Sacrum

The sacrum (/ˈsækrəm/ or /ˈseɪkrəm/; plural: sacra or sacrums[1]), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of sacral vertebrae S1–S5 between 18 and 30 years of age.[2]

The sacrum is situated at the upper, back part of the pelvic cavity, between the two wings of the pelvis. It forms joints with four other bones. The two projections at the sides of the sacrum are called the alae (wings), and articulate with the ilium at the L-shaped sacroiliac joints. The upper part of the sacrum connects with the last lumbar vertebra (L5), and its lower part with the coccyx (tailbone) via the sacral and coccygeal cornua.

The sacrum has three different surfaces which are shaped to accommodate surrounding pelvic structures. Overall it is concave (curved upon itself). The base of the sacrum, the broadest and uppermost part, is tilted forward as the sacral promontory internally. The central part is curved outward toward the posterior, allowing greater room for the pelvic cavity.

In all other quadrupedal vertebrates, the pelvic vertebrae undergo a similar developmental process to form a sacrum in the adult, even while the bony tail (caudal) vertebrae remain unfused. The number of sacral vertebrae varies slightly. For instance, the S1–S5 vertebrae of a horse will fuse, the S1–S3 of a dog will fuse, and four pelvic vertebrae of a rat will fuse between the lumbar and the caudal vertebrae of its tail.[3] The Stegosaurus dinosaur had a greatly enlarged neural canal in the sacrum, characterized as a "posterior brain case”.[4]

Sacrum
Gray95
Sacrum, pelvic surface
Gray241
Image of a male pelvis (sacrum is in center)
Details
Identifiers
LatinOs sacrum
MeSHD012447
TAA02.2.05.001
FMA16202
Anatomical terms of bone

History and etymology

English sacrum was introduced as a technical term in anatomy in the mid-18th century, as a shortening of the Late Latin name os sacrum "sacred bone", itself a translation of Greek ἱερόν ὀστέον, the term found in the writings of Galen.[5][5][6][7][8][9][10] Prior to the adoption of sacrum, the bone was also called holy bone in English,[11] paralleling German heiliges Bein or Heiligenbein (alongside Kreuzbein[12]) and Dutch heiligbeen.[11][13][14]

The origin of Galen's term is unclear. Supposedly the sacrum was the part of an animal offered in sacrifice (since the sacrum is the seat of the organs of procreation).[15] Others attribute the adjective ἱερόν to the ancient belief that this specific bone would be indestructible.[13] As the Greek adjective ἱερός may also mean "strong", it has also been suggested that os sacrum is a mistranslation of a term intended to mean "the strong bone". This is supported by the alternative Greek name μέγας σπόνδυλος by the Greeks, translating to "large vertebra", translated into Latin as vertebra magna.[5][16]

In Classical Greek the bone was known as κλόνις (Latinized clonis); this term is cognate to Latin clunis "buttock", Sanskrit śróṇis "haunch" and Lithuanian šlaunis "hip, thigh".[17][18] The Latin word is found in the alternative Latin name of the sacrum, ossa clunium, as it were "bones of the buttocks".[11] Due to the fact that the os sacrum is broad and thick at its upper end,[13] the sacrum is alternatively called os latum, "broad bone".[11][16]

Structure

The sacrum is a complex structure providing support for the spine and accommodation for the spinal nerves. It also articulates with the hip bones. The sacrum has a base, an apex, and three surfaces – a pelvic, dorsal and a lateral surface. The base of the sacrum, which is broad and expanded, is directed upward and forward. On either side of the base is a large projection known as an ala of sacrum and these alae (wings) articulate with the sacroiliac joints. The alae support the psoas major muscles and the lumbosacral trunk which connects the lumbar plexus with the sacral plexus. In the articulated pelvis the alae are continuous with the iliac fossa. Each ala is slightly concave from side to side, and convex from the back and gives attachment to a few of the fibers of the iliacus muscle. The posterior quarter of the ala represents the transverse process, and its anterior three-quarters the costal process of the first sacral segment. Each ala also serves as part of the border of the pelvic brim. The alae also form the base of the lumbosacral triangle. The iliolumbar ligament and lumbosacral ligaments are attached to the ala.

