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diff --git a/assets/thumb.txt b/assets/thumb.txt new file mode 100644 index 00000000..566ad980 --- /dev/null +++ b/assets/thumb.txt @@ -0,0 +1,1479 @@ +[Jump to content](#bodyContent) + +Main menu + +Main menu + +move to sidebar + +hide + +Navigation + +- [Main page](/wiki/Main_Page "Visit the main page [z]") +- [Contents](/wiki/Wikipedia:Contents "Guides to browsing Wikipedia") +- [Current + events](/wiki/Portal:Current_events "Articles related to current events") +- [Random + article](/wiki/Special:Random "Visit a randomly selected article [x]") +- [About + Wikipedia](/wiki/Wikipedia:About "Learn about Wikipedia and how it works") +- [Contact + us](//en.wikipedia.org/wiki/Wikipedia:Contact_us "How to contact Wikipedia") + +Contribute + +- [Help](/wiki/Help:Contents "Guidance on how to use and edit Wikipedia") +- [Learn to + edit](/wiki/Help:Introduction "Learn how to edit Wikipedia") +- [Community + portal](/wiki/Wikipedia:Community_portal "The hub for editors") +- [Recent + changes](/wiki/Special:RecentChanges "A list of recent changes to Wikipedia [r]") +- [Upload + file](/wiki/Wikipedia:File_upload_wizard "Add images or other media for use on Wikipedia") +- [Special pages](/wiki/Special:SpecialPages) + +[ + + +](/wiki/Main_Page) + +[ Search](/wiki/Special:Search "Search Wikipedia [f]") + +Search + +Appearance + +- [Donate](https://donate.wikimedia.org/?wmf_source=donate&wmf_medium=sidebar&wmf_campaign=en.wikipedia.org&uselang=en) +- [Create + account](/w/index.php?title=Special:CreateAccount&returnto=Thumb "You are encouraged to create an account and log in; however, it is not mandatory") +- [Log + in](/w/index.php?title=Special:UserLogin&returnto=Thumb "You're encouraged to log in; however, it's not mandatory. [o]") + +Personal tools + +- [Donate](https://donate.wikimedia.org/?wmf_source=donate&wmf_medium=sidebar&wmf_campaign=en.wikipedia.org&uselang=en) +- [ Create + account](/w/index.php?title=Special:CreateAccount&returnto=Thumb "You are encouraged to create an account and log in; however, it is not mandatory") +- [ Log + in](/w/index.php?title=Special:UserLogin&returnto=Thumb "You're encouraged to log in; however, it's not mandatory. [o]") + +Pages for logged out editors [learn more](/wiki/Help:Introduction) + +- [Contributions](/wiki/Special:MyContributions "A list of edits made from this IP address [y]") +- [Talk](/wiki/Special:MyTalk "Discussion about edits from this IP address [n]") + +## Contents + +move to sidebar + +hide + +- [](#) + (Top) +- [](#Definition) + 1 Definition + + Toggle Definition subsection + - [](#Thumb_and_fingers) + 1.1 Thumb and fingers +- [](#Opposition_and_apposition) + 2 Opposition and apposition + + Toggle Opposition and apposition subsection + - [](#Humans) + 2.1 Humans + - [](#Other_primates) + 2.2 Other primates + - [](#Other_placental_mammals) + 2.3 Other placental mammals + - [](#Marsupials) + 2.4 Marsupials + - [](#Reptiles) + 2.5 Reptiles + - [](#Dinosaurs) + 2.6 Dinosaurs + + - [](#Birds) + 2.6.1 Birds + - [](#Pterosaurs) + 2.6.2 Pterosaurs + - [](#Amphibians) + 2.7 Amphibians +- [](#Human_anatomy) + 3 Human anatomy + + Toggle Human anatomy subsection + - [](#Skeleton) + 3.1 Skeleton + - [](#Muscles) + 3.2 Muscles + + - [](#Extrinsic) + 3.2.1 Extrinsic + - [](#Intrinsic) + 3.2.2 Intrinsic + - [](#Variations) + 3.3 Variations + - [](#Grips) + 3.4 Grips +- [](#Human_evolution) + 4 Human evolution +- [](#See_also) + 5 See also +- [](#Notes) + 6 Notes +- [](#References) + 7 References +- [](#External_links) + 8 External links + +Toggle the table of contents + +# Thumb + +103 languages + +- [अंगिका](https://anp.wikipedia.org/wiki/%E0%A4%85%E0%A4%82%E0%A4%97%E0%A5%82%E0%A4%A0%E0%A4%BE "अंगूठा – Angika") +- [Ænglisc](https://ang.wikipedia.org/wiki/%C3%9E%C5%ABma "Þūma – Old English") +- [العربية](https://ar.wikipedia.org/wiki/%D8%A5%D8%A8%D9%87%D8%A7%D9%85 "إبهام – Arabic") +- [Aragonés](https://an.wikipedia.org/wiki/Pulgar "Pulgar – Aragonese") +- [ܐܪܡܝܐ](https://arc.wikipedia.org/wiki/%DC%9F%DC%AA%DC%AC%DC%90 "ܟܪܬܐ – Aramaic") +- [अवधी](https://awa.wikipedia.org/wiki/%E0%A4%85%E0%A4%99%E0%A5%81%E0%A4%A0%E0%A4%BE "अङुठा – Awadhi") +- [Azərbaycanca](https://az.wikipedia.org/wiki/Ba%C5%9F_barmaq "Baş barmaq – Azerbaijani") +- [Basa + Bali](https://ban.wikipedia.org/wiki/Inan_lima "Inan lima – Balinese") +- [বাংলা](https://bn.wikipedia.org/wiki/%E0%A6%AC%E0%A7%83%E0%A6%A6%E0%A7%8D%E0%A6%A7%E0%A6%BE%E0%A6%99%E0%A7%8D%E0%A6%97%E0%A7%81%E0%A6%B2%E0%A6%BF "বৃদ্ধাঙ্গুলি – Bangla") +- [閩南語 / + Bân-lâm-gú](https://zh-min-nan.wikipedia.org/wiki/T%C5%8Da-th%C3%A2u-b%C3%BA "Tōa-thâu-bú – Minnan") +- [Bikol + Central](https://bcl.wikipedia.org/wiki/Tangan "Tangan – Central Bikol") +- [Български](https://bg.wikipedia.org/wiki/%D0%9F%D0%B0%D0%BB%D0%B5%D1%86 "Палец – Bulgarian") +- [Boarisch](https://bar.wikipedia.org/wiki/Daam "Daam – Bavarian") +- [Bosanski](https://bs.wikipedia.org/wiki/Palac "Palac – Bosnian") +- [Brezhoneg](https://br.wikipedia.org/wiki/Meud "Meud – Breton") +- [Català](https://ca.wikipedia.org/wiki/Polze "Polze – Catalan") +- [Чӑвашла](https://cv.wikipedia.org/wiki/%D0%9F%D0%B0%D1%88-%D0%BF%D3%B3%D1%80%D0%BD%D0%B5 "Паш-пӳрне – Chuvash") +- [Čeština](https://cs.wikipedia.org/wiki/Palec "Palec – Czech") +- [Dansk](https://da.wikipedia.org/wiki/Tommelfinger "Tommelfinger – Danish") +- [Deitsch](https://pdc.wikipedia.org/wiki/Daume "Daume – Pennsylvania German") +- [Deutsch](https://de.wikipedia.org/wiki/Daumen "Daumen – German") +- [ދިވެހިބަސް](https://dv.wikipedia.org/wiki/%DE%84%DE%AE%DE%91%DE%AA%DE%88%DE%A6%DE%87%DE%A8_%DE%87%DE%A8%DE%82%DE%8E%DE%A8%DE%8D%DE%A8 "ބޮޑުވައި އިނގިލި – Divehi") +- [Eesti](https://et.wikipedia.org/wiki/P%C3%B6ial "Pöial – Estonian") +- [Ελληνικά](https://el.wikipedia.org/wiki/%CE%91%CE%BD%CF%84%CE%AF%CF%87%CE%B5%CE%B9%CF%81%CE%B1%CF%82 "Αντίχειρας – Greek") +- [Эрзянь](https://myv.wikipedia.org/wiki/%D0%9F%D0%B5%D0%BB%D1%8C%D0%BA%D0%B0 "Пелька – Erzya") +- [Español](https://es.wikipedia.org/wiki/Dedo_pulgar "Dedo pulgar – Spanish") +- [Esperanto](https://eo.wikipedia.org/wiki/Dikfingro "Dikfingro – Esperanto") +- [Euskara](https://eu.wikipedia.org/wiki/Erpuru "Erpuru – Basque") +- [فارسی](https://fa.wikipedia.org/wiki/%D8%B4%D8%B3%D8%AA "شست – Persian") +- [Français](https://fr.wikipedia.org/wiki/Pouce_(anatomie) "Pouce (anatomie) – French") +- [Frysk](https://fy.wikipedia.org/wiki/Tomme "Tomme – Western Frisian") +- [Gaeilge](https://ga.wikipedia.org/wiki/Ord%C3%B3g "Ordóg – Irish") +- [Gàidhlig](https://gd.wikipedia.org/wiki/%C3%92rdag "Òrdag – Scottish Gaelic") +- [Galego](https://gl.wikipedia.org/wiki/Polgar "Polgar – Galician") +- [ગુજરાતી](https://gu.wikipedia.org/wiki/%E0%AA%85%E0%AA%82%E0%AA%97%E0%AB%82%E0%AA%A0%E0%AB%8B "અંગૂઠો – Gujarati") +- [한국어](https://ko.wikipedia.org/wiki/%EC%97%84%EC%A7%80%EC%86%90%EA%B0%80%EB%9D%BD "엄지손가락 – Korean") +- [Հայերեն](https://hy.wikipedia.org/wiki/%D4%B2%D5%B8%D6%82%D5%A9_%D5%B4%D5%A1%D5%BF "Բութ մատ – Armenian") +- [हिन्दी](https://hi.wikipedia.org/wiki/%E0%A4%85%E0%A4%82%E0%A4%97%E0%A5%81%E0%A4%B7%E0%A5%8D%E0%A4%A0 "अंगुष्ठ – Hindi") +- [Hrvatski](https://hr.wikipedia.org/wiki/Palac "Palac – Croatian") +- [Ido](https://io.wikipedia.org/wiki/Polexo "Polexo – Ido") +- [Bahasa + Indonesia](https://id.wikipedia.org/wiki/Ibu_jari "Ibu jari – Indonesian") +- [Italiano](https://it.wikipedia.org/wiki/Pollice_(dito) "Pollice (dito) – Italian") +- [עברית](https://he.wikipedia.org/wiki/%D7%90%D7%92%D7%95%D7%93%D7%9C "אגודל – Hebrew") +- [Jawa](https://jv.wikipedia.org/wiki/Jempol "Jempol – Javanese") +- [ಕನ್ನಡ](https://kn.wikipedia.org/wiki/%E0%B2%B9%E0%B3%86%E0%B2%AC%E0%B3%8D%E0%B2%AC%E0%B3%86%E0%B2%B0%E0%B2%B3%E0%B3%81 "ಹೆಬ್ಬೆರಳು – Kannada") +- [Қазақша](https://kk.wikipedia.org/wiki/%D0%91%D0%B0%D1%80%D0%BC%D0%B0%D2%9B "Бармақ – Kazakh") +- [Kiswahili](https://sw.wikipedia.org/wiki/Kidole_gumba "Kidole gumba – Swahili") +- [Kreyòl + ayisyen](https://ht.wikipedia.org/wiki/Pous_(anatomi) "Pous (anatomi) – Haitian Creole") +- [Latina](https://la.wikipedia.org/wiki/Pollex_(anatomia) "Pollex (anatomia) – Latin") +- [Latviešu](https://lv.wikipedia.org/wiki/%C4%AAk%C5%A1%C4%B7is "Īkšķis – Latvian") +- [Ligure](https://lij.wikipedia.org/wiki/P%C5%93uxo_(dio) "Pœuxo (dio) – Ligurian") +- [Lombard](https://lmo.wikipedia.org/wiki/Mazza-pioeugg "Mazza-pioeugg – Lombard") +- [Македонски](https://mk.wikipedia.org/wiki/%D0%9F%D0%B0%D0%BB%D0%B5%D1%86 "Палец – Macedonian") +- [मराठी](https://mr.wikipedia.org/wiki/%E0%A4%85%E0%A4%82%E0%A4%97%E0%A4%A0%E0%A4%BE "अंगठा – Marathi") +- [Bahasa + Melayu](https://ms.wikipedia.org/wiki/Ibu_jari "Ibu jari – Malay") +- [閩東語 / + Mìng-dĕ̤ng-ngṳ̄](https://cdo.wikipedia.org/wiki/Du%C3%A2i-c%C4%81i "Duâi-cāi – Mindong") +- [မြန်မာဘာသာ](https://my.wikipedia.org/wiki/%E1%80%9C%E1%80%80%E1%80%BA%E1%80%99_(%E1%80%81%E1%80%94%E1%80%B9%E1%80%93%E1%80%AC%E1%80%97%E1%80%B1%E1%80%92) "လက်မ (ခန္ဓာဗေဒ) – Burmese") +- [Nederlands](https://nl.wikipedia.org/wiki/Duim_(vinger) "Duim (vinger) – Dutch") +- [नेपाली](https://ne.wikipedia.org/wiki/%E0%A4%AC%E0%A5%82%E0%A4%A2%E0%A5%80_%E0%A4%94%E0%A4%81%E0%A4%B2%E0%A4%BE "बूढी औँला – Nepali") +- [日本語](https://ja.wikipedia.org/wiki/%E8%A6%AA%E6%8C%87 "親指 – Japanese") +- [Norsk + bokmål](https://no.wikipedia.org/wiki/Tommel "Tommel – Norwegian Bokmål") +- [Norsk + nynorsk](https://nn.wikipedia.org/wiki/Tommelfinger "Tommelfinger – Norwegian Nynorsk") +- [Occitan](https://oc.wikipedia.org/wiki/Poce "Poce – Occitan") +- [ਪੰਜਾਬੀ](https://pa.wikipedia.org/wiki/%E0%A8%85%E0%A9%B0%E0%A8%97%E0%A9%82%E0%A8%A0%E0%A8%BE "ਅੰਗੂਠਾ – Punjabi") +- [Pangasinan](https://pag.wikipedia.org/wiki/Tangan "Tangan – Pangasinan") +- [پنجابی](https://pnb.wikipedia.org/wiki/%D8%A7%D9%86%DA%AF%D9%88%D9%B9%DA%BE%D8%A7 "انگوٹھا – Western Punjabi") +- [Plattdüütsch](https://nds.wikipedia.org/wiki/Dumen "Dumen – Low German") +- [Polski](https://pl.wikipedia.org/wiki/Kciuk "Kciuk – Polish") +- [Português](https://pt.wikipedia.org/wiki/Polegar "Polegar – Portuguese") +- [Ripoarisch](https://ksh.wikipedia.org/wiki/Dumm "Dumm – Colognian") +- [Română](https://ro.wikipedia.org/wiki/Deget_mare "Deget mare – Romanian") +- [Русский](https://ru.wikipedia.org/wiki/%D0%91%D0%BE%D0%BB%D1%8C%D1%88%D0%BE%D0%B9_%D0%BF%D0%B0%D0%BB%D0%B5%D1%86 "Большой палец – Russian") +- [संस्कृतम्](https://sa.wikipedia.org/wiki/%E0%A4%85%E0%A4%99%E0%A5%8D%E0%A4%97%E0%A5%81%E0%A4%B7%E0%A5%8D%E0%A4%A0%E0%A4%83 "अङ्गुष्ठः – Sanskrit") +- [ᱥᱟᱱᱛᱟᱲᱤ](https://sat.wikipedia.org/wiki/%E1%B1%A6%E1%B1%9F%E1%B1%B2%E1%B1%9F%E1%B1%A2_%E1%B1%A0%E1%B1%9F%E1%B1%B9%E1%B1%B4%E1%B1%A9%E1%B1%B5 "ᱦᱟᱲᱟᱢ ᱠᱟᱹᱴᱩᱵ – Santali") +- [Scots](https://sco.wikipedia.org/wiki/Thoum "Thoum – Scots") +- [Sicilianu](https://scn.wikipedia.org/wiki/Puseri "Puseri – Sicilian") +- [سنڌي](https://sd.wikipedia.org/wiki/%D8%A2%DA%B1%D9%88%D9%BA%D9%88 "آڱوٺو – Sindhi") +- [Slovenčina](https://sk.wikipedia.org/wiki/Palec_(prst) "Palec (prst) – Slovak") +- [Soomaaliga](https://so.wikipedia.org/wiki/Suul "Suul – Somali") +- [کوردی](https://ckb.wikipedia.org/wiki/%D8%A6%DB%95%D8%B3%D9%BE%DB%8E_%DA%A9%D9%88%DA%98%DB%95 "ئەسپێ کوژە – Central Kurdish") +- [Српски / + srpski](https://sr.wikipedia.org/wiki/%D0%9F%D0%B0%D0%BB%D0%B0%D1%86 "Палац – Serbian") +- [Srpskohrvatski / + српскохрватски](https://sh.wikipedia.org/wiki/Palac "Palac – Serbo-Croatian") +- [Sunda](https://su.wikipedia.org/wiki/Indung_leungeun "Indung leungeun – Sundanese") +- [Suomi](https://fi.wikipedia.org/wiki/Peukalo "Peukalo – Finnish") +- [Svenska](https://sv.wikipedia.org/wiki/Tumme "Tumme – Swedish") +- [Tagalog](https://tl.wikipedia.org/wiki/Hinlalaki "Hinlalaki – Tagalog") +- [தமிழ்](https://ta.wikipedia.org/wiki/%E0%AE%AA%E0%AF%86%E0%AE%B0%E0%AF%81_%E0%AE%B5%E0%AE%BF%E0%AE%B0%E0%AE%B2%E0%AF%8D "பெரு விரல் – Tamil") +- [తెలుగు](https://te.wikipedia.org/wiki/%E0%B0%AC%E0%B1%8A%E0%B0%9F%E0%B0%A8_%E0%B0%B5%E0%B1%87%E0%B0%B2%E0%B1%81 "బొటన వేలు – Telugu") +- [ไทย](https://th.wikipedia.org/wiki/%E0%B8%99%E0%B8%B4%E0%B9%89%E0%B8%A7%E0%B8%AB%E0%B8%B1%E0%B8%A7%E0%B9%81%E0%B8%A1%E0%B9%88%E0%B8%A1%E0%B8%B7%E0%B8%AD "นิ้วหัวแม่มือ – Thai") +- [Türkçe](https://tr.wikipedia.org/wiki/Ba%C5%9Fparmak "Başparmak – Turkish") +- [Tyap](https://kcg.wikipedia.org/wiki/A%CC%B1turugbak_mbwak "A̱turugbak mbwak – Tyap") +- [Українська](https://uk.wikipedia.org/wiki/%D0%92%D0%B5%D0%BB%D0%B8%D0%BA%D0%B8%D0%B9_%D0%BF%D0%B0%D0%BB%D0%B5%D1%86%D1%8C "Великий палець – Ukrainian") +- [اردو](https://ur.wikipedia.org/wiki/%D8%A7%D9%86%DA%AF%D9%88%D9%B9%DA%BE%D8%A7 "انگوٹھا – Urdu") +- [ئۇيغۇرچە / + Uyghurche](https://ug.wikipedia.org/wiki/%D8%A8%D8%A7%D8%B4_%D8%A8%D8%A7%D8%B1%D9%85%D8%A7%D9%82 "باش بارماق – Uyghur") +- [Tiếng + Việt](https://vi.wikipedia.org/wiki/Ng%C3%B3n_c%C3%A1i "Ngón cái – Vietnamese") +- [Võro](https://fiu-vro.wikipedia.org/wiki/P%C3%A4kk "Päkk – Võro") +- [Walon](https://wa.wikipedia.org/wiki/P%C3%B4ce "Pôce – Walloon") +- [Winaray](https://war.wikipedia.org/wiki/Tamuragk%C3%B4 "Tamuragkô – Waray") +- [吴语](https://wuu.wikipedia.org/wiki/%E6%8B%87%E6%8C%87 "拇指 – Wu") +- [Yorùbá](https://yo.wikipedia.org/wiki/%C3%80t%C3%A0np%C3%A0k%C3%B2 "Àtànpàkò – Yoruba") +- [粵語](https://zh-yue.wikipedia.org/wiki/%E6%89%8B%E6%8C%87%E5%85%AC "手指公 – Cantonese") +- [中文](https://zh.wikipedia.org/wiki/%E6%8B%87%E6%8C%87 "拇指 – Chinese") +- [Betawi](https://bew.wikipedia.org/wiki/Jempol "Jempol – Betawi") + +[Edit +links](https://www.wikidata.org/wiki/Special:EntityPage/Q83360#sitelinks-wikipedia "Edit interlanguage links") + +- [Article](/wiki/Thumb "View the content page [c]") +- [Talk](/wiki/Talk:Thumb "Discuss improvements to the content page [t]") + +English + +- [Read](/wiki/Thumb) +- [Edit](/w/index.php?title=Thumb&action=edit "Edit this page [e]") +- [View + history](/w/index.php?title=Thumb&action=history "Past revisions of this page [h]") + +Tools + +Tools + +move to sidebar + +hide + +Actions + +- [Read](/wiki/Thumb) +- [Edit](/w/index.php?title=Thumb&action=edit "Edit this page [e]") +- [View history](/w/index.php?title=Thumb&action=history) + +General + +- [What links + here](/wiki/Special:WhatLinksHere/Thumb "List of all English Wikipedia pages containing links to this page [j]") +- [Related + changes](/wiki/Special:RecentChangesLinked/Thumb "Recent changes in pages linked from this page [k]") +- [Upload + file](//en.wikipedia.org/wiki/Wikipedia:File_Upload_Wizard "Upload files [u]") +- [Permanent + link](/w/index.php?title=Thumb&oldid=1274819517 "Permanent link to this revision of this page") +- [Page + information](/w/index.php?title=Thumb&action=info "More information about this page") +- [Cite this + page](/w/index.php?title=Special:CiteThisPage&page=Thumb&id=1274819517&wpFormIdentifier=titleform "Information on how to cite this page") +- [Get shortened + URL](/w/index.php?title=Special:UrlShortener&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FThumb) +- [Download QR + code](/w/index.php?title=Special:QrCode&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FThumb) + +Print/export + +- [Download as + PDF](/w/index.php?title=Special:DownloadAsPdf&page=Thumb&action=show-download-screen "Download this page as a PDF file") +- [Printable + version](/w/index.php?title=Thumb&printable=yes "Printable version of this page [p]") + +In other projects + +- [Wikimedia + Commons](https://commons.wikimedia.org/wiki/Category:Thumbs) +- [Wikidata + item](https://www.wikidata.org/wiki/Special:EntityPage/Q83360 "Structured data on this page hosted by Wikidata [g]") + +Appearance + +move to sidebar + +hide + +From Wikipedia, the free encyclopedia + +First digit of the hand + +This article is about the digit of the hand. For other uses, see [Thumb +(disambiguation)](/wiki/Thumb_(disambiguation) "Thumb (disambiguation)"). + +[TABLE] + +The **thumb** is the first +[digit](/wiki/Digit_(anatomy) "Digit (anatomy)") of the +[hand](/wiki/Hand "Hand"), next to the [index +finger](/wiki/Index_finger "Index finger").^([\[A\]](#cite_note-2)) When +a person is standing in the medical [anatomical +position](/wiki/Anatomical_position "Anatomical position") (where the +palm is facing to the front), the thumb is the outermost digit. The +Medical Latin English noun for thumb is +[*pollex*](https://en.wiktionary.org/wiki/pollex "wikt:pollex") (compare +[*hallux*](/wiki/Toe#Hallux "Toe") for big toe), and the corresponding +adjective for thumb is +[*pollical*](https://en.wiktionary.org/wiki/pollical "wikt:pollical"). + +## Definition + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=1 "Edit section: Definition")\] + +[TABLE] + +### Thumb and fingers + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=2 "Edit section: Thumb and fingers")\] + +The English word *finger* has two +[senses](/wiki/Finger_numbering "Finger numbering"), even in the context +of appendages of a single typical human hand: 1) Any of the five +terminal members of the hand. 2) Any of the four terminal members of the +hand, other than the thumb.^([\[2\]](#cite_note-3)) + +Linguistically, it appears that the original sense was the first of +these two: \**penkwe-ros* (also rendered as \**penqrós*) was, in the +inferred [Proto-Indo-European +language](/wiki/Proto-Indo-European_language "Proto-Indo-European language"), +a suffixed form of \**penkwe* (or \**penqe*), which has given rise to +many +[Indo-European](/wiki/Indo-European_languages "Indo-European languages")-family +words (tens of them defined in English dictionaries) that involve, or +stem from, concepts of fiveness. + +The thumb shares the following with each of the other four fingers: + +- Having a skeleton of [phalanges](/wiki/Phalanges "Phalanges"), + joined by hinge-like joints that provide flexion toward the palm of + the hand +- Having a dorsal surface that features hair and a nail, and a + hairless palmar aspect with + [fingerprint](/wiki/Fingerprint "Fingerprint") ridges + +The thumb contrasts with each of the other four fingers by being the +only one that: + +- Is opposable to the other four fingers +- Has two [phalanges](/wiki/Phalanges "Phalanges") rather than three. + However, recently there have been reports that the thumb, like other + fingers, has three phalanges, but lacks a metacarpal + bone.^([\[3\]](#cite_note-4)) +- Has greater breadth in the [distal](/wiki/Distal "Distal") phalanx + than in the [proximal](/wiki/Proximal "Proximal") phalanx +- Is attached to such a mobile + [metacarpus](/wiki/Metacarpus "Metacarpus") (which produces most of + the opposability) +- Curls horizontally instead of vertically + +and hence the etymology of the word: \**tum* is Proto-Indo-European for +'swelling' (cf 'tumor' and 'thigh') since the thumb is the stoutest of +the fingers. + +## Opposition and apposition + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=3 "Edit section: Opposition and apposition")\] + +### Humans + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=4 "Edit section: Humans")\] + +Anatomists and other researchers focused on human anatomy have hundreds +of definitions of *opposition*.