Acupuncture is the use of fine needles to stimulate areas or points on the body. The standard filiform needle is one of nine needles that are most commonly used. Some needles used for acupuncture techniques do not penetrate the skin. They are used for pressure stimulation, and scraping. 

The biomedical model of acupuncture effectiveness is in the stimulation of areas that are of least resistance in the bioelectrical field. The acupuncture needle creates an irritation, which sends the signal through the sympathetic nervous system to the brain. The brain then interprets the signal to release a myriad of compounds to the targeted area for the healing response. Acupuncture has also been shown to increase the uptake and regeneration of released compounds for healing, thereby offering a faster than normal recovery time.

For more information about Acupuncture, you can follow the link to the National Institutes of Health Complementary Medicine Department.

http://nccam.nih.gov/health/acupuncture/