(3.00)
Now we’ll look at the muscles for the big toe. To build up a picture of them, we’ll first take the middle group of muscles out of the picture so that we’re again looking at just the interossei. The muscles for the big toe are flexor hallucis brevis, adductor hallucis, and abductor hallucis. We’ll look at them in that order.
Flexor hallucis brevis has two almost distinct parts, which arise here from the cuboid and third cuneiform bones. Flexor hallucis brevis gives rise to two tendons of insertion, which attach first to the medial and lateral sesamoid bones, then to the base of the proximal phalanx of the big toe. The tendon of flexor hallucis longus - which we’ll add to the picture for a moment - runs between the two halves of flexor hallucis brevis.
Here’s adductor hallucis. It arises by two heads, an oblique head, and a transverse head. The oblique head arises from the bases of the middle three metatarsals, the transverse head arises from the deep transverse metatarsal ligament.
These two heads converge, and merge with the medial head of flexor hallucis brevis, sharing its insertion on the medial sesamoid bone, and on the base of the proximal phalanx.
Medial to flexor hallucis brevis is abductor hallucis. Abductor hallucis is the most medial of all the foot muscles. It arises here, on the medial side of the calcaneus. The tendon of abductor hallucis merges with the medial part of flexor hallucis brevis, and inserts with it here, on the medial sesamoid bone, and on the base of the proximal phalanx.
The main action of all three of the short muscles of the big toe is to produce flexion at the MP joint. In addition, adductor and abductor hallucis brevis can produce adduction and abduction of ...
(3.00)
Now we’ll look at the muscles for the big toe. To build up a picture of them, we’ll first take the middle group of muscles out of the picture so that we’re again looking at just the interossei. The muscles for the big toe are flexor hallucis brevis, adductor hallucis, and abductor hallucis. We’ll look at them in that order.
Flexor hallucis brevis has two almost distinct parts, which arise here from the cuboid and third cuneiform bones. Flexor hallucis brevis gives rise to two tendons of insertion, which attach first to the medial and lateral sesamoid bones, then to the base of the proximal phalanx of the big toe. The tendon of flexor hallucis longus - which we’ll add to the picture for a moment - runs between the two halves of flexor hallucis brevis.
Here’s adductor hallucis. It arises by two heads, an oblique head, and a transverse head. The oblique head arises from the bases of the middle three metatarsals, the transverse head arises from the deep transverse metatarsal ligament.
These two heads converge, and merge with the medial head of flexor hallucis brevis, sharing its insertion on the medial sesamoid bone, and on the base of the proximal phalanx.
Medial to flexor hallucis brevis is abductor hallucis. Abductor hallucis is the most medial of all the foot muscles. It arises here, on the medial side of the calcaneus. The tendon of abductor hallucis merges with the medial part of flexor hallucis brevis, and inserts with it here, on the medial sesamoid bone, and on the base of the proximal phalanx.
The main action of all three of the short muscles of the big toe is to produce flexion at the MP joint. In addition, adductor and abductor hallucis brevis can produce adduction and abduction of the big toe.
Lastly, there are two short muscles for the fifth toe, a short flexor and an abductor. Here’s the flexor, flexor digiti minimi brevis. It’s an outlying interosseous muscle that’s been given a long name. Here’s the abductor, abductor digiti minimi. It arises all the way back here, on the calcaneus. It’s inserted here, on the proximal phalanx of the fifth toe.