^([\[4\]](#cite_note-vanNierop-2008-5)) +Some anatomists^([\[5\]](#cite_note-Brownetal-2004-6)) restrict +*opposition* to when the thumb is approximated to the fifth finger +(little finger) and refer to other approximations between the thumb and +other fingers as *apposition*. To anatomists, this makes sense as two +intrinsic hand muscles are named for this specific movement (the +[opponens +pollicis](/wiki/Opponens_pollicis_muscle "Opponens pollicis muscle") and +[opponens digiti +minimi](/wiki/Opponens_digiti_minimi_muscle "Opponens digiti minimi muscle") +respectively). + +Other researchers use another +definition,^([\[4\]](#cite_note-vanNierop-2008-5)) referring to +opposition-apposition as the transition between flexion-abduction and +extension-adduction; the *side* of the distal thumb phalanx thus +approximated to the palm or the hand's radial side (side of index +finger) during *apposition* and the *pulp* or "palmar" side of the +distal thumb phalanx approximated to either the palm or other fingers +during *opposition*. + +Moving a limb back to its neutral position is called reposition and a +rotary movement is referred to as +[circumduction](/wiki/Circumduction_(anatomy) "Circumduction (anatomy)"). + +Primatologists and hand research pioneers +[John](/wiki/John_Napier_(primatologist) "John Napier (primatologist)") +and [Prudence Napier](/wiki/Prudence_Hero_Napier "Prudence Hero Napier") +defined opposition as: "A movement by which the pulp surface of the +thumb is placed squarely in contact with – or diametrically opposite +to – the terminal pads of one or all of the remaining fingers." For this +*true*, pulp-to-pulp opposition to be possible, the thumb must rotate +about its long axis (at the [carpometacarpal +joint](/wiki/Carpometacarpal_joint "Carpometacarpal joint")).^([\[6\]](#cite_note-Primates-FAQ-7)) +Arguably, this definition was chosen to underline what is unique to the +human thumb. + +### Other primates + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=5 "Edit section: Other primates")\] + +[](/wiki/File:BonoboFishing02_cropped.jpeg) + +A [bonobo](/wiki/Bonobo "Bonobo") "fishing" for termites, an example of +incomplete/"untrue" +opposition^([\[7\]](#cite_note-8)\[*[better source needed](/wiki/Wikipedia:NOTRS "Wikipedia:NOTRS")*\]) + +- [Primates](/wiki/Primate "Primate") fall into one of six + groups:^([\[8\]](#cite_note-PrimateAnatomy8-9)) + - Thumbless: [spider monkey](/wiki/Spider_monkey "Spider monkey") + and [colobus](/wiki/Colobus "Colobus") + - Nonopposable thumbs: [tarsiers](/wiki/Tarsier "Tarsier") (which + are found in the islands of Southeast Asia), + [marmosets](/wiki/Marmoset "Marmoset") (which are [New World + monkeys](/wiki/New_World_monkeys "New World monkeys")) + - Pseudo-opposable thumbs: all + [strepsirrhines](/wiki/Strepsirrhine "Strepsirrhine") (lemurs, + pottos and lorises) and [Cebidae](/wiki/Cebidae "Cebidae") + (capuchin and squirrel monkeys, which are [New World + monkeys](/wiki/New_World_monkeys "New World monkeys")) + - Opposable thumbs: [Old World + monkeys](/wiki/Old_World_monkey "Old World monkey") + (Circopithecidae) except colobus, and all [great + apes](/wiki/Hominidae "Hominidae") + - Opposable with comparatively long thumbs: + [gibbons](/wiki/Gibbon "Gibbon") (or lesser apes) + - Yet to be classified: other [New World + monkeys](/wiki/New_World_monkeys "New World monkeys") + ([tamarins](/wiki/Tamarin "Tamarin"), Aotidae: night or owl + monkeys, Pitheciidae: titis, sakis and uakaris, Atelidae: howler + and woolly monkeys) + +The spider monkey compensates for being virtually thumbless by using the +hairless part of its long, prehensile tail for grabbing objects. In +[apes](/wiki/Ape "Ape") and [Old World +monkeys](/wiki/Old_World_monkeys "Old World monkeys"), the thumb can be +rotated around its axis, but the extensive area of contact between the +pulps of the thumb and index finger is a human +characteristic.^([\[9\]](#cite_note-Jones-Lederman-2006-p12-10)) + +*[Darwinius masillae](/wiki/Darwinius "Darwinius")*, an +[Eocene](/wiki/Eocene "Eocene") primate [transitional +fossil](/wiki/Transitional_fossil "Transitional fossil") between +[prosimian](/wiki/Prosimian "Prosimian") and +[simian](/wiki/Simian "Simian"), had hands and feet with highly flexible +digits featuring opposable thumbs and +halluces.^([\[10\]](#cite_note-PloS-Darwinius-2009-11)) + +### Other placental mammals + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=6 "Edit section: Other placental mammals")\] + +- [Giant pandas](/wiki/Giant_panda "Giant panda") — five clawed + fingers plus an extra-long [sesamoid + bone](/wiki/Sesamoid_bone#Panda_anatomy "Sesamoid bone") beside the + true first finger that, though not a true finger, works like an + opposable thumb.^([\[11\]](#cite_note-12)) +- Most [rodents](/wiki/Rodents "Rodents") have a partly opposable toe + on each front paw, letting them + grasp.^([\[12\]](#cite_note-order-13)) + - In some *[mice](/wiki/Muridae "Muridae")*, the hallux ("big + toe") is clawless and fully opposable, including + [arboreal](/wiki/Arboreal "Arboreal") species such as + *[Hapalomys](/wiki/Hapalomys "Hapalomys")*, + *[Chiropodomys](/wiki/Chiropodomys "Chiropodomys")*, + *[Vandeleuria](/wiki/Vandeleuria "Vandeleuria")*, and + *[Chiromyscus](/wiki/Chiromyscus "Chiromyscus")*; and + [saltatorial](/wiki/Saltatorial "Saltatorial"), bipedal species + such as *[Notomys](/wiki/Notomys "Notomys")* and possibly some + [Gerbillinae](/wiki/Gerbillinae "Gerbillinae").^([\[13\]](#cite_note-14)) + - The East African [maned rat](/wiki/Maned_rat "Maned rat") + (*Lophiomys imhausi*), an arboreal, porcupine-like rodent, has + four fingers on its hands and feet and a partially opposable + thumb.^([\[14\]](#cite_note-15)) + +Additionally, in many [polydactyl +cats](/wiki/Polydactyl_cats "Polydactyl cats"), both the [innermost +toe](/wiki/Innermost_toe "Innermost toe") and [outermost +toe](/wiki/Outermost_toe "Outermost toe") +([pinky](/wiki/Little_finger "Little finger")) may become opposable, +allowing the cat to perform more complex +tasks.^(\[*[citation\ needed](/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")*\]) + +### Marsupials + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=7 "Edit section: Marsupials")\] + +[](/wiki/File:Ailurops_ursinus_Naemundung_5_North_Sulawesi_cropped.JPG) + +[](/wiki/File:Oppossumthumb.jpg) + +Left: Opposable toes of the [Sulawesi bear +cuscus](/wiki/Sulawesi_bear_cuscus "Sulawesi bear cuscus") forelimb +Right: Opposable thumb on rear foot of an opossum + +- In most [phalangerid](/wiki/Phalangerid "Phalangerid") + [marsupials](/wiki/Marsupial "Marsupial") (a family of + [possums](/wiki/Phalangeriformes "Phalangeriformes")) except species + *[Trichosurus](/wiki/Trichosurus "Trichosurus")* and + *[Wyulda](/wiki/Wyulda "Wyulda")*, the first and second toes of the + forefoot are opposable to the other three. In the hind foot, the + first toe is clawless but opposable and provides firm grip on + branches. The second and third toes are partly + [syndactylous](/wiki/Dactyly "Dactyly"), united by skin at the top + joint while the two separate nails serve as hair combs. The fourth + and fifth toes are the largest of the hind + foot.^([\[15\]](#cite_note-Nowak-1999-16)) +- [Koalas](/wiki/Koala "Koala") have five toes on their fore and hind + feet with sharp curved claws except for the first toe of the hind + foot. The first and second toes of the forefeet are opposable to the + other three, which enables the koala to grip smaller branches and + search for fresh leaves in the outer canopy. Similar to the + phalangerids, the second and third toes of the hind foot are fused + but have separate claws.^([\[16\]](#cite_note-McDade-2003-koala-17)) +- [Opossums](/wiki/Opossum "Opossum") are New World marsupials with + opposable thumbs in the hind feet giving these animals their + characteristic grasping capability (with the exception of the [water + opossum](/wiki/Water_opossum "Water opossum"), the webbed feet of + which restrict + opposability).^([\[17\]](#cite_note-McDade-2003-opossum-18)) +- The mouse-like + [microbiotheres](/wiki/Microbiotheria "Microbiotheria") were a group + of South American marsupials most closely related to Australian + marsupials. The only extant member, *[Dromiciops + gliroides](/wiki/Monito_del_Monte "Monito del Monte")*, is not + closely related to opossums but has paws similar to these animals, + each having opposable toes adapted for + gripping.^([\[18\]](#cite_note-McDade-2003-microbiotheres-19)) + +### Reptiles + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=8 "Edit section: Reptiles")\] + +- The front feet of [chameleons](/wiki/Chameleons "Chameleons") are + organized into a medial bundle of toes 1, 2 and 3, and a lateral + bundle of toes 4 and 5, and the hind feet are organized into a + medial bundle of toes 1 and 2, and a lateral bundle of toes 3, 4 and + 5.^([\[19\]](#cite_note-20)) + +### Dinosaurs + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=9 "Edit section: Dinosaurs")\] + +- Dinosaurs belonging to the family of bird-like dinosaur + [Troodontidae](/wiki/Troodontidae "Troodontidae") had a partially + opposable finger. It is possible that this adaptation was used to + better manipulate ground objects or moving undergrowth branches when + searching for prey.^([\[20\]](#cite_note-russell1982-21)) +- The small predatory dinosaur + *[Bambiraptor](/wiki/Bambiraptor "Bambiraptor")* may have had + mutually opposable first and third fingers and a forelimb + manoeuvrability that would allow the hand to reach its mouth. Its + forelimb morphology and range of motion enabled two-handed + prehension, one-handed clutching of objects to the chest, and use of + the hand as a hook.^([\[21\]](#cite_note-22)) +- *[Nqwebasaurus](/wiki/Nqwebasaurus "Nqwebasaurus")* — a + [coelurosaur](/wiki/Coelurosaur "Coelurosaur") with a long, + three-fingered hand which included a partially opposable thumb (a + "killer claw").