as lateral epicondylitis but more commonly you hear that referred to as tennis elbow.
Okay just a reminder regarding what the ulna looks like, recall that it is more complex and
larger more proximally and distally it becomes much smaller, it is going to and this distal region
is really where we're focusing on so the ulna becomes much slender less complex and has little
involvement with the radiocarpal or wrist joint. It is this lateral radius that is the major player of
the forearm in the wrist joint and you can see that it widens significantly the more distal
you get and it is the, so right in this region, this inferior most carpal articular surface so you can
really see a straight on image of this inferior view. So it is this region right here of the radius
that will articulate with the proximal row of carpal bones to form the radiocarpal wrist joint.
So speaking of carpal bones these are the small bones that are shaded here in green.
The proximal row are the ones that are going to articulate with the radius that portion of the
radius that we just saw so three out of the four will articulate not this small pisiform right
here it's a little bit more anteriorly placed so it's not going to be articulating with the radius.
I do want you to be able to differentiate one of the carpal bones don't worry about
memorizing the names of every carpal bone but I do want you to be able to distinguish
the scaphoid bone sometimes you hear scaphoid, scaphoid is how you'll hear me say it.
So as you can see it's in this proximal row and it is the lateral most in this proximal
row so on the same side as this first digit here. We want you to be able to identify the
scaphoid for a few reasons. First this is the most frequently fractured carpal bone,
so a bit more clinically relevant than some of the other carpal bones. Additionally the
scaphoid is located deep within the anatomical snuffbox region, which is a region we will spend
a bit of time on in this session. So this is the scaphoid please be able to identify this one.
Right here is going to be the distal row of the carpels another row of four.
Then we get to the metacarpals which are shaded here in orange, these are the bones that are
located in the palm region and they're noticeably longer than the phalanges which are more distal.
They are numbered 1-5 from lateral to medial and this first metacarpal is notably
stouter it's associated with the thumb and the count continues medially so the first
digits always lateral when you're talking about the hand then it goes from there two three
four and five is the most medial oops well five is medial how about that.
There are three sets of phalanges and they get smaller the more distal you get.
The proximal phalanges are shaded here in this kind of pinkish purplish color.
The middle or intermediate phalanges are shaded in this light purple so these are the middle
phalanges, notice that the first digit does not have a middle phalange this is why you there are
14 phalanges in all not 15. And lastly the distal phalanges which are shaded here in this light blue
these I always I think the distal flanges are so distinct in
shape and even though they're quite small they're quite distinctive.
Excellent that should be it in terms of the osteology. Please take time to review and
reach out to me or any of my anatomy colleagues with any questions. Have a great rest of your day