The Muscles of the Foot
There is only one muscle that may be seen on the dorsal surface of the foot: extensor digitorum brevis, the short extensor of the toes. Its belly is situated on the upper, lateral surface of the calcaneus and talus, and splits into four tendons that run to the first four phalanges. When the toes are pulled up, it may be seen as a flat bump that echoes the shape of the lateral malleolus, lower and more forward. Its form generally lends bulk to this area when the foot is relaxed.
The bottom of the foot is covered with a complex network of muscles that, grouped together, form a fan radiating outward from the heel to the toes. Most of them are covered by the fat pads that buffer the contact between the foot and the ground.
The outer edges of this fan are the most prominent forms. On the medial side of the fan is abductor hallucis (
HAL-uh-sis, from hallux, the big toe), whose mass can be seen especially toward the heel and middle of the foot. On the lateral side is abductor digiti minimi (
DIJ-ih-tee MIN-ih-mee, the smallest digit), which can be seen mostly along the side of the fifth metatarsal.
These two muscles, grouped with neighboring forms, divides the sole of the foot into two columns. Between them there is a furrow running from the heel to the second toe, stopping short of the head of the metatarsal. In this furrow one may see evidence of flexor digitorum brevis, if the toes are flexed from an extended position.
The ball of the foot is formed by the heads of the metatarsals. Here there is often a notable transverse plane break or fold. There is also one at the forward edge of the fat pad of the heel.