Orthopedics Sports Injuries Tendonitis Print Watershed Zone of Tendon Medically reviewed by a board-certified physician Written by twitter linkedin Written by Jonathan Cluett, MD Dr. Jonathan Cluett is a board-certified orthopedic surgeon with subspecialty training in sports medicine and arthroscopic surgery. Learn about our editorial policy Jonathan Cluett, MD Updated on May 17, 2019 Konstantin Inozemtsev/Getty Images More in Orthopedics Sports Injuries Tendonitis Overuse Injuries Sprains & Strains Fractures & Broken Bones Physical Therapy Orthopedic Surgery Osteoporosis Pediatric Orthopedics Shoulder & Elbow Hip & Knee Hand & Wrist Leg, Foot & Ankle Assistive Devices & Orthotics Medication & Injections View All A watershed zone of the tendon is a part of the tendon tissue that has the weakest blood supply. Watershed zones are important because they are the areas of tendon that are prone to injury. There are hundreds of tendons in our bodies, yet we commonly see only a select few tendon problems. These problem types of tendonitis occur in watershed zones of the tendon where the blood supply to that specific area of tissue is furthest away. The blood vessels that feed oxygen and nutrients to the tissue are far up and down the tendon, and must filter to the watershed zone through small capillaries. This watershed zone relies on distant blood supply and is therefore prone to injury. Tendons with watershed zones that are prone to tendonitis or tendon ruptures include: Achilles tendonRotator cuff tendonPosterior tibial tendonTennis elbow A watershed in nature is an area of land where the water flow is directed to a specific river or body of water. The ridges and mountain tops are furthest from these large bodies of water, much like the watershed zones of tendons are furthers from the strongest blood flow. Was this page helpful? Thanks for your feedback! Get exercise tips to make your workouts less work and more fun. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Continue Reading