Patella of age. Due to the great stress on the patellofemoral joint during resisted knee flexion, the articular cartilage of the patella is among the thickest in the human body. The lower part of the posterior surface has vascular canaliculi filled and is filled by fatty tissue, the infrapatellar fat pad. Emarginations (i.e. "patella emarginata", a "missing piece") are common laterally on the proximal edge. Bipartite patellas are the result of an ossification of a second cartilaginous layer at the location of an emargination. Previously, bipartite patellas were explained as the failure of several ossification centres to fuse, but this idea
Composition of the human body mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium. All 11 are necessary for life. The remaining elements are trace elements, of which more than a dozen are thought on the basis of good evidence to be necessary for life. All of the mass of the trace elements put together (less than 10 grams for a human body) do not add up to the body mass of magnesium, the least common of the 11 non-trace elements.