In the middle of the base is a large oval articular surface, the upper surface of the body of the first sacral vertebra, which is connected with the under surface of the body of the last lumbar vertebra by an intervertebral fibrocartilage. Behind this is the large triangular orifice of the sacral canal, which is completed by the lamina and spinous process of the first sacral vertebra. The superior articular processes project from it on either side; they are oval, concave, directed backward and medialward, like the superior articular processes of a lumbar vertebra. They are attached to the body of the first sacral vertebra and to the each ala, by short thick pedicles; on the upper surface of each pedicle is a vertebral notch, which forms the lower part of the foramen between the last lumbar and first sacral vertebrae.

The apex is directed downward and presents an oval facet for articulation with the coccyx. The sacral canal as a continuation of the vertebral canal runs throughout the greater part of the sacrum. The sacral angle is the angle formed by the true conjugate with the two pieces of sacrum. Normally it is greater than 60 degrees. A sacral angle of lesser degree suggests funneling of the pelvis.

Promontory

The sacral promontory marks part of the border of the pelvic inlet, and comprises the iliopectineal line and the linea terminalis.[19] The sacral promontory articulates with the last lumbar vertebra to form the sacrovertebral angle, an angle of 30 degrees from the horizontal plane that provides a useful marker for a sling implant procedure.

Surfaces

Gray95
Pelvic surface
Gray96
Dorsal surface

The pelvic surface of the sacrum is concave from the top, and curved slightly from side to side. Its middle part is crossed by four transverse ridges, which correspond to the original planes of separation between the five sacral vertebrae. The body of the first segment is large and has the form of a lumbar vertebra; the bodies of the next bones get progressively smaller, are flattened from the back, and curved to shape themselves to the sacrum, being concave in front and convex behind. At each end of the transverse ridges, are the four anterior sacral foramina, diminishing in size in line with the smaller vertebral bodies. The foramina give exit to the anterior divisions of the sacral nerves and entrance to the lateral sacral arteries. Each part at the sides of the foramina is traversed by four broad, shallow grooves, which lodge the anterior divisions of the sacral nerves. They 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 discs.

The dorsal surface of the sacrum is convex and narrower than the pelvic surface. In the middle line is the median sacral crest, surmounted by three or four tubercles—the rudimentary spinous processes of the upper three or four sacral vertebrae. On either side of the median sacral crest is a shallow sacral groove, which gives origin to the multifidus muscle. The floor of the groove is formed by the united laminae of the corresponding vertebrae. The laminae of the fifth sacral vertebra, and sometimes those of the fourth, do not meet at the back, resulting in a fissure known as the sacral hiatus in the posterior wall of the sacral canal. The sacral canal is a continuation of the spinal canal and runs throughout the greater part of the sacrum. Above the sacral hiatus, it is triangular in form. The canal lodges the sacral nerves, via the anterior and posterior sacral foramina.

On the lateral aspect of the sacral groove is a linear series of tubercles produced by the fusion of the articular processes which together form the indistinct medial sacral crest. The articular processes of the first sacral vertebra are large and oval-shaped. Their facets are concave from side to side, face to the back and middle, and articulate with the facets on the inferior processes of the fifth lumbar vertebra.

The tubercles of the inferior articular processes of the fifth sacral vertebra, known as the sacral cornua, are projected downward and are connected to the cornua of the coccyx. At the side of the articular processes are the four posterior sacral foramina; they are smaller in size and less regular in form than those at the front, and transmit the posterior divisions of the sacral nerves. On the side of the posterior sacral foramina is a series of tubercles, the transverse processes of the sacral vertebrae, and these form the lateral sacral crest. The transverse tubercles of the first sacral vertebra are large and very distinct; they, together with the transverse tubercles of the second vertebra, give attachment to the horizontal parts of the posterior sacroiliac ligaments; those of the third vertebra give attachment to the oblique fasciculi of the posterior sacroiliac ligaments; and those of the fourth and fifth to the sacrotuberous ligaments.

Sobo 1909 18
Lateral surface

The lateral surface of the sacrum is broad above, but narrows into a thin edge below. The upper half presents in front an ear-shaped surface, the auricular surface, covered with cartilage in the immature state, for articulation with the ilium. Behind it is a rough surface, the sacral tuberosity, on which are three deep and uneven impressions, for the attachment of the posterior sacroiliac ligament. The lower half is thin, and ends in a projection called the inferior lateral angle. Medial to this angle is a notch, which is converted into a foramen by the transverse process of the first piece of the coccyx, and this transmits the anterior division of the fifth sacral nerve. The thin lower half of the lateral surface gives attachment to the sacrotuberous and sacrospinous ligaments, to some fibers of the gluteus maximus at the back and to the coccygeus in the front.

