Hello all this is Dr Alsup and in this learning objective video we will be discussing the basics  
Hello all this is Dr Alsup and in this learning objective video we will be discussing the basics  

of the lower limb neurovasculature. So again this will be an introduction and certain components  
of the lower limb neurovasculature. So again this will be an introduction and certain components  

of this will be returned to in more detail. Such as specifically the innervation as we delve into  
of this will be returned to in more detail. Such as specifically the innervation as we delve into  

those regions. But for now let's talk basics of the arteries veins nerves and of course lymphatics.  
those regions. But for now let's talk basics of the arteries veins nerves and of course lymphatics.  

And I always like to start with arteries  because understanding these names will  
And I always like to start with arteries  because understanding these names will  

help with the veins as well. And similar to what we had in the upper limb there is one  
help with the veins as well. And similar to what we had in the upper limb there is one  

major primary source to the lower limb except for the gluteal region so this back region  
major primary source to the lower limb except for the gluteal region so this back region  

here and we'll talk about some of those in upcoming sessions as well as the medial  
here and we'll talk about some of those in upcoming sessions as well as the medial  

thigh the medial thigh will be supplied by the obturator. But all the rest of the lower limb  
thigh the medial thigh will be supplied by the obturator. But all the rest of the lower limb  

is going to be supplied by the femoral  artery. And that femoral artery is going  
is going to be supplied by the femoral  artery. And that femoral artery is going  

to be the continuation of the external iliac artery so kind of past the inguinal ligament  
to be the continuation of the external iliac artery so kind of past the inguinal ligament  

the name changes from external iliac to femoral artery. And we will see it dominantly will supply  
the name changes from external iliac to femoral artery. And we will see it dominantly will supply  

the, it'll be a very large component of the femoral triangle which we will discuss in another  
the, it'll be a very large component of the femoral triangle which we will discuss in another  

another learning objective video. And that femoral artery will change its name throughout its length.  
another learning objective video. And that femoral artery will change its name throughout its length.  

But as the femoral artery it with its major branch the deep artery of the thigh will supply the  
But as the femoral artery it with its major branch the deep artery of the thigh will supply the  

majority of the muscles of the thigh except for of course that medial thigh region as we discussed.  
majority of the muscles of the thigh except for of course that medial thigh region as we discussed.  

The femoral artery will transition  its name to the popliteal artery  
The femoral artery will transition  its name to the popliteal artery  

right around the region of what's referred to as the adductor hiatus which is located in the tendon  
right around the region of what's referred to as the adductor hiatus which is located in the tendon  

of the adductor magnus muscle. So it's kind of the adductor magnus will allow protected passage of  
of the adductor magnus muscle. So it's kind of the adductor magnus will allow protected passage of  

the femoral vasculature down to the more distal portions of the lower limb. The popliteal artery  
the femoral vasculature down to the more distal portions of the lower limb. The popliteal artery  

supplies structures associated with the knee joint as you can kind of see right around here  
supplies structures associated with the knee joint as you can kind of see right around here  

so there will be numerous anastomoses around the knee similar to what you have in most other joints.  
so there will be numerous anastomoses around the knee similar to what you have in most other joints.  

At the distal end of the popliteal fossa there's going to be that popliteal fossa is an important  
At the distal end of the popliteal fossa there's going to be that popliteal fossa is an important  

area in the posterior knee region and here the popliteal artery will end by bifurcating into the  
area in the posterior knee region and here the popliteal artery will end by bifurcating into the  

anterior as well as the posterior tibial arteries. So let's talk a little bit more about those.  
anterior as well as the posterior tibial arteries. So let's talk a little bit more about those.  

These arteries will supply the rest of the lower limb so the leg and the foot. And their basic  
These arteries will supply the rest of the lower limb so the leg and the foot. And their basic  

positions are focused around that interosseous membrane or that sheet-like connective tissue that  
positions are focused around that interosseous membrane or that sheet-like connective tissue that  

connects the tibial and fibular bodies or shafts. So the anterior tibial artery will be located  
connects the tibial and fibular bodies or shafts. So the anterior tibial artery will be located  

anterior to the interosseous membrane and so it makes sense that it will be supplying muscles  
anterior to the interosseous membrane and so it makes sense that it will be supplying muscles  

of the anterior compartment of the leg. As this artery passes over the dorsal ankle  
of the anterior compartment of the leg. As this artery passes over the dorsal ankle  

so kind of this region here its name  will change to the dorsalis pedis artery.
so kind of this region here its name  will change to the dorsalis pedis artery.

