Hello everyone! It’s Megan from Kenhub here, and in this tutorial, we'll be discussing the regions of the lower limb. So in the image you can now see in front of you, we have the entirety of the lower limbs highlighted in green. Our lower limbs are built for support and locomotion and are divided into an anterior surface and a posterior surface. In this image, we can see the anterior surface or the front of the lower limbs. These two surfaces are then broken even further down into regions. So why do we divide the body into regions? Well, each region or portion of the body – for example, the head and neck, the trunk of the body, the upper limbs and of course the lower limbs – are divided into regions to help clinicians in the identification of injuries or pathologies to underlying organs, bones or muscles. So the body is divided into many, many regions and will actually cover them across five different tutorials but as you know in today’s tutorial, we’ll focus on the regions of the lower limb.
As we look at the regions of the lower limb, we’ll first look at the regions of the anterior surface and end with the regions of the posterior surface. The first region of the anterior surface that we’ll look at is the femoral trigone. This region which you see here highlighted in green is a triangular area found on the upper inner part of the thigh. This area is bounded superiorly by the inguinal ligament, medially by the adductor longus muscle and laterally by the sartorius muscle. The contents of the femoral trigone include the femoral nerve and its terminal branches, the femoral artery and some of its branches, the femoral vein and its proximal tributaries as well as the deep inguinal lymph nodes and associated lymphatic vessels. A useful mnemonic for remembering the contents of the femoral trigone is NAVEL – N for nerve, A for artery, V for vein, E for empty space and L for lymph nodes – and what do you know, we have NAVEL. This mnemonic is extra handy because it also lists the structures in the order they are situated working from lateral to medial.
Situated lateral to the femoral trigone and above the knee is the anterior thigh region. This region of the lower limb contains the quadriceps femoris muscle which we can now see highlighted in green. So I know that image has changed slightly but don’t worry, we’re still viewing the thigh from an anterior perspective. We’ve simply removed the skin so that we can see the quadriceps femoris more clearly. We can see it’s made up of the rectus femoris muscle and the three vastus muscles – the vastus medialis, the vastus lateralis and the vastus intermedius which is found deep to the recuts femoris.
The next region of the lower limb is this region seen here highlighted in green. It’s known as the genual region which is basically a fancy word for the knee region. If we remove the skin and muscles in this region, we can see that it includes the condyles of the distal femur and the proximal tibia, the head of the fibula and the patella as well as the joints and ligaments situated between these bony structures. In the next illustration, we can see the anterior crural region which is the anterior part of the leg situated between the knee and ankle regions. This region contains structures such as the shafts of the tibia and fibula as well as the muscles of the anterior compartment of the leg. This region also contains the nerves and vessels that supply these muscles.
The final region on the anterior surface of the lower limb that we’ll look at is the dorsum of the foot. This region of the foot is basically the superior surface or the top of the foot. It contains several structures including some bones at the foot namely the tarsal bones, the metatarsals and the phalanges of the foot. It also contains the extensor digitorum brevis muscle, the extensor hallucis brevis muscle, the dorsalis pedis vessels, the dorsal venous network, the deep peroneal nerve and its branches as well as the tendons of the anterior muscles of the lower leg.
So now that we’ve covered the regions of the anterior surface of the lower limb, let’s move on to look at the regions of the posterior surface. The first region we can see here is the posterior thigh region. This region of course contains the muscles of the posterior compartment of the thigh and if we remove the skin from this area, we can see these muscles namely the biceps femoris muscle, the semitendinosus muscle and the semimembranosus muscle. This region also contains the sciatic nerve and its branches as well as the vessels that supply and drain these muscles.
The next region we can see is the popliteal region which is situated just inferior to the posterior thigh region. This region is situated posterior to the knee or the anterior genual region and is marked by the popliteal fossa which is a well-defined fat-filled space. This region contains structures such as the popliteal artery and vein, the tibial nerve, the common peroneal nerve, the small saphenous vein and the popliteal lymph nodes.
Below the popliteal region is the posterior leg region. This region contains the muscles of the posterior compartment of the leg, the posterior tibial artery and veins as well as the tibial nerve. Next, we see the lateral retromalleolar region. This region is basically this small area seen here situated posterior to the lateral malleolus of the fibula. The tendons of the peroneus longus and peroneus brevis pass through this region. The region we can now see highlighted in green is the calcaneal region which is also known as the heel region. This is a region of the foot that’s marked by the posterior protrusion of a large bone of the tarsus known as the calcaneus which is funnily enough the bone that forms the heel of the foot.
The final region of the lower limb that we’re going to look at is the sole of the foot. This region is found on the inferior aspect of the foot and is the part of the foot that makes contact with the ground. It’s also known as the plantar region of the foot. This region contains the intrinsic muscles of the sole of the foot as well as the tendons of the deep flexors of the posterior compartment of the leg and the tendon of the peroneus longus muscle. It also contains the medial and lateral plantar arteries as well as the plantar veins of the foot.
So before we bring this tutorial to a close, let’s quickly summarize what we’ve learned today. So first we focused on the anterior surface of the lower limb which included the femoral trigone which is bordered superiorly by the inguinal ligament, laterally by the sartorius and medially by the adductor longus then we had the anterior thigh region which contains the quadriceps femoris followed by the genual region which is also known as the knee region. We then had the anterior crural region and lastly the dorsum of the foot.
We then moved on to the posterior surface of the lower limb where we looked at the posterior thigh region which contains the muscles of the posterior compartment of the thigh followed by the popliteal region which forms the posterior aspect of the knee region. Below this, we found the posterior leg region. Next, we had the lateral retromalleolar region which is found posterior to the lateral malleolus of the fibula followed by the calcaneal region which forms the heel of the foot. The last region we looked at was the sole of the foot.
So that brings us to the end of our tutorial on the regions of the lower limb. I hope you found it useful and thanks for watching.
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