{{Short description|Carpal bone in the wrist}} {{redirect|Hamatum|its use in taxonomy|List of Latin and Greek words commonly used in systematic names#H{{!}}List of Latin and Greek words commonly used in systematic names}} {{Infobox bone | Name = Hamate bone | Latin = os hamatum | Image = ArticulatedHighlightedHamate.png | Caption = Right hand anterior view (palmar view). Hamate bone shown in red. | Image2 = OsCrochuDroit.jpg | Caption2 = The right hamate bone; anterior aspect. (After Charpy.) | Origins = | Insertions = | Pronunciation = {{IPAc-en|'|h|ei|m|@|t}} | Articulations = Articulates with five bones: <br />the lunate proximally<br />the fourth and fifth metacarpals distally<br />the triquetrum medially<br />the capitate laterally }} thumb|Hamate of the right hand as seen on X-ray (labeled H) The '''hamate bone''' (from Latin {{wikt-lang|la|hamatus}}, {{gloss|hooked}}), or '''unciform bone''' (from Latin {{wikt-lang|la|uncus}}, {{gloss|hook}}), Latin {{lang|la|'''os hamatum'''}} and occasionally abbreviated as just '''hamatum''',<ref>{{Cite journal|last1=Gdoura|first1=F.|last2=Trigui|first2=M.|last3=Ellouze|first3=Z.|last4=Hamed|first4=Y. B.|last5=Ayadi|first5=K.|last6=Keskes|first6=H.|date=October 2010|title=Hamatum osteoblastoma|journal=Orthopaedics & Traumatology, Surgery & Research |volume=96|issue=6|pages=712–716|doi=10.1016/j.otsr.2010.02.014|issn=1877-0568|pmid=20692218|doi-access=free}}</ref><ref>{{Cite journal|last1=Mei|first1=Guo-Hua|last2=Wang|first2=Hai-Ming|last3=Fan|first3=Cun-Yi|last4=Zhang|first4=Chang-Qing|last5=Zeng|first5=Bing-Fang|date=October 2014|title=Possibility of the hamatum carpometacarpal joint as a new joint donor site for interphalangeal joint restoration|journal=European Journal of Orthopaedic Surgery & Traumatology: Orthopedie Traumatologie|volume=24|issue=7|pages=1175–1180|doi=10.1007/s00590-013-1300-4|issn=1633-8065|pmid=23982116|s2cid=25697262 }}</ref><ref>{{Cite journal|last1=Alp|first1=Nazmi Bülent|last2=Kaleli|first2=Tufan|last3=Kalay|first3=Onur Can|last4=Karpat|first4=Fatih|last5=Akdag|first5=Gokhan|last6=Macunluoglu|first6=Aslı Ceren|last7=Oral|first7=Gamze Saygı|date=2020|title=The Effect of Hamatum Curvature Angle on Carpal Tunnel Volumetry: A Mathematical Simulation Model|journal=Computational and Mathematical Methods in Medicine|volume=2020|article-number=7582181|doi=10.1155/2020/7582181|issn=1748-6718|pmc=7312712|pmid=32617118|doi-access=free }}</ref> is a bone in the human wrist readily distinguishable by its wedge shape and a hook-like process ("hamulus") projecting from its palmar surface.