Articulations

The sacrum articulates with four bones:

Rotation of the sacrum superiorly and anteriorly whilst the coccyx moves posteriorly relative to the ilium is sometimes called "nutation" (from the Latin term nutatio which means "nodding") and the reverse, postero-inferior motion of the sacrum relative to the ilium whilst the coccyx moves anteriorly, "counter-nutation".[20] In upright vertebrates, the sacrum is capable of slight independent movement along the sagittal plane. On bending backward the top (base) of the sacrum moves forward relative to the ilium; on bending forward the top moves back.[21]

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

Variations

In some cases the sacrum will consist of six pieces or be reduced in number to four.[22] 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.

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.

Development

The somites that give rise to the vertebral column begin to develop from head to tail along the length of the notochord. At day 20 of embryogenesis the first four pairs of somites appear in the future occipital bone region. Developing at the rate of three or four a day, the next eight pairs form in the cervical region to develop into the cervical vertebrae; the next twelve pairs will form the thoracic vertebrae; the next five pairs the lumbar vertebrae and by about day 29 the sacral somites will appear to develop into the sacral vertebrae; finally on day 30 the last three pairs will form the coccyx.[23]

Clinical significance

Congenital disorders

The congenital disorder, spina bifida, occurs as a result of a defective embryonic neural tube, characterised by the incomplete closure of vertebral arch or of the incomplete closure of the surface of the vertebral canal.[7] The most common sites for spina bifida malformations are the lumbar and sacral areas.

Another congenital disorder is that of caudal regression syndrome also known as sacral agenesis. This is characterised by an abnormal underdevelopment in the embryo (occurring by the seventh week) of the lower spine.[24] Sometimes part of the coccyx is absent, or the lower vertebrae can be absent, or on occasion a small part of the spine is missing with no outward sign.

Fracture

Sacral fractures are relatively uncommon; however, they are often associated with neurological deficits. In the presence of neurological signs, most of the times they are treated with surgical fixation.[25]

Cancer

The sacrum is one of the main sites for the development of the sarcomas known as chordomas that are derived from the remnants of the embryonic notochord.[26]

In osteopathic medicine

Sacral diagnosis is a common issue in osteopathic manipulative medicine. There are many types of sacral diagnoses, such as torsion and shear. To diagnose a sacral torsion, the axis of rotation is found with the axis named after its superior pole. If the opposite side of the pole is rotated anteriorly, it is rotated towards the pole, in which case it is called either a right-on-right (R on R) or left-on-left (L on L) torsion. The first letter in the diagnosis pertains to the direction of rotation of the superior portion of the sacrum opposite the side of the superior axis pole, and the last letter pertains to the pole.[27]

Other animals

In dogs the sacrum is formed by three fused vertebrae. The sacrum in the horse is made up of five fused vertebrae.[28] In birds the sacral vertebrae are fused with the lumbar and some caudal and thoracic vertebrae to form a single structure called the synsacrum. In the frog the ilium is elongated and forms a mobile joint with the sacrum that acts as an additional limb to give more power to its leaps.

Additional images

Gray242

Image of a female pelvis seen anteriorly, sacrum at centre.

Gray97

Lateral surfaces of sacrum and coccyx.

Gray98

Base of sacrum.

Gray99

Median sagittal section of the sacrum.

Gray404

Left levator ani from within.

Gray803

The posterior divisions of the sacral nerves.

Slide2CORO

Sacrum. Pelvic surface.

Slide4CORO

Sacrum. Dorsal surface.

