Hello anatomy colleagues this is Dr Alsup and in this video we will be discussing the
bones or the osteology of the lower limb. As with much of this session, much of this is an
introduction to begin to familiarize yourself with the basic players in this region
and we will continue to add detail as we work through the upcoming sessions.
Let us start proximally and work our way distally and this first bone I hope you feel is a review
as we have covered it in other areas and this is the coxal or hip bone which of course is paired.
This bone is often discussed in the three parts that develop and will eventually fuse.
There is the superior, more fan shaped ilium which is shaded in light blue here,
the posterior and robust ischium that is shaded in orange, so you can see a bit of it from this
anterior view, and the smallest and most anteriorly placed pubis, which is shaded in green in these
images and these two pubis bones will articulate at the pubic symphysis which is located right here.
All three of these parts will fuse during childhood in this fairly deep socket-shaped region,
this whole region here is referred to as the acetabulum.The acetabulum faces laterally and this
will receive the head of the femur to form the hip joint so a very important region of this bone.
Speaking of the femur let's discuss this longest bone of the body.
This is the bone of the thigh and it's quite robust in both its proximal so this is proximal
and distal portions. The major structure I want to point out on
or point out proximally on the femur today is the head of the femur. This is the ball in the
ball and socket joint formed at the hip and it will articulate or join with the acetabulum that
we saw in this previous slide so there's a pretty good fit there in terms of those structures. On its
distal most end there are the condyles so I'm going to circle both here of which there are two
there's a medial and a lateral. Now how do I know which one is medial and which one is lateral? That
is always the question how are we going to be able to identify these. For me the easiest way
is to look at which one is on the same side as the head, so which one is on the same side as the head,
well it's this one right here. So this one is going to be the medial the head of the femur
must be medially placed in order to articulate with the acetabulum of the coxal bone
therefore this is the medial condyle and this is the lateral condyle. Also of note we are looking
at a posterior view of the femur mainly because this affords the clearest picture of the condyles
you can really see how bulbous they are from this view and that is less true from the anterior view.
Moving to the patella, these are the largest sesamoid bones in the body. A sesamoid bone
is a bone that forms within a tendon and this is certainly the case of the patella which forms
in the tendon of the quadriceps femoris muscle or the quads in the anterior thigh. The patella is the
bone that you can feel when you're touching the anterior portion of your knee region. It's pretty
distinct looking with a rougher looking anterior side so this is anterior and a smoother articular
posterior side this is the portion this is the side that will articulate with the femur.
Moving to the bones of the leg similar to what we have in the forearm of the upper limb there
are two bones. The more medial of the two is the tibia so tibia is the medial one and this bone
is considerably thicker larger than its lateral counterpart the fibula and it's the major weight
bearer of the leg. The proximal portion of the tibia is the portion that's involved with the knee
joint and this entire superior region, so kind of this whole region right about here, is referred to
it also has these articular surfaces that you can see from this superior view here,
this region right here is called the tibial plateau. And on the tibial plateau you will have
the condyles and these will articulate with the femoral condyles we saw in the previous picture.
Now I wouldn't ask you to tell me which one is which which one's medial which one's lateral here
but I did put this image in here because I wanted to show you just how
shallow these condyles are so think about how loose that fit is between the femoral condyles
which have these fairly bulbous condyles right here fitting in this extremely shallow area
here so the stability of the knee joint is not so much coming from the fit of the bones.
Now when you are looking at a complete view of the tibia you can get an idea of which one
is medial and which is lateral and that's by looking at this structure on the opposite or
distal end of the tibia called the medial melalus or malleolus you'll hear it either way.
The medial malleolus is as its name would suggest medial and it's pretty hard to miss if you put
your hand on the medial side of your ankle region that is the bump you feel on the medial side. So
if you can find the medial malleolus you have a pretty good idea of which one is the medial
condyle and this would be the lateral condyle so that shallow area right here.
Now the lateral and much thinner counterpart in the leg is the fibula. When looking at an isolated
fibula as we are here it can be difficult to tell which side is superior and which side
is inferior as these portions of the bone look relatively similar. My best advice is that the
head of the fibula which is this superior portion here is less tapered. It's a slightly more bulbous
whereas the lateral malleolus or malleolus is going to be on the distal end and it certainly
is more tapered. Also it'd be pretty mean of us to give you an image that is upside down so
this is going to be more superior place superiorly placed whereas this will be more inferiorly placed.
If you palpate the lateral side of your ankle area you are touching the lateral malleolus.
Now finally we have reached the ankle and foot region we are looking at a view of the dorsal
foot so if you were to look straight down at the tops of your feet that is a dorsal view.
There are seven tarsal bones which are shaded in green here, so one less than what we had with the
carpal bones but certainly relatively larger than the carpal bones, and we do want you to be able
to differentiate two of the tarsal bones. The most superior of the tarsals is the talus or the talus
you'll hear it either way which is the tarsal bone that plays a role in the ankle joint. And just
inferior to the talus is the largest tarsal bone which is the calcaneus sometimes you hear this
referred to as the heel bone, it is identifiable or easily identifiable just due to its size.
And you do not have to memorize the names of these other tarsal bones but here are the rest
of those right here. There are five metatarsals organized from 1-5 from medial to
lateral and these are shaded in orange here. I know this is medial because this is associated
with the great toe you can see that these bones here a little bit kind of more solid
and robust so this would be your first metatarsal second third
fourth and fifth so first will always be the more medial and associated with your great
toe or big toe. Shaded in pink are the proximal phalanges, light purple are the middle
or intermediate phalanges, notice that there is not a middle phalange associated with the first digit,
and lastly in light blue these are the distal phalanges. And notice that the more lateral you get
in terms of the distal phalanges they become quite small and not particularly well developed.
So those are the bones of the lower limb in a nutshell and with an image with them
all together I kind of wanted to go through them once more to make sure that we're on the
same page regarding location. So starting proximally we have the coxal bones here
close to the trunk this is your sacrum right here. The ilium is going to be more superiorly placed
the ischium is not as easy to see here because it's mainly in a posterior view you can see a
little bit of it right here, and then the pubis are going to be the smallest ones that are
more anteriorly placed, so those are the coxal bones. You can even see a bit of the acetabulum
right here so that's going to be the acetabulum. And that's going to articulate with the head of
the femur. So femur here of course this is the unpaired or excuse me there's only one femur
associated with each thigh. Distally you will have the medial and the lateral condyles,
so you can see the medial it's going to be here the lateral you can't see quite as well
but it would be over here. This is a good image for seeing where the patella articulates with
the femur so here's your patella here very anteriorly placed. The tibia when we're looking at
the leg is clearest in this particular image with the tibial plateau kind of up in this region here,
and the medial malleolus or malalus here you can barely see the fibula
in this image and this is because the leg has been rotated a little medially and the
fibula is so thin that even with a slight bit of rotation there you almost lose complete view of it.
You can see a little peak of the lateral malleolus right here and even over here in this image.
You can see the talus here that is going to articulate with the lower ends of the
tibia and the fibula and the rest of the tarsal bones, you have metatarsals here
and then all of the phalanges which are your distal most bones
associated with the lower limb. Excellent thank you for your time and attention here. Please
always feel free to reach out with any questions and I hope you have an excellent rest of your day