Hello anatomy friends this is Dr Alsup and in this video we will be discussing the joints of
the wrist region. So first we will start with actually naming these joints but then we'll
also discuss the movements that can occur at each and hopefully this will help in our discussions
of the forearm muscles, and as usual we will discuss any pertinent clinical information.
So the primary joint in the wrist region is as you might imagine the wrist joint,
but it's actually called the radiocarpal joint which tells you exactly which
bones are articulating. This joint will be the emphasis of the rest of this learning objective
but before we get into that I do want to mention that there are joints that are close to the wrist
joint and often will move in unison with the wrist joint or increase the range of motion
of the wrist joint. So just proximal to the radiocarpal joint is the distal radioulnar
joint and I'm quite serious when I say it is just proximal to so very closely related.
The distal radioulnar joint is the most distal of the three articulations between the radius and
the ulna we talked about the proximaoradial ulnar joint when discussing the elbow region there'll be
an interosseous membrane connecting the shafts between that's the second joint and then the
distal radioulnar joint is the most distal. And it will partner with the others particularly that
proximal radioulnar to allow pronation and supination of the radioulnar joints.
Now between each and every carpal bone there will be an intercarpal joint,
and sometimes the joint between the proximal and the distal row so this would be the proximal
row this would be the distal row, excuse me, is sometimes referred to as the midcarpal joint
but just as a group we can call these intercarpal joints. They are plane joints which means that they
have gliding movement so very slight gliding movements and these gliding movements will
serve to increase the overall range of motion of the radiocarpal joint.
Let's talk a few more specifics regarding the radiocarpal joint. This joint is formed
by the distal end of the radius and the proximal row of carpal bones except for
the pisiform which is a small sesamoid bone it's more anteriorly placed. Also not playing a distinct
role in this joint is the ulna. The ulna does not reach distally enough to have a meaningful role
here. There is an articular disc which obviously you can't see here we're just looking at the bone
but there is an articular disc between the distal head of the ulna and the proximal row of carpals.
The wrist joint is a synovial condyloid joint sometimes you hear condyloid joints referred to
as ellipsoid joints which means that is capable of more movements than say in a hinge joint but
not as much as in a ball and socket joint so no rotation occurring in a condyloid joint.
The wrist can flex and extend with flexion having the greater range of motion.
It can also abduct sometimes referred to as radial deviation, think of moving
the wrist and the hand with it away from the body as well as being able to
ADduct sometimes referred to as ulnar deviation so think of the wrist and the hand moving back
towards the body. Anytime that a joint can flex, abduct, extend, and adduct it can circumduct.
So you do have circumduction or moving the wrist with the hand with it in a circular motion.
Lastly let's consider a fairly common clinical consideration in this area. The most or one of
the most common types of fractures of the upper extremity is referred to as a Colles fracture
and this is a fracture to the distal radius and you can see the fracture line right there.
Again I mentioned this is often referred to as one of the most common fractures of the
upper extremity, sometimes you even see it in some literature as the most common fracture,
either way it's something we need to consider. And these types of fractures of the distal
radius are most common in older individuals and particularly those with lower bone densities.
The common cause is an amazing acronym but not so amazing when it's actually happening to you.
That acronym is FOOSH and you'll hear this come up in anatomy later as well
as in some of the clinical lectures, and this stands for Falling On an Outstretched Hand.
So what that will do depending on how you fall will transmit force to different types of bones
in this particular case obviously it's transmitting it to the distal radius.
And if you think about falling what is an initial reaction if you're falling you're going to put
your hand out and try to break your false some and protect or prevent falling straight on your face
and head so that's a very common mechanism for some fractures of the upper extremity.
As you might imagine since this fracture is directly affecting the distal radius this can
greatly affect the wrist joint, particularly in terms of the ability to do the movements
that can occur at a wrist joint, but it can also affect the ligaments and the tendons in this area
so an important clinical consideration in the wrist region. All right excellent we have made
it to the summary slide, certainly an area that we need to consider as we move into our discussion of
the muscles of the forearm that will extend past the wrist joint. Please take time to review and
always feel free to reach out with any questions. Have a great rest of your day