Probably you’ve heard of the “biceps”, but you might not have thought of it as the “sommelier’s muscle”! And yet, the action of opening a wine bottle sums up the two major actions of this muscle.
But first of all, be warned that you have a biceps muscle in your thigh as well — so to be clear, the biceps in your arm is called biceps brachii (“two-headed muscle of the arm”).
The biceps brachii attaches to your forearm on the anterior side, and thus flexes the elbow — pulling the forearm toward the shoulder, and thus folding your upper limb in two. But it also supinates the forearm — this is a rotational action that twists the forearm (and the hand with it) from a “palm backward” (or downward) position to a “palm forward” (or upward) position.
Supination has many uses, such as turning your cupped hands upward to “drink soup“, begging for mercy as you “supplicate”, or perhaps even expressing a certain attitude with “…’sup bro!” — and these can be helpful mnemonics for remembering this action.
The reason for this lesser-known action of the biceps brachii is that the muscle attaches to the inner surface of the radius (of the two long bones in your forearm, this is the one that sits on the lateral or thumb side). As the muscle contracts, that surface is pulled toward the shoulder, rotating the radius laterally, which carries the hand with it.
When opening a wine bottle, supination is used to twist the corkscrew clockwise, inserting it into the cork. This is followed by flexion at the elbow, as you pull the cork out of the bottle. Be mindful, though, that this only works with your right hand! Supination with your left hand achieves the opposite, which is helpful at the end — twisting counterclockwise, to get that corkscrew out of the cork.