Hitchhiker’s thumb is a thumb that’s hypermobile, or very flexible, and able to bend backward beyond the normal range of motion. People with hitchhiker’s thumb have distal joints that can bend back as far as 90 degrees. Hitchhiker’s thumb can occur in one or both thumbs.
Hitchhiker's thumb is otherwise known as distal hyperextensibility of the thumb. This is because of the genetic traits that make a person bend his thumb.
Some people have "hitchhiker's thumbs," which bend backwards with a large angle between the two segments (phalanges). The myth is that there are just two kinds of thumbs, straight thumbs (S) and hitchhiker's thumbs (H), and the trait is controlled by a single gene with two alleles.
The Hitchhiker's Thumb is often referenced as a visual trait of genetic inheritance. Here we discuss the science behind it and how we.