Dorsum of Foot – Anatomy of the Foot

00:00 So let’s start off by looking at the dorsum of the foot, and here we’ve got two dissections showing the dorsum of the foot. We have the lateral aspect down here, and we have the medial aspect here.

00:12 The superficial dissection and then with some structures removed, again, we have the lateral aspects and we have the medial aspect. But what we can see are the inferior extensor retinaculum here, this Y-shaped one here, and these are holding down the tendons that pass into the foot, those tendons of the long muscles from the leg. And we can see the tendon of extensor hallucis longus, the tendon of tibialis anterior, and the tendons of extensor digitorum longus here passing. On this side, these have been removed and we can really see the muscle bellies of extensor digitorum brevis. So extensor digitorum brevis is one of the muscles I want to talk about. This originates from the calcaneus, and it inserts into the long extensor tendons of extensor digitorum longus for digits 2 to 4. So we can see that these muscles here, extensor digitorum brevis, are passing towards the long tendons of extensor digitorum longus.

01:17 We can see them here. And these are going to help extension. We also have extensor hallucis brevis, and this again is coming from the calcaneus and it runs with extensor digitorum brevis, but specifically, goes to the proximal phalanx of the great toe, reinforcing extension of the great toe, again, helping to extend the digits. We can see extensor hallucis brevis passing in this direction towards the great toe. So we have extensor digitorum brevis and extensor hallucis brevis, the only muscles that we can see on the dorsum of the foot in this superficial layer. Later on, we’ll have a look deeper on some dorsal interossei here.

02:02 But the main fleshy parts on the top on the dorsum of the foot are the extensor digitorum brevis and extensor hallucis brevis muscles. We can see that these muscles are supplied by the deep fibular nerve that’s continued down from the anterior compartment into the dorsum of the foot. And we can see the function, extensor digitorum brevis, extends digits 2 to 4, and it aids extensor digitorum longus. Extensor hallucis brevis extends the great toe and aids extensor hallucis longus. So here, we can see as these muscles pass into the dorsum of the foot, we have these tendinous sheaths that are within the tendons as they are going underneath the flexor retinaculum, and these are helping to prevent friction.

02:54 As I mentioned, a similar arrangement occurs in the wrist. We can see the Y-shaped extensor retinaculum here which is holding down these tendons. We can see these tendons, these long tendons, extensor digitorum here, extensor hallucis longus here, and the tendinous sheath of tibialis anterior here. We can see these passing down into the dorsum of the foot.

03:19 And here, we can see some of those neurovascular relations. We see we’ve got the deep fibular nerve that’s passing into the dorsum of the foot accompanied by the anterior tibial artery that will eventually become the dorsalis pedis artery. So if we have a look, only two of the 20 muscles located within the foot are found in the dorsal compartment, extensor digitorum brevis and extensor hallucis brevis. Extensor hallucis brevis is actually, as I mentioned, part of extensor digitorum brevis. And together, they form a fleshy mass on the lateral aspect of the foot. These are positioned deep to the long tendons of extensor digitorum longus, and they are supplied by the deep fibular nerve. We can see them running down here. We’ve got extensor hallucis brevis once again, and we’ve got extensor digitorum brevis deep to these long tendons. What we can see is if we remove these tendons, we can see the dorsalis pedis artery running over the dorsum of the foot as a direct continuation of the anterior tibial artery. This gives rise to the lateral tarsal artery, which we can see here, and it then carries on and gives rise to the arcuate artery. It then continues and it bifurcates distally into the first dorsal metatarsal artery. We can see the first dorsal metatarsal artery running here, and the deep plantar artery. And we’ll explore this connection in later lectures. The deep plantar artery forms the deep plantar arch, and this occurs on the plantar aspect. So we’ll return to this in a later lecture.