A subcategory of plastic and reconstructive surgery, microsurgery is any type of surgery which requires magnification with a microscope. It has allowed for significant progress in all fields of surgery and is utilized in specialty surgeries such as neurosurgery and transplant surgery. In plastic and reconstructive surgery, it is used in the transfer of free living tissue, or free flap, over distances which would not allow the use of the blood supply of origin. The free flap is usually comprised of several tissue types including the skin, muscle, fat and bone and can be isolated on a feeding artery and vein. Therefore, any form of free flap, such as the use of abdominal musculature in the free form to reconstruct a breast following a mastectomy, is in need of microsurgical repair.
In its most advanced form, a free flap can be a functional muscle transfer. For example, in reconstructive surgery, a thigh muscle, such as the gracilis muscle, can be excised and transferred to the face. In cases where a patient suffers from facial paralysis, this muscle can be attached in a new position, and reconnected to both the arterial and venous blood supply as well as the facial nerves in order for the muscle to function creating a relearned smile.