A "trick thumb" isn't a medically recognized term. The phrase likely refers to one of two distinct concepts:
1. Trigger Thumb: A Medical Condition
This is a far more common interpretation. Trigger thumb, also known as stenosing tenosynovitis, is a condition affecting the tendons that flex the fingers and thumb. Trigger Finger - Trigger Thumb - OrthoInfo - AAOS It causes a locking or catching sensation when bending and straightening the digit. Other symptoms include pain and stiffness. The Mayo Clinic notes that it can cause a finger (including the thumb) to get stuck in a bent position, straightening suddenly with a snap. Trigger finger - Symptoms and causes - Mayo Clinic The thumb is frequently affected, just like other fingers. Trigger Finger: Symptoms, Causes, & Treatment Treatment options range from conservative methods to surgery. Treatment Options for Trigger Finger and Trigger Thumb | HSS
2. The "Thumb Trick" for Wildlife Observation: A Safety Technique
Alternatively, "trick thumb" might refer to a technique for judging safe viewing distance from wildlife. The Leave No Trace Center for Outdoor Ethics describes a method where you extend your arm, make a thumbs-up gesture, close one eye, and see if your thumb can completely cover the animal. If it can't, you're too close. Using the Thumb Trick: Keep a Safe Distance From Wildlife - Leave ... This "thumb trick" ensures responsible wildlife viewing. Do You Know The Thumb Trick? - Leave No Trace
3. Magic Trick Props: A Less Likely Interpretation
Lastly, "trick thumb" could allude to props used in magic tricks, like fake thumb tips used to create illusions. Magic Thumb - Amazon.com This interpretation is less likely given the question's general phrasing.
