Section 53 IPC is -
When a person arrested on a charge of commiting an offence of such anature & under such circumstances that there are reasonable grounds for believing that an examination of his person will offer some evidence , it shall be lawful for a registered medical practioner acting at the request of a police officer not below the rank of sub inspector.sec 363 is kidnapping. From Textbook of forensic medicine, V.V.Pillai, pg no 15 (16 edition)
Kidnapping
An accused can be examined by a medical practitioner at request of police, even without his consent or by force
Toure
Penjury
Medico legal procedures