The valves of the heart, situated between the right auricle and ventricle, and left auricle and ventricle, and between the ventricles and large arteries, are represented by curved lines.
"Special Report on Diseases of Cattle"
U.S. Department of Agriculture J.R. Mohler
In the interval between the contractions these valves hang down into the ventricles.
"Special Report on Diseases of Cattle"
U.S. Department of Agriculture J.R. Mohler
When the walls of the ventricles squeeze down to drive out their blood into the lungs and around the body, like all other muscles they harden as they contract and thump the pointed lower end, or apex, of the heart against the wall of the chest, thus making what is known as the beat of the heart, which you can readily feel by laying your hand upon the left side of your chest, especially after you have been running or going quickly upstairs.
"A Handbook of Health"
Woods Hutchinson