(3.14)
Now we’ll move on, to look at the numerous small muscles on the plantar aspect of the foot. The intricacy of these muscles reminds us that our human foot has evolved from feet that had many other functions besides that of being walked on. Since some of the smaller muscles are now almost vestigial structures, we’ll be looking at them quite briefly.
We’ll look at the small plantar muscles in four groups, first the interosseous muscles; then the short muscles that occupy the middle of the foot; then the short muscles for the big toe; and lastly the ones for the fifth toe.
Here are the interosseous muscles. There are seven of them, two for each of the three middle toes, and one for the fifth toe. The interosseous muscles arise from the shafts of the metatarsals, and insert into the bases of the proximal phalanges. The action of the interosseous muscles is to flex the toes at the MP joints.
Now we’ll look at the middle group of muscles. These are all closely associated with the tendon of flexor digitorum longus. The middle group consists of the tiny lumbrical muscles, flexor accessorius, and, superficial to them, flexor digitorum brevis, which we’ll see again in a moment. The four lumbricals are just like the lumbricals in the hand. We won’t look at them in detail.
Flexor accessorius, also called quadratus plantae, arises by two heads from from here and here on the calcaneus. Flexor accessorius inserts here, into the deep aspect of the tendon of flexor digitorum longus. Flexor accessorius aids in flexing the toes.
Now we’ll add flexor digitorum brevis to the picture - here it is again. Flexor digitorum brevis arises from here on the calcaneus. Flexor digitorum brevis divides to form four tendons. Each of these ...
(3.14)
Now we’ll move on, to look at the numerous small muscles on the plantar aspect of the foot. The intricacy of these muscles reminds us that our human foot has evolved from feet that had many other functions besides that of being walked on. Since some of the smaller muscles are now almost vestigial structures, we’ll be looking at them quite briefly.
We’ll look at the small plantar muscles in four groups, first the interosseous muscles; then the short muscles that occupy the middle of the foot; then the short muscles for the big toe; and lastly the ones for the fifth toe.
Here are the interosseous muscles. There are seven of them, two for each of the three middle toes, and one for the fifth toe. The interosseous muscles arise from the shafts of the metatarsals, and insert into the bases of the proximal phalanges. The action of the interosseous muscles is to flex the toes at the MP joints.
Now we’ll look at the middle group of muscles. These are all closely associated with the tendon of flexor digitorum longus. The middle group consists of the tiny lumbrical muscles, flexor accessorius, and, superficial to them, flexor digitorum brevis, which we’ll see again in a moment. The four lumbricals are just like the lumbricals in the hand. We won’t look at them in detail.
Flexor accessorius, also called quadratus plantae, arises by two heads from from here and here on the calcaneus. Flexor accessorius inserts here, into the deep aspect of the tendon of flexor digitorum longus. Flexor accessorius aids in flexing the toes.
Now we’ll add flexor digitorum brevis to the picture - here it is again. Flexor digitorum brevis arises from here on the calcaneus. Flexor digitorum brevis divides to form four tendons. Each of these enters one of the tendon sheaths, along with a tendon of flexor digitorum longus. Inside the tendon sheath, which we’ll remove, the brevis tendon splits into two halves, which encircle the longus tendon. Flexor digitorum brevis inserts here, on the bases of the middle phalanges. Flexor digitorum brevis assists in producing flexion at the PIP and MP joints. Lying superficial to flexor digitorum brevis is the plantar aponeurosis, which we’ve looked at already.