From Surf Wiki (app.surf) — the open knowledge base

Lumbricals of the hand

Muscles in the central compartment of the hand

Field	Value
Name	Lumbricals of the hand
Latin	musculi lumbricales manus
Image	Lumbricales (hand).png
Caption	The muscles of the left hand. Palmar surface. (first lumbricalis labeled at bottom right of muscular group)
Origin	Flexor digitorum profundus
Insertion	Extensor expansion
Blood	Superficial palmar arch, common palmar digital arteries, deep palmar arch, dorsal digital artery
Nerve	Third and fourth deep branch of ulnar nerve, first and second median nerve
Action	Flex metacarpophalangeal joints, extend interphalangeal joints
part_of	Hand

The lumbricals are intrinsic muscles of the hand that flex the metacarpophalangeal joints, and extend the interphalangeal joints. p. 97

The lumbrical muscles of the foot also have a similar action, though they are of less clinical concern.

Structure

The lumbricals are four, small, worm-like muscles on each hand. These muscles are unusual in that they do not attach to bone. Instead, they attach proximally to the tendons of flexor digitorum profundus, and distally to the extensor expansions.

Fourth	bipennate	One head originates on the radial side of the flexor digitorum profundus tendon corresponding to the little finger, while the other originates on the ulnar side of the tendon for the ring finger.	The muscle passes posteriorly along the radial side of the little finger to insert on its extensor expansion.

Lumbricals labeled at bottom left. Left hand, palmar view.

Nerve supply

The first and second lumbricals (the most radial two) are innervated by the median nerve. The third and fourth lumbricals (most ulnar two) are innervated by the deep branch of ulnar nerve.

This is the usual innervation of the lumbricals (occurring in 60% of individuals). However 1:3 (median:ulnar - 20% of individuals) and 3:1 (median:ulnar - 20% of individuals) also exist. The lumbrical innervation always follows the innervation pattern of the associated muscle unit of flexor digitorum profundus (i.e. if the muscle units supplying the tendon to the middle finger are innervated by the median nerve, the second lumbrical will also be innervated by the median nerve).

Blood supply

Four separate sources supply blood to these muscles: the superficial palmar arch, the common palmar digital artery, the deep palmar arch, and the dorsal digital artery.

Function

The lumbrical muscles, with the help of the interosseous muscles, simultaneously flex the metacarpophalangeal joints while extending both interphalangeal joints of the digit on which it inserts. The lumbricals are used during an upstroke in writing.

Etymology

The term "lumbrical" comes from the Latin, meaning "worm".

Additional images

File:Gray416.png|Tendons of forefinger and vincula tendina File:Slide2yyy.JPG|Lumbricals of the hand File:Slide5RRR.JPG|Lumbricals of the hand File:Slide14RRR.JPG|Lumbricals muscle File:Slide6PPP.JPG|Lumbricals muscle File:Slide4VVV.JPG|Lumbricals muscle File:Slide4AAAA.JPG|Lumbricals muscle File:Slide9AAAA.JPG|Lumbricals muscle File:Slide1MAI.JPG|Muscles of hand, cross section File:Slide1dsds.JPG|Wrist joint. Deep dissection. Anterior, palmar view File:Slide2dsds.JPG|Wrist joint. Deep dissection. Anterior, palmar view File:Slide3dsds.JPG|Wrist joint. Deep dissection. Anterior, palmar view

References

(October 2007). "The vascular anatomy of the lumbrical muscles in the hand". Journal of Plastic, Reconstructive & Aesthetic Surgery.
(January 2014). "A biomechanical and evolutionary perspective on the function of the lumbrical muscle". The Journal of Hand Surgery.
(April 2003). "Lumbrical tears in rock climbers". Journal of Hand Surgery.
(February 1996). "Innervation of the lumbrical muscles". Journal of Hand Surgery (Edinburgh, Scotland).
(1999). "Last's Anatomy: Regional and Applied". Churchill Livingstone.
(June 1998). "The blood supply of the lumbrical muscles". Journal of Hand Surgery.
(2018-12-01). "The effects of the communicating branch between medial and lateral plantar nerves on the innervations of the foot lumbrical muscles". Journal of the Anatomical Society of India.

Info: Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

muscles-of-the-upper-limb hand

Want to explore this topic further?

Ask Mako anything about Lumbricals of the hand — get instant answers, deeper analysis, and related topics.

Research with Mako

Free with your Surf account

Content sourced from Wikipedia, available under CC BY-SA 4.0.

This content may have been generated or modified by AI. CloudSurf Software LLC is not responsible for the accuracy, completeness, or reliability of AI-generated content. Always verify important information from primary sources.

Report