hello anatomy friends this is dr alsup and welcome to station number four which is the
last station regarding the bones of the upper limb so we are finishing with the distal most bones
of the wrist and the hand so those carpal bones metacarpals and phalanges
and during this conversation we'll also look at the joints that are associated with these uh
the wrist and hand so starting with the carpal bones these are going to be
the ones that are shaded in different colors here and i'm going to circle the proximal row
this is the row that is going to articulate with the radius
and this right here is going to be the distal row and these are articulating with the metacarpals
so you will have four bones per row and the only one that you are going to have to identify
is this lateral most bone in the proximal row which is your scaphoid this is
the most clinically relevant of the carpal bones because it's most commonly fractured and we talked
about how avascular necrosis can occur in the lectures here so that is going to be the lateral
most in the proximal row but just for fun let's go through the other ones just so you you get your
get to kind of go through them together so this is going to be the lunate this is the triquetrum
and this is the pisiform the pisiform is that sesamoid bone that's sitting right
on top of the triketrum the pisiform will form within that flexor carpi ulnaris tendon
so this is from lateral to medial and i know this is lateral because you can really tell
this is the first digit here it doesn't have an intermediate phalange the bones are just a
little bit stouter but also shorter so we know we're looking at the first digit and
first digit when you're in anatomical position is always lateral hopefully we're getting that down
by this point when we're looking at the distal row from lateral to medial you'll have the trapezium
the trapezoid so um i'll put a tr here um then we have the capitate and the hamate so again
the only one that you have to identify for a practical setting will be the scaphoid but i
just wanted to put these in here just in case you wanted to to kind of go through them with me now
one thing i want to talk about regarding the carpal bones is the carpal tunnel and
we talked a little bit about clinically why that is relevant but i wanted to show you this area
and the carpal tunnel is going to be formed by the carpal bones which are going to be the floor
of the carpal tunnel and you can't see that in this image because we also have the roof of the
carpal tunnel which is the transverse carpal ligament sometimes referred to as the flexor
retinaculum and so that's going to completely occlude the view of the carpal bones when present
and it's been removed here but recall that we're going to have tendons that are going
to be traveling through the carpal tunnel from the anterior compartment of the forearm or the
flexor compartment as well as that median nerve which is also going to be in there and surrounding
those tendons will be the tendon sheaths that can become inflamed in a form of bursitis
which can lead to pinching of that median nerve so that is what leads to carpal tunnel syndrome
okay back to the bones and the joints so there are those carpal bones this that is shaded in
light orange are going to be your metacarpals and your metacarpals are going to form that
skeleton of the palm of the hand and recall that we number these one to five from lateral
to medial so this would be the first metacarpal the second third fourth and fifth now you can
see that these uh the distal row of the carpal bones are going to articulate with the metacarpals
or that more proximal end of the metacarpals and these would be the cmc or carpo metacarpal joints
the cmcs 2 through 5 are going to be examples of plane joints but recall that this joint right
here between the first metacarpal and the trapezium is going to form a saddle joint
which is capable of more movements than you have in these other carpe metacarpal joints
okay the joint between the metacarpals and the proximal phalanges are going to be
your metacarpophalangeal joints so between the distal end of the metacarpals and the proximal end
of the proximal phalanges are going to be your mp joints and these are examples of condyloid joints
okay so shaded in pink are going to be your proximal phalanges shaded in kind of a light
purple are going to be your middle phalanges or intermediate phalanges and notice that you do
not have an intermediate phalange associated with the first digit you only have proximal and distal
and so these light blue are going to be your distal phalanges this whole complex right here
of the first digit is often referred to as the pollux and you'll have a hallux associated with
the big toe of the foot so the joint between the proximal phalange and the intermediate phalange
are going to be your p i p joints so you'll have those across the board here
and then the joint between the intermediate and the distal phalanges will be your dip
joints which i'm going to kind of draw a line through those this particular joint right here
in the first since you don't have the intermediate is just referred to as the interphalangeal joint
all right and those pips and dips as well as this interphalangeal joint will be examples of hinge
joints so only capable of flexion and extension excellent so those are the bones of the upper limb
so let's get into some of the specific joints in this region and then we'll move on to muscles
thanks for your time and attention here and always feel free to reach out with any questions