Answer: Hymen hardly tears because it is situated deep.
Step 1: In a young child, the hymen lies relatively deep within the vulva and the introitus is small. Full penetration usually does not occur.
Step 2: Because the act is often limited to vulval penetration without reaching the deeply placed hymen, the hymen frequently remains intact even after rape.
Step 3: An intact hymen therefore does NOT rule out sexual assault in a child. The hymen may also fail to rupture if it is tough, fleshy and elastic, or when penetration is incomplete. Among the options, the deep situation of the hymen in a child is the key reason it hardly tears. Ref: Gautam Biswas, Review of Forensic Medicine and Toxicology, 2nd edition, pg 332.