See also

References

This article incorporates text in the public domain from page 106 of the 20th edition of Gray's Anatomy (1918)

  1. ^ Oxford Dictionaries and Webster's New College Dictionary (2010) admit the plural sacrums alongside sacra; The American Heritage Dictionary, Collins Dictionary and Webster's Revised Unabridged Dictionary (1913) give sacra as the only plural.
  2. ^ Kilincer, Cumhur; et al. (2009). "Sacrum anatomy". Scientific spine. Trakya Üniversitesi Rektörlüğü, Yerleşkesi, 22030 Edirne, Turkey: Self. Retrieved 8 November 2015.
  3. ^ "Skeletal system" (PDF). Dept. of Biology. Gambier, Ohio: Kenyon College. Retrieved 9 November 2015.
  4. ^ Galton, P.M.; Upchurch, P. (2004). "Stegosauria". In Weishampel, D.B.; Dodson, P.; Osmólska, H. (eds.). The Dinosauria (2nd ed.). University of California Press. p. 361. ISBN 0-520-24209-2.
  5. ^ a b c Hyrtl, J. (1880). Onomatologia Anatomica. Wien: Wilhelm Braumüller. K.K. Hof- und Universitätsbuchhändler. Geschichte und Kritik der anatomischen Sprache der Gegenwart
  6. ^ Liddell, H.G.; Scott, R. (1940). Jones, Sir Henry Stuart; McKenzie, Roderick (eds.). A Greek-English Lexicon. Oxford: Clarendon Press.
  7. ^ a b Anderson, D.M. (2000). Dorland’s illustrated medical dictionary (29th edition). Philadelphia/London/Toronto/Montreal/Sydney/Tokyo: W.B. Saunders Company.
  8. ^ His, W. (1895). Die anatomische Nomenclatur. Nomina Anatomica. Leipzig: Verlag Veit & Comp. Der von der Anatomischen Gesellschaft auf ihrer IX. Versammlung in Basel angenommenen Namen
  9. ^ Federative Committee on Anatomical Terminology (FCAT) (1998). Terminologia Anatomica. Stuttgart: Thieme.
  10. ^ Lewis, C.T.; Short, C. (1879). A Latin Dictionary. Oxford: Clarendon Press. founded on Andrews' edition of Freund's Latin dictionary
  11. ^ a b c d Schreger, C.H.Th. (1805). Synonymia Anatomica. Fürth: im Bureau für Literatur. Synonymik der anatomischen Nomenclatur
  12. ^ "cross bone", also of unclear origin. According to Grimm, Deutsches Wörterbuch (""Kreuz", meaning 8a".), Kreuz "cross" is used of the sacral area of the spine, but also of the spine as a whole, with usage examples from the 17th-century (Christian Weise, Isaacs Opferung, 1682, 3.11). Notabilia Venatoris by Hermann Friedrich von Göchhausen (1710) and Teutscher Jäger by Johann Friedrich von Flemming (1719, p. 94) also give kreuz as hunting terminology for a specific bone of the stag.
  13. ^ a b c Foster, F.D. (1891–1893). An Illustrated Medical Dictionary. New York: D. Appleton and Company. Being a dictionary of the technical terms used by writers on medicine and the collateral sciences, in the Latin, English, French, and German languages.CS1 maint: Date format (link)
  14. ^ Everdingen, J.J.E. van, Eerenbeemt; A.M.M. van den (2012). Pinkhof Geneeskundig woordenboek (12de druk ed.). Houten: Bohn Stafleu Van Loghum.CS1 maint: Multiple names: authors list (link)
  15. ^ "sacrum". Online Etymology Dictionary.
  16. ^ a b Hyrtl, J. (1875). Lehrbuch der Anatomie des Menschen. Mit Rücksicht auf physiologische Begründung und praktische Anwendung (Dreizehnte Auflage ed.). Wien: Wilhelm Braumüller K.K. Hof- und Universitätsbuchhändler.
  17. ^ used by Antimachus; see Liddell, Henry George; Scott, Robert. "klo-nis". A Greek-English Lexicon.
  18. ^ Kraus, L.A. (1844). Kritisch-etymologisches medicinisches Lexikon (Dritte Auflage ed.). Göttingen: Verlag der Deuerlich- und Dieterichschen Buchhandlung.
  19. ^ Kirschner, Celeste G. (2005). Netter's Atlas Of Human Anatomy For CPT Coding. Chicago: American medical association. p. 274. ISBN 1-57947-669-4.
  20. ^ Joseph D. Kurnik, DC. "The AS Ilium Fixation, Nutation, and Respect".
  21. ^ Maitland, J (2001). Spinal Manipulation Made Simple. Berkeley: North Atlantic Books, p. 72.
  22. ^ Gray, Henry (1918). Anatomy of the Human Body. Lea & Febiger. p. 111.
  23. ^ Larsen, W.J. Human Embryology.2001.Churchill Livingstone Pages 63-64 ISBN 0-443-06583-7
  24. ^ Sonek JD; Gabbe SG; Landon MB; Stempel LE; Foley MR; Shubert-Moell K (March 1990). "Antenatal diagnosis of sacral agenesis syndrome in a pregnancy complicated by diabetes mellitus". Am. J. Obstet. Gynecol. 162 (3): 806–8. doi:10.1016/0002-9378(90)91015-5. PMID 2180307.
  25. ^ Mirghasemi, Alireza; Mohamadi, Amin; Ara, Ali Majles; Gabaran, Narges Rahimi; Sadat, Mir Mostafa (November 2009). "Completely displaced S-1/S-2 growth plate fracture in an adolescent: case report and review of literature". Journal of Orthopaedic Trauma. 23 (10): 734–738. doi:10.1097/BOT.0b013e3181a23d8b. ISSN 1531-2291. PMID 19858983.
  26. ^ "Understanding Chordoma - Chordoma Foundation". www.chordomafoundation.org. Retrieved 2017-04-07.
  27. ^ Wedel, F.P. "D.O." (PDF). A.T. Still University School of Osteopathic Medicine. Retrieved 18 February 2014.
  28. ^ King, Christine, BVSc, MACVSc, and Mansmann, Richard, VMD, PhD. "Equine Lameness." Equine Research, Inc. 1997.

