Lateral Compartment of the Leg

00:01 Now let's have a look at the lateral compartment of the leg.

00:05 The lateral compartment of the leg contains a few muscles.

00:08 We have fibularis brevis, and we have fibularis longus.

00:12 Now let's have a look at fibularis longus.

00:15 This is the most superficial of these muscles in the lateral compartment and it gives rise to a very long, slender, tendon that passes around the lateral malleolus which we find on the fibular.

00:26 Here we can see it's originating from the head of the fibular, and also the lateral surface of the proximal fibular before that tendon then runs posterior to the lateral malleolus to then run along sole of the foot.

00:38 It ends up by inserting onto the base of the first metatarsal and also the medial cuneiform bone.

00:46 Fibularis brevis, which we can see here.

00:49 This has an origin further inferior than fibularis longus is coming from the mid portion of the lateral fibular.

00:56 It follows the same course passing posterior to the lateral malleolus.

01:00 But this muscle then passes to the base of the fifth metatarsal.

01:07 The function of these two muscles are very similar.

01:09 They help with inversion of the foot and they also serve as weak plantar flexors.

01:16 The innervation of these muscles is by the superficial fibular nerve.

01:20 Remember the superficial fibular nerve is a branch of the common fibular nerve when that branched away from the sciatic.

01:27 So we've seen the sciatic nerve gives rise to the tibial nerve, and also the common fibular nerve.

01:33 The common fibular nervous splitting into two, the superficial fibular nerve which supplies this lateral compartment and the deep fibular nerve which supplies the anterior compartment.

01:43 The tibial nerve, which we'll see later, will go on to supply the posterior compartment.

01:49 Here again, we can remind ourselves where the sciatic nerve is located.

01:52 We can see it here, giving rise to the tibial nerve here which descends in the posterior compartment.

01:58 Here it's bifurcating into the common fibular nerve, the deep fibular nerve here and the superficial fibular nerve is located here.

02:05 So this is a good reminder of the distribution of nerves from the sciatic nerve down to the leg.

02:11 If we were to then remind ourselves of the retinacular, we spoke of the extensor retinacular on the dorsal surface of the foot.

02:18 Here we can see we have a fibular retinacular as well.

02:21 We have a superior fibular retinacular here, which is passing from the lateral malleolus to the calcaneus.

02:28 And here, we have an inferior fibular retinaculum which is running from the calcaneus to the calcaneus.

02:34 These are important ligamentous structures that help to hold the tendons of these two muscles in position as they pass around the posterior aspect of the lateral condyle of the fibular.

02:46 Holding them in position, so when forces exerted onto them with flexion and extension, they remain in the right position.

02:53 There's no bow stricken that can take place.