Before going through the answer, I strongly recommend you do not try this on anybody.
To harm the heart you must know its defenses. They include the sternum (breastbone) and cardiac fluid, while the nervous system controls the heart.
To attack the heart you must disable the control.
It can be done by applying sufficient force on the sternum. The human knee can provide that force. One only needs to bend his knee and even a small strike on the opponent's sternum can be enough to stun the heart. This lethal action is rarely used in kick boxing for a knock out because of the possibility to kill the opponent.
So even though the knee is not sharp, it is enough to stop the heart and can even lead to death.
The canine teeth
well if your lungs get damaged then it could hurt your heart very badly.
The sharpest part of the body that is rigid is probably the Vomer (nasal bone). Not so rigid but can be sharp is a fingernail. Vomer Vomer Vomer Vomer Vomer Vomer
Yes the fang is the most sharpest tooth in a snakes mouth
Fovea centralis
It is most likely silver or gold as their shiny and if light shines down,the reflection will be the sharpest Adapted from my brain LOL-_-
I have the sharpest eyes in my classroom.
a great whites teeth are its most incredible defense structure its front row of teeth are the sharpest.
it has the sharpest blade
The most inferior part of the human body is the foot. The most superior is the head.
The sharpest handsaws are made of highly tempered steel. The sharpest power saw blades are carbide tipped.
It is the brain part of the human body that contains the most neonates.
maybe not the sharpest but pretty close.