External links

  • Anatomy photo:43:os-0401 at the SUNY Downstate Medical Center - "The Female Pelvis: Articulated bones of pelvis"
  • Anatomy photo:43:st-0401 at the SUNY Downstate Medical Center - "The Female Pelvis: Bones"
  • pelvis at The Anatomy Lesson by Wesley Norman (Georgetown University)
  • Sacrum - BlueLink Anatomy - University of Michigan Medical School
Axial skeleton

The axial skeleton is the part of the skeleton that consists of the bones of the head and trunk of a vertebrate. In the human skeleton, it consists of 80 bones and is composed of six parts; the skull bones, the ossicles of the middle ear, the hyoid bone, the rib cage, sternum and the vertebral column. The axial skeleton together with the appendicular skeleton form the complete skeleton. Another definition of axial skeleton is the bones including the vertebrae, sacrum, coccyx, ribs, and sternum.

Canticum Sacrum

Canticum Sacrum ad Honorem Sancti Marci Nominis is a 17-minute choral-orchestral piece composed in 1955 by Igor Stravinsky (1882–1971) in tribute "To the City of Venice, in praise of its Patron Saint, the Blessed Mark, Apostle." The piece is compact and stylistically varied, ranging from established neoclassical modes to experimental new techniques. The second movement, "Surge, Aquilo", represents Stravinsky's first movement based entirely on a tone row.

Though most often abbreviated "Canticum Sacrum", the piece's full name is Canticum Sacrum ad honorem Sancti Marci Nominis, or Canticle to Honor the Name of Saint Mark.

Caudal regression syndrome

Caudal regression syndrome, or sacral agenesis (or hypoplasia of the sacrum), is a rare birth defect. It is a congenital disorder in which the fetal development of the lower spine—the caudal partition of the spine—is abnormal. It occurs at a rate of approximately one per 25,000 live births.

Some babies are born with very small differences compared to typical development, and others have significant changes. Most grow up to be otherwise normal adults who have difficulty with walking and incontinence.

Coccygectomy

Coccygectomy is a surgical procedure in which the coccyx or tailbone is removed. It is considered a required treatment for sacrococcygeal teratoma and other germ cell tumors arising from the coccyx. Coccygectomy is the treatment of last resort for coccydynia (coccyx pain) which has failed to respond to nonsurgical treatment. Non surgical treatments include use of seat cushions, external or internal manipulation and massage of the coccyx and the attached muscles, medications given by local injections under fluoroscopic guidance, and medications by mouth.To remove the coccyx, an incision is made from the tip of the coccyx to its joint with the sacrum. The coccyx is cut away from the surrounding tissues, cut off at the joint with the sacrum, and removed. If the tip of the sacrum is rough, it is filed down. The wound is closed in layers.

