The Abdomen.
—The abdomen is the largest cavity in the body. It is oval in form, the extremities of the oval being directed upward and downward.
To facilitate description, the abdomen is artificially divided into two parts:
An upper and larger part, the abdomen proper.
A lower and smaller part, the pelvis.
These two cavities are not separated from each other, but the limit between them is a line drawn around the brim of the true pelvis.
The abdomen proper differs from the other great cavities of the body, in being bounded for the most part by muscles and fascia.
It varies in capacity and shape according to the condition of the viscera which it contains and in addition, it varies in form and extent with age and sex.
Boundaries.—The diaphragm forms the dome over the abdomen, the cavity of the abdomen extending high into the bony thorax.
The lower end of the abdomen is limited by the bones of the pelvis.