^([\[22\]](#cite_note-23)) + +In addition to these, some other dinosaurs may have had partially or +completely opposed toes in order to manipulate food and/or grasp prey. + +#### Birds + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=10 "Edit section: Birds")\] + +[](/wiki/File:Bird-feets-en.svg) + +Four types of bird feet +(right foot diagrams) + +See also: [Dactyly § Anisodactyly](/wiki/Dactyly#Anisodactyly "Dactyly") + +- Most [birds](/wiki/Bird "Bird") have at least one opposable toe on + the foot, in [various + configurations](/wiki/Dactyly#In_birds "Dactyly"), though these are + seldom called "thumbs". They are more often known simply as + [halluxes](/wiki/Toe#Hallux "Toe"). + +#### Pterosaurs + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=11 "Edit section: Pterosaurs")\] + +- The [wukongopterid](/wiki/Wukongopteridae "Wukongopteridae") + pterosaur *[Kunpengopterus](/wiki/Kunpengopterus "Kunpengopterus")* + bore an opposable first toe on each wing. The presence of opposable + thumbs in this taxon is thought to be an arboreal + adaptation.^([\[23\]](#cite_note-Zhouetal2021-24)) + +### Amphibians + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=12 "Edit section: Amphibians")\] + +- *[Phyllomedusa](/wiki/Phyllomedusa "Phyllomedusa")*, a genus of + frogs native to South + America.^([\[24\]](#cite_note-Phyllomedusa-25)) + +## Human anatomy + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=13 "Edit section: Human anatomy")\] + +### Skeleton + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=14 "Edit section: Skeleton")\] + +The skeleton of the thumb consists of the [first metacarpal +bone](/wiki/First_metacarpal_bone "First metacarpal bone") which +articulates [proximally](/wiki/Proximal "Proximal") with the +[carpus](/wiki/Carpal_bones "Carpal bones") at the [carpometacarpal +joint](/wiki/Articulatio_carpometacarpea_pollicis "Articulatio carpometacarpea pollicis") +and [distally](/wiki/Distal "Distal") with the [proximal +phalanx](/wiki/Proximal_phalanges "Proximal phalanges") at the +[metacarpophalangeal +joint](/wiki/Metacarpophalangeal_joint "Metacarpophalangeal joint"). +This latter bone articulates with the [distal +phalanx](/wiki/Distal_phalanges "Distal phalanges") at the +[interphalangeal +joint](/wiki/Interphalangeal_articulations_of_hand "Interphalangeal articulations of hand"). +Additionally, there are two [sesamoid +bones](/wiki/Sesamoid_bone "Sesamoid bone") at the metacarpophalangeal +joint. + +### Muscles + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=15 "Edit section: Muscles")\] + +Main article: [Muscles of the +thumb](/wiki/Muscles_of_the_thumb "Muscles of the thumb") + +The muscles of the thumb can be compared to +[guy-wires](/wiki/Guy-wire "Guy-wire") supporting a flagpole; tension +from these muscular guy-wires must be provided in all directions to +maintain stability in the articulated column formed by the bones of the +thumb. Because this stability is actively maintained by muscles rather +than by articular constraints, most muscles attached to the thumb tend +to be active during most thumb motions.^([\[25\]](#cite_note-26)) + +The muscles acting on the thumb can be divided into two groups: The +extrinsic hand muscles, with their muscle bellies located in the +forearm, and the intrinsic hand muscles, with their muscle bellies +located in the hand proper.^([\[26\]](#cite_note-27)) + +#### Extrinsic + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=16 "Edit section: Extrinsic")\] + +[](/wiki/File:Musculus_flexor_pollicis_longus.png) + +[](/wiki/File:Gray419.png) + +Flexor pollicis longus (left) and deep muscles of dorsal forearm (right) + +A [ventral](/wiki/Ventral "Ventral") forearm muscle, the [flexor +pollicis +longus](/wiki/Flexor_pollicis_longus_muscle "Flexor pollicis longus muscle") +(FPL) originates on the anterior side of the +[radius](/wiki/Radius_(bone) "Radius (bone)") distal to the [radial +tuberosity](/wiki/Radial_tuberosity "Radial tuberosity") and from the +[interosseous +membrane](/wiki/Interosseous_membrane_of_forearm "Interosseous membrane of forearm"). +It passes through the [carpal +tunnel](/wiki/Carpal_tunnel "Carpal tunnel") in a separate [tendon +sheath](/wiki/Tendon_sheath "Tendon sheath"), after which it lies +between the heads of the flexor pollicis brevis. It finally attaches +onto the base of the distal phalanx of the thumb. It is innervated by +the [anterior interosseus +branch](/wiki/Anterior_interosseous_nerve "Anterior interosseous nerve") +of the [median nerve](/wiki/Median_nerve "Median nerve") +(C7-C8)^([\[27\]](#cite_note-Platzer-162-28)) It is a persistence of one +of the former [contrahentes](/wiki/Contrahentes "Contrahentes") muscles +that pulled the fingers or toes together. + +Three dorsal forearm muscles act on the thumb: + +The [abductor pollicis +longus](/wiki/Abductor_pollicis_longus_muscle "Abductor pollicis longus muscle") +(APL) originates on the dorsal sides of both the +[ulna](/wiki/Ulna "Ulna") and the radius, and from the interosseous +membrane. Passing through the first tendon compartment, it inserts to +the base of the first [metacarpal bone](/wiki/Metacarpus "Metacarpus"). +A part of the tendon reaches the trapezium, while another fuses with the +tendons of the extensor pollicis brevis and the abductor pollicis +brevis. Except for abducting the hand, it flexes the hand towards the +palm and abducts it radially. It is innervated by the [deep branch of +the radial +nerve](/wiki/Deep_branch_of_the_radial_nerve "Deep branch of the radial nerve") +(C7-C8).^([\[28\]](#cite_note-Platzer-168-29)) + +The [extensor pollicis +longus](/wiki/Extensor_pollicis_longus_muscle "Extensor pollicis longus muscle") +(EPL) originates on the dorsal side of the ulna and the interosseous +membrane. Passing through the third tendon compartment, it is inserted +onto the base of the distal phalanx of the thumb. It uses the dorsal +tubercle on the lower extremity of the radius as a +[fulcrum](/wiki/Lever "Lever") to extend the thumb and also dorsiflexes +and abducts the hand at the wrist. It is innervated by the [deep branch +of the radial +nerve](/wiki/Deep_branch_of_the_radial_nerve "Deep branch of the radial nerve") +(C7-C8).^([\[28\]](#cite_note-Platzer-168-29)) + +The [extensor pollicis +brevis](/wiki/Extensor_pollicis_brevis_muscle "Extensor pollicis brevis muscle") +(EPB) originates on the ulna distal to the abductor pollicis longus, +from the interosseus membrane, and from the dorsal side of the radius. +Passing through the first tendon compartment together with the abductor +pollicis longus, it is attached to the base of the proximal phalanx of +the thumb. It extends the thumb and, because of its close relationship +to the long abductor, also abducts the thumb. It is innervated by the +[deep branch of the radial +nerve](/wiki/Deep_branch_of_the_radial_nerve "Deep branch of the radial nerve") +(C7-T1).^([\[28\]](#cite_note-Platzer-168-29)) + +The tendons of the extensor pollicis longus and extensor pollicis brevis +form what is known as the [anatomical snuff +box](/wiki/Anatomical_snuff_box "Anatomical snuff box") (an indentation +on the lateral aspect of the thumb at its base) The radial artery can be +palpated anteriorly at the wrist (not in the snuffbox). + +#### Intrinsic + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=17 "Edit section: Intrinsic")\] + +[](/wiki/File:Gray426.png) + +[](/wiki/File:Gray428.png) + +Thenar (left) and dorsal interossei (right) muscles + +There are three [thenar +muscles](/wiki/Thenar_eminence "Thenar eminence"): + +The [abductor pollicis +brevis](/wiki/Abductor_pollicis_brevis_muscle "Abductor pollicis brevis muscle") +(APB) originates on the [scaphoid +tubercle](/wiki/Scaphoid_bone "Scaphoid bone") and the [flexor +retinaculum](/wiki/Flexor_retinaculum_of_the_hand "Flexor retinaculum of the hand"). +It inserts to the radial sesamoid bone and the proximal phalanx of the +thumb. It is innervated by the [median +nerve](/wiki/Median_nerve "Median nerve") +(C8-T1).^([\[29\]](#cite_note-Platzer-176-30)) + +The [flexor pollicis +brevis](/wiki/Flexor_pollicis_brevis_muscle "Flexor pollicis brevis muscle") +(FPB) has two heads. The superficial head arises on the flexor +retinaculum, while the deep head originates on three carpal bones: the +[trapezium](/wiki/Trapezium_(bone) "Trapezium (bone)"), +[trapezoid](/wiki/Trapezoid_bone "Trapezoid bone"), and +[capitate](/wiki/Capitate_bone "Capitate bone"). The muscle is inserted +onto the radial sesamoid bone of the metacarpophalangeal joint. It acts +to flex, adduct, and abduct the thumb, and is therefore also able to +oppose the thumb. The superficial head is innervated by the [median +nerve](/wiki/Median_nerve "Median nerve"), while the deep head is +innervated by the [ulnar nerve](/wiki/Ulnar_nerve "Ulnar nerve") +(C8-T1).^([\[29\]](#cite_note-Platzer-176-30)) + +The [opponens +pollicis](/wiki/Opponens_pollicis_muscle "Opponens pollicis muscle") +originates on the tubercle of the trapezium and the flexor retinaculum. +It is inserted onto the radial side of the first metacarpal. It opposes +the thumb and assists in adduction. It is innervated by the [median +nerve](/wiki/Median_nerve "Median nerve").^([\[29\]](#cite_note-Platzer-176-30)) + +Other muscles involved are: + +The [adductor +pollicis](/wiki/Adductor_pollicis_muscle "Adductor pollicis muscle") +also has two heads. The transversal head originates along the entire +third metacarpal bone, while the oblique head originates on the carpal +bones proximal to the third metacarpal. The muscle is inserted onto the +ulnar sesamoid bone of the metacarpophalangeal joint. It adducts the +thumb, and assists in opposition and flexion. It is innervated by the +deep branch of the [ulnar nerve](/wiki/Ulnar_nerve "Ulnar nerve") +(C8-T1).