Coccyx

The coccyx (pl: coccyges), commonly referred to as the tailbone, is the final segment of the vertebral column in all apes, and analogous structures in certain other mammals such as horses. In tailless primates (e.g. humans and other great apes) since Nacholapithecus (a Miocene hominoid), the coccyx is the remnant of a vestigial tail.

In animals with bony tails, it is known as tailhead or dock, in bird anatomy as tailfan.

It comprises three to five separate or fused coccygeal vertebrae below the sacrum, attached to the sacrum by a fibrocartilaginous joint, the sacrococcygeal symphysis, which permits limited movement between the sacrum and the coccyx.

Hip bone

The hip bone (os coxae, innominate bone, pelvic bone or coxal bone) is a large irregular bone, constricted in the center and expanded above and below. In some vertebrates (including humans before puberty) it is composed of three parts: the ilium, ischium, and the pubis.

The two hip bones join at the pubic symphysis and together with the sacrum and coccyx (the pelvic part of the spine) comprise the skeletal component of the pelvis – the pelvic girdle which surrounds the pelvic cavity. They are connected to the sacrum, which is part of the axial skeleton, at the sacroiliac joint. Each hip bone is connected to the corresponding femur (thigh bone) (forming the primary connection between the bones of the lower limb and the axial skeleton) through the large ball and socket joint of the hip.

Holy Roman Empire

The Holy Roman Empire (Latin: Sacrum Imperium Romanum; German: Heiliges Römisches Reich) was a multi-ethnic complex of territories in Western and Central Europe that developed during the Early Middle Ages and continued until its dissolution in 1806 during the Napoleonic Wars. The largest territory of the empire after 962 was the Kingdom of Germany, though it also came to include the neighboring Kingdom of Bohemia, the Kingdom of Burgundy, the Kingdom of Italy, and numerous other territories.On 25 December 800, Pope Leo III crowned the Frankish king Charlemagne as Emperor, reviving the title in Western Europe, more than three centuries after the fall of the earlier ancient Western Roman Empire in 476. The title continued in the Carolingian family until 888 and from 896 to 899, after which it was contested by the rulers of Italy in a series of civil wars until the death of the last Italian claimant, Berengar I, in 924. The title was revived again in 962 when Otto I was crowned emperor, fashioning himself as the successor of Charlemagne and beginning a continuous existence of the empire for over eight centuries. Some historians refer to the coronation of Charlemagne as the origin of the empire, while others prefer the coronation of Otto I as its beginning. Scholars generally concur, however, in relating an evolution of the institutions and principles constituting the empire, describing a gradual assumption of the imperial title and role.The exact term "Holy Roman Empire" was not used until the 13th century, but the concept of translatio imperii, the notion that he—the sovereign ruler—held supreme power inherited from the ancient emperors of Rome, was fundamental to the prestige of the emperor. The office of Holy Roman Emperor was traditionally elective, although frequently controlled by dynasties. The mostly German prince-electors, the highest-ranking noblemen of the empire, usually elected one of their peers as "King of the Romans", and he would later be crowned emperor by the Pope; the tradition of papal coronations was discontinued in the 16th century.

The empire never achieved the extent of political unification as was formed to the west in France, evolving instead into a decentralized, limited elective monarchy composed of hundreds of sub-units: kingdoms, principalities, duchies, counties, prince-bishoprics, Free Imperial Cities, and other domains. The power of the emperor was limited, and while the various princes, lords, bishops, and cities of the empire were vassals who owed the emperor their allegiance, they also possessed an extent of privileges that gave them de facto independence within their territories. Emperor Francis II dissolved the empire on 6 August 1806 following the creation of the Confederation of the Rhine by emperor Napoleon I the month before.

Median sacral artery

The median sacral artery (or middle sacral artery) is a small vessel that arises posterior to the abdominal aorta and superior to its bifurcation.

It descends in the middle line in front of the fourth and fifth lumbar vertebræ, the sacrum and coccyx, ending in the glomus coccygeum (coccygeal gland).

Minute branches pass from it, to the posterior surface of the rectum.

On the last lumbar vertebra it anastomoses with the lumbar branch of the iliolumbar artery; in front of the sacrum it anastomoses with the lateral sacral arteries, sending offshoots into the anterior sacral foramina.

