This is a tutorial on the fascia and retinacula of the foot. We’re looking here at an inferior view of the foot. This is the plantar surface of the foot. I’ve removed away the skin layer and this here is the plantar aponeurosis. This is similar to the palmar aponeurosis that we have in the hand.
Posteriorly here, we can see the attachment of this plantar aponeurosis on the calcaneus. Actually, it attaches to the medial process of the calcaneal tuberosity. And then it extends forward and expands along the digits. That forms this longitudinal band of fibers.
It’s not shown on this model here, but just distal to the metatarsal phalangeal joint, we’ve got some connections, horizontal connections between these longitudinal bands. These horizontal connections form the superficial transverse metatarsal ligament. You can see the deep ligament, which is actually shown in this model (but the superficial one isn’t).
You can see the deep transverse metatarsal ligament running over the MTP joints. The superficial metatarsal ligaments are not shown here, but these are just formed by transverse fibers interconnecting these longitudinal fibers.
The plantar aponeurosis is essentially a thickening of the deep fascia of the foot. It supports the longitudinal arches of the foot.
I’ve just rotated the model around and we’re looking anteriorly at the foot and the leg now, the distal end of the leg. I’m just going to show you the extensor retinacula.
These retinacula hold the extensor tendons in place. We’ve also got retinacula in the hand. I showed it in the tutorials I did on the hand and the wrist. We looked at the flexor and extensor retinaculum which held the tendons in place there. These are the extensor retinaculum, which lie anteriorly on the distal leg.
This one here is the superior extensor retinaculum and then you’ve got the inferior extensor retinaculum below it. It’s not shown very well on this model, but the superior extensor retinaculum attaches to the anterior margins of the tibia and on the anterior margin of the fibula. It’s actually shown out of place here, but you can see how it holds the extensor tendons in place. This retinaculum is just a thickening of the deep fascia of the leg.
Just below it is the inferior extensor retinaculum. You can see the shape of this retinaculum. It’s actually in this y-shape. It’s sort of a y lying on its side. You’ve got this upper arm and a lower arm.
Laterally, you can see the attachment of the inferior extensor retinaculum superiorly on the calcaneus. And then the upper arm attaches to the medial malleolus and the lower arm extends medially over the foot. It actually extends right down to join with the plantar aponeurosis. It’s not shown accurately in this model, but it extends right down medially on the foot to join with the plantar aponeurosis.
In this view, you can also see this retinaculum. The tendons which pass posteromedially on the distal leg are the flexor tendons. This is the flexor retinaculum and it holds these tendons in place and it actually overlies the tarsal tunnel.
The flexor retinaculum attaches to the medial malleolus. It runs inferomedially on the calcaneus and it actually attaches a bit below what it’s shown her so it also blends with the plantar aponeurosis.
I’ll just rotate the model around so we’re now looking posteriorly here at a posterior view. We can see the flexor tendons running behind the medial malleolus inside the tarsal tunnel and underneath the flexor retinaculum.
I’ll just isolate the flexor retinaculum so you can just see this area underneath the flexor retinaculum. You’ve got this depression between the medial malleolus and the medial and posterior sides of the talus. There’s a depression here just behind the medial malleolus and just by the medial part of the talus, the medial and posterior part of the talus.
This area underneath the flexor retinaculum is the tarsal tunnel. You’ve got this depression between the medial talus and the medial malleolus and you’ve got this area posteriorly and medially on the calcaneus and the shelf of bone, this sustentaculum talus. This area underneath the flexor retinaculum is the tarsal tunnel.
We’ll just take a look at some of the structures that run through the tarsal tunnel. We’ll start off medially.
Just looking medially just behind the medial malleolus, we can see these two tendons. You’ve got the tendon of the tibialis posterior, which lies deep to the tendon of the extensor digitorum longus. The tibialis posterior tendon actually is more medial and extensor digitorum longus tendon which sits on top of it is just a little bit lateral.
And just lateral to these tendons, you’ve got some important vessels. I’ve just brought them in here. These are the posterior tibial artery and the posterior tibial vein. In this region, you can actually palpate the posterior tibial pulse.
The medial malleolus is easy to feel. It’s this lump on the medial aspect of the ankle. If you just feel a little bit behind the medial malleolus, you can feel the posterior tibial pulse.
We’ve also got the tibial nerve, which runs in the tarsal tunnel. And then finally, we’ve got this tendon which is the flexor hallucis longus tendon. This lies most posterior and laterally and it runs behind the talus and then under that shelf of bone in the calcaneus, the sustentaculum talus. You can see that here just running underneath that shelf of bone.
That’s the flexor retinaculum and the tarsal tunnel and the contents of the tarsal tunnel, which is quite important to know.
Just rotating the leg laterally, we’ll just take a look at the fibular retinacula. We’ve got a superior fibular retinaculum and an inferior fibular retinaculum.
The superior fibular retinaculum is here. You can see its attachment on the lateral malleolus and superiorly on the calcaneus. These two retinaculum hold the peroneal tendons in place, so the tendons of the peroneus longus and peroneus brevis or fibularis longus and fibularis brevis.
The inferior fibular retinaculum, you can see here. It actually blends with the inferior extensor retinaculum. You can see that here.