An endoscope is an inspection instrument composed of image sensor, optical lens, light source and mechanical device, which is used to look deep into the body by way of openings such as the mouth or anus. A typical endoscope applies several modern technologies including optics, ergonomics, precision mechanics, electronics, and software engineering. With an endoscope, it is possible to observe lesions that cannot be detected by X-ray, making it useful in medical diagnosis. Endoscopes use tubes which are only a few millimeters thick to transfer illumination in one direction and high-resolution images in real time in the other direction, resulting in minimally invasive surgeries. It is used to examine the internal organs like the throat or esophagus. Specialized instruments are named after their target organ. Examples include the cystoscope (bladder), nephroscope (kidney), bronchoscope (bronchus), arthroscope (joints) and colonoscope (colon), and laparoscope. They can be used to examine visually and diagnose, or assist in surgery such as an arthroscopy.

உள்நோக்குக்கருவி (Endoscope) அல்லது அகநோக்கி என்பது என்பது மருத்துவ நோக்கில் உடலின் உட்பகுதியைப் பார்க்கப் பயன்படும் ஒரு கருவியாகும். பொதுவாக இது கண்ணாடியாலான மெல்லிய குழாய் கருவியாகும். அக நோக்குக் கருவி என்ற பெயராலும் இது அழைக்கப்படுகிறது.