The mechanism of mechanoreception?
A mechanical stimulus can act on a tissue with elastic and viscoelastic properties in two ways [1, 2]:


distort the cellular membrane which leads to opening of ion channels.
create tension on the extracellular matrix or cytoskeleton, to which a ion channel is bound, thus leading to opening of the channel.


Stretch-activated ion channels opening leads to the formation of an action potential, if there is enough ionic flow to trigger depolarization [1, 3].



References:


Wikipedia contributors, "Stretch-activated ion channel," Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/w/index.php?title=Stretch-activated_ion_channel&amp;oldid=606349902 (accessed July 12, 2014).
Grigg P. Biophysical studies of mechanoreceptors. J. Appl. Physiol. 1986 Apr;60(4):1107-15. PubMed PMID: 2422151. 
Wikipedia contributors, "Mechanotransduction," Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/w/index.php?title=Mechanotransduction&amp;oldid=593605473 (accessed July 12, 2014).