The trapezoid bone (lesser multangular bone) is a carpal bone in tetrapods, including humans. It is the smallest bone in the distal row of carpal bones that give structure to the palm of the hand. It may be known by its wedge-shaped form, the broad end of the wedge constituting the dorsal, the narrow end the palmar surface; and by its having four articular facets touching each other, and separated by sharp edges. It is homologous with the "second distal carpal" of reptiles and amphibians.
Trapezoid bone
Left hand anterior view (palmar view). Trapezoid bone shown in red.
The trapezoid is a four-sided carpal bone found within the hand. The trapezoid is found within the distal row of carpal bones.[1]: 708
Surfaces
The superior surface, quadrilateral, smooth, and slightly concave, articulates with the scaphoid.
The inferior surface articulates with the proximal end of the second metacarpal bone; it is convex from side to side, concave from before backward and subdivided by an elevated ridge into two unequal facets.
The dorsal and palmar surfaces are rough for the attachment of ligaments, the former being the larger of the two.
The medial surface is concave and smooth in front, for articulation with the capitate; rough behind, for the attachment of an interosseous ligament.
Function
The carpal bones function as a unit to provide a bony superstructure for the hand.[1]: 708
Clinical Significance
Isolated fractures of the trapezoid are rare, representing 0.4% of the total, thus being the least common of all carpal fractures. This is due to the bone being in a fairly protected position. Distally, it forms a stable, relatively immobile joint with the second metacarpal, radially and proximally it forms strong ligaments with the trapezium and the capitate ulnarly, scaphoid respectively.
However, injury can occur through axial force applied to the second metacarpal base. Subluxations, such as ones caused by delivering a blow, are not uncommon. Direct trauma to the bone can also cause fracture.
Due to its rarity, standard treatment has not been established. A wide range of treatments are possible, including rest, surgery and casting.[2]
History
The etymology derives from the Greek trapezion which means "irregular quadrilateral," from tra- "four" and peza "foot" or "edge." Literally, "a little table" from trapeza meaning "table" and -oeides "shaped."
Additional images
Position of trapezoid bone (shown in red). Left hand. Animation.
Trapezoid bone of the left hand. Close up. Animation.
Trapezoid bone.
Right hand posterior view (dorsal view). Thumb on bottom.
Trapezoid shown in yellow. Left hand. Dorsal surface.
Trapezoid shown in yellow. Left hand. Palmar surface.
Transverse section across the wrist (palm on top, thumb on left). Trapezoid bone shown in yellow (labelled as "Lesser Multang").
Cross section of wrist (thumb on left). Trapezoid shown in red (labelled as "Lesser Multang").
See also
Wikimedia Commons has media related to Trapezoid bone.
This article incorporates text in the public domain from page 225 of the 20th edition ofGray's Anatomy(1918)
^ abDrake, Richard L.; Vogl, Wayne; Tibbitts, Adam W.M. Mitchell; illustrations by Richard; Richardson, Paul (2005). Gray's anatomy for students. Philadelphia: Elsevier/Churchill Livingstone. ISBN978-0-8089-2306-0.
^Sadowski, RM; Montilla, RD (2008). "Rare isolated trapezoid fracture: a case report". Hand (N Y). 3 (4): 372–4. doi:10.1007/s11552-008-9100-8. PMC2584218. PMID 18780025.
trapezoid, bone, trapezoid, bone, lesser, multangular, bone, carpal, bone, tetrapods, including, humans, smallest, bone, distal, carpal, bones, that, give, structure, palm, hand, known, wedge, shaped, form, broad, wedge, constituting, dorsal, narrow, palmar, s. The trapezoid bone lesser multangular bone is a carpal bone in tetrapods including humans It is the smallest bone in the distal row of carpal bones that give structure to the palm of the hand It may be known by its wedge shaped form the broad end of the wedge constituting the dorsal the narrow end the palmar surface and by its having four articular facets touching each other and separated by sharp edges It is homologous with the second distal carpal of reptiles and amphibians Trapezoid boneLeft hand anterior view palmar view Trapezoid bone shown in red The left trapezoid bone DetailsArticulationsarticulates with four bones scaphoid proximallysecond metacarpal distallytrapezium bone laterallycapitate mediallyIdentifiersLatinos trapezoideum os multangulum minusMeSHD051223TA98A02 4 08 010TA21257FMA23724Anatomical terms of bone edit on Wikidata Contents 1 Structure 1 1 Surfaces 2 Function 3 Clinical Significance 4 History 5 Additional images 6 See also 7 ReferencesStructure EditThe trapezoid is a four sided carpal bone found within the hand The trapezoid is found within the distal row of carpal bones 1 708 Surfaces Edit The superior surface quadrilateral smooth and slightly concave articulates with the scaphoid The inferior surface articulates with the proximal end of the second metacarpal bone it is convex from side to side concave from before backward and subdivided by an elevated ridge into two unequal facets The dorsal and palmar surfaces are rough for the attachment of ligaments the former being the larger of the two The lateral surface convex and smooth articulates with the trapezium The medial surface is concave and smooth in front for articulation with the capitate rough behind for the attachment of an interosseous ligament Function EditThe carpal bones function as a unit to provide a bony superstructure for the hand 1 708 Clinical Significance EditIsolated fractures of the trapezoid are rare representing 0 4 of the total thus being the least common of all carpal fractures This is due to the bone being in a fairly protected position Distally it forms a stable relatively immobile joint with the second metacarpal radially and proximally it forms strong ligaments with the trapezium and the capitate ulnarly scaphoid respectively However injury can occur through axial force applied to the second metacarpal base Subluxations such as ones caused by delivering a blow are not uncommon Direct trauma to the bone can also cause fracture Due to its rarity standard treatment has not been established A wide range of treatments are possible including rest surgery and casting 2 History EditThe etymology derives from the Greek trapezion which means irregular quadrilateral from tra four and peza foot or edge Literally a little table from trapeza meaning table and oeides shaped Additional images Edit Position of trapezoid bone shown in red Left hand Animation Trapezoid bone of the left hand Close up Animation Trapezoid bone Right hand posterior view dorsal view Thumb on bottom Trapezoid shown in yellow Left hand Dorsal surface Trapezoid shown in yellow Left hand Palmar surface Transverse section across the wrist palm on top thumb on left Trapezoid bone shown in yellow labelled as Lesser Multang Cross section of wrist thumb on left Trapezoid shown in red labelled as Lesser Multang See also Edit Wikimedia Commons has media related to Trapezoid bone This article uses anatomical terminology Carpal boneReferences Edit This article incorporates text in the public domain from page 225 of the 20th edition of Gray s Anatomy 1918 a b Drake Richard L Vogl Wayne Tibbitts Adam W M Mitchell illustrations by Richard Richardson Paul 2005 Gray s anatomy for students Philadelphia Elsevier Churchill Livingstone ISBN 978 0 8089 2306 0 Sadowski RM Montilla RD 2008 Rare isolated trapezoid fracture a case report Hand N Y 3 4 372 4 doi 10 1007 s11552 008 9100 8 PMC 2584218 PMID 18780025 Portal Anatomy Retrieved from https en wikipedia org w index php title Trapezoid bone amp oldid 1093188374, wikipedia, wiki, book, books, library,