^([\[29\]](#cite_note-Platzer-176-30)) + +The first [dorsal +interosseous](/wiki/Dorsal_interossei_of_the_hand "Dorsal interossei of the hand"), +one of the central muscles of the hand, extends from the base of the +thumb metacarpal to the radial side of the proximal phalanx of the index +finger.^([\[30\]](#cite_note-Platzer-174-31)) + +### Variations + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=18 "Edit section: Variations")\] + +Further information: [Hitchhiker's +thumb](/wiki/Hitchhiker%27s_thumb "Hitchhiker's thumb"), [brachydactyly +type D](/wiki/Brachydactyly_type_D "Brachydactyly type D"), +[triphalangeal thumb](/wiki/Triphalangeal_thumb "Triphalangeal thumb"), +and [polydactyly](/wiki/Polydactyly "Polydactyly") + +[](/wiki/File:Hitchhikers_thumb.jpg) + +[Hitchhiker's thumb](/wiki/Hitchhiker%27s_thumb "Hitchhiker's thumb") + +There is a variation of the human thumb where the angle between the +first and second (proximal and distal) +[phalanges](/wiki/Distal_phalanges "Distal phalanges") varies between 0° +and almost 90° when the thumb is in a +[thumbs-up](/wiki/Thumbs_Up "Thumbs Up") +gesture.^([\[31\]](#cite_note-hitchthumbmyth-32)) + +It has been suggested that the variation is an autosomal [recessive +trait](/wiki/Recessive_trait "Recessive trait"), called a [hitchhiker's +thumb](/wiki/Hitchhiker%27s_thumb "Hitchhiker's thumb"), with +[homozygous](/wiki/Homozygous "Homozygous") carriers having an angle +close to 90°.^([\[32\]](#cite_note-33)) However this theory has been +disputed, since the variation in thumb angle is known to fall on a +continuum and shows little evidence of the +[bi-modality](/wiki/Bimodal_distribution "Bimodal distribution") seen in +other recessive genetic traits.^([\[31\]](#cite_note-hitchthumbmyth-32)) + +Other variations of the thumb include [brachydactyly type +D](/wiki/Brachydactyly_type_D "Brachydactyly type D") (which is a thumb +with a congenitally short distal phalanx), a [triphalangeal +thumb](/wiki/Triphalangeal_thumb "Triphalangeal thumb") (which is a +thumb which has 3 phalanges instead of the usual two), and +[polysyndactyly](/wiki/Polysyndactyly "Polysyndactyly") (which is a +combination of radial polydactyly and syndactyly). + +### Grips + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=19 "Edit section: Grips")\] + +[](/wiki/File:Gripclosed.jpg) + +[](/wiki/File:Iverson_grip_1950.jpg) + +Left: In a power grip the object is in contact with the palm. +Right: Cricketer [Jack Iverson's](/wiki/Jack_Iverson "Jack Iverson") +"bent finger grip", an unusual pad-to-side precision grip designed to +confuse batsmen. + +One of the earlier significant contributors to the study of hand grips +was orthopedic primatologist and paleoanthropologist [John +Napier](/wiki/John_Napier_(primatologist) "John Napier (primatologist)"), +who proposed organizing the movements of the hand by their anatomical +basis as opposed to work done earlier that had only used arbitrary +classification.^([\[33\]](#cite_note-34)) Most of this early work on +hand grips had a pragmatic basis as it was intended to narrowly define +compensable injuries to the hand, which required an understanding of the +anatomical basis of hand movement. Napier proposed two primary +[prehensile](/wiki/Prehensile "Prehensile") grips: the *precision grip* +and the *power grip*.^([\[34\]](#cite_note-35)) The precision and power +grip are defined by the position of the thumb and fingers where: + +- The **power grip** is when the fingers (and sometimes palm) clamp + down on an object with the thumb making counter pressure. Examples + of the power grip are gripping a hammer, opening a jar using *both + your palm and fingers*, and during pullups. +- The **precision grip** is when the intermediate and distal phalanges + ("fingertips") and the thumb press against each other. Examples of a + precision grip are writing with a pencil, opening a jar *with the + fingertips alone*, and gripping a ball (only if the ball is not + tight against the palm). + +[](/wiki/File:Distal-phalanges-thumb-index_Journal.pone.0011727.g001.png) + +Thumb and index finger during pad-to-pad precision +grasping^([\[35\]](#cite_note-PLOS-2010-36)) + +Opposability of the thumb should not be confused with a precision grip +as some animals possess semi-opposable thumbs yet are known to have +extensive precision grips ([Tufted +Capuchins](/wiki/Cebus_apella "Cebus apella") for +example).^([\[36\]](#cite_note-37)) Nevertheless, precision grips are +usually only found in higher apes, and only in degrees significantly +more restricted than in humans.^([\[37\]](#cite_note-38)) + +The pad-to-pad pinch between the thumb and index finger is made possible +because of the human ability to passively hyperextend the [distal +phalanx](/wiki/Distal_phalanges "Distal phalanges") of the index finger. +Most non-human primates have to flex their long fingers in order for the +small thumb to reach +them.^([\[9\]](#cite_note-Jones-Lederman-2006-p12-10)) + +In humans, the distal pads are wider than in other primates because the +soft tissues of the finger tip are attached to a horseshoe-shaped edge +on the underlying bone, and, in the grasping hand, the distal pads can +therefore conform to uneven surfaces while pressure is distributed more +evenly in the finger tips. The distal pad of the human thumb is divided +into a proximal and a distal compartment, the former more deformable +than the latter, which allows the thumb pad to mold around an +object.^([\[9\]](#cite_note-Jones-Lederman-2006-p12-10)) + +In robotics, almost all [robotic +hands](/wiki/Robotic_hand "Robotic hand") have a long and strong +opposable thumb. Like human hands, the thumb of a robotic hand also +plays a key role in gripping an object. One inspiring approach of +robotic grip planning is to mimic human thumb placement. +^([\[38\]](#cite_note-39)) In a sense, human thumb placement indicates +which surface or part of the object is good for grip. Then the robot +places its thumb to the same location and plans the other fingers based +on the thumb placement. + +The function of the thumb declines physiologically with aging. This can +be demonstrated by assessing the motor sequencing of the +thumb.^([\[39\]](#cite_note-40)) + +## Human evolution + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=20 "Edit section: Human evolution")\] + +A primitive autonomization of the first [carpometacarpal +joint](/wiki/Carpometacarpal_joint "Carpometacarpal joint") (CMC) may +have occurred in dinosaurs. A real differentiation appeared an estimated +70 mya in early primates, while the shape of the human thumb CMC finally +appears about 5 mya. The result of this evolutionary process is a human +CMC joint positioned at 80° of pronation, 40 of abduction, and 50° of +flexion in relation to an axis passing through the second and third CMC +joints.^([\[40\]](#cite_note-Brüser-167-41)) + +Opposable thumbs are shared by some [primates](/wiki/Primate "Primate"), +including most +[catarrhines](/wiki/Catarrhini "Catarrhini").^(\[*[citation\ needed](/wiki/Wikipedia:Citation_needed "Wikipedia:Citation needed")*\]) +The climbing and suspensory behaviour in +[orthograde](/wiki/Orthograde_posture "Orthograde posture") apes, such +as [chimpanzees](/wiki/Common_chimpanzee "Common chimpanzee"), has +resulted in elongated hands while the thumb has remained short. As a +result, these primates are unable to perform the pad-to-pad grip +associated with opposability. However, in +[pronograde](/wiki/Pronograde "Pronograde") monkeys such as +[baboons](/wiki/Baboon "Baboon"), an adaptation to a terrestrial +lifestyle has led to reduced finger length and thus hand proportions +similar to those of humans. Consequently, these primates have dexterous +hands and are able to grasp objects using a pad-to-pad grip. It can thus +be difficult to identify hand adaptations to manipulation-related tasks +based solely on thumb +proportions.^([\[41\]](#cite_note-Moyà-Solà-1999-42)) + +The evolution of the fully opposable thumb is usually associated with +*[Homo habilis](/wiki/Homo_habilis "Homo habilis")*, a forerunner of +*[Homo +sapiens](/wiki/Homo_sapiens "Homo sapiens")*.^([\[42\]](#cite_note-43)) +This, however, is the suggested result of evolution from *[Homo +erectus](/wiki/Homo_erectus "Homo erectus")* (around 1 +[mya](/wiki/Mya_(unit) "Mya (unit)")) via a series of intermediate +[anthropoid](/wiki/Simian "Simian") stages, and is therefore a much more +complicated link. + +Modern humans are unique in the musculature of their forearm and hand. +Yet, they remain autapomorphic, meaning each muscle is found in one or +more non-human primates. The extensor pollicis brevis and flexor +pollicis longus allow modern humans to have great manipulative skills +and strong flexion in the thumb.^([\[43\]](#cite_note-44)) + +However, a more likely scenario may be that the specialized precision +gripping hand (equipped with opposable thumb) of *[Homo +habilis](/wiki/Homo_habilis "Homo habilis")* preceded walking, with the +specialized adaptation of the spine, pelvis, and lower extremities +preceding a more advanced hand. And, it is logical that a conservative, +highly functional adaptation be followed by a series of more complex +ones that complement it. With *[Homo +habilis](/wiki/Homo_habilis "Homo habilis")*, an advanced +grasping-capable hand was accompanied by facultative +[bipedalism](/wiki/Bipedalism "Bipedalism"), possibly implying, assuming +a co-opted evolutionary relationship exists, that the latter resulted +from the former as obligate bipedalism was yet to +follow.