Lumbricals of the hand: Difference between revisions

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{{Short description|Muscles in the central compartment of the hand}}

:''For {{for|the foot muscles, see [[|Lumbrical muscle of the foot]]''}}

{{Muscle infobox |

{{Infobox muscle

Name = {{PAGENAME}} |

| ImageName = Gray427.pngLumbricals |of the hand

| Latin = musculi lumbricales manus

Caption = The muscles of the left hand. Palmar surface. |

| OriginImage = |Lumbricales (hand).png

| Caption = The muscles of the left hand. Palmar surface. (first |lumbricalis labeled at bottom right of muscular group)

Insertion = |

| Origin = [[Flexor digitorum profundus]]

Blood = |

| Insertion = [[Extensor expansion]]

Nerve = [[ulnar nerve]], [[median nerve]] |

| Blood = [[Superficial palmar arch]], [[common palmar digital arteries]], [[deep palmar arch]], [[dorsal digital arteries of hand|dorsal digital artery]]

Action = |

| Nerve = Third and fourth [[deep branch of ulnar nerve]], first and second [[median nerve]] |

| Action = [[Flexion|Flex]] [[metacarpophalangeal joint]]s, [[Extension (kinesiology)|extend]] [[Interphalangeal articulations of hand|interphalangeal joints]]

| part_of = [[Hand]]

}}

The '''lumbrical muscleslumbricals''' are intrinsic [[muscle]]s inof the [[fingerhand]]s that allow [[flexion at|flex]] the metacarpophalangeal [[metacarpophalangeal joint]]s,<ref whilename="Gosling97" maintaining/> and [[extension at(kinesiology)|extend]] the [[Interphalangeal articulations of hand|interphalangeal joints]].<ref name = Gosling97>{{cite book | vauthors = Gosling JA, Harris PF, Humpherson JR, Whitmore I, Willan PL | title = Human Anatomy: Color Atlas and Textbook | edition = 5th | year = 2008 | publisher = Mosby | ___location = Philadelphia | isbn = 978-0-7234-3451-1 | ref = Gosling }}

p. 97</ref><ref name=":0">{{cite journal | vauthors = Bilge O, Pinar Y, Ozer MA, Govsa F | title = The vascular anatomy of the lumbrical muscles in the hand | journal = Journal of Plastic, Reconstructive & Aesthetic Surgery | volume = 60 | issue = 10 | pages = 1120–6 | date = October 2007 | pmid = 17825776 | doi = 10.1016/j.bjps.2006.06.023 }}</ref>

ThereThe are[[lumbrical alsomuscle of the foot|lumbrical muscles of the [[foot]] thatalso have a similar action, though thesethey are of less clinical concern.

There are four of these small worm-like muscles on each hand. This muscles are unusual in that they do not attach to bone, instead attaching proximally to the tendons of [[flexor digitorum profundus]] and distally to extensor expansions on the dorsal surface (back of) the hand.

== Structure ==

The medial two lumbricals, those of the ring and the little finger, are bifurcated (attach proximally to two tendons each). Their motor supply comes from the [[ulnar nerve]].

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]],<ref name="Gosling97" /><ref name=":0" /><ref name=":1">{{cite journal | vauthors = Wang K, McGlinn EP, Chung KC | title = A biomechanical and evolutionary perspective on the function of the lumbrical muscle | journal = The Journal of Hand Surgery | volume = 39 | issue = 1 | pages = 149–55 | date = January 2014 | pmid = 24369943 | pmc = 4155599 | doi = 10.1016/j.jhsa.2013.06.029 }}</ref> and distally to the [[extensor expansion]]s.<ref name = Gosling97/><ref name=":1" /> The first and second lumbricals are [[Anatomical terms of muscle|unipennate]], while the third and fourth lumbricals are [[Anatomical terms of muscle|bipennate]].<ref name=":0" /><ref>{{cite journal | vauthors = Schweizer A | title = Lumbrical tears in rock climbers | journal = Journal of Hand Surgery | volume = 28 | issue = 2 | pages = 187–9 | date = April 2003 | pmid = 12631495 | doi = 10.1016/S0266-7681(02)00250-4 | s2cid = 244111 | citeseerx = 10.1.1.539.6140 }}</ref>

