Walter Martindale

Wrists don't really have muscles. Lots of tendons from the forearm muscles, lots of ligaments, and lots of small joints. To stretch tendons and ligaments (I'm not sure how wise it is to stretch ligaments) you need to apply gentle pressure for long times. To stretch muscles you also need to apply pressure for longer periods than we usually do in warm up exercises. The physio who works on my back from time to time will strap someone into a stretch for 20 minutes at a time (OUCH - but it works) to increase muscle length. The stimulus from the long stretch somehow causes the body to add sarcomeres, lengthening (and strengthening) the muscle.
W (sarcomeres are the little contractile units that work in series to shorten muscle - muscle fibres are made up of sarcomeres strung end-to-end, and muscle fibres are in parallel making up the bulk of a muscle)

To strengthen the muscles of the forearms, you can squeeze a rubber ball, do lots of suburi, do "roll-ups" with a stick, a rope, and a weight... reverse wrist curls with a bar or dumbbell, etc., etc...

My wrist hangover is still going on from early January. grrr