What are the similarities in the structure of the upper and lower extremities? How can this be explained? What are the differences?

Both limbs consist of three sections formed by bones of a similar type (shoulder, forearm, hand and thigh, lower leg, foot), between which there are articular joints that provide mobility, the structure of the hand and foot also has much in common. This similarity in structure is explained by similar functions, since in human ancestors both limbs performed the function of locomotion. Differences arise in a person as a result of the fact that the hands become an organ of labor activity, and the legs retain the role of support when moving. The bones of the lower extremities are thicker and more massive, their joints are less mobile, the big toe is connected to the rest, the heel bone is pronounced. The bones of the upper limbs are less massive, the thumb is opposed to the rest, the carpometacarpal joint of the thumb is very mobile.

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