R has various meanings in the Muscles category. Discover the full forms, definitions, and usage contexts of R in Muscles.
The rectum is the final straight portion of the large intestine in some mammals, and the gut in others. The human rectum is about 12 centimetres long, and begins at the rectosigmoid junction, at the level of the third sacral vertebra or the sacral promontory depending upon what definition is used.
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