Anatomy & Physiology: Muscles—Extensor Indicis.
Structure.
- Origin: posterior surface of ulna.
- Insertion: tendon of extensor digitorum of index finger.
Function.
- One of the deep distal four group.
- Concentric action: extends distal and middle phalanges of index finger at interphalangeal joints, proximal phalanx of index finger at metacarpophalangeal joint and hand at wrist joint. Lesser: adduction index finger at MCP; supination.
- Reverse mover action: extension of 2nd metacarpal at MCP; extension of proximal phalanx at PIP; middle phalanx extension at DIP.
- Eccentric action: controls/restrains/slows index finger flexion at MCP, DIP, PIP; wrist flexion; abduction of index finger; pronation.
- Isometric action: stabilize MCP, DIP, PIP of index finger; wrist; radioulnar joints.
- Innervation: deep radial nerve.
- Arterial supply: posterior interosseus artery; perforating branches of anterior interosseus artery.
Clinical Significance.
References
Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.
Cedars-Sinai. (2018). Vertebrae of the spine. Retrieved from https://www.cedars-sinai.org/health-library/diseases-and-conditions/v/vertebrae-of-the-spine.html
Clark, M., Lucett, S., Sutton, B. G., & National Academy of Sports Medicine. (2014). NASM essentials of corrective exercise training. Burlington, MA: Jones & Bartlett Learning.
Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.
Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.
