Adnexa are structures attached to some the body's organs that play a role in their functions. These appendages may support organ function, protect the organ, or be involved in other ways. Some common examples of adnexa include the skin appendages, accessory visual structures, and adnexa uteri, the accessory organs attached to the uterus. Students of human anatomy learn to name organs and their accessory parts as they explore the function of various parts of the body.
The skin appendages include structures like hairs, sweat and sebaceous glands, and nails. These are not part of the skin itself but they are attached and directly adjacent to the skin. They also promote healthy skin function. The nails, for example, protect very tender areas of the skin that cannot be exposed to the environment without risk of injury. Likewise, sweat glands provide a way for the body to regulate heat as well as express toxins through the skin.
In the case of the adnexa uteri, the structures include the fallopian tubes attached to the uterus along with the ovaries. The uterus is also supported by a number of ligaments that hold it in place and maintain the positioning of other aspects of the pelvic anatomy. These ligaments may be considered important appendages, along with the vaginal canal, the structure that opens onto the uterus.
The accessory visual structures or adnexa of the eye include the eyelids, eyebrow, and eyelashes. All help to protect the eye, along with the glands that lubricate the eye to reduce the risk of injury and carry away small particles of material that land on the surface of the eye. Eyebrows and eyelashes filter out large materials that could be injurious to the eye, keeping the surface of the eye as clean as possible to reduce the risks of irritation and infection.
Although they are not directly part of the organs they support, the adnexa are an important part of the anatomy of the area the organ is located in. They also serve an important function directly related to the workings of the organ. With the uterus, for example, the ovaries are needed to release eggs and the fallopian tubes need to move the eggs so that they can land in the uterus, where they can be fertilized and implanted, eventually developing into a fetus. Injury to one of the adnexa can impair the function of the organ, as seen in burn victims who lose their eyelids and experience eye problems as a result.