It is crossed by the left common iliac vein and accompanied by a pair of venæ comitantes; these unite to form a single vessel that opens into the left common iliac vein.

The median sacral artery is morphologically the direct continuation of the abdominal aorta. It is vestigial in humans, but large in animals with tails such as the crocodile.

Nomina sacra

In Christian scribal practice, nomina sacra (singular: nomen sacrum from Latin sacred name) is the abbreviation of several frequently occurring divine names or titles, especially in Greek manuscripts of Holy Scripture. A nomen sacrum consists of two or more letters from the original word spanned by an overline.

Metzger lists 15 such expressions from Greek papyri: the Greek counterparts of God, Lord, Jesus, Christ, Son, Spirit, David, Cross, Mother, Father, Israel, Savior, Man, Jerusalem, and Heaven. These nomina sacra are all found in Greek manuscripts of the 3rd century and earlier, except Mother, which appears in the 4th.Nomina sacra also occur in some form in Latin, Coptic, Armenian (indicated by the pativ), Gothic, Old Nubian, and Cyrillic (indicated by the titlo).

O sacrum convivium

O sacrum convivium is a Latin prose text honoring the Blessed Sacrament. It was included as an antiphon to Magnificat in the vespers of the liturgical office on the feast of Corpus Christi. The text of the office is attributed with some probability to Saint Thomas Aquinas. Its sentiments express the profound affinity of the Eucharistic celebration, described as a banquet, to the Paschal mystery : "O sacred banquet at which Christ is consumed, the memory of his Passion is recalled, our souls are filled with grace, and the pledge of future glory is given to us."

Paschal Triduum

Easter Triduum (Latin: Triduum Paschale), Holy Triduum (Latin: Triduum Sacrum), or Paschal Triduum, or The Three Days, is the period of three days that begins with the liturgy on the evening of Maundy Thursday, reaches its high point in the Easter Vigil, and closes with evening prayer on Easter Sunday. It recalls the passion, death, burial, and resurrection of Jesus, as portrayed in the canonical Gospels.In the Anglican, Lutheran, Methodist, and Reformed traditions, the Paschal Triduum straddles the two liturgical seasons of Lent and Easter in the Church calendar; however, in the Roman Catholic tradition, since the 1955 reform by Pope Pius XII, the Easter Triduum has been more clearly distinguished as a separate liturgical period. Previously, all these celebrations were advanced by more than twelve hours. The Mass of the Lord's Supper and the Easter Vigil were celebrated in the morning of Thursday and Saturday respectively, and Holy Week and Lent were seen as ending only on the approach of Easter.

After the Gloria in Excelsis Deo at the Mass of the Lord's Supper all church bells are silenced and the organ is not used. The period that lasted from Thursday morning to before Easter Sunday began was once, in Anglo-Saxon times, referred to as "the still days".In the Catholic Church, weddings, which were once prohibited throughout the entire season of Lent and during certain other periods as well, are prohibited during the Triduum. Lutherans still discourage weddings during the entirety of Holy Week and the Easter Triduum.

Pelvis

The pelvis (plural pelves or pelvises) is either the lower part of the trunk of the human body between the abdomen and the thighs (sometimes also called pelvic region of the trunk) or the skeleton embedded in it (sometimes also called bony pelvis, or pelvic skeleton).

The pelvic region of the trunk includes the bony pelvis, the pelvic cavity (the space enclosed by the bony pelvis), the pelvic floor, below the pelvic cavity, and the perineum, below the pelvic floor. The pelvic skeleton is formed in the area of the back, by the sacrum and the coccyx and anteriorly and to the left and right sides, by a pair of hip bones.

The two hip bones connect the spine with the lower limbs. They are attached to the sacrum posteriorly, connected to each other anteriorly, and joined with the two femurs at the hip joints. The gap enclosed by the bony pelvis, called the pelvic cavity, is the section of the body underneath the abdomen and mainly consists of the reproductive organs (sex organs) and the rectum, while the pelvic floor at the base of the cavity assists in supporting the organs of the abdomen.

In mammals, the bony pelvis has a gap in the middle, significantly larger in females than in males. Their young pass through this gap when they are born.

Posterior sacroiliac ligament

The posterior sacroiliac ligament is situated in a deep depression between the sacrum and ilium behind; it is strong and forms the chief bond of union between the bones.

It consists of numerous fasciculi, which pass between the bones in various directions.

