Final answer:
A rigid instrument called an endoscope is used in the procedure proctoscopy to examine the anus and lower rectum. The endoscope is a device that transmits light to illuminate internal parts and is used for exploring the body and performing surgery.
Step-by-step explanation:
In the procedure proctoscopy, a rigid instrument called an endoscope is used to examine the anus and lower rectum. The endoscope is a device that transmits light down one fiber bundle to illuminate internal parts and transmits the reflected light back out through another bundle for observation. It is used to explore the body through various orifices or minor incisions, and can also be used for surgery and obtaining samples.