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Extensor Indicis Anatomy: Origin, Insertion, Action

Extensor Indicis origin, insertion, action, and innervation

Extensor Indicis

O, I, A of the Extensor Indicis

Origin: Posterior surface of the ulna (distal to extensor pollicis longus) and the interosseous membrane
Insertion: Dorsal surface of the base of the middle phalanx and distal phalanx of the index digit
Actions: Extension of the second digit (index finger)
Innervation: Radial nerve (C6, C7, C8)
Vascular Supply: Posterior interosseous artery from the ulnar artery

Primary Actions of the Extensor Indicis:

1. Extension of the second digit at the metacarpophalangeal joint

  Agonists: Extensor Digitorum

  Antagonists: 

  • First Dorsal Interosseous
  • First Palmar Interosseous
  • First Lumbrical
  • Flexor Digitorum Superficialis
  • Flexor Digitorum Profundus

2. Extension of the second digit at the proximal interphalangeal joint

  Agonists:

  • Extensor Digitorum
  • First Lumbrical
  • First Dorsal Interosseous
  • First Palmar Interosseous

  Antagonists:

  • Flexor Digitorum Superficialis
  • Flexor Digitorum Profundus

2. Extension of the second digit at the distal interphalangeal joint

  Agonists:

  • Extensor Digitorum
  • First Lumbrical
  • First Dorsal Interosseous,
  • First Palmar Interosseous

  Antagonists: Flexor Digitorum Profundus

Secondary Actions of the Extensor Indicis:

1. Assists with adduction of the second digit at the carpometacarpal joint

  Agonists: First Palmar Interosseous

  Antagonists: First Dorsal Interosseous

extensor-indicis-fea

Information about cause and effect of extensor indicis pain:

Extensor Indicis Muscle: Hand and Finger Pain


Basic Clinical Massage Therapy

basic_clinical_massa

Out of the scores of books in my office Basic Clinical Massage Therapy is by far the most referenced book in my library. The musculoskeletal system is overlaid on human models allowing you to learn the precise location, origin and insertions of each muscle. The models are pictured in various poses throughout the book which also helps you visualize muscles in motion and their actions relationship with the skeletal structure and other muscles. Though it is written for massage therapists, it is an excellent book for anyone who wants to learn about the muscular system. MT's will benefit from recommended treatments for each muscle.

Anatomy Coloring Book

coloring_book

The Anatomy Coloring Book is one of the best study and reference books for beginning anatomy students. The diagrams are clearly labeled and allow you to see the relationship and placement of the various structures of the body. You will also be surprised how the act of coloring will help with recall. But this is not just a beginners book, it is also great for practitioners and therapists to have on hand to use with clients and patients to use as a visual reference.

 

References:

The Trigger Point Therapy Workbook – Claire Davies, Amber Davies, and David G. Simons

Basic Clinical Massage Therapy: Integrating Anatomy and Treatment – James H. Clay and David M. Pounds

Trigger Point Therapy for Myofascial Pain – Donna Finando and Steven Finando