Hello anatomy colleagues this is Dr Alsup and we will be discussing the basics of the bones
as well as the joints of the lower limb. And as we did with the upper limb we are just
introducing the bones and joints and we will go into more detail on certain areas
in upcoming sessions. So really the goal is for us to get used to these terms or really
the names and just get a basic understanding of where these bones and joints are located.
So it'll seem like a lot of new names and it is but do be aware that we will talk about these
in subsequent videos and learning objectives and in the lab as we go through this material.
So where we had a pectoral girdle associated with the upper limb there is a pelvic girdle that is
associated with the lower limb that serves to connect the axial skeleton to the lower appendage.
So again the pelvic girdle is in an intermediate position between the trunk and the appendages.
We discussed the coxal bones or the hip bones in more detail during the pelvic portion of the
curriculum but recall that there are two coxal bones that articulate with one another at the
anterior pubic symphysis which is a cartilaginous joint. And posteriorly these articulate with
the sacrum at the sacroiliac or SI joints, you'll often hear it abbreviated that way.
Recall that the sacrum and its close neighbor the coccyx are going to be the fused portions of
the vertebral column. So the pelvic girdle is not only serving to connect to the axial skeleton
which the vertebral column certainly is but specifically a portion of the
vertebral column which is unique that did not occur with the pectoral girdle. The coxal bones
will articulate with the head of the femur at the acetabulum which you can see a little bit
of it right here on the sides. And then that forms the hip joint which is
similar to the shoulder joint is a ball and socket joint and thus highly
mobile but doesn't have the same degree of range of motion as we saw in the shoulder.
Moving to the thigh there is a single bone per thigh called the femur which just so
happens to be the longest bone in the body. And as mentioned the head of the femur will
articulate with the coxal bone to form the hip joint. The distal portions of the femur
will articulate with the tibia and the patella to form the complex
knee joint and we will spend quite a bit of time breaking down the details of the knee
in future sessions as it's a frequently injured area therefore very clinically relevant.
Moving to the leg we have a pair of bones, we will have the medial considerably larger
tibia. It's also going to be the weight-bearing bone in the leg. And then the fibula which is
lateral and relatively thin, compared to certainly the tibia. And really only the tibia is going to
play a direct articulation role in the knee joint. The fibula you see doesn't quite reach the femur
so not playing a role specifically in the articulation of the knee joint but there will be
ligaments that attach to the fibula. Both the tibia and the fibula will articulate in differing ways
to the talus which is one of your tarsal bones in order to form the talocrural or ankle joint
distally, and you can palpate on the lateral side of your ankle region and you will be feeling the
fibula, whereas on the medial side if you palpate around the ankle region you're feeling the tibia.
Similar to what we had with the radius and ulna, the tibia and fibula
will articulate with one another in three regions, thus forming three separate joints. There will be
a proximal tibiofibular joint as well as a distal tibiofibular joint and then you will
have an intermediate tibiofibular joint that connects the bodies or the shafts
of the tibia and fibula via an interosseous membrane so an example of a fibrous joint.
In the ankle and hindfoot region there will be seven tarsal bones so one less tarsal bone than
carpals but these are notably larger in size. And I do want you now to be able to identify
two of these, specifically the talus or the "tay-lus" sometimes you hear it referred to as that. This is
going to be the more superiorly positioned tarsal bone. And so it will approximately articulate with
both the tibia and the fibula as we mentioned at the talocrural joint or that ankle joint,
and it will also articulate with some of the other tarsal bones at intertarsal joints. But
in particular I want you to focus on this articulation with the calcaneus which is
this large bone here often referred to as the heel bone at the subtalar joint. And we'll come back
to this joint in terms of talking about some specific actions that occur in the foot region.
The four distal tarsal bones will articulate with the metatarsals at the tarsometatarsal joints.
There are five metatarsals similar to what we had with the metacarpals of the
hand but a big difference here is that the first metatarsal which you have right here
is the medial most metatarsal rather than the lateral most as we had with the first metacarpal.
So the first metatarsal excuse me is associated with the big or the great toe. And will
continue in sequence from medial lateral so that's the first this would be the second the third
the fourth and the fifth metatarsal. As mentioned the metatarsals will articulate with four of those
distal tarsals at the tarsometatarsal joints and distally the metatarsals will articulate with
proximal phalanges at the metatarsophalangeal joint which is a mouthful for sure
so very often abbreviated as MP or MTP joints. The organization of the phalanges of the toes
is extremely similar to the phalanges of the fingers and they do have the same name so
the good thing is if you learn the pattern for one you will know the pattern for the other. So this
means that there are five proximal phalanges four intermediate phalanges so we're missing
an intermediate phalange associated with the first digit excuse me and five distal phalanges.
The joints between the proximal and intermediate phalanges
are going to be the proximal interphalangeal or PIP joints and the joint between the
intermediate and distal phalanges are the distal interphalangeal or DIP joints.
All right we have reached the summary slide that has this handy table of the bones and
joints we have discussed. Again these are a lot of new names and you will become more
familiar with these as we continue our discussions within musculoskeletal anatomy, so begin getting
used to these terms and realize that these will continue to come up and we'll add some
familiarity as we go. Thank you for your time and attention here, and have a great rest of your day.