BIO 135
Long Bones of the Distal Limb Segment
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The markings of the tibia, fibula, ulna, and radius.
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 proporionately 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 of course 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.
This
page maintained by Bill Snyder.
Last updated August 20, 2008