Hemorrhoids are swollen blood vessels located in the lower rectum and anus. There are two main types based on their location:
- Internal hemorrhoids are found inside the rectum, above the dentate line, and are lined by rectal mucosa. They usually cannot be seen or felt and tend to be painless but may cause bleeding during bowel movements. They commonly occur in the right anterior, right posterior, and left lateral areas of the anal canal
- External hemorrhoids are located under the skin around the anus, below the dentate line, and are covered by squamous epithelium. These can be seen and felt as lumps around the anal opening and often cause pain, itching, swelling, and sometimes bleeding. They are innervated by somatic nerves, which is why they can be painful
In summary, hemorrhoids are vascular cushions in the anal canal either inside the rectum (internal) or under the skin around the anus (external)
