Hello anatomy friends this is Dr Alsup and in this video we will be discussing the joints in the
ankle region which will actually involve more than just the ankle joint. Our first goal will
be to actually locate these so we're going to identify the articulating bones then of course
determine the actions or movements possible at these joints. We'll discuss a few ligaments
certainly not all of them and of course discuss clinical considerations throughout as appropriate.
So as mentioned when discussing the joints in this region there are certainly more than
just the ankle joint more properly called the talocrural joint which you can see here outlined
in this dashed blue. Although the ankle joint is the largest in this region and most prominent
but just superior to the ankle joint there will be the inferior tibiofibular joint and distal to
the ankle joint we will have intertarsal joints which are covered up here by ligaments and fascia
two of which we're going to discuss which are the subtalar and the transverse tarsal joints.
We will start with the most proximal of these joints which is the inferior
tibiofibular joint and here it's outlined it could even be extended a little bit further down here
it's outlined in this dashed line and the name of the joint is very descriptive. It is going to
be the most inferior of the three tibiofibular joints and there's a similar pattern to what we
had in the forearm between the radius and the ulna, recall that there were three joints there you had
one kind of proximal or superior one interosseous membrane connecting the bodies or shafts and then
one inferior or distal joint and that's exactly what you have between the tibia and the fibula.
The largest difference between the forearm and the leg is the degree of movement occurring where
there was pronation and supination in the forearm there is very little movement allowed at the
tibiofibular joints. However the integrity of the inferior tibiofibular joint is essential in the
stability of that ankle joint which is just distal it's like right here. Really this this joint
will kind of serve to keep the lateral malleolus which is this region right here of the fibula
firmly against the lateral surface of the talus or the talus you'll hear it either way.
Damage to the ligaments associated with the inferior tibiofibular joint like this one yellow
one here which for fun but not for memorization is called the anterior tibiofibular ligament
or even the distal portions of the interosseus membrane which is going
to kind of extend down into this region. If you have some type of stretching or
tearing associated with these this is often referred to as a high ankle sprain.
Now moving to the big one the true ankle joint or the talocrural joint. This is formed by the
distal tibia mainly when we're talking about the more proximal bones you can see it forming this
roof-like portion here as well as the distal fibula articulating with the superior portion of
the talus or the talus which is your most superior tarsal bone. The medial malleolus of the tibia
and the lateral malleolus of the fibula or the malleolus you'll hear it either way will flank the
joint and really serve to grip the talus tightly to best allow for the hinge motions at this joint.
And speaking of hinge motions this occurs because this is a hinge joint
with the major actions being plantar flexion and dorsiflexion. Dorsiflexion I always conceptualize
as digging in one's heels kind of into the ground with the toes pointing up or the forefoot pointing
up whereas plantar flexion is what occurs when you stand on your toes or the ball of your foot
so the heel is going to be moved superiorly and the toes kind of more inferiorly.
Oftentimes people have a difficult time conceptualizing this joint as a hinge joint
because it very very often occurs with other actions in the foot region as well such as
inversion and knee version and even a little bit of wobbling which yes is a scientific term there
which can happen in plantar flexion. But it's really this hinge motion
this plantarflexion and dorsiflexion that most characteristically occurs at the ankle joint.
Now let's talk a little about the ligaments associated with the ankle joint. Similar to other
hinge joints there are ligaments on the medial side and the lateral side which in essence are
called collateral ligaments. The difference here is the collateral ligaments of the ankle joint are
not organized as one solid structure but instead an amalgamation of smaller ligaments. Additionally
while supporting and promoting the hinge movements that occur at the ankle joint
these ligaments also serve to stabilize during some foot motions particularly inversion and
eversion. So starting on the medial side which is this image here we have the medial or the deltoid
ligaments which are composed of four parts we're not going to have you memorize these but I do want
you to understand that they all proximally attach to the medial malleolus or malelus
of the tibia. And their fibers intermingle forming this really robust protection
in this medial area. So these medial ligaments or deltoid ligaments are noticeably stronger than
their lateral counterparts and these stabilize during eversion and with ever this is eversion
here the sole of the foot is going to move more laterally and if you evert and then invert your
foot moving the sole of the foot more medially you will notice you have a greater range of motion and
inversion than you do with eversion. So this partly is due to the fact that those medial
or deltoid ligaments are so robust so you only have so much range of motion in terms of eversion.
On the lateral side you have the aptly named lateral ligaments of which there are three:
anterior talofibular, calcaneofibular, and you cannot see the posterior talofibular ligament
in this illustration it'd be back here. These all have attachment on the lateral malleolus
of the fibula but as you can see here they don't interweave together such as what you
had up here with the medial ligaments. So due to this and other reasons they are relatively weaker
than their medial counterparts and will allow a greater range of motion in inversion of the foot
for which it provides stabilization during that movement.
One of the three of these ligaments is the most prone to injury such as sprains or even complete
tears and this would be the anterior talofibular ligament which I just outlined or the ATFL
which you can see right here between the fibula and the talus or the talus so the most commonly
injured of the ligaments. So let's take a moment and consider ankle sprains and this is the most
common injury to the ankle region and is also one of the most common musculoskeletal injuries.
This includes damage to the ligaments in this region of the ankle which can range widely in
severity from overly stretched to completely torn but it most commonly occurs in the lateral
ligaments with an over inversion so too much inversion occurring when the foot is kind of
planted down or planter flex so when the foot is kind of stuck down in plantar flexion and then you
have too much inversion occurring the ankle just kind of rolls in fact you often hear this referred
to as a rolled ankle. Again due to the mechanism of the injury it is those lateral ligaments
that are most commonly damaged in particular that ATFL or the anterior talofibular ligament.
Moving distally we get to all the tarsal bones and since there are seven tarsal bones
this means there are numerous intertarsal joints or joints between the tarsal bones
but we're going to focus on two: the subtalar and the transverse tarsal. Mainly due to
the fact that they are the major players in those actions we keep bringing up inversion
and eversion. Again inversion is bringing the soul of the foot or the plantar surface more
medially or pulling that medial surface of the foot more superiorly whereas eversion is bringing
the sole of the foot more laterally pulling that lateral surface of the foot more superiorly.
In terms of basic locations of these joints the subtalar joint is located between the talus or
the talus and your heel bone or your calcaneus meaning the joint is inferior to the talus.
It is at this joint that the majority of the mobility occurs for inversion and eversion. The
transverse tarsal joint is a bit more complicated as this is a complex joint formed by two
separate intertarsal joints but they're located kind of on the same plane as you can see here
indicated by this dashed line so between the talus and the navicular and between the calcaneus down
here and so calcaneus and the cuboid right here. Don't worry so much about memorizing the navicular
or the cuboid or these specific names of these joints I just wanted to kind of put these here
to kind of better describe but I do want you to understand that it's kind of just distal
to that talus calcaneus complex so right here before you get to the rest of the tarsal bones.
While not the primary joint for inversion and eversion it certainly will augment
these motions so you commonly see including in our resources
that inversion and eversion occur at both the subtalar and transverse tarsal joints.
All right excellent thanks for sticking with me to talk about this important region
of anatomy and and particularly in terms of joints. Please take time to review these major points
outlined in the summary slide and as always if you have any questions please reach out to me or any
of my anatomy colleagues. Thank you for your time and attention and have a great rest of your day