Would you have expected to have found more Meissner's corpuscles and Merkel discs on the palm or on the posterior shoulder? why?

The answer is on the palm.

Meissner's corpuscles and Merkel's disks are types of tactile mechanoreceptors. They have gated ion channels which open and close in response to pressure, touch sound. Meissner's corpuscles are fast adapting, encapsulated neurons whereas, Merkel's disk are slow-adapting, non-capsulated neuron. They responds to vibrations and fine touch; they are located in the skin where there is no hair such as the palms and fingers.