The posterior tibial artery travels  posterior to the interosseous membrane,  
The posterior tibial artery travels  posterior to the interosseous membrane,  

so it's behind the interosseous membrane, and it as well as its branches will supply  
so it's behind the interosseous membrane, and it as well as its branches will supply  

the posterior compartment of the leg  as well as the lateral compartment.  
the posterior compartment of the leg  as well as the lateral compartment.  

And about at the level of the calcaneus or that large tarsal heel bone the posterior  
And about at the level of the calcaneus or that large tarsal heel bone the posterior  

tibial artery will end by bifurcating into the medial and lateral plantar arteries. And so it is  
tibial artery will end by bifurcating into the medial and lateral plantar arteries. And so it is  

the dorsalis pedis artery that we discussed here and these medial and lateral plantar arteries  
the dorsalis pedis artery that we discussed here and these medial and lateral plantar arteries  

that will have numerous branches it will create anastomotic arcades and supply the foot.  
that will have numerous branches it will create anastomotic arcades and supply the foot.  

Alright now on to veins. Similar again to the upper limb there are superficial and deep veins, but  
Alright now on to veins. Similar again to the upper limb there are superficial and deep veins, but  

it is the deep veins that are typically the largest in the lower limb unlike what we had  
it is the deep veins that are typically the largest in the lower limb unlike what we had  

with the upper limb. An important concept when discussing veins of the lower limbs is that  
with the upper limb. An important concept when discussing veins of the lower limbs is that  

all of these veins have valves. So valves are very important when we are talking the lower  
all of these veins have valves. So valves are very important when we are talking the lower  

limb. So valves are those cusps of endothelium within the veins which are really important in  
limb. So valves are those cusps of endothelium within the veins which are really important in  

terms of guiding the directionality of  blood flow proximally towards the heart. 
terms of guiding the directionality of  blood flow proximally towards the heart. 

In this region this blood flow is going against gravity so these valves are very important. Okay a  
In this region this blood flow is going against gravity so these valves are very important. Okay a  

little bit about the superficial veins. These are located in the subcutaneous tissue and there  
little bit about the superficial veins. These are located in the subcutaneous tissue and there  

are many many superficial veins but the two most prominent are the great and small saphenous veins.  
are many many superficial veins but the two most prominent are the great and small saphenous veins.  

The great saphenous vein is the longest and it is dominant in the medial portion of the medial leg
The great saphenous vein is the longest and it is dominant in the medial portion of the medial leg

so you can kind of see it going this entire way so it's very prominent in that medial region.
so you can kind of see it going this entire way so it's very prominent in that medial region.

And it's most accessible at the medial malleolus so at that palpable portion
And it's most accessible at the medial malleolus so at that palpable portion

this right here of the medial ankle. The great saphenous vein will drain into the femoral vein.
this right here of the medial ankle. The great saphenous vein will drain into the femoral vein.

The small saphenous vein is going to be associated with the posterior leg so it's running in that  
The small saphenous vein is going to be associated with the posterior leg so it's running in that  

superficial fascia of the posterior leg and it will drain into the deeper popliteal vein.  
superficial fascia of the posterior leg and it will drain into the deeper popliteal vein.  

The superficial veins will consistently drain into the deep veins via what's referred to as  
The superficial veins will consistently drain into the deep veins via what's referred to as  

perforating veins and these are fairly prominent in the lower limb. And so these perforating veins  
perforating veins and these are fairly prominent in the lower limb. And so these perforating veins  

will penetrate the deep fascia and also contain valves, so valves valves valves very important.
will penetrate the deep fascia and also contain valves, so valves valves valves very important.

Now again these veins are working against gravity. They have that deep fascia tightly  
Now again these veins are working against gravity. They have that deep fascia tightly  

surrounding the muscles to when contracting help move the blood in the right direction.  
surrounding the muscles to when contracting help move the blood in the right direction.  

So again in this region we will  have deep veins, these deep veins  
So again in this region we will  have deep veins, these deep veins  

similar to what we had in the upper limb are often referred to as accompanying veins  
similar to what we had in the upper limb are often referred to as accompanying veins  

or venae comitantes as they are going to travel in pairs around the artery so very  
or venae comitantes as they are going to travel in pairs around the artery so very  

very closely associated with the arteries often wrapped up very tightly in connective tissue.
very closely associated with the arteries often wrapped up very tightly in connective tissue.

Now occasionally the great saphenous vein in really any lower limb vein can become  
Now occasionally the great saphenous vein in really any lower limb vein can become  

varicose. And so this means dilated, this will affect the valve's ability to properly close,  
varicose. And so this means dilated, this will affect the valve's ability to properly close,  

allows blood to flow inferiorly or in that wrong direction. Occasionally a deep vein thrombosis or  
allows blood to flow inferiorly or in that wrong direction. Occasionally a deep vein thrombosis or  

DVT can occur typically caused by venous stasis or stagnation and this can be due to  
DVT can occur typically caused by venous stasis or stagnation and this can be due to  

a multitude of reasons such as inactivity of the muscles or an insufficiency of that musculovenous  
a multitude of reasons such as inactivity of the muscles or an insufficiency of that musculovenous  

pump. So what's making the veins or the blood within the veins move in the correct direction.  
pump. So what's making the veins or the blood within the veins move in the correct direction.  