==Structure== The hamate is an irregularly shaped carpal bone found within the hand. The hamate is found within the distal row of carpal bones, and abuts the metacarpals of the little finger and ring finger.<ref name=GRAYS2005>{{cite book|last=Drake|first=Richard L.|title=Gray's anatomy for students|year=2005|publisher=Elsevier/Churchill Livingstone|location=Philadelphia|isbn=978-0-8089-2306-0|author2=Vogl, Wayne |author3=Tibbitts, Adam W.M. Mitchell |author4=illustrations by Richard |author5= Richardson, Paul }}</ref>{{rp|708–709}}
Adjacent to the hamate on the ulnar side, and slightly proximal and ulnar to it, is the pisiform bone. Adjacent on the radial side is the capitate, and proximal is the lunate bone.<ref name=GRAYS2005 />{{rp|708–709}}
===Surfaces=== The hamate bone has six surfaces: * The '''''superior part''''', of the apex of the wedge, is narrow, convex, smooth, and articulates with the lunate. * The '''''inferior''''' articulates with the fourth and fifth metacarpal bones, by concave facets which are separated by a ridge. * The '''''dorsal''''' is triangular and rough for ligamentous attachment. * The '''''palmar''''' presents, at its lower and ulnar side, a curved, hook-like process, the hamulus, directed forward and laterally. * The '''''medial''''' articulates with the triangular bone by an oblong facet, cut obliquely from above, downward and medialward. * The '''''lateral''''' articulates with the capitate by its upper and posterior part, the remaining portion being rough, for the attachment of ligaments.
===Hook=== thumbnail|Hamate bone of the right hand. Hook highlighted in red. The ''hook of hamate'' ({{langx|la|hamulus}}) is found at the proximal, ulnar side of the hamate bone. The hook is a curved, hook-like process that projects 1–2 mm distally and radially.<ref name=EATHORNE2005>{{cite journal|last=Eathorne|first=SW|title=The wrist: clinical anatomy and physical examination—an update.|journal=Primary Care|date=March 2005|volume=32|issue=1|pages=17–33|pmid=15831311|doi=10.1016/j.pop.2004.11.009}}</ref> The ulnar nerve hooks around the hook of hamate as it crosses towards the medial side of hand.
The hook forms the ulnar border of the carpal tunnel, and the radial border for Guyon's canal. Numerous structures attach to it, including ligaments from the pisiform, the transverse carpal ligament, and the tendon of flexor carpi ulnaris.<ref name=EATHORNE2005 />
Its medial surface gives origin to the flexor digiti minimi brevis and opponens digiti minimi; its lateral side is grooved for the passage of the flexor tendons into the palm of the hand.
===Development=== The ossification of the hamate starts at the sixth month of life on average.<ref name=CHLT>{{cite journal|last1=Balachandran|first1=Ajay|last2=Kartha|first2=Moumitha|last3=Krishna|first3=Anooj|last4=Thomas|first4=Jerry|last5=K|first5=Prathilash|last6=TN|first6=Prem|last7=GK|first7=Libu|last8=B|first8=Krishnan|last9=John|first9=Liza|title=A Study of Ossification of Capitate, Hamate, Triquetral & Lunate in Forensic Age Estimation|journal=Indian Journal of Forensic Medicine & Toxicology|date=2014|volume=8|issue=2|pages=218–224|doi=10.5958/0973-9130.2014.00720.8|url=http://www.indianjournals.com/ijor.aspx?target=ijor:ijfmt&volume=8&issue=2&article=052|access-date=18 August 2014|issn=0973-9130|url-access=subscription}}</ref> The said bone does not fully ossify until about the 15th year of life.<ref name=EATHORNE2005 />
===Other animals=== The bone is also found in many other mammals, and is homologous with the "fourth distal carpal" of reptiles and amphibians.
==Function== {{expand section|date=September 2022}} The carpal bones function as a unit to provide a bony superstructure for the hand.<ref name=GRAYS2005 /> It forms a concave palmar arch that helps create the carpal tunnel and acts as an attachment site for ligaments and muscles involved in grip and muscle control. The flexor retinaculum of the hand and muscles of the hypothenar eminence attach to the hook of the hamate, which helps to stabilize the ulnar border of the carpal tunnel and form Guyon's Canal.
==Clinical significance== The hamate bone is the bone most commonly fractured when a golfer hits the ground hard with a golf club on the downswing or a hockey player hits the ice with a slap shot. The fracture is usually a hairline fracture, commonly missed on normal X-rays. Symptoms are pain aggravated by gripping, tenderness over the hamate and symptoms of irritation of the ulnar nerve. This is characterized by numbness and weakness of the fifth digit with partial involvement of the fourth digit as well, the "ulnar 1½ fingers".
