Have a look here to understand the anatomy of a human joint.
It may sound like a lame excuse, but the authors say men are wired to view women's anatomy as objects.
If he made reference to the lower part of the anatomy, take away 10.
late 14c., "study of the structure of living beings;" c.1400, "anatomical structures," from Old French anatomie, from Late Latin anatomia, from Greek anatomia, from anatome "dissection," from ana- "up" (see ana-) + temnein "to cut" (see tome). "Dissection" (1540s), "mummy" (1580s), and "skeleton" (1590s) were primary senses of this word in Shakespeare's day; meaning "the science of the structure of organized bodies" predominated from 17c. Often mistakenly divided as an atomy or a natomy.
The scyence of the Nathomy is nedefull and necessarye to the Cyrurgyen 
anatomy a·nat·o·my (ə-nāt'ə-mē)
The morphological structure of a plant or an animal or of any of its parts.
The science of the shape and structure of organisms and their parts.
Dissection of an animal to study the structure, position, and interrelation of its various parts.
The human body.