{{Short description|Uscles widely present in the hands of mammals}} The '''contrahentes''' (singular '''contrahens''') are muscles widely present in the hands of mammals, including monkeys.<ref name="Yamamoto-1988">{{harvnb|Yamamoto|Murakami|Ohtsuka|1988}}</ref> They are on the palmar/plantar side. There is one each for digits I, II, IV and V, but not III. They pull the fingers/toes down and together.
==Human anatomy== In humans, the adductor pollicis muscle in the hand and the adductor hallucis in the foot are well-developed remnants of the first contrahens, though they have lost the insertion on the distal phalanx of the thumb or big toe.<ref name="Yamamoto-1988" /> The other contrahentes only appear as rare atavistic abnormalities.<ref>{{harvnb|Stark|Otter|Boyes|Rickard|1979}}</ref> In other mammals, the contrahentes may have their origin either on the carpus or the metacarpus, which suggests that the palmar interossei muscles also contain elements of the contrahentes.<ref name="Yamamoto-1988" /> They appear in the human fetus as a layer of flesh that mostly disappears.{{cn|date=August 2023}}
==In other animals== The contrahens of the fourth digit is absent in dogs but present in cats and rabbits.<ref name="Yamamoto-1988" />
In primates, the contrahentes vary in number between zero and four. By their insertion onto the proximal phalanges they facilitate convergence of the digits.<ref name="Wright-2003">{{harvnb|Wright|Simons|Gursky|2003| p=100}}</ref>
In tarsiers, they facilitate the grip by increasing the pressure between the large distal pads and the gripped surface by simultaneously flexing the metacarpophalangeal joints and the proximal interphalangeal joints and extending the distal interphalangeal joints. <ref name="Wright-2003" />
==Notes== {{reflist}}
==References== {{refbegin|30em}} * {{cite journal | last1 = Stark | first1 = HH | last2 = Otter | first2 = TA | last3 = Boyes | first3 = JH | last4 = Rickard | first4 =TA | title = "Atavistic contrahentes digitorum" and associated muscle abnormalities of the hand: a cause of symptoms. Report of three cases | journal = J Bone Joint Surg Am | year = 1979 | volume = 61 | issue = 2 | pages = 286–289 | doi = 10.2106/00004623-197961020-00023 | pmid = 422616 | url = http://www.ejbjs.org/cgi/reprint/61/2/286 | url-access = subscription }} * {{cite journal | last1 = Tubbs | first1 = R. Shane | last2 = Salter | first2 = E. George | last3 = Oakes | first3 = W. Jerry | title = Contrahentes digitorum muscle | journal = Clinical Anatomy | volume = 18 | issue = 8 | pages = 606–608 | date = 26 September 2005 | access-date = 7 January 2010 | pmid = 16187298 | doi = 10.1002/ca.20157 | s2cid = 27523606 | url = http://www3.interscience.wiley.com/journal/112096939/abstract | archive-url = https://archive.today/20130105144146/http://www3.interscience.wiley.com/journal/112096939/abstract | url-status = dead | archive-date = 5 January 2013 | url-access = subscription}} * {{cite book | last1 = Wright | first1 = Patricia C. | last2 = Simons | first2 = Elwyn L. | last3 = Gursky | first3 = Sharon | title = Tarsiers: past, present, and future | publisher = Rutgers University Press | year = 2003 | isbn = 9780813532363 | url = https://books.google.com/books?id=9g_TwVzDOI0C&pg=PA100 }} * {{cite journal | last1 = Yamamoto | first1 = Chugo | last2 = Murakami | first2 = Takuro | last3 = Ohtsuka | first3 = Aiji | title = Homology of the adductor pollicis and contrahentes muscles: a study of monkey hands | journal = Acta Med Okayama | date = Aug 1988 | issue = 4 | volume = 42 | pages = 215–26 | url = http://ousar.lib.okayama-u.ac.jp/file/31000/20070110212158/fulltext.pdf | pmid = 3177007 | access-date = 2011-03-15 | archive-url = https://web.archive.org/web/20110718172316/http://ousar.lib.okayama-u.ac.jp/file/31000/20070110212158/fulltext.pdf | archive-date = 2011-07-18 | url-status = dead }} {{refend}}
{{Muscles of upper limb}} {{Muscles of lower limb}}
Category:Muscles of the upper limb Category:Hand Category:Muscles of the lower limb Category:Foot