The extensor digiti minimi (extensor digiti quinti proprius) is a slender muscle of the
forearm
The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is most often used to describe the entire appendage of the upper limb, but which in anat ...
, placed on the ulnar side of the
extensor digitorum communis, with which it is generally connected.
It arises from the common extensor tendon by a thin tendinous slip and frequently from the
intermuscular septa between it and the adjacent muscles.
Its tendon passes through a compartment of the extensor retinaculum, posterior to distal radio-ulnar joint, then divides into two as it crosses the dorsum of the hand, and finally joins the
extensor digitorum tendon. All three tendons attach to the dorsal digital expansion of the fifth digit (little finger). There may be a slip of tendon to the fourth digit.
Variations
An additional fibrous slip from the
lateral epicondyle; the tendon of insertion may not divide or may send a slip to the
ring finger.
Absence of muscle rare; fusion of the belly with the
extensor digitorum communis not uncommon.
Variations to the fifth extensor compartment, which the extensor digiti minimi runs through, may cause tenosynovitis and can limit the use of the extensor digiti minimi.
Extensor digiti minimi can also be bifurcated, which means split, at many different points in the muscle.
Functions
The extensor digiti minimi is a two joint muscle. It acts as an extensor in both joints. It extends the wrist, which means it moves the back of the hand toward the back of the forearm. It also extends the little finger, which means it straightens the little finger from a fist.
Additional images
File:Gray214.png, Bones of left forearm. Posterior aspect.
File:Musculusextensordigitiminimi.png, Posterior surface of the forearm. Superficial muscles.
File:Gray421.png, Transverse section across distal ends of radius and ulna.
File:Gray422.png, Transverse section across the wrist and digits.
File:Slide5SSSS.JPG, Extensor digiti minimi muscle
File:Slide11SSSS.JPG, Extensor digiti minimi muscle '
File:Slide13TTTT.JPG, Extensor digiti minimi muscle
File:Slide1MAM.JPG, Muscles of hand. Posterior view.
File:Slide2TAT.JPG, Muscles of hand. Posterior view.
References
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External links
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Muscles of the upper limb