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Information about Pelvic Surface Of Sacrum

Bone: Pelvic surface of sacrum
Sacrum, pelvic surface.
Latinfacies pelvica ossis sacri
subject #24 106
Dorlands/Elsevier f_01/12352396
The pelvic surface of sacrum is concave from above downward, and slightly so from side to side.

Its middle part is crossed by four transverse ridges, the positions of which correspond with the original planes of separation between the five segments of the bone.

The portions of bone intervening between the ridges are the bodies of the sacral vertebrae.

The body of the first segment is of large size, and in form resembles that of a lumbar vertebra; the succeeding ones diminish from above downward, are flattened from before backward, and curved so as to accommodate themselves to the form of the sacrum, being concave in front, convex behind.

At the ends of the ridges are seen the anterior sacral foramina, four in number on either side, somewhat rounded in form, diminishing in size from above downward, and directed lateralward and forward; they give exit to the anterior divisions of the sacral nerves and entrance to the lateral sacral arteries.

Lateral to these foramina are the lateral parts of the sacrum, each consisting of five separate segments at an early period of life; in the adult, these are blended with the bodies and with each other.

Each lateral part is traversed by four broad, shallow grooves, which lodge the anterior divisions of the sacral nerves, and are separated by prominent ridges of bone which give origin to the Piriformis muscle.

If a sagittal section be made through the center of the sacrum, the bodies are seen to be united at their circumferences by bone, wide intervals being left centrally, which, in the fresh state, are filled by the intervertebral fibrocartilages.

In some bones this union is more complete between the lower than the upper segments.

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This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.


Spine [ edit]
general structures: body of vertebra, vertebral arch (pedicle, lamina, vertebral notch), foramina (vertebral, intervertebral), processes (transverse, articular, spinous) cervical vertebrae: C1 (anterior arch, posterior arch, lateral mass), C2 (dens), C7, posterior tubercle, foramen transversarium thoracic vertebrae: costal facets (superior, inferior, transverse) lumbar vertebrae: accessory process, mammillary process sacrum/coccyx: pelvic surface (anterior sacral foramina, dorsal surface (posterior sacral foramina, median sacral crest, medial sacral crest, lateral sacral crest), lateral surface, base, sacral hiatus
The sacrum 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.
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Latin}}} 
Official status
Official language of: Vatican City
Used for official purposes, but not spoken in everyday speech
Regulated by: Opus Fundatum Latinitas
Roman Catholic Church
Language codes
ISO 639-1: la
ISO 639-2: lat
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Elsevier, the world's largest publisher of medical and scientific literature, forms part of the Reed Elsevier group. Based in Amsterdam, the company has substantial operations in the UK, USA and elsewhere.
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The sacrum 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.
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The lumbar vertebrae are the largest segments of the movable part of the vertebral column, and are characterized by the absence of the foramen transversarium within the transverse process, and by the absence of facets on the sides of the body.
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At the ends of the transverse ridges of the pelvic surface of the sacrum are seen the anterior sacral foramina (or pelvic sacral foramina), four in number on either side, somewhat rounded in form, diminishing in size from above downward, and directed lateralward and forward.
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The five sacral nerves emerge from the sacrum. Although the vertebral components of the sacrum are fused into a single bone, the sacral vertebrae are still used to number the sacral nerves.
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The lateral sacral arteries arise from the posterior division of the internal iliac artery; there are usually two, a superior and an inferior.

Superior

The superior, of large size, passes medialward, and, after anastomosing with branches from the middle sacral, enters the
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The piriformis (from Latin piriformis = "pear shaped") is a muscle in the gluteal region of the lower limb.

