Muscles of Sole of Foot: Layers 4 – Anatomy of the Foot

00:00 fifth digit. Now let’s turn to the fourth layer. This is the interosseous layer between the metatarsals. Again, similar to the hand, we have a whole series of dorsal and plantar interossei muscles. We have three plantar interossei and we have four dorsal interossei.

00:18 We can see the dorsal interossei are coming from adjacent metatarsals. So we can see we’ve got the first dorsal interossei here, second, third, and fourth. And these are coming from the two adjacent metatarsal bones, whereas here, the plantar interossei, we can see these are only coming from the third, fourth, and fifth metatarsals, only coming from one of them.

00:44 So we have our bipennate and unipennate musculature. So if we look at the origins and insertions of this interossei muscle, then the plantar interossei originate from the medial surface of the third or fifth metatarsals. And they insert on the medial surface of the proximal phalanx of digits 3 to 5. The dorsal interossei run from adjacent surfaces of the first to fifth metatarsals, and their insertions are quite different. The first dorsal interossei attaches to the medial surface of the proximal phalanx of digit two, whereas, the second, third and fourth dorsal interossei attach to the lateral surface of the proximal phalanx of digits 2 to 4. So there’s a difference there for the first, the second, third, and fourth dorsal interossei. All of the interossei are supplied by the plantar nerve. So the plantar interossei are involved in adducting digits 3 to 5. Remember, we can use PAD for the plantar interossei adduct the digits. And they’re also important in flexing the metatarsophalangeal joints. The dorsal interossei, these are involved in abducting. So we have DAB, dorsal interossei abduct digits 2 to 4, and these were also involved in flexing the metatarsophalangeal joints. So if we were to remove the plantar aponeurosis and we were