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)
Medico legal procedures
Kidnapping
An accused can be examined by a medical practitioner at request of police, even without his consent or by force
Toure
Penjury
An accused can be examined by a medical practitioner at request of police, even without his consent or by force