Origin and insertion

It originates from the anterior (front) part of the sacrum, the part of the spine in the gluteal region, and from the superior
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Intervertebral discs (or intervertebral fibrocartilage) lie between adjacent vertebrae in the spine. Each disc forms a cartilaginous joint to allow slight movement of the vertebrae, and acts as a ligament to hold the vertebrae together.
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eMedicine is an online clinical medical knowledge base that was founded in 1996 by Scott Plantz and Richard Lavely, two medical doctors. It was sold to WebMD in January 2006.
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The State University of New York Health Science Center at Brooklyn, better known as SUNY Downstate Medical Center, is an academic medical center and is the only one of its kind in the Borough of Brooklyn in New York City.
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Public domain comprises the body of knowledge and innovation (especially creative works such as writing, art, music, and inventions) in relation to which no person or other legal entity can establish or maintain proprietary interests within a particular legal jurisdiction.
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Henry Gray's Anatomy of the Human Body (or Gray's Anatomy as it has commonly been shortened) is an English-language human anatomy textbook widely regarded as a classic work on the subject.
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vertebral column (backbone or spine) is a column of 34 vertebrae, the sacrum, intervertebral discs, and the coccyx situated in the dorsal aspect of the torso, separated by spinal discs. It houses the spinal cord in its spinal canal.
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The body is the largest part of a vertebra, and is more or less cylindrical in shape.

Its upper and lower surfaces are flattened and rough, and give attachment to the intervertebral fibrocartilages, and each presents a rim around its circumference.
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The vertebral arch (or neural arch) is the posterior part of a vertebra.

It consists of a pair of pedicles and a pair of laminae, and supports seven processes:
  • four articular processes
  • two transverse processes
  • one spinous process


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The pedicles (from Latin pediculus, "small foot") are two short, thick processes, which project backward, one on either side, from the upper part of the body, at the junction of its posterior and lateral surfaces.
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The laminæ are two broad plates directed backward and medially from the pedicles.

They fuse in the middle line posteriorly, and so complete the posterior boundary of the vertebral foramen.
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Spine [ edit]
general structures: body of vertebra, vertebral arch (pedicle, lamina, vertebral notch), foramina (vertebral, intervertebral), processes (transverse, articular, spinous) cervical vertebrae:
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In a typical vertebra, the vertebral foramen is the foramen formed by the anterior segment (the body), and the posterior part, the vertebral arch.

The vertebral foramen begins at cervical vertebrae #1 (atlas) and continues inferior to lumbar vertebrae #5.
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intervertebral foramina (singular: foramen; also called neural foramina). The foramen allows for the passage of the spinal nerve root, dorsal root ganglion, the spinal artery of the segmental artery, communicating veins between the internal and external plexuses,
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The transverse processes of a vertebra, two in number, project one at either side from the point where the lamina joins the pedicle, between the superior and inferior articular processes. They serve for the attachment of muscles and ligaments.
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The articular processes (zygapophyses) of a vertebra, two superior and two inferior, spring from the junctions of the pedicles and laminæ.
  • The superior processes project upward from a lower vertebra, and their articular surfaces are directed more or less backward.

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The spinous process of a vertebra is directed backward and downward from the junction of the laminae (in humans), and serves for the attachment of muscles and ligaments. In animals without an erect stance, the process points upward and may slant forward or backward.
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In vertebrates, cervical vertebrae (singular: vertebra) are those vertebrae immediately behind (caudal to) the skull.

Variation among species

In some species, some parts of the skull may be composed of vertebra-like elements, e.g.
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In anatomy, the atlas (C1) is the topmost (first) cervical vertebra of the spine.

It is named for the Atlas of mythology, because it supports the globe of the head.
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The anterior arch of the atlas forms about one-fifth of the ring of the atlas: its anterior surface is convex, and presents at its center the anterior tubercle for the attachment of the Longus colli muscles; posteriorly it is concave, and marked by a smooth, oval or circular facet
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In a cervical vertebra, the posterior arch forms about two-fifths of the circumference of the ring: it ends behind in the posterior tubercle, which is the rudiment of a spinous process and gives origin to the Recti capitis posteriores minores.
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The lateral masses are the most bulky and solid parts of the atlas, in order to support the weight of the head.

Each carries two articular facets, a superior and an inferior.
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