What body part does Gemini rule?

I'm curious, could you tell me which specific body part is associated with the astrological sign of Gemini? It's a fascinating topic that I've always been intrigued by, and I'm eager to learn more about the connection between astrology and the human body. Is there a particular body part that Gemini is said to rule over, or is it more of a conceptual LINK that cannot be reduced to a single anatomical feature?