A thrombus formed from a DVT may break away from the vein  
A thrombus formed from a DVT may break away from the vein  

and make its way all the way to the  pulmonary artery causing obstruction  
and make its way all the way to the  pulmonary artery causing obstruction  

of that pulmonary artery. This is referred to as a pulmonary embolism which I know you are  
of that pulmonary artery. This is referred to as a pulmonary embolism which I know you are  

likely quite familiar with at this point or  a thromboembolism which can be an emergent  
likely quite familiar with at this point or  a thromboembolism which can be an emergent  

situation but it's from these veins that  the thrombus typically initially forms.
situation but it's from these veins that  the thrombus typically initially forms.

Now onto the innervation of the lower limb. There are two main plexuses that will contribute to both  
Now onto the innervation of the lower limb. There are two main plexuses that will contribute to both  

the afferent and efferent innervation of the lower limb. The lumbar plexus plays the smaller  
the afferent and efferent innervation of the lower limb. The lumbar plexus plays the smaller  

but I would argue not too small role and in terms of afferent and efferent innervation it  
but I would argue not too small role and in terms of afferent and efferent innervation it  

will innervate the anterior medial compartments of the thigh in addition to cutaneous innervation in  
will innervate the anterior medial compartments of the thigh in addition to cutaneous innervation in  

additional areas distally and we'll get more into the cutaneous innervation in upcoming sessions.  
additional areas distally and we'll get more into the cutaneous innervation in upcoming sessions.  

The sacral plexus is the major  plexus in terms of the lower limb. It will  
The sacral plexus is the major  plexus in terms of the lower limb. It will  

innervate all of the regions of the lower limbs so this includes the gluteal region  
innervate all of the regions of the lower limbs so this includes the gluteal region  

posterior thigh and the distal limb. The prominent nerve from the sacral plexus is the sciatic nerve,  
posterior thigh and the distal limb. The prominent nerve from the sacral plexus is the sciatic nerve,  

which happens to be the largest nerve in the body. I always really enjoy watching  
which happens to be the largest nerve in the body. I always really enjoy watching  

students discover the sciatic nerve and dissection as it is so impressive in size.  
students discover the sciatic nerve and dissection as it is so impressive in size.  

There are postganglionic sympathetics that travel in branches of these plexuses.  
There are postganglionic sympathetics that travel in branches of these plexuses.  

We need those sympathetics in order to serve roles in vasoconstriction and initiating  
We need those sympathetics in order to serve roles in vasoconstriction and initiating  

secretion of sweat. So those sympathetics do make their way to the limbs but the parasympathetics  
secretion of sweat. So those sympathetics do make their way to the limbs but the parasympathetics  

do not, which makes sense when you think about the role parasympathetics play that has very  
do not, which makes sense when you think about the role parasympathetics play that has very  

little to do with the limbs. Last but not least let's discuss the lymphatics of the region again similar  
little to do with the limbs. Last but not least let's discuss the lymphatics of the region again similar  

to the upper limb so common theme there are a lot of similarities between the upper and the  
to the upper limb so common theme there are a lot of similarities between the upper and the  

lower limbs. There are superficial and deep sets of lymph vessels. The superficial lymph tend to  
lower limbs. There are superficial and deep sets of lymph vessels. The superficial lymph tend to  

drain into what's referred to as the superficial inguinal lymph nodes. Whereas the deep lymph  
drain into what's referred to as the superficial inguinal lymph nodes. Whereas the deep lymph  

vessels will drain into the deep inguinal lymph nodes. And those superficial inguinal lymph nodes  
vessels will drain into the deep inguinal lymph nodes. And those superficial inguinal lymph nodes  

tend to drain into the deep inguinal lymph nodes right around the region of the femoral triangle.  
tend to drain into the deep inguinal lymph nodes right around the region of the femoral triangle.  

All right excellent. We have covered the basics of the neurovasculature in lymphatics of the lower  
All right excellent. We have covered the basics of the neurovasculature in lymphatics of the lower  

limb. Much more to come here but we want to start getting used to these terms and general locations.  
limb. Much more to come here but we want to start getting used to these terms and general locations.  

I thank you for your time and attention here and as always have a great rest of your day
I thank you for your time and attention here and as always have a great rest of your day