In traditional astrology, each zodiac sign is thought to rule or govern a different body part. Aries rules the head, Taurus the neck, Gemini the shoulders, Cancer the chest, Leo the heart, Virgo the intestines, Libra the kidneys, Scorpio the reproductive organs, Sagittarius the hips, Capricorn the knees, Aquarius the ankles, and Pisces the feet.
Typically an Astrologer will use this system while looking at your birth chart to determine the source of current or potential illness. This system reflects the holistic philosophy underlying traditional astrology, where different parts of the cosmos are seen as interrelated and interconnected.