AP (anteroposterior)

AP (anteroposterior): In anatomy, AP stands for anteroposterior: from front-to-back. For example, an AP X-ray of the chest is taken from front-to-back. AP in this respect is the opposite of PA, which stands for posteroanterior: from back-to-front.
Found on http://www.medterms.com/script/main/art.asp?articlekey=9208
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