Detailed answer

Stretch marks, also known as striae, occur in the middle layer of the skin called the dermis. They are caused by rapid stretching or tearing of the skin, commonly associated with weight gain, growth spurts, or pregnancy. Since bones do not have skin covering them, stretch marks cannot develop directly on bones. However, stretch marks can form on the skin surrounding bones, such as the abdomen, thighs, breasts, or upper arms, if there is significant stretching of the skin in those areas.