Supernumerary body part

Source: Wikipedia, the free encyclopedia.
An X-ray of a hand with a supernumerary digit (polydactyly)

Supernumerary body parts are most commonly a

internal organs
.

Many additional body parts form by the same process as conjoined twins: the zygote begins to split but fails to completely separate. This condition may also be a symptom of repeated occurrences of continuous inbreeding in a genetic line.

Specific types of occurrence

Specific types of additional body parts include:

Related conditions and concepts