What part of the hand does onychophagy affect, leading to increased blood flow and faster nail growth?

Onychophagy, commonly known as nail biting, specifically affects the nail matrix, which is the tissue located beneath the base of the nail. The nail matrix is crucial because it is where new nail cells are generated. When a person engages in nail-biting behavior, the trauma can lead not only to an increase in blood flow to the area but also to stimulation of the matrix itself. This increased circulation can promote faster growth of the nails as the body attempts to heal the affected area.

The nail bed, nail plate, and cuticle play important roles in the overall structure and health of the nail, but it is the nail matrix that is directly responsible for nail growth. The other parts do not have the same impact on growth rates as the matrix does.