Plantar Muscles of the Foot: Layer 4

00:01 So now let's talk about the fourth and final layer of the muscles on the sole of the foot.

00:07 So here we can see we have a series of muscles again, which you should be familiar with when we looked at the hand.

00:13 Here we have the plantar interossei muscles, and later on we'll talk about the dorsal interossei muscles.

00:21 So if we just look at the plantar interossei muscles, we can see these are originating from the medial sides of metatarsal 3-5.

00:31 They go on to then insert into the medial surface of proximal phalanges of digits 3-5.

00:38 So here we can see them coming from metatarsals and passing towards the proximal phalanges.

00:44 These muscles are associated with adduction of the toes 3-5, and the metatarsophalangeal joint.

00:52 Remember, these are our pad muscles, our plantar interossei muscles are associated with adduction, they help to move the toes towards the great toe, associated with adduction of toes 3-5.

01:07 So now let's look at the dorsal interossei muscles and these positions more dorsally within the foot.

01:13 We can see they originate from the adjacent surfaces of metatarsal 1-5 as they are wedged between those metatarsals.

01:21 And they extend distally both to the lateral surface surface of proximal phalanges 2-4 digits, and also the medial surface of the proximal phalanx of digit 2.

01:32 These muscles are important in abduction.

01:35 So we can see here, that toes 2-4 are abducted via these dorsal interossei muscles and the metatarsophalangeal joint.

01:44 The second toe can actually be abducted either side of its long axis due to the orientation of these muscles.

01:52 So here, we can see the second toe can be abducted either side of its long axis.

01:58 So it can be abducted both medially and laterally.

02:03 So now let's look at the innervation of these muscles in the fourth layer.

02:07 And here, we have some slight differences from what we've seen before.

02:11 So we have the lateral plantar nerve, which is supplying the dorsal and the plantar interossei.

02:16 But actually, because of that dorsal positioning, the deep fibular nerve actually contributes to the first to dorsal interossei muscles.

02:25 So we've got a slight difference there.

02:26 We're not relying solely on the lateral and medial plantar nerves.

02:30 We've got a contribution here from the deep fibular nerve.