Insinuate
In the biomedical sciences, to introduce slowly, through a winding or narrow passage, or by a persistent movement.
The term 'insinuate' in this sense carries the connotation of introducing artfully and gently, as a cardiologist would do in insinuating a catheter (a tube) into the arteries of ones heart.
The origin of 'insinuate' is curious.
It came from the Latin <I>in-</I>, in + <I>sinus</I>, the bosom, so it literally meant 'in the bosom.'