Haemorrhoids

WHAT ARE

Haemorrhoids are part of the normal anatomy of both men and women and are located in the lower part of the rectum, near the anal canal, already at birth. They are a complex of arteries, capillaries and veins. These blood vessels are equipped with valves that open and close to swell and shrink haemorrhoids, which are secured to the anus lining through fibrous ligaments. The haemorrhoidal plexus (i.e. the complex of cushions formed by the blood vessels of haemorrhoids) is made up of internal haemorrhoids and external haemorrhoids:

• Internal haemorrhoids are the haemorrhoidal cushions located above the "dentate line" (i.e. the upper verge of the anatomical anal canal; it is also known as "pain line", because painful stimuli can be felt underneath it). Internal haemorrhoids are insensitive, since they are covered by rectal mucosa, which does not have sensory innervations.
• External haemorrhoids are the haemorrhoidal cushions located underneath the "dentate line". External haemorrhoids are covered by anoderm, a very sensitive skin layer that also forms the outer lining of the anus.

Haemorrhoids optimize anal continence, especially for liquids and gases, since they close the anus when they swell due to blood inflow.