These muscles were drawn for a goat, but the anatomy is essentially the same. Just remember that the back legs for mountain ram musculature isn't going to be as stocky; they slope down to allow more muscle in the back for jumping up and down mountains. The shoulders are also more powerfully muscled than a regular goat's. The neck muscles of a ram are thicker and more stocky and powerful to be able to power that awesome head ramming.
Also, check out this video of a little mountain goat with tons of personality: