Lectures

Posterior Compartment – Anatomy of the Leg

by James Pickering, PhD
(1)

Questions about the lecture
My Notes
  • Required.
Save Cancel
    Learning Material 2
    • PDF
      Slides 06 LowerLimbAnatomy Pickering.pdf
    • PDF
      Download Lecture Overview
    Report mistake
    Transcript

    00:00 If we now move on to the posterior compartment of the leg, we can see we have both superficial and deep layers that I mentioned. Let’s deal with the superficial layers first.

    00:11 On here, we can see most superficially closest to the skin, we have gastrocnemius. And this has two heads. There’s a lateral head to gastrocnemius we can see running over here.

    00:26 This is a lateral head of gastrocnemius, and here we can see the medial head of gastrocnemius.

    00:32 So here, we have the posterior view of a right leg. We have the lateral head of gastrocnemius here, and we have the medial head here. Deep to gastrocnemius, we find we have soleus, and this is a large muscle, a very fleshy muscle that is sitting directly deep to gastrocnemius.

    00:53 So gastrocnemius, the lateral head, comes from the lateral condyle of the femur while the medial head comes from the medial condyle of the femur. Soleus, this comes from the posterior surface of the fibula, and also as we mentioned in the osteology lecture, it comes from the soleal line of the tibia. Both of these muscles pass through the posterior aspect of the calcaneus via the calcaneal tendon. They’re supplied by the tibial nerve.

    01:24 So these muscles in the posterior compartment are supplied by the tibial nerve, one of those divisions that are coming away from the sciatic nerve. Gastrocnemius and soleus are both involved in plantarflexion of the ankle, so enabling you to stand on tiptoes. And because gastrocnemius crosses the knee joints, then it can actually flex the knee as well. One other muscle that I haven’t mentioned is plantaris. Plantaris is running alongside the medial aspect of the lateral head, and this gives rise to a very thin and long tendon that runs between gastrocnemius and soleus. So we can see plantaris. It’s coming from the inferior aspect of the lateral supracondylar ridge of the femur, and its long tendon passes between the soleus muscle and the gastrocnemius muscle. It has a long tendon that then blends with the calcaneal tendon inserting on to the calcaneus. It’s in the posterior compartment. So it’s also supplied by the tibial nerve, and it is a weak plantarflexor of the ankle. If we look at more deep layers, then there are three muscles here that I want to talk about, first of all. We have popliteus, flexor digitorum longus, and flexor hallucis longus.

    02:47 So we can see these if we look into the deep compartments. We have popliteus here. We have flexor digitorum longus.

    02:56 We have flexor hallucis longus. And we also have this muscle here, which is tibialis posterior, and I’ll come to that in a moment. So popliteus, we can see coming from these lateral aspects of the leg. It’s coming from the lateral surface of the femoral condyle.

    03:14 We can see it’s passing across to the tibia. We then have long muscles that give rise to tendons that pass into the foot, flexor digitorum longus and flexor hallucis longus. So we can see popliteus coming from the lateral aspects of the lateral condyle of the femur. It also comes from the lateral meniscus, and it passes to the posterior tibia above the soleal line which we mentioned before. Flexor digitorum longus, this is coming from the posterior surface of the tibia below the soleal line, and this passes to the distal phalanges of digits 2 to 5. Flexor hallucis longus, this is coming from the lower two-thirds of the posterior fibula, and also their interosseous membrane. It passes to the distal phalanx of the great toe. All of these muscles, as they’re in the posterior compartment, are supplied by the tibial nerve. Popliteus, this is going to be a weak knee flexor.

    04:18 It’s also involved in unlocking the knee by lateral rotation of the femur on a stable tibia.

    04:24 So when you’re in standing position and the femoral condyle is tightly articulating with the tibial plateau, then popliteus is important in unlocking the knee enabling flexion to occur.

    04:41 Flexor digitorum longus flexes the digits 2 to 5, and it also helps to plantarflex the ankle. Flexor hallucis longus flexes the great toe and is also a weak plantarflexor.

    04:55 Now let’s turn to the deep layer within the posterior compartment. There are four muscles here I would like to talk about. We have popliteus; we have tibialis posterior, flexor digitorum longus, and flexor digitorum hallucis. And we can see that we have this muscle here, popliteus, important in unlocking the knee from its fully extended position.

    05:20 Then we have tibialis posterior, and then flexor digitorum longus, and flexor hallucis longus then they’re going to pass tendons into the foot. So if we look at popliteus, it comes from the lateral aspects of the lateral condyle of the femur, and also the lateral meniscus. It passes to the posterior tibia above the soleal line. And this muscle is important. It’s innervated via the tibial nerve, and it’s a weak knee flexor as it does technically across the knee joint. But its prime responsibility is to unlock the knee bilaterally rotating the femur when the femur and the tibia are stable. So when the knee is fully extended, it can unlock the knee allowing flexion to occur. Flexor digitorum longus and flexor hallucis longus, as we can see, pass long tendons into the foot, into the sole of the foot. And these two muscles flexor digitorum longus, comes from the posterior surface of the tibia below the soleal line, and it passes to the distal phalanges of digits 2 to 5. Flexor hallucis longus, this passes from the lower two-thirds of the posterior fibula and interosseous membrane specifically to the distal phalanx of the great toe.

    06:44 These three muscles are associated with flexing the digits 2 to 5 if you’ll flex the digitorum longus, and the great toe if you’ll flex the hallucis longus, as their names would suggest. FDL, flexor digitorum longus, is also a plantarflexor of the ankle, and flexor hallucis longus is also a plantarflexor but somewhat weaker. Tibialis posterior is coming from the posterior tibia below the soleal line. It also comes from the posterior surface of the fibula and the interosseous membrane. It passes to the tuberosity of the navicular bone. This muscle is important in plantarflexing the ankle, and also, inverting the foot.

    07:31 So tibialis anterior and tibialis posterior work together with foot inversion. All of these muscles are supplied by the tibial nerve, just like the gastrocnemius, the soleus, and the plantaris muscle were supplied by the tibial nerve, so these deeper muscles within the posterior compartment are also supplied by the tibial nerve. So if we look at the


    About the Lecture

    The lecture Posterior Compartment – Anatomy of the Leg by James Pickering, PhD is from the course Lower Limb Anatomy.


    Included Quiz Questions

    1. Posterior surface of the fibula
    2. Anterior supracondylar ridge of the femur
    3. Lateral supracondylar ridge of the femur
    4. Posterior supracondylar ridge of the femur
    5. Anterior surface of the fibula
    1. Gastrocnemius
    2. Popliteus
    3. Soleus
    4. Fibularis lingua
    5. Tibialis anterior
    1. Flexor hallucis longus
    2. Plantaris
    3. Popliteus
    4. Gastrocnemius
    5. Soleus
    1. Tibialis posterior
    2. Plantaris
    3. Popliteus
    4. Gastrocnemius
    5. Soleus

    Author of lecture Posterior Compartment – Anatomy of the Leg

     James Pickering, PhD

    James Pickering, PhD


    Customer reviews

    (1)
    5,0 of 5 stars
    5 Stars
    5
    4 Stars
    0
    3 Stars
    0
    2 Stars
    0
    1  Star
    0