If a tendon raises up when you touch your pinky to your thumb, it could be a sign of a few different things, most of which are related to the muscles and tendons of the hand. Here are a few possible explanations:

1. **Tendon Movement**: The tendon you’re seeing could be the **flexor tendon** of the hand, which helps in the movement of your fingers. When you bring your pinky and thumb together, it could cause this tendon to become more visible or pronounced, especially if your muscles are particularly well-defined or if you’re using the muscle with more force than usual.

2. **Accessory Tendon or Anomaly**: Some people have an **accessory tendon** that is more prominent, which can become visible when the fingers are moved in certain ways. This might be harmless, but if it’s noticeable or unusual, it could be worth investigating further with a healthcare professional.

3. **Tendon or Ligament Issue**: If the tendon or structure you see raising up is something new or unusual for you, it could suggest an injury or inflammation in the tendon or surrounding tissue, which might be related to overuse or strain. Inflammation or swelling in the tendon sheath could cause this type of bulging.

4. **Trigger Finger or Tendonitis**: Conditions like **trigger finger** or **tendonitis** can sometimes lead to abnormal movement or prominence of the tendons in the fingers. Inflammation or irritation in the tendons can make them more visible or pronounced, particularly when the hand is moved.

If the raised tendon is associated with pain, discomfort, or difficulty moving the fingers, it might be worth consulting a doctor or hand specialist to rule out any issues with the tendons or ligaments.