^([\[44\]](#cite_note-45)) Walking may have been a by-product of +busy hands and not vice versa. + +[HACNS1](/wiki/HACNS1 "HACNS1") (also known as [Human Accelerated +Region](/wiki/Human_accelerated_regions "Human accelerated regions") 2) +is a [gene enhancer](/wiki/Enhancer_(genetics) "Enhancer (genetics)") +"that may have contributed to the evolution of the uniquely opposable +human thumb, and possibly also modifications in the +[ankle](/wiki/Ankle "Ankle") or [foot](/wiki/Foot "Foot") that allow +humans to [walk](/wiki/Walk "Walk") on two legs". Evidence to date shows +that of the 110,000 gene enhancer sequences identified in the human +[genome](/wiki/Genome "Genome"), HACNS1 has undergone the most change +during the [human evolution](/wiki/Human_evolution "Human evolution") +since the [chimpanzee–human last common +ancestor](/wiki/Chimpanzee%E2%80%93human_last_common_ancestor "Chimpanzee–human last common ancestor").^([\[45\]](#cite_note-46)) + +## See also + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=21 "Edit section: See also")\] + +- [Pollicization](/wiki/Pollicization "Pollicization") +- [Prehensility](/wiki/Prehensility "Prehensility") +- [Thumb signal](/wiki/Thumb_signal "Thumb signal") +- [Thumb twiddling](/wiki/Thumb_twiddling "Thumb twiddling") +- [Thumb war](/wiki/Thumb_war "Thumb war") + +## Notes + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=22 "Edit section: Notes")\] + +1. **[^](#cite_ref-1)** + [clinicalconsiderations](http://www.wesnorman.com/clinicalconsiderations.htm) + at The Anatomy Lesson by Wesley Norman (Georgetown University) +2. **[^](#cite_ref-3)** + ["Definition of + FINGER"](https://www.merriam-webster.com/dictionary/finger). + *www.merriam-webster.com*. 2024-09-26. Retrieved 2024-09-30. +3. **[^](#cite_ref-4)** Haeri, Seyed Mohammad Jafar, et al. "Human + thumb consists of three phalanges and lacks metacarpal? A + morphometric study on the long bones of the hand." Surgical and + Radiologic Anatomy 44.8 (2022): + 1101-1109.[https://doi.org/10.1007/s00276-022-02986-9](https://doi.org/10.1007/s00276-022-02986-9) +4. ^ [^(***a***)](#cite_ref-vanNierop-2008_5-0) + [^(***b***)](#cite_ref-vanNierop-2008_5-1) [van Nierop et al. + 2008](#CITEREFvan_Nieropvan_der_HelmOverbeekeDjajadiningrat2008), + p. 34 +5. **[^](#cite_ref-Brownetal-2004_6-0)** [Brown et al. + 2004](#CITEREFBrownFreemanCuccurulloFreeman2004) +6. **[^](#cite_ref-Primates-FAQ_7-0)** ["Primates FAQ: Do any primates + have opposable thumbs?"](https://www.primates.com/faq/). Wisconsin + Regional Primate Research Center. Retrieved 20 November 2010. +7. **[^](#cite_ref-8)** ["The Thumb is the + Hero"](https://query.nytimes.com/gst/fullpage.html?res=9F04E3D8173BF932A25752C0A967948260). + *The New York Times*. January 11, 1981. Retrieved 20 November 2010. + “The "fishing rod" a chimp strips of leaves and pokes into a termite + nest to bring up a snack is as far as he'll ever get toward orbiting + the planets.” +8. **[^](#cite_ref-PrimateAnatomy8_9-0)** [Ankel-Simons + 2007](#CITEREFAnkel-Simons2007), p. 345 +9. ^ [^(***a***)](#cite_ref-Jones-Lederman-2006-p12_10-0) + [^(***b***)](#cite_ref-Jones-Lederman-2006-p12_10-1) + [^(***c***)](#cite_ref-Jones-Lederman-2006-p12_10-2) [Jones & + Lederman 2006](#CITEREFJonesLederman2006), Evolutionary Development + and Anatomy of the Hand, p. 12 +10. **[^](#cite_ref-PloS-Darwinius-2009_11-0)** [Franzen et al. + 2009](#CITEREFFranzenGingerichHabersetzerHurum2009), pp. 15–18 +11. **[^](#cite_ref-12)** ["The Panda's + Thumb"](http://www.athro.com/evo/pthumb.html). Athro. 2000. + Retrieved 21 November 2010. +12. **[^](#cite_ref-order_13-0)** Stefoff, Rebecca (2008). [*The Rodent + Order*](https://books.google.com/books?id=7Gle7-L46TYC&pg=PA63). + Marshall Cavendish. pp. 62–63, 71–73. + [ISBN](/wiki/ISBN_(identifier) "ISBN (identifier)") [978-0-7614-3073-5](/wiki/Special:BookSources/978-0-7614-3073-5 "Special:BookSources/978-0-7614-3073-5"). +13. **[^](#cite_ref-14)** [Ellerman 1941](#CITEREFEllerman1941), p. 2 +14. **[^](#cite_ref-15)** Grzimek, Bernhard (2003). Hutchins, Michael; + Kleiman, Devra G.; Geist, Valerius; et al. (eds.). [*Grzimek's + Animal Life Encyclopedia, Vol 16, Mammals + V*](https://archive.org/details/grzimeksanimalli0002grzi_c1l6/page/293/mode/2up) + (2nd ed.). Farmington Hills, MI: Gale Group. p. 293. + [ISBN](/wiki/ISBN_(identifier) "ISBN (identifier)") [978-0-7876-7750-3](/wiki/Special:BookSources/978-0-7876-7750-3 "Special:BookSources/978-0-7876-7750-3"). +15. **[^](#cite_ref-Nowak-1999_16-0)** [Nowak 1999](#CITEREFNowak1999), + p. 89 +16. **[^](#cite_ref-McDade-2003-koala_17-0)** [McDade + 2003](#CITEREFMcDade2003), vol 13, p. 44 +17. **[^](#cite_ref-McDade-2003-opossum_18-0)** [McDade + 2003](#CITEREFMcDade2003), vol 12, p. 250 +18. **[^](#cite_ref-McDade-2003-microbiotheres_19-0)** [McDade + 2003](#CITEREFMcDade2003), vol 12, p. 274 +19. **[^](#cite_ref-20)** Anderson, Christopher V. & Higham, Timothy E. + (2014). "Chameleon anatomy". In Tolley, Krystal A. & Herrel, Anthony + (eds.). *The Biology of Chameleons*. Berkeley: University of + California Press. pp. 7–55. + [ISBN](/wiki/ISBN_(identifier) "ISBN (identifier)") [9780520276055](/wiki/Special:BookSources/9780520276055 "Special:BookSources/9780520276055"). +20. **[^](#cite_ref-russell1982_21-0)** Russell, D. A.; Séguin, R. + (1982). ["Reconstruction of the small Cretaceous theropod + *Stenonychosaurus inequalis* and a hypothetical + dinosauroid"](https://archive.org/details/syllogeus37nati). + *Syllogeus*. **37**: 1–43. +21. **[^](#cite_ref-22)** [Senter 2006](#CITEREFSenter2006) +22. **[^](#cite_ref-23)** [de Klerk et al. + 2000](#CITEREFde_KlerkForsterSampsonChinsamy2000), p. 327. *The left + manus shows that the flexed digit I had the potential to partially + oppose digits II and III.* +23. **[^](#cite_ref-Zhouetal2021_24-0)** Zhou, X.; Pêgas, R. V.; Ma, W.; + Han, G.; Jin, X.; Leal, M. E. C.; Bonde, N.; Kobayashi, Y.; + Lautenschlager, S.; Wei, X.; Shen, C.; Ji, S. (2021). ["A new + darwinopteran pterosaur reveals arborealism and an opposed + thumb"](https://doi.org/10.1016%2Fj.cub.2021.03.030). *[Current + Biology](/wiki/Current_Biology "Current Biology")*. **31** (11): + 2429–2436.e7. + [Bibcode](/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2021CBio...31E2429Z](https://ui.adsabs.harvard.edu/abs/2021CBio...31E2429Z). + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1016/j.cub.2021.03.030](https://doi.org/10.1016%2Fj.cub.2021.03.030). + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [33848460](https://pubmed.ncbi.nlm.nih.gov/33848460). +24. **[^](#cite_ref-Phyllomedusa_25-0)** Bertoluci, Jaime (18 December + 2002). ["Pedal luring in the leaf-frog Phyllomedusa burmeisteri + (Anura, Hylidae, + Phyllomedusinae)"](https://doi.org/10.11606%2Fissn.2316-9079.v1i2p93-95). + *Phyllomedusa: Journal of Herpetology*. **1** (2): 93. + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.11606/issn.2316-9079.v1i2p93-95](https://doi.org/10.11606%2Fissn.2316-9079.v1i2p93-95). +25. **[^](#cite_ref-26)** [Austin 2005](#CITEREFAustin2005), p. 339 +26. **[^](#cite_ref-27)** ["Muscles of the + thumb"](http://www.eatonhand.com/mus/mus131.htm). Eaton hand. + Retrieved 11 May 2010. +27. **[^](#cite_ref-Platzer-162_28-0)** [Platzer + 2004](#CITEREFPlatzer2004), p. 162 +28. ^ [^(***a***)](#cite_ref-Platzer-168_29-0) + [^(***b***)](#cite_ref-Platzer-168_29-1) + [^(***c***)](#cite_ref-Platzer-168_29-2) [Platzer + 2004](#CITEREFPlatzer2004), p. 168 +29. ^ [^(***a***)](#cite_ref-Platzer-176_30-0) + [^(***b***)](#cite_ref-Platzer-176_30-1) + [^(***c***)](#cite_ref-Platzer-176_30-2) + [^(***d***)](#cite_ref-Platzer-176_30-3) [Platzer + 2004](#CITEREFPlatzer2004), p. 176 +30. **[^](#cite_ref-Platzer-174_31-0)** [Platzer + 2004](#CITEREFPlatzer2004), p. 174 +31. ^ [^(***a***)](#cite_ref-hitchthumbmyth_32-0) + [^(***b***)](#cite_ref-hitchthumbmyth_32-1) ["Myth's of Human + Genetics: Hitchhiker's + Thumb"](http://udel.edu/~mcdonald/myththumb.html). Retrieved 7 + November 2012. +32. **[^](#cite_ref-33)** ["Thumb, Distal Hyperextensibility + of"](https://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=274200). + *OMIM*. NCBI. Retrieved 5 February 2010. +33. **[^](#cite_ref-34)** [Slocum & Pratt + 1946](#CITEREFSlocumPratt1946), [McBride 1942](#CITEREFMcBride1942), + p. 631 +34. **[^](#cite_ref-35)** [Napier 1956](#CITEREFNapier1956), pp. 902–913 +35. **[^](#cite_ref-PLOS-2010_36-0)** [Almécija, Moyà-Solà & Alba + 2010](#CITEREFAlmécijaMoyà-SolàAlba2010) +36. **[^](#cite_ref-37)** [Costello & Fragaszy + 1988](#CITEREFCostelloFragaszy1988), pp. 235–245 +37. **[^](#cite_ref-38)** [Young 2003](#CITEREFYoung2003), pp. 165–174, + [Christel, Kitzel & Niemitz + 2004](#CITEREFChristelKitzelNiemitz2004), pp. 165–194, [Byrne & + Byrne 1993](#CITEREFByrneByrne1993), p. 241 +38. **[^](#cite_ref-39)** Lin, Yun; Sun, Yu (2015). "Robot grasp + planning based on demonstrated grasp strategies". *The International + Journal of Robotics Research*. **34**: 26–42. + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1177/0278364914555544](https://doi.org/10.1177%2F0278364914555544). + [S2CID](/wiki/S2CID_(identifier) "S2CID (identifier)") [10178250](https://api.semanticscholar.org/CorpusID:10178250). +39. **[^](#cite_ref-40)** Bodranghien, Florian; Mahé, Helene; Baude, + Benjamin; Manto, Mario U.; Busegnies, Yves; Camut, Stéphane; Habas, + Christophe; Marien, Peter; de Marco, Giovanni (2017-05-10). ["The + Click Test: A Novel Tool to Quantify the Age-Related Decline of Fast + Motor Sequencing of the + Thumb"](https://hal.parisnanterre.fr//hal-02310540/file/Bodranghienetal.TheClickTestANovelTooltoQuantifytheAge-RelatedDeclineofFastMotorSequencingoftheThumbCurrentagingscience2017.pdf) + (PDF). *Current Aging Science*. **10** (4): 