関: sacral、sacral vertebra

WordNet

of or relating to sacred rites; "sacral laws"
of or relating to or near the sacrum
one of the bony segments of the spinal column

PrepTutorEJDIC

聖礼の
脊椎骨

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/03/13 20:02:31」(JST)

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For other uses, see Sacrum (disambiguation).

Not to be confused with cecum.

In humans, the sacrum (plural: sacrums or sacra) is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx (tailbone). It consists of usually five initially unfused vertebrae which begin to fuse between ages 16–18 and are usually completely fused into a single bone by age 34.

It is curved upon itself and placed obliquely (that is, tilted forward). It is kyphotic—that is, concave facing forward. The base projects forward as the sacral promontory internally, and articulates with the last lumbar vertebra to form the prominent sacrovertebral angle. The central part is curved outward toward the posterior, allowing greater room for the pelvic cavity. The two lateral projections of the sacrum are called ala (wings), and articulate with the ilium at the L-shaped sacroiliac joints.

Etymology

The name is derived from the Latin (os) sacrum, (sacer, sacra, sacrum, "sacred"), a translation of the Greek hieron (osteon), meaning sacred or strong bone.^[1] Since the sacrum is the seat of the organs of procreation, animal sacra were offered in sacrifices. In Slavic languages and in German this bone is called the 'cross bone' (Kreuzbein),^[2] in Dutch 'holy bone' (Heiligbeen).

Parts

The pelvic surface of the sacrum is concave from above downward, and slightly so from side to side.
The dorsal surface of the sacrum is convex and narrower than the pelvic.
The lateral surface of the sacrum is broad above, but narrowed into a thin edge below.
The base of the sacrum, which is broad and expanded, is directed upward and forward.
The apex (apex oss. sacri) is directed downward, and presents an oval facet for articulation with the coccyx.
The vertebral canal (canalis sacralis; sacral canal) runs throughout the greater part of the bone; above, it is triangular in form; below, its posterior wall is incomplete, from the non-development of the laminae and spinous processes. It lodges the sacral nerves, and its walls are perforated by the anterior and posterior sacral foramina through which these nerves pass out.

Articulations

The sacrum articulates with four bones:

the last lumbar vertebra above
the coccyx (tailbone) below
the illium portion of the hip bone on either side

Rotation of the sacrum forward a few degrees vis-à-vis the ilia is sometimes called "nutation" (from the Latin term nutatio which means "nodding"), and the reverse (posterior) motion "counter-nutation."^[3] In upright vertebrates, the sacrum is capable of slight independent movement along the sagittal plane. When you bend backward the top (base) of the sacrum moves forward relative to the ilium; when you bend forward the top moves back.^[4]

The sacrum is called so when referred to all of the parts combined. Its parts are called sacral vertebrae when referred individually.

Sexual dimorphism

The sacrum is noticeably sexually dimorphic (differently shaped in males and females).

In the female the sacrum is shorter and wider than in the male; the lower half forms a greater angle with the upper; the upper half is nearly straight, the lower half presenting the greatest amount of curvature. The bone is also directed more obliquely backward; this increases the size of the pelvic cavity and renders the sacrovertebral angle more prominent.

In the male the curvature is more evenly distributed over the whole length of the bone, and is altogether larger than in the female.

Variations

In some cases the sacrum will consist of six pieces [1] or be reduced in number to four [2]. The bodies of the first and second vertebrae may fail to unite.

Sometimes the uppermost transverse tubercles are not joined to the rest of the ala on one or both sides, or the sacral canal may be open throughout a considerable part of its length, in consequence of the imperfect development of the laminae and spinous processes.

The sacrum also varies considerably with respect to its degree of curvature.

Additional images

Vertebral column.
Pelvis
Sacrum, dorsal surface.
Lateral surfaces of sacrum and coccyx.
Base of sacrum.
Median sagittal section of the sacrum.
Vertebral column.
Left Levator ani from within.
The posterior divisions of the sacral nerves.
Median sagittal section of male pelvis.
Median sagittal section of female pelvis.

References

^ Online Etymology Dictionary
^ LEO E-G Results for "sacrum"
^ Joseph D. Kurnik, DC. "The AS Ilium Fixation, Nutation, and Respect". http://www.chiroweb.com/archives/14/26/18.html.
^ Maitland, J (2001). Spinal Manipulation Made Simple. Berkeley: North Atlantic Books, p. 72.

External links

SUNY Labs 43:os-0401 - "The Female Pelvis: Articulated bones of pelvis"
SUNY Labs 43:st-0401 - "The Female Pelvis: Bones"
sacrum at eMedicine Dictionary

This article incorporates text from a public domain edition of Gray's Anatomy.

UpToDate Contents

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English Journal

Anterior thigh flap extended hemipelvectomy and spinoiliac arthrodesis.