{| class="wikitable"

The lumbrical muscles of the index and middle finger are innervated by the [[median nerve]].

| '''#''' || '''Form''' || '''Origin''' || '''Insertion'''

|-

| First || [[unipennate]] || It originates from the radial side of the most radial tendon of the flexor digitorum profundus (corresponding to the index finger). || It passes posteriorly along the radial side of the index finger to insert on the [[extensor expansion]] near the [[metacarpophalangeal joint]].

|-

| Second || unipennate || It originates from the radial side of the second most radial tendon of the flexor digitorum profundus (which corresponds to the middle finger). || It passes posteriorly along the radial side of the middle finger and inserts on the extensor expansion near the metacarpophalangeal joint.

|-

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

|-

| 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.

|}

{{Clear}}

[[File:1121 Intrinsic Muscles of the Hand Superficial sin.png|thumb|right|Lumbricals labeled at bottom left. Left hand, palmar view.]]

===Nerve supply===

There are also lumbrical muscles of the [[foot]] that have a similar action, though these are of less clinical concern.

The first and second lumbricals (the most radial two) are [[Nerve|innervated]] by the [[median nerve]]. The third and fourth lumbricals (most ulnar two) are innervated by the deep branch of [[ulnar nerve]].<ref name="pmid8676031">{{cite journal | vauthors = Lauritzen RS, Szabo RM, Lauritzen DB | title = Innervation of the lumbrical muscles | journal = Journal of Hand Surgery (Edinburgh, Scotland) | volume = 21 | issue = 1 | pages = 57–8 | date = February 1996 | pmid = 8676031 | doi = 10.1016/s0266-7681(96)80013-1 | s2cid = 8084761 }}</ref>

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 muscle|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).<ref>{{cite book |last1=Sinnatamby |first1=Chummy S. | name-list-style = vanc |title=Last's Anatomy: Regional and Applied |date=1999 |publisher=Churchill Livingstone |___location=Edinburgh |isbn=978-0-443-05611-6 |edition=10th | pages = 64, 82 }}</ref>

==See also==

* [[Lumbrical muscle of the foot]]

==External=Blood linkssupply===

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 arteries of hand|dorsal digital artery]].<ref>{{cite journal | vauthors = Zbrodowski A, Mariéthoz E, Bednarkiewicz M, Gajisin S | title = The blood supply of the lumbrical muscles | journal = Journal of Hand Surgery | volume = 23 | issue = 3 | pages = 384–8 | date = June 1998 | pmid = 9665531 | doi = 10.1016/S0266-7681(98)80063-6 | s2cid = 26384944 }}</ref>

* {{MuscleLoyola|lumh}}

== Function ==

The lumbrical muscles, with the help of the interosseous muscles, simultaneously flex the [[metacarpophalangeal joint]]s while extending both [[Interphalangeal articulations of hand|interphalangeal joint]]s 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]]".<ref>{{Cite journal|last1=Bozer|first1=Cüneyt|last2=Uzmansel|first2=Deniz|last3=Dönmez|first3=Didem|last4=Parlak|first4=Muhammed|last5=Beger|first5=Orhan|last6=Elvan|first6=Özlem|date=2018-12-01|title=The effects of the communicating branch between medial and lateral plantar nerves on the innervations of the foot lumbrical muscles|url=http://www.sciencedirect.com/science/article/pii/S000327781730624X|journal=Journal of the Anatomical Society of India|language=en|volume=67|issue=2|pages=130–132|doi=10.1016/j.jasi.2018.11.006|s2cid=81678124 |issn=0003-2778|url-access=subscription}}</ref>

==Additional images==

<gallery mode="packed" heights="85">

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

</gallery>

== References ==

{{Reflist|30em}}

{{Muscles of upper limb}}

{{Authority control}}

[[Category:Muscles of the upper limb]]

[[Category:Muscles of the upper limb]]

[[fr:Muscle lombrical]]

[[Category:Hand]]