When I was like ten, I was climbing a wooden ladder up a tree (the "rungs" were pieces of wood hammered into the tree itself) when I stepped on a loose rung, which fell out, followed by my heel, down to the ground. I basically impaled my heel with the rusty nail. The nail was stopped by the BONE itself (calcaneus).
It hurt, but the booster shot that followed made my arm sore for like three days, which also sucked.
RANDOM RANT
BONES OF THE FOOT
The "long bones" of the foot are the metatarsals. They articular at their distal ends with the phalanges (toe bones). Humans have an interested phalangeal formula: 2-3-3-3-3.
At their proximal ends, the metatarsals meet four different bones. Digit I articulates with the medial cuneiform; Digits II & III with the intermediate cuneiform; and Digit IV with the lateral cuneiform. Digit V is special--it gets its own articulation with the cuboid. The cuboid is often impacted by stress fractures by people with bad posture.
The medial, intermediate, and lateral cuneiforms are affixed to the navicular bone. The navicular bone is attached to the main "hinge" of the ankle--the talus. The talus is what connects the foot bone to the leg bone.But what about the cuboid? It's attached to the giant calcaneus, or "heel bone." In all mammals, the heel bone functions as leverage for the Achilles' tendon. That tendon, in turn, is essentially responsible for muscle movement in the hind limb of mammals. Snap that tendon and it's all over.
I should note that, in almost all other mammals (except bears, racoons, and some fossil carnivorans), the foot is held digigrade--animals walk on their tippy-toes. This is the same in birds and non-avian dinosaurs...and most archosaurs, actually. The ankle structure in reptiles is far simpler than in mammals. In archosaurs (my specialty), there are two types:
Crocodile-normal: the ankle bones (calcaneum and astragalus) move somewhat independently of each other. There is a joint at the articulation between the ankle and the leg bones, and the ankle bones themselves, allowing the foot to "swivel" outward during locomotion.
Ornithodiran: The astragalus and calcaneum are a functional unit. In many taxa, they are fused together. The ornithodiran ankle is a simple hinge, allowing movement in one plane exclusively. In dinosaurs, the astragalus develops a prominent upward process that grows against the tibia, strengthening the ankle joint. In many birds, this process actually fuses to the tibia during ontogeny.
/SCIENCE LESSON
Topic: I got hit in the head with a hammer... (Read 2843 times)
