hello all this is Dr. Alsup and in this video we're going to be discussing the bones of
the wrists more specifically the carpus as well as the hand
all right so we have quite a bit to get through so let's go ahead and get started
with the bones of the wrist and really you can consider the radius as part of the wrist but
really we're focusing on what's referred to as the carpus and there are two rows of these carpal
bones each row will have four bones the proximal row is the row that articulates with the radius
the distal row is the row that articulates with the metacarpals and I have here from lateral to
medial the names of the bones am I going to ask you a question about the order of the carpal bones
the answer is no but I do have these here in order for you to be able to
to have seen these names in case they ever come up we'll talk a little bit more about the scaphoid
in the next slide but I do want to mention this one here the pisiform the pisiform is this
pea shaped bone right here it's an example of a of a sesamoid bone so a bone that is going to form
within a tendon specifically the flexor carpi ulnaris tendon so that's a unique type of bone
it's not there at birth it will develop with movement of that flexor carpi ulnaris over time
and it will not directly articulate with the radius unlike the other three
now the scaphoid this is going to be the lateral most bone of the proximal row so you can see this
here and the reason I want to discuss this one is because it is the most frequently fractured of the
carpal bones and similar to what we had with the Colles fracture where you have that fall on the
outstretched hand or fall on the palm that type of injury can also cause a fracture of the scaphoid
it could the individual could fall directly on the scaphoid it could cause a displacement of
the radius to kind of cause this fracture right here and I wanted to mention mention it because
it is the most frequent of the fractures of the carpal bone also this type of fracture is often
misdiagnosed early because often it doesn't show up specifically on a radiograph that happens right
after the injury with time because of the poor blood supply in this region it will become more
prominent within a radiograph but oftentimes this can be my misdiagnosed as like a sprained wrist
one other thing I want to talk about in terms of the carpal bones is the
formation of the carpal tunnel so these carpal bones are going to form the floor
of the carpal tunnel then you're going to have a ligament referred to as the transverse carpal
ligament or often you'll see it referred to as the flexor retinaculum and basically this forms
this tunnel these structures form this tunnel and what is going to travel through the that tunnel
well it's going to be the long tendons associated with the muscles in the forearm so they're going
to traverse this region in order to go and help move the joints associated with the hand
as well as the tendon sheath so you remember those long kind of bursa like structures that
are going to surround these tendons but also importantly traveling through the carpal tunnel
you're going to have the median nerve which is one of the terminal branches of the brachial plexus
and so when a lot of times you hear people say I have carpal tunnel well we all have a carpal
tunnel but what they're typically saying is that I have carpal tunnel syndrome and what this
is is just a reduction of the size of the carpal tunnel and that can affect the structures within
typically what's happening is you're going to have an inflammation of those tendon sheaths that are
surrounding those long tendons and that can cause compression of that median nerve because recall
you have the all these structures traveling through here and if you have a reduction
in size that can pinch on things and what this can present as is kind of a tingling
associated with the hand because this is going to provide sensory innervation
to certain portions of the hand as well as diminished or complete absence of sensation
also the median nerve is going to provide motor innervation to the muscles right here in
what's referred to as the thenar eminence that plays a role in terms of movement of the thumb
so with very severe carpal tunnel syndrome this can lead to the loss of coordination of
the thumb as well as a loss of movement or strength of movement in the thumb
all right moving on to the metacarpal so we're moving from proximal to distal the metacarpals are
what's making up the bulk of kind of the the palm region they're going to be five metacarpals and
they're numbered one through five starting lateral to medial so the one associated with the thumb
region is metacarpal one, two, three, four, five so remember thumb side is always going to be lateral
when you're in anatomical position and pinky finger or fifth digit is going to be medial
the metacarpals are going to articulate with the carpal bones at the carpometacarpal
joints and then they're also going to articulate with the proximal phalanges
at the metacarpophalangeal joints and you'll often see these abbreviated as MP or MCP joints
so you can see if I'm flexing right here these are going to form the kind of the knuckle region here
and then the phalanges and this is really where the number of bones uh really increases there
are going to be quite a few phalanges 14 and all you'll have five proximal phalanges
four intermediate or middle and the one you do not have one you do not have an intermediate or medial
phalange in the first digit or the thumb and then you have five distal phalanges you can see that
these are quite uniquely shaped throughout this first digit is often referred to as the pollux
or the thumb side so that's going to be right here and you're going to have two major types
of joints that are being formed here so the joint between the proximal and the intermediate
so I'm circling one right here is going to be the PIP or the proximal interphalangeal joints
and the joint between the intermediate phalanges and the distal phalanges are going to be the DIP
or the distal interphalangeal joints so you'll hear PIP and DIP very often and since you do
not have a middle or intermediate phalange associated with this first digit this joint
that I have circled right here is just referred to as the interphalangeal joint or the IP joint
all right excellent so those are a lot we got through all those bones pretty quickly they are
not tremendously different from one another so we don't have to spend too much time there
the great thing too is that this organization is very similar to what you will have in the foot
all right so hopefully this one is going to pop up really quickly which
is the most frequently fractured carpal bone
and I hope that you kind of immediately went oh I remember this this is the only one that we talked
about in more detail other than of course that pisiform and that is the scaphoid the scaphoid
is the lateral most of your proximal row of carpal bones the scaphoid so in that fall with
an outstretched hand that foosh type of injury with that extended kind of palm like this
that could cause a fracture to the scaphoid and it's often misdiagnosed because it doesn't show
up that fracture doesn't show up very clearly on early radiographs all right excellent thanks
so much for your time here and let's move on to some of the joints of the upper limb thank you