=The Ankle.=--The ankle or _tarsus_ has but seven bones where the wrist has eight. They are the _os calcis_ or _heel bone_, which is the largest and strongest and forms the tuberosity of the heel; the _astragalus_, which is next largest and helps to form the ankle-joint; the _cuboid_; the _navicular_ (_boat-like_) or _scaphoid_; and the internal, middle, and external _cuneiform bones_. The astragalus is above and partially in front of the os calcis, to which is attached the _tendo Achillis_. The _cuboid_ is on the outer side of the foot, in front of the os calcis and behind the metatarsals. It is noticeable in _congenital club-foot_, in which condition the tarsal bones may be distorted in shape and misplaced. The _navicular_ or _scaphoid_ is on the inner side of the foot, between the astragalus and the three cuneiform bones. =The Foot.=--There are five _metatarsal bones_ in the foot, corresponding to the five metacarpals in the hand, and the toes have the same number of _phalanges_ as the fingers, though they are shorter and stronger. The big toe corresponds to the thumb. [Illustration: FIG. 80.--Bones of the right foot, dorsal surface: 1, Astragalus; 2, talus; 3, os calcis, 4, navicular; 5, internal cuneiform; 6, middle cuneiform; 7, external cuneiform; 8, cuboid; 9, metatarsus; 10-14, phalanges. (Leidy.)] _Fracture_ of the os calcis and the astragalus are most commonly caused by a fall from a height, while the metatarsals and phalanges are generally broken by something heavy falling upon them. Because of their delicate structure, their distance from the heart, and the differences of temperature to which they are subjected, the tarsal bones are especially liable to become _tubercular_, amputation of the feet even becoming necessary at times. In diabetes there may be a perforating ulcer on the sole of the foot and the bone may become diseased. [Illustration: FIG. 81.] [Illustration: FIG. 82.] [Illustration: FIG. 83. FIG. 81.--Superficial muscles of the leg from inner side: 1, Vastus internus; 2, sartorius; 3, gracilis; 4, semitendinosus; 5, semimembranosus; 6, inner head of gastrocnemius; 7, soleus; 8, tendon of plantaris; 9, tendon of tibialis posticus; 10, flexor longus digitorum; 11, flexor longus hallucis; 12, tibialis anticus; 13, abductor hallucis. (Dorland’s Dictionary.) FIG. 82.--Muscles of leg and foot (from before): 1, Tendon of rectus femoris; 2, vastus internus; 3, vastus externus; 4, sartorius; 5, iliotibial band; 6, inner head of gastrocnemius; 7, inner part of soleus; 8, tibialis anticus; 9, extensor proprius hallucis; 10, extensor longus digitorum; 11, peroneus longus; 12, peroneus brevis; 13, peroneus tertius; 14, origin of extensor brevis digitorum. (Dorland’s Dictionary.)