Name
Pronunciation
(eks-TEN-sor IN-di-sis)
Origin/Proximal Attachment
Postero-lateral surface of ulna (distal to extensor pollicis longus)
Interosseous membrane
Antebrachial fascia
Insertion/Distal Attachment
Base of middle & distal phalanx of index (2nd) finger
Action/Relevance
Extends 2nd digit (MCP & IP joints)
Adducts 2nd digit
Assists to extend the hand at the wrist
Stabilizes MCP joint for flexion of IP solely
Innervation
Radial nerve - posterior interosseous (C6, 7,8)
Notes
Extensor indicis is one of the deep muscles on the extensor aspect of the forearm. It originates from the:
* extensor surface of the ulna at a level between the middle and distal thirds
* adjacent interosseous membrane
It inserts into the extensor expansion of the index finger. At this point, it lies to the ulnar side of extensor digitorum.
It acts to:
* extend all the joints of the index finger
* assist wrist extension
Extensor indicis is innervated by the posterior interosseous nerve (C7,C8).