The upper part (short posterior sacroiliac ligament) is nearly horizontal in direction, and pass from the first and second transverse tubercles on the back of the sacrum to the tuberosity of the ilium.

The lower part (long posterior sacroiliac ligament) is oblique in direction; it is attached by one extremity to the third transverse tubercle of the back of the sacrum, and by the other to the posterior superior spine of the ilium.

Prayer of Consecration to the Sacred Heart

For the prayers by Saint Marguerite Marie Alacoque and Blessed Mary of the Divine Heart, please see: Act of Consecration to the Sacred Heart of JesusThe Prayer of Consecration to the Sacred Heart is a Roman Catholic prayer composed by Pope Leo XIII. It was included in the 1899 encyclical Annum sacrum issued by Leo XIII as he consecrated the entire world to the Sacred Heart of Jesus.

The consecration was influenced by two letters written to the pope by Sister Mary of the Divine Heart Droste zu Vischering who stated that in visions of Jesus Christ she had been told to request the consecration.

Presentation (obstetrics)

In obstetrics, the presentation of a fetus about to be born specifies which anatomical part of the fetus is leading, that is, is closest to the pelvic inlet of the birth canal. According to the leading part, this is identified as a cephalic, breech, or shoulder presentation. A malpresentation is any presentation other than a vertex presentation (with the top of the head first).

Religious war

A religious war or holy war (Latin: bellum sacrum) is a war primarily caused or justified by differences in religion. In the modern period, debates are common over the extent to which religious, economic, or ethnic aspects of a conflict predominate in a given war. According to the Encyclopedia of Wars, out of all 1,763 known/recorded historical conflicts, 123, or 6.98%, had religion as their primary cause. Matthew White's The Great Big Book of Horrible Things gives religion as the cause of 13 of the world's 100 deadliest atrocities. In several conflicts including the Israeli–Palestinian conflict, the Syrian civil war, and the wars in Afghanistan and Iraq, religious elements are overtly present but variously described as fundamentalism or religious extremism—depending upon the observer's sympathies. However, studies on these cases often conclude that ethnic animosities drive much of the conflicts.Some historians argue that what is termed "religious wars" is a largely "Western dichotomy" and a modern invention from the past few centuries, arguing that all wars that are classed as "religious" have secular (economic or political) ramifications. Similar opinions were expressed as early as the 1760s, during the Seven Years' War, widely recognized to be "religious" in motivation, noting that the warring factions were not necessarily split along confessional lines as much as along secular interests.According to Jeffrey Burton Russell, numerous cases of supposed acts of religious wars such as the Thirty Years' War, the French Wars of Religion, the Sri Lankan Civil War, 9/11 and other terrorist attacks, the Bosnian War, and the Rwandan Civil War were all primarily motivated by social, political, and economic issues rather than religion. For example, in the Thirty Years' War the dominant participant on the "Protestant" side for much of the conflict was France, led by Cardinal Richelieu.

Sacrococcygeal symphysis

The sacrococcygeal symphysis (sacrococcygeal articulation, articulation of the sacrum and coccyx) is an amphiarthrodial joint, formed between the oval surface at the apex of the sacrum, and the base of the coccyx.

It is a slightly moveable joint which is frequently, partially or completely, obliterated in old age, homologous with the joints between the bodies of the vertebrae.

Sacroiliac joint

The sacroiliac joint or SI joint (SIJ) is the joint between the sacrum and the ilium bones of the pelvis, which are connected by strong ligaments. In humans, the sacrum supports the spine and is supported in turn by an ilium on each side. The joint is strong, supporting the entire weight of the upper body. It is a synovial plane joint with irregular elevations and depressions that produce interlocking of the two bones. The human body has two sacroiliac joints, one on the left and one on the right, that often match each other but are highly variable from person to person.

Shrine of Venus Cloacina

The Shrine of Venus Cloacina (Sacellum Cloacinae or Sacrum Cloacina) — the "Shrine of Venus of the Sewer" — was a small sanctuary on the Roman Forum, honoring the divinity of the Cloaca Maxima, the spirit of the "Great Drain" or Sewer of Rome. Cloacina, the Etruscan goddess associated with the entrance to the sewer system, was later identified with the Roman goddess Venus for unknown reasons, according to Pliny the Elder.

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