Extensor indicis muscle

Extensor indicis proprius
Transverse section across distal ends of radius and ulna. (Label "Ext. indic. prop." visible at bottom center.)
The mucous sheaths of the tendons on the back of the wrist. (Extensor indicis proprius visible going into second digit.)
Latin	musculus extensor indicis
Gray's	subject #125 456
Origin	ulna
Insertion	index finger (extensor hood)
Artery	posterior interosseous artery
Nerve	posterior interosseous nerve
Actions	extends index finger, wrist

The extensor indicis proprius (Extensor indicis) is a narrow, elongated muscle, placed medial to, and parallel with, the extensor pollicis longus.

Origin and insertion

It arises from the dorsal surface of the body of the ulna below the origin of the Extensor pollicis longus and from the interosseous membrane.

Its tendon passes under the dorsal carpal ligament in the same compartment as that which transmits the tendons of the Extensor digitorum communis, and opposite the head of the second metacarpal bone, joins the ulnar side of the tendon of the Extensor digitorum communis which belongs to the index finger.

Action

The Extensor indicis proprius extends the index finger, and by its continued action assists in extending the wrist.

Additional images

Bones of left forearm. Posterior aspect.

Posterior surface of the forearm. Deep muscles.

Transverse section across the wrist and digits.

External links

• LUC exi
• SUNY Labs 09:05-0106 - "Extensor Region of Forearm and Dorsum of Hand: Deep Muscles of Extensor Region"
• lesson5musofpostforearm at The Anatomy Lesson by Wesley Norman (Georgetown University)
• Duke Orthopedics extensor_indicis
• Extensor+indicis+muscle at eMedicine Dictionary

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.