Plantar Muscles of the Foot: Layer 3

00:01 Now let's look at the third layer of the muscles on the sole of the foot.

00:07 So these muscles are primarily associated with the fifth digit.

00:11 So flexor digiti minimi brevis.

00:14 And that of the great toe or the first digit, we've got abductor hallucis and we also have flexor hallucis brevis.

00:23 So abductor hallucis and flexor hallucis brevis there associated with the right toe.

00:29 If we look at flexor digital minimi brevis, we can see that it's originating from the base of the fifth metatarsal and it passes distally on the lateral aspect to insert into the base of the proximal phalanx of the little toe or the fifth digit.

00:46 This muscle is associated with flexion of the little toe at the metatarsal phalangeal joint.

00:54 If we then turn our attention to a adductor hallucis, the origin of adductor hallucis, its transverse head.

01:01 Notice there are two heads here, we can see the transverse head is coming from the ligaments associated with the metatarsal phalangeal joints of bones 3-5.

01:11 The oblique head is coming from the base of metatarsal 2-4.

01:17 This muscle goes to insert onto the lateral side of the proximal phalanx of the first digit.

01:23 It's associated as its name suggests, with adduction of the great toe.

01:29 So now, we have flexor hallucis brevis.

01:32 Flexor hallucis brevis originates from the lateral cuneiform its plantar surface, and also the cuboids plantar surface.

01:41 So originates from two of the tarsal bones we've spoken about previously.

01:45 Inserts into the lateral and medial sides of the base of the proximal phalanx of the great toe.

01:52 So insert into the base of the proximal phalanx of the great toe, or the first digit.

01:58 As its name suggests is associated flexion of the great toe and the metatarsal phalangeal joint.

02:05 Innervation of this third layer, again is going to be via contributions of our lateral plantar nerve, which is going to supply both abductor hallucis and flexor digiti minimi brevis.

02:16 And the medial plantar nerve is going to supply flexor hallucis brevis on this medial aspect.