305–318. + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.2174/1874609810666170511100318](https://doi.org/10.2174%2F1874609810666170511100318). + [ISSN](/wiki/ISSN_(identifier) "ISSN (identifier)") [1874-6128](https://search.worldcat.org/issn/1874-6128). + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [28494715](https://pubmed.ncbi.nlm.nih.gov/28494715). +40. **[^](#cite_ref-Brüser-167_41-0)** [Brunelli + 1999](#CITEREFBrunelli1999), p. 167 +41. **[^](#cite_ref-Moyà-Solà-1999_42-0)** [Moyà-Solà, Köhler & Rook + 1999](#CITEREFMoyà-SolàKöhlerRook1999), pp. 315–6 +42. **[^](#cite_ref-43)** [Leakey, Tobias & Napier + 1964](#CITEREFLeakeyTobiasNapier1964): "\[In Homo habilis\] the + pollex is well developed and fully opposable and the hand is capable + not only of a power grip but of, at least, a simple and usually well + developed precision grip." +43. **[^](#cite_ref-44)** Diogo, R.; Richmond, B. G.; Wood, B. (2012). + "Evolution and homologies of primate and modern human hand and + forearm muscles, with notes on thumb movements and tool use". + *Journal of Human Evolution*. **63** (1): 64–78. + [Bibcode](/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2012JHumE..63...64D](https://ui.adsabs.harvard.edu/abs/2012JHumE..63...64D). + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1016/j.jhevol.2012.04.001](https://doi.org/10.1016%2Fj.jhevol.2012.04.001). + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [22640954](https://pubmed.ncbi.nlm.nih.gov/22640954). +44. **[^](#cite_ref-45)** [Harcourt-Smith & Aiello + 2004](#CITEREFHarcourt-SmithAiello2004) +45. **[^](#cite_ref-46)** ["HACNS1: Gene enhancer in evolution of human + opposable + thumb"](http://www.sciencecodex.com/gene_enhancer_in_evolution_of_human_opposable_thumb). + Science Codex. September 4, 2008. Retrieved December 16, 2009. + +1. **[^](#cite_ref-2)** In some countries and cultures, the thumb is + considered a finger. Elsewhere, it is considered a 'digit' due to + the few features it has in difference with the other four digits, + such as the larger gap, missing phalanx and horizontal curling + movement. + +## References + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=23 "Edit section: References")\] + +- Almécija, S.; Moyà-Solà, S.; Alba, D. M. (2010). ["Early Origin for + Human-Like Precision Grasping: A Comparative Study of Pollical + Distal Phalanges in Fossil + Hominins"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908684). + *PLOS ONE*. **5** (7): e11727. + [Bibcode](/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2010PLoSO...511727A](https://ui.adsabs.harvard.edu/abs/2010PLoSO...511727A). + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1371/journal.pone.0011727](https://doi.org/10.1371%2Fjournal.pone.0011727). + [PMC](/wiki/PMC_(identifier) "PMC (identifier)") [2908684](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908684). + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [20661444](https://pubmed.ncbi.nlm.nih.gov/20661444). +- Ankel-Simons, Friderun (2007). "Chapter 8: Postcranial Skeleton". + *Primate Anatomy* (3rd ed.). Academic Press. p. 345. + [ISBN](/wiki/ISBN_(identifier) "ISBN (identifier)") [978-0-12-372576-9](/wiki/Special:BookSources/978-0-12-372576-9 "Special:BookSources/978-0-12-372576-9"). +- Austin, Noelle M. (2005). "Chapter 9: The Wrist and Hand Complex". + In Levangie, Pamela K.; Norkin, Cynthia C. (eds.). *Joint Structure + and Function: A Comprehensive Analysis* (4th ed.). + Philadelphia: F. A. Davis Company. + [ISBN](/wiki/ISBN_(identifier) "ISBN (identifier)") [978-0-8036-1191-7](/wiki/Special:BookSources/978-0-8036-1191-7 "Special:BookSources/978-0-8036-1191-7"). +- Brown, David P.; Freeman, Eric D.; Cuccurullo, Sara; Freeman, Ted L. + (2004). ["Upper Extremities—Hand Region: Range of Motion of the + Digits"](https://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=physmedrehab&part=A4492#A4530). + In Cuccurullo, Sara (ed.). *Physical Medicine and Rehabilitation + Board Review*. Demos Medical Publishing. + [ISBN](/wiki/ISBN_(identifier) "ISBN (identifier)") [978-1-888799-45-3](/wiki/Special:BookSources/978-1-888799-45-3 "Special:BookSources/978-1-888799-45-3"). + ([NCBI](/wiki/National_Center_for_Biotechnology_Information "National Center for Biotechnology Information")) +- Brunelli, Giovanni R. (1999). ["Stability in the first + carpometacarpal + joint"](https://books.google.com/books?id=-pzGRMvXFzAC&pg=PA167). In + Brüser, Peter; Gilbert, Alain (eds.). *Finger bone and joint + injuries*. Taylor & Francis. + [ISBN](/wiki/ISBN_(identifier) "ISBN (identifier)") [978-1-85317-690-6](/wiki/Special:BookSources/978-1-85317-690-6 "Special:BookSources/978-1-85317-690-6"). +- Byrne, R.W.; Byrne, J.M.E. (1993). ["Complex Leaf-Gathering Skills + of Mountain Gorillas (Gorilla g. beringei): Variability and + Standardization"](https://web.archive.org/web/20090920100630/http://www.st-andrews.ac.uk/~www_sp/people/personal/rwb/publications/1993%20Byrne_Byrne_AJP.pdf) + (PDF). *American Journal of Primatology*. **31** (4): 241–261. + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1002/ajp.1350310402](https://doi.org/10.1002%2Fajp.1350310402). + [ISSN](/wiki/ISSN_(identifier) "ISSN (identifier)") [0275-2565](https://search.worldcat.org/issn/0275-2565). + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [31936992](https://pubmed.ncbi.nlm.nih.gov/31936992). + [S2CID](/wiki/S2CID_(identifier) "S2CID (identifier)") [84429453](https://api.semanticscholar.org/CorpusID:84429453). + Archived from [the + original](http://www.st-andrews.ac.uk/~www_sp/people/personal/rwb/publications/1993%20Byrne_Byrne_AJP.pdf) + (PDF) on September 20, 2009. +- Christel, Marianne I.; Kitzel, Stefanie; [Niemitz, + Carsten](/wiki/Carsten_Niemitz "Carsten Niemitz") (30 November + 2004). "How Precisely do Bonobos (Pan paniscus) Grasp Small + Objects?". *International Journal of Primatology*. **19** (1): + 165–194. + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1023/A:1020319313219](https://doi.org/10.1023%2FA%3A1020319313219). + [S2CID](/wiki/S2CID_(identifier) "S2CID (identifier)") [23567551](https://api.semanticscholar.org/CorpusID:23567551). +- Costello, Michael B.; Fragaszy, Dorothy M. (March 1988). + ["Prehension in Cebus and Saimiri: I. Grip type and hand + preference"](http://www3.interscience.wiley.com/cgi-bin/fulltext/110487513/PDFSTART). + *American Journal of Primatology*. **15** (3): 235–245. + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1002/ajp.1350150306](https://doi.org/10.1002%2Fajp.1350150306). + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [31968893](https://pubmed.ncbi.nlm.nih.gov/31968893). + [S2CID](/wiki/S2CID_(identifier) "S2CID (identifier)") [86556774](https://api.semanticscholar.org/CorpusID:86556774).^(\[*[dead\ link](/wiki/Wikipedia:Link_rot "Wikipedia:Link rot")*\]) +- de Klerk, W.J.; Forster, C.A.; Sampson, S.D.; Chinsamy, A.; Ross, + C.F. (2000). ["A new coelurosaurian dinosaur from the Early + Cretaceous of South + Africa"](https://wayback.archive-it.org/all/20120130211657/http://rosslab.uchicago.edu/publications/De%20Klerk%20et%20al.%202000.pdf) + (PDF). *Journal of Vertebrate Paleontology*. **20** (2): 324–332. + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1671/0272-4634(2000)020\[0324:ancdft\]2.0.co;2](https://doi.org/10.1671%2F0272-4634%282000%29020%5B0324%3Aancdft%5D2.0.co%3B2). + [S2CID](/wiki/S2CID_(identifier) "S2CID (identifier)") [128622530](https://api.semanticscholar.org/CorpusID:128622530). + Archived from [the + original](http://rosslab.uchicago.edu/publications/De%20Klerk%20et%20al.%202000.pdf) + (PDF) on 2012-01-30. +- Diogo, R; Richmond, BG; Wood, B (2012). "Evolution and homologies of + primate and modern human hand and forearm muscles, with notes on + thumb movements and tool use". *Journal of Human Evolution*. **63** + (1): 64–78. + [Bibcode](/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2012JHumE..63...64D](https://ui.adsabs.harvard.edu/abs/2012JHumE..63...64D). + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1016/j.jhevol.2012.04.001](https://doi.org/10.1016%2Fj.jhevol.2012.04.001). + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [22640954](https://pubmed.ncbi.nlm.nih.gov/22640954). +- Ellerman, John Reeves (1941). [*The families and genera of living + rodents. Vol. II. Family + Muridae*](https://archive.org/stream/familiesgeneraof02elle#page/2/mode/2up/search/Lophiomyidae). + London: British Museum (Natural History). +- Franzen, JL; Gingerich, PD; Habersetzer, J; Hurum, JH; von + Koenigswald, W; et al. (2009). Hawks, John (ed.). ["Complete Primate + Skeleton from the Middle Eocene of Messel in Germany: Morphology and + Paleobiology"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2683573). + *PLOS ONE*. **4** (5): e5723. + [Bibcode](/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[2009PLoSO...4.5723F](https://ui.adsabs.harvard.edu/abs/2009PLoSO...4.5723F). + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1371/journal.pone.0005723](https://doi.org/10.1371%2Fjournal.pone.0005723). + [PMC](/wiki/PMC_(identifier) "PMC (identifier)") [2683573](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2683573). + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [19492084](https://pubmed.ncbi.nlm.nih.gov/19492084). +- Harcourt-Smith, W E H; Aiello, L C (May 2004). ["Fossils, feet and + the evolution of human bipedal + locomotion"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1571304). + *Journal of Anatomy*. **204** (5): 403–16. + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1111/j.0021-8782.2004.00296.x](https://doi.org/10.1111%2Fj.0021-8782.2004.00296.x). + [PMC](/wiki/PMC_(identifier) "PMC (identifier)") [1571304](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1571304). + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [15198703](https://pubmed.ncbi.nlm.nih.gov/15198703). +- Hsu, Ar-Tyan; Meng-Tsu Hu; Fong Ching Su (July 2008). ["Effect of + Gender, Flexibility and Thumb Type on Thumb Tip + Generation"](http://www.jbiomech.com/article/S0021-9290%2808%2970148-9/abstract). + *Journal of Biomechanics*. **41** (Supplement 1): S148. + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1016/S0021-9290(08)70148-9](https://doi.org/10.1016%2FS0021-9290%2808%2970148-9). +- [Jones, Lynette A.](/wiki/Lynette_Jones "Lynette Jones"); [Lederman, + Susan J.](/wiki/Susan_Lederman "Susan Lederman") (2006). [*Human + hand + function*](https://archive.org/details/humanhandfunctio0000jone). + Oxford University Press US. + [ISBN](/wiki/ISBN_(identifier) "ISBN (identifier)") [9780195173154](/wiki/Special:BookSources/9780195173154 "Special:BookSources/9780195173154"). +- [Leakey, LSB](/wiki/Louis_Leakey "Louis Leakey"); [Tobias, + PV](/wiki/Phillip_V._Tobias "Phillip V. Tobias"); [Napier, + JR](/wiki/John_Napier_(primatologist) "John Napier (primatologist)") + (April 1964). ["A New Species of Genus Homo from Olduvai + Gorge"](http://purple.niagara.edu/wje/Bio121/Leaky%201964%20habilis.pdf) + (PDF). *Nature*. **202** (4927): 7–9. + [Bibcode](/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[1964Natur.202....7L](https://ui.adsabs.harvard.edu/abs/1964Natur.202....7L). + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1038/202007a0](https://doi.org/10.1038%2F202007a0). + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [14166722](https://pubmed.ncbi.nlm.nih.gov/14166722). + [S2CID](/wiki/S2CID_(identifier) "S2CID (identifier)") [12836722](https://api.semanticscholar.org/CorpusID:12836722).^(\[*[permanent\ dead\ link](/wiki/Wikipedia:Link_rot "Wikipedia:Link rot")*\]) +- McBride, Earl Duwain (1942). [*Disability evaluation: principles of + treatment of compensable + injuries*](https://books.google.com/books?id=YIpgQgAACAAJ). + Lippincott. p. 631. +- McDade, Melissa C. (2003). "Koalas (*Phascolartidae*)". In Hutchins, + Michael; Kleiman, Devra G.; Geist, Valerius; et al. (eds.). + *Grzimek's animal life encyclopedia: Volumes 12–16, Mammals I–V* + (2nd ed.). Farmington Hills, MI: Gale Group. +- Moyà-Solà, Salvador; Köhler, Meike; Rook, Lorenzo (January 5, 1999). + ["Evidence of hominid-like precision grip capability in the hand of + the Miocene ape + Oreopithecus"](http://www.pnas.org/content/96/1/313.full.pdf) (PDF). + *PNAS*. **96** (1): 313–317. + [Bibcode](/wiki/Bibcode_(identifier) "Bibcode (identifier)"):[1999PNAS...96..313M](https://ui.adsabs.harvard.edu/abs/1999PNAS...96..313M). + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1073/pnas.96.1.313](https://doi.org/10.1073%2Fpnas.96.1.313). + [PMC](/wiki/PMC_(identifier) "PMC (identifier)") [15136](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC15136). + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [9874815](https://pubmed.ncbi.nlm.nih.gov/9874815). +- Napier, John Russell (November 1956). ["The prehensile movements of + the human hand"](https://doi.org/10.1302%2F0301-620X.38B4.902). *J + Bone Joint Surg Br*. **38** (4): 902–913. + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1302/0301-620X.38B4.902](https://doi.org/10.1302%2F0301-620X.38B4.902). + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [13376678](https://pubmed.ncbi.nlm.nih.gov/13376678). +- Nowak, Ronald M. (1999). [*Walker's mammals of the world, Volume + 2*](https://books.google.com/books?id=T37sFCl43E8C&pg=PA89) + (6th ed.). JHU Press. + [ISBN](/wiki/ISBN_(identifier) "ISBN (identifier)") [978-0-8018-5789-8](/wiki/Special:BookSources/978-0-8018-5789-8 "Special:BookSources/978-0-8018-5789-8"). +- Platzer, Werner (2004). *Color Atlas of Human Anatomy, Vol. 1: + Locomotor System* (5th ed.). Thieme. + [ISBN](/wiki/ISBN_(identifier) "ISBN (identifier)") [3-13-533305-1](/wiki/Special:BookSources/3-13-533305-1 "Special:BookSources/3-13-533305-1"). +- Senter, Phil (2006). "Comparison of forelimb function between + *Deinonychus* and *Bambiraptor* (Theropoda: Dromaeosauridae)". + *Journal of Vertebrate Paleontology*. **26** (4): 897–906. + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1671/0272-4634(2006)26\[897:COFFBD\]2.0.CO;2](https://doi.org/10.1671%2F0272-4634%282006%2926%5B897%3ACOFFBD%5D2.0.CO%3B2). + [S2CID](/wiki/S2CID_(identifier) "S2CID (identifier)") [85919882](https://api.semanticscholar.org/CorpusID:85919882). +- Slocum, D.B.; Pratt, D.R. (1946). ["Disability Evaluation for the + Hand"](http://www.ejbjs.org/cgi/reprint/28/3/491.pdf) (PDF). + *Journal of Bone and Joint Surgery*. **28** (3): 491–5. + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [20992193](https://pubmed.ncbi.nlm.nih.gov/20992193).^(\[*[permanent\ dead\ link](/wiki/Wikipedia:Link_rot "Wikipedia:Link rot")*\]) +- van Nierop, Onno A.; van der Helm, Aadjan; Overbeeke, Kees J.; + Djajadiningrat, Tom J.P. (2008). ["A natural human hand + model"](http://www.ece.uvic.ca/~btill/papers/mocap/vanNierop_etal_2008.pdf) + (PDF). *Visual Comput*. **24** (1): 31–44. + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1007/s00371-007-0176-x](https://doi.org/10.1007%2Fs00371-007-0176-x). +- Young, Richard W. (January 2003). ["Evolution of the human hand: the + role of throwing and + clubbing"](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1571064). + *Journal of Anatomy*. **202** (1): 165–174. + [doi](/wiki/Doi_(identifier) "Doi (identifier)"):[10.1046/j.1469-7580.2003.00144.x](https://doi.org/10.1046%2Fj.1469-7580.2003.00144.x). + [PMC](/wiki/PMC_(identifier) "PMC (identifier)") [1571064](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1571064). + [PMID](/wiki/PMID_(identifier) "PMID (identifier)") [12587931](https://pubmed.ncbi.nlm.nih.gov/12587931). + +## External links + +\[[edit](/w/index.php?title=Thumb&action=edit§ion=24 "Edit section: External links")\] + +- [](/wiki/File:Commons-logo.svg) + Media related to + [Thumbs](https://commons.wikimedia.org/wiki/Category:Thumbs "commons:Category:Thumbs") + at Wikimedia Commons +- [](/wiki/File:Wiktionary-logo-en-v2.svg) + The dictionary definition of + [*thumb*](https://en.wiktionary.org/wiki/thumb "wiktionary:thumb") + at Wiktionary + +[TABLE] + +[TABLE] + + + +Retrieved from +"[https://en.wikipedia.org/w/index.php?title=Thumb&oldid=1274819517](https://en.wikipedia.org/w/index.php?title=Thumb&oldid=1274819517)" + +[Category](/wiki/Help:Category "Help:Category"): + +- [Fingers](/wiki/Category:Fingers "Category:Fingers") + +Hidden categories: + +- [Articles with short + description](/wiki/Category:Articles_with_short_description "Category:Articles with short description") +- [Short description is different from + Wikidata](/wiki/Category:Short_description_is_different_from_Wikidata "Category:Short description is different from Wikidata") +- [Articles needing additional references from April + 2024](/wiki/Category:Articles_needing_additional_references_from_April_2024 "Category:Articles needing additional references from April 2024") +- [All articles needing additional + references](/wiki/Category:All_articles_needing_additional_references "Category:All articles needing additional references") +- [Articles containing uncoded-language + text](/wiki/Category:Articles_containing_uncoded-language_text "Category:Articles containing uncoded-language text") +- [All articles lacking reliable + references](/wiki/Category:All_articles_lacking_reliable_references "Category:All articles lacking reliable references") +- [Articles lacking reliable references from August + 2024](/wiki/Category:Articles_lacking_reliable_references_from_August_2024 "Category:Articles lacking reliable references from August 2024") +- [All articles with unsourced + statements](/wiki/Category:All_articles_with_unsourced_statements "Category:All articles with unsourced statements") +- [Articles with unsourced statements from August + 2012](/wiki/Category:Articles_with_unsourced_statements_from_August_2012 "Category:Articles with unsourced statements from August 2012") +- [Articles with unsourced statements from December + 2014](/wiki/Category:Articles_with_unsourced_statements_from_December_2014 "Category:Articles with unsourced statements from December 2014") +- [All articles with dead external + links](/wiki/Category:All_articles_with_dead_external_links "Category:All articles with dead external links") +- [Articles with dead external links from January + 2025](/wiki/Category:Articles_with_dead_external_links_from_January_2025 "Category:Articles with dead external links from January 2025") +- [Articles with dead external links from February + 2020](/wiki/Category:Articles_with_dead_external_links_from_February_2020 "Category:Articles with dead external links from February 2020") +- [Articles with permanently dead external + links](/wiki/Category:Articles_with_permanently_dead_external_links "Category:Articles with permanently dead external links") +- [Articles with dead external links from October + 2022](/wiki/Category:Articles_with_dead_external_links_from_October_2022 "Category:Articles with dead external links from October 2022") +- [Commons category link is on + Wikidata](/wiki/Category:Commons_category_link_is_on_Wikidata "Category:Commons category link is on Wikidata") + +- This page was last edited on 9 February 2025, at 12:35 (UTC). +- Text is available under the [Creative Commons Attribution-ShareAlike + 4.0 + License](/wiki/Wikipedia:Text_of_the_Creative_Commons_Attribution-ShareAlike_4.0_International_License "Wikipedia:Text of the Creative Commons Attribution-ShareAlike 4.0 International License"); + additional terms may apply. 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