2.4.5: Long and short toe extensor muscles (3:24)
Long and short toe extensor muscles
Now we’ll look at the muscles which produce movement of the toes. We’ll look at the extensor muscles first. There are two long extensors to the toes, and two short ones. The long extensors are two of the four muscles that we left out of the picture in the last section.
Here’s extensor hallucis longus. Extensor hallucis longus arises from the interosseous membrane, and from the adjoining fibula. Lying on top of extensor hallucis longus is extensor digitorum longus. Extensor digitorum longus has a long line of origin here on the fibula. This gap is for the common peroneal nerve.
To see all the muscles of the anterior compartment together, we’ll add tibialis anterior to the picture, here it is. We saw tibialis anterior in the last section. It almost covers up extensor hallucis longus. We’ll also add peroneus tertius, which arises in continuity with extensor digitorum longus.
Here are the tendons of all these musces passing under the extensor retinaculum: peroneus tertius, extensor digitorum longus, extensor hallucis longus, and tibialis anterior.
The tendon of extensor hallucis longus inserts partly into the extensor expansion of the first MP joint, and partly here, into the base of the distal phalanx of the big toe.
The tendons of extensor digitorum longus insert, by way of the extensor expansion of each toe, into the bases of the middle and distal phalanges. The extensor expansion of the toe is quite similar to the extensor expansion of the finger, which is described in some detail in Volume 1 of this atlas. Here’s the action of extensor hallucis longus: it extends both joints of the the big toe. Here’s the action of extensor digitorum longus: its action is mainly at the MP joint.
The two long toe extensor muscles have another important action besides extending the toes. They’re also quite powerful dorsiflexors of the ankle.
Now let’s add the short extensors to the picture. Here they are. They lie beneath the tendons of the long extensors. Extensor hallucis brevis goes to the big toe, the three slips of extensor digitorum brevis go to the middle three toes. The short toe extensors arise here, on the front of the calcaneus.
The tendons of the short extensors join the corresponding long extensor tendons. The action of the short extensors is the same as that of the long extensors, except that they don’t dorsiflex the ankle.