| Ilium of pelvis | |
|---|---|
 Overview of Ilium as largest region of the pelvis. | |
 Capsule of hip-joint (distended). Posterior aspect. (Ilium labeled at top.) | |
| Details | |
| Identifiers | |
| Latin | os ilium |
| MeSH | D007085 |
| TA98 | A02.5.01.101 |
| TA2 | 1317 |
| FMA | 16589 |
| Anatomical terms of bone | |
Theilium (/ˈɪliəm/) (pl.:ilia) is the uppermost and largest region of thecoxal bone, and appears in mostvertebrates includingmammals andbirds, but notbony fish. All reptiles have an ilium exceptsnakes, with the exception of some snake species which have a tiny bone considered to be an ilium.[1]
The ilium of thehuman is divisible into two parts, the body and the wing; the separation is indicated on the top surface by a curved line, thearcuate line, and on the external surface by the margin of theacetabulum.
The name comes from theLatin (ile,ilis), meaning "groin" or "flank".[2]
The ilium consists of the body andwing. Together with theischium andpubis, to which the ilium is connected, these form the pelvic bone, with only a faint line indicating the place of union.
The body (Latin:corpus) forms less than two-fifths of theacetabulum; and also forms part of the acetabular fossa. The internal surface of the body is part of the wall of thelesser pelvis and gives origin to some fibers of theobturator internus.
Thewing (Latin:ala) is the large expanded portion which bounds thegreater pelvis laterally. It has an external and an internal surface, a crest, and two borders—an anterior and a posterior.
In humans,biiliac width is an anatomical term referring to the widest measure of the pelvis between the outer edges of the upper iliac bones.
Biiliac width has the following common synonyms:pelvic bone width,biiliac breadth, intercristal breadth/width,bi-iliac breadth/width and biiliocristal breadth/width.
It is best measured by anthropometriccalipers (an anthropometer designed for such measurement is called a pelvimeter). Attempting to measure biiliac width with atape measure along a curved surface is inaccurate.
The biiliac width measure is helpful inobstetrics because a pelvis that is significantly too small or too large can have complications. For example, a large baby or a small pelvis often lead to death unless acaesarean section is performed.[3]
It is also used byanthropologists to estimate body mass.[4]
ThecladeDinosauria is divided into theSaurischia andOrnithischia based onhip structure, including importantly that of the ilium.[5] In both saurischians and ornithischians, the ilium extends laterally to both sides from the axis of the body. The other two hip bones, theischium and thepubis, extend ventrally down from the ilium towards the belly of the animal. Theacetabulum, which can be thought of as a "hip-socket", is an opening on each side of the pelvic girdle formed where the ischium, ilium, andpubis all meet, and into which the head of the femur inserts. The orientation and position of the acetabulum is one of the main morphological traits that caused dinosaurs to walk in an upright posture with their legs directly underneath their bodies. The brevis fossa is a deep groove in the underside of the postacetabular process, the rear part of the ilium. The brevis shelf is the bony ridge at the inner side of thefossa, the bone wall forming the internal face of the rear part of the ilium, which functions as an attachment area for a tail muscle, themusculus caudofemoralis brevis.[6] Often, close to the hip-socket the lower edge of the outer face of the postacetabular process is positioned higher than the edge of the brevis shelf, exposing the latter in side view.
The 'English' nameilium as bone of thepelvis can be traced back to the writings of anatomistsAndreas Vesalius, who coined the expressionos ilium.[7] In this expressionilium can be considered as the genitive plural of the nominative singular of the nounile.[7] Ile in classical Latin can refer to theflank of the body,[8] or to thegroin,[8] or thepart of the abdomen from the lowest ribs to the pubes.[8] Ile is usually encountered as plural (ilia) in classical Latin.[8] Theos ilium can literally be translated asbone (Latin:os[8] )of the flanks.
More than a millennium earlier, theossa ilium were described by the Greek physicianGalen, and referred to as, with a quite similar expression, τά πλατέα λαγόνων ὀστᾶ,the flat bones of the flanks,[7] with λαγών forflank.[9] In anatomic Latin, the expressionos lagonicum[10] can also be found, based on Ancient Greek λαγών. Inmodern Greek, the nominalized adjective λαγόνιο[11] is used to refer to theos ilium.
In Latin and Greek, it is not uncommon to nominalize adjectives, e.g.stimulantia fromremedia stimulantia[12] or ὁ ἐγκέφαλος from ὁ ἐγκέφαλος μυελός.[13] The nameilium as used in English[14][15] can not be considered as nominalized adjective derived from the full Latin expressionos ilium, asilium in this expression is a genitive plural of a noun[7] and not a nominative singular of an adjective. The formilium in English is however thought to be derived from the Latin wordilium,[16] an orthographic variant in Latin ofile,[8][16]flank orgroin.[8] Whereas the expression of Andreas Vesaliusos ilium appropriately expressesbone of the flanks, the sole termilium as used in English, lacks this precision and has to be literally translated asgroin orflank.
There exists however in classical Latin an adjectiveilius/ilia/ilium. This adjective however means notwith respect to the flanks, butTrojan.[8]Troy is referred to in classical Latin asIlium,[8]Ilion[8] orIlios[17] and in ancient Greek as Ἴλιον[9] or Ἴλιος.[9]
The first editions of the official Latin nomenclature,Nomina Anatomica of the first 80 years (first in 1895) used the Vesalian expressionos ilium.[18][19][20][21][22][23] In the subsequent editions from 1983[24] and 1989,[25] the expressionos ilium was altered toos ilii. This latter expression supposes a genitive singular of the alternate nounilium instead of a genitive plural of the nounile. Quite inconsistently, in the 1983 edition[24] of theNomina Anatomica, the genitive plural ofile (instead ofilium) is still being used in such expressions asvena circumflexa ilium superficialis. In the current 1998 edition of theNomina Anatomica, rebaptized asTerminologia Anatomica, the expressionos ilium is reintroduced andos ilii deleted.
This article incorporates text in thepublic domain frompage 236 of the 20th edition ofGray's Anatomy(1918)
| International | |
|---|---|
| Other | |
