Part 6: Distal Limb Bones
In order to facilitate comparison between similar bones and to highlight similarities in structure and names of markings, I have put the pair of bones of the more distal limb segment together rather than featuring one limb at a time. To examine one limb at a time, and how bones connect, review your textbook and A Brief Atlas of the Human Body. Markings for which you are responsible are listed in Lab Exercise 7. You will need to be able to distinguish left from right for the tibia only.
Identification: The tibia is a large, heavy bone and thus potentially confused with the femur or humerus. Note that its superior end is rather flat-topped and lacks any sort of a rounded head. The other three bones are more slender and could be confused with each other. The fibula is distinguished by being longer and proportionately more slender than any other bone (the specimens are not quite to scale here). Also note that it is enlarged and pointed at both ends. The ulna is best identified by the distinctive U-shaped notch made by the olecranon and coracoid processes (think U for Ulna). The radius' most distinctive feature is the nearly perfectly round, flat-topped head (think radial).
Determining side: You only need to tell right from left for the tibia, not the smaller bones. To do so, first orient the tibia so that the larger flatter end is superior (up). The anterior crest (shin) should be anterior (front). Finally, the medial side can be determined by the medial malleolus (remember that the malleoli bracket the ankle and since the tibia is the medial bone of the lower limb, its malleolus must be medial). A right tibia is shown.