The hook of hamate is particularly prone to fracture-related complications such as non-union due to its tenuous blood supply.<ref name=EATHORNE2005 />
It is also a common injury in baseball players. Several professional baseball players have had the bone removed during the course of their careers.<ref>{{cite news |first=Chris |last=Snow |url=http://archive.boston.com/sports/baseball/redsox/articles/2006/06/01/pea_to_have_surgery/ |title=Peña to have surgery |work=The Boston Globe |date=June 1, 2006 |access-date=September 2, 2011}}</ref><ref>{{cite web |first=John |last=Manuel |url=http://www.baseballamerica.com/today/features/040331wrist.html |title=Wrist Troubles Drain Prospects' Power |publisher=Baseball America |date=March 31, 2004 |access-date=September 2, 2011}}</ref><ref>{{cite news |first=Amalie |last=Benjamin |url=http://archive.boston.com/sports/baseball/redsox/articles/2007/07/27/hes_gaining_in_arms_race/ |title=He's gaining in arms race |work=The Boston Globe |date=July 27, 2007 |access-date=September 2, 2011}}</ref><ref>{{cite news |agency=Associated Press |url=https://www.espn.com/mlb/news/story?id=5160329 |title=Dickerson has hand, wrist surgery |publisher=ESPN |date=May 3, 2010 |access-date=September 2, 2011}}</ref><ref>{{cite web |first=Kieran |last=Carobine |url=https://philliesnation.com/archives/2011/03/domonic-browns-surgery-a-success/ |title=Domonic Brown's Surgery A Success |publisher=Phillies Nation |date=March 8, 2011 |access-date=September 2, 2011}}</ref><ref>{{cite web |url= https://www.cbssports.com/fantasy/baseball/news/angels-mike-trout-undergoes-hamate-surgery/ |title=Angels' Mike Trout: Undergoes hamate surgery |date=July 5, 2023 |work=CBS Sports |access-date=August 4, 2023}}</ref> This condition has been called "Wilson's Wrist".<ref>WILSON JN. Profiles of the carpal canal. ''J Bone Joint Surg Am''. 1954 Jan;36-A(1):127–132</ref>
The calcification of the hamate bone is seen on X-rays during puberty and is sometimes used in orthodontics to determine if an adolescent patient is suitable for orthognathic intervention (i.e. before or at their growth spurt).{{cn|date=January 2023}}
==Etymology== The etymology derives from the Latin ''hamatus'' "hooked," from ''hamus'' which means "hook".
==Additional images== <gallery> File:Hamate bone (left hand) - animation01.gif|Position of hamate bone (shown in red). Left hand. Animation. File:Hamate bone (left hand) - animation04.gif|Hamate bone of the left hand. The hook-like process is called hamulus. Image:Hamate bone.jpg|Hamate bone. File:RightHumanAnteriorDistalRadiusUlnaCarpals - Hamate bone.png|Right hand anterior view (palmar view). Thumb on top. File:RightHumanPosteriorDistalRadiusUlnaCarpals - Hamate bone.png|Right hand posterior view (dorsal view). Thumb on bottom. Image:Gray219 - Hamate bone.png|Bones of the left hand. Palmar surface. Hamate shown in yellow. Image:Gray220 - Hamate bone.png|Bones of the left hand. Dorsal surface. Hamate shown in yellow. Image:Gray422 - Hamate bone.png|Transverse section across the wrist and digits. Hamate shown in yellow. File:Ospoignet - Hamate bone.png|Cross section of wrist (thumb on left). Hamate shown in red. File:Slide1dsds - Hamate bone.png|Right wrist joint. Deep dissection. Anterior (palmar) view. </gallery>
== See also == {{Commons}} {{Anatomy-terms}} * Carpal bone * Hypothenar hammer syndrome
== References == {{Gray's}} {{Reflist}}
{{Bones of upper extremity}} {{Portal bar|Anatomy}} {{Authority control}}
{{DEFAULTSORT:Hamate Bone}} Category:Wrist Category:Bones of the hand Category:Carpal bones