Mavrogenis AF, Soultanis K, Patapis P, Papagelopoulos PJ.SourceFirst Department of Orthopaedics, Attikon University Hospital, Athens University Medical School, 41 Ventouri Street, 15562 Holargos, Athens, Greece.
Surgical oncology.Surg Oncol.2011 Dec;20(4):e215-21. Epub 2011 Jul 27.
We present the technique of anterior thigh flap extended external hemipelvectomy with spinoiliac arthrodesis in treatment of the patient with recurrent low-grade pelvic chondrosarcoma extending to the lower lumbar spine. Extended hemipelvectomy involves skeletal resection beyond the standard hemipel
PMID 21798737

Treatment strategy for chondromyxoid fibroma of the sacrum.

Ahuja SK, McCanna SP, Horn EM.SourceDepartment of Neurological Surgery, Indiana University School of Medicine, Goodman Campbell Brain and Spine, 1801 North Senate Street, Suite 610, Indianapolis, Indiana 46202, USA.
Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia.J Clin Neurosci.2011 Nov;18(11):1550-2. Epub 2011 Aug 24.
We present a 59-year-old woman with a rare sacral chondromyxoid fibroma discovered incidentally and treated with curettage, bone grafting, and lumbopelvic fixation. At 1year following surgery she remains symptom-free, has successfully fused her lumbopelvic construct and has no signs of tumor progres
PMID 21868234

Japanese Journal

Osteoarticular Involvement among 202 Brucellosis Cases Identified in Central Anatolia Region of Turkey

Turan Hale,Serefhanoglu Kivanc,Karadeli Elif,Togan Turhan,Arslan Hande
Internal Medicine 50(5), 421-428, 2011
… Magnetic resonance images of thoracic, lumbar or sacral vertebrae were acquired from patients with back pain, low back pain and sacro-iliac joint pain. …
NAID 130000649852

CSF tau protein is a useful marker for effective treatment of superficial siderosis of the central nervous system: Two case reports

Ikeda Tokuhei,Noto Daisuke,Noguchi-Shinohara Moeko,Ono Kenjiro,Takahashi Kazuya,Ishida Chiho,Yoshita Mitsuhiro,Kawaguchi Masahito,Kawahara Norio,Iwasa Kazuo,Tomita Katsuro,Yamada Masahito
Clinical Neurology and Neurosurgery 112(1), 62-64, 2010-01
… Patient 2 was bleeding from thickened dura at the level of the sacral vertebrae. …
NAID 120001613737

Related Pictures

★リンクテーブル★

リンク元	「椎骨」「仙椎」「sacral vertebra」
関連記事	「sacral」

「椎骨」

Bone: Sacrum
	Sacrum, pelvic surface
	Image of pelvis. Sacrum is in center.
Latin	os sacrum
Gray's	subject #24 106
MeSH	Sacrum

　　[★]

英: vertebral bone, vertebra vertebae
同: 脊椎骨

種類

頚椎	cervical vertebrae	7
胸椎	thoracic vertebrae	12
腰椎	limbar vertebrae	5
仙椎	sacral vertebrae	5
尾椎	coccygeal vertebrae	1(5-6)

特徴

	環椎	軸椎	頚椎	胸椎	腰椎
椎体の特徴	なし	歯突起	小型で、横径が前後径より長い。上面は凹み、下面は膨らむ	心臓型である。肋骨頭と関節する窩(facet)を持つ	巨大。上方ないし下方から見ると腎臓型
椎孔の特徴	歯突起が通る		大型で三角	円形で、頚椎と腰椎よりも小型である。	三角形。胸椎よりも大きく、頚椎よりも小さい。
横突起の特徴	横突孔がある。	横突孔がある。	横突孔がある。第7頚椎では小型あるいは欠如。椎骨動脈と伴行静脈と交感神経叢が横突孔を通るが、ただし第７頚椎では小さな頚骨静脈を通すのみ。前結節と後結節がある。	長く丈夫で、後外側に伸びる。第1から第12胸椎に向かって短くなる（第1～第10胸椎には肋骨の結節と関節するための関節面がある）	長く細い。この突起の基部の後面に副突起がある。
関節突起の特徴	後頭顆を受ける	下関節面は下前方に向く。	上関節面は上後方に向く。下関節面は下前方に向く。	上関節面は後方やや外側に向く。下関節面は、前方やや内側に向く。	上関節面は後内側（ないし内側）を向く。下関節面は、前外側（ないし外側）を向く。上関節突起の後面には乳様突起がある。
棘突起の特徴	なし	先が二分する	第3～第5頚椎では短く先が二分する。第6頚椎では長いが、第7頚椎ではさらに長い。	長く後下方に傾斜する。先端は下位の椎体の高さに達する。	短く丈夫である。
その他	前弓、後弓、前結節、後結節、歯突起窩	歯突起