document_title: London water supply infrastructure

question_text: where does the tap water in london come from

text: London water supply infrastructure

text: Early London water supply[edit]

text: Until the late 16th century, London citizens relied on the River Thames, its tributaries, or one of around a dozen natural springs for their water supplies. In 1247 work began on building the Great Conduit from the spring at Tyburn. This was a lead pipe which led via Charing Cross, Strand, Fleet Street and Ludgate to a large cistern or tank in Cheapside.[1][2] The city authorities appointed keepers of the conduits who controlled access so that users such as brewers, cooks and fishmongers would pay for the water they used. Wealthy Londoners living near the conduit pipe could obtain permission for a connection to their homes, but this did not prevent unauthorised tapping of conduits. Otherwise - particularly for households which could not take a gravity-feed - water from the conduits was provided to individual households by water carriers or "cobs".[2] Records of frequent drownings indicate that many poorer citizens collected water from the Thames or nearby streams running into the Thames. The Grand Conduit system was extended over the centuries and in the 15th century was supplemented by a conduit from springs at Paddington, and another at Highgate which supplied Cripplegate.[3]

text: Sixteenth century[edit]

text: In 1582, Dutchman Peter Morice (died 1588) developed one of the first pumped water supply systems for the City of London, powered by undershot waterwheels housed in the northernmost arches of London Bridge spanning the River Thames. The machinery was largely destroyed in the Great Fire of London in 1666 but replacements engineered by his grandson remained under the bridge until the early 19th century, before the New London Bridge was erected in the 1830s.[citation needed]

text: Seventeenth century[edit]

text: Hugh Myddleton was the driving force behind the construction of the New River, the engineering project that brought fresh water from Hertford, Hertfordshire to 17th century London. After the initial project encountered financial difficulties, Myddleton helped fund the project through to completion. The New River was constructed between 1609 and 1613 (being officially opened on 29 September that year), 38 miles (60 km) long. It starts at an elevation of 40 metres.[4] It was not initially a financial success, and cost Myddleton substantial sums, although in 1612 he was successful in securing monetary assistance from King James I.[citation needed] The New River Company became one of the largest private water companies, supplying the City of London and other central areas.[2]

text: The construction of London's current water distribution infrastructure dates back to the Great Fire of London in 1666, which destroyed most of the city's previous water infrastructure, most of which was made of wood and lead.[2] One waterworks not affected by the fire was at Shadwell by the Thames which dated from 1660. The city's water supply and distribution infrastructure has been continuously updated and upgraded since then.

text: Eighteenth century[edit]

text: The Chelsea Waterworks Company was established in 1723 "for the better supplying the City and Liberties of Westminster and parts adjacent with water".[5] The company received a Royal Charter on 8 March 1723.[6] The company created extensive ponds in the area bordering Chelsea and Pimlico using water from the tidal Thames.

text: Waterworks were established in East London, at West Ham in 1743 and at Lea Bridge before 1767.

text: The Borough Waterworks Company was formed in 1770, originally supplying water to a brewery and the surrounding area, which spanned the distance between London and Southwark Bridges. The adjacent area was supplied by the London Bridge Waterworks Company.

text: The Lambeth Waterworks Company was founded in 1785 to supply water to south and west London. It was established on the south bank of the River Thames close to the present site of Hungerford Bridge where the Royal Festival Hall now stands. The first water intake of the company was on the south side of the river and supplied directly from the river. After complaints that the water was foul, the intake was moved to the middle of the river.[7]

text: Nineteenth century[edit]

text: New companies[edit]

text: As London spread in the 19th century, new facilities were needed to service the increasing population in newly developed areas. Several new water supply companies were established leading to an arrangement of up to nine private water companies each with a geographic monopoly.

text: The Lambeth Waterworks company expanded in 1802 to supply Kennington and about this time replaced its wooden pipes with iron ones.[7]

text: The South London Waterworks Company was established by private act of parliament in 1805. The company extracted water from the Thames beside Vauxhall Bridge.

text: The West Middlesex Waterworks Company was founded in 1806 to supply water to the Marylebone and Paddington areas of London. In 1808 the company installed cast iron pipes to supply water from its intakes at Hammersmith.[8]

text: The East London Waterworks Company was founded by Act of Parliament in 1806, and also acquired existing waterworks at Shadwell, Lea Bridge and West Ham.

text: The Grand Junction Waterworks Company was created in 1811 to take advantage of a clause in the Grand Junction Canal Company's Act which allowed them to supply water brought by the canal from the River Colne and River Brent, and from a reservoir in the north-west Middlesex supplied by land drainage. It was thought that these waters would be better than those of the Thames, but in fact they were found to be of poor quality and insufficient to meet demand. After trying to resolve these problems the company resorted to taking their supply from the River Thames at a point near Chelsea Hospital[9]

text: Expansion[edit]

text: Although the legislation that established the London water companies intended that they would compete for customers, in 1815 the East London company drew up a legal agreement with the New River Company defining a boundary between their areas of supply.

text: The London Bridge Waterworks Company was dissolved in 1822, and its water supply licence was purchased by the New River Company. Later that same year, the Borough Waterworks Company purchased the London Bridge licence from the New River Company, and it was renamed the Southwark Water Company. The company extracted water from the River Thames using steam engines to pump it to a cistern at the top of a 60-foot-high (18 m) tower.[10]

text: The West Middlesex Waterworks Company established a 3.5 million gallon reservoir at Campden Hill near Notting Hill. In 1825 the company built a new reservoir at Barrow Hill next to Primrose Hill in North London.

text: In 1825, the ponds of the Chelsea Waterwork Company were used as the basis of the Grosvenor Canal which was opened to traffic that year. By this time there were complaints about the quality of the water that the company was drawing from the River Thames, and in 1829, under engineer James Simpson the Chelsea Waterworks Company became the first in the country to install a slow sand filtration system to purify the water.[11]

text: In 1829, the East London Waterworks Company moved their source of water further up river to Lea Bridge as a result of pollution caused by population growth. Clean water was now abstracted from the natural channel which had been by-passed by the Hackney Cut, to a new reservoir at Old Ford.[12] In 1830 the company gained a lease on the existing reservoir at Clapton.

text: In 1832 the Lambeth Waterworks Company built a reservoir at Streatham Hill, and in 1834 obtained an Act of Parliament to extend its area of supply. In the same year, the Company purchased 16 acres (65,000 m2) of land in Brixton and built a reservoir and works on Brixton Hill adjacent to Brixton Prison.[13]

text: In 1833 the South London Waterworks Company was supplying 12,046 houses with approximately 12,000 gallons of water.[14] In 1834, the company was renamed the Vauxhall Water Company.[10]

text: The Grand Junction Waterworks Company built a pumping station near Kew Bridge at Brentford in 1838 to house its new steam pump and two similar pumps purchased from Boulton, Watt and Company in 1820. The water was taken from the middle of the river and pumped into filtering reservoirs and to a 200 ft (61 m) high water tower to provide gravity feed to the area. A six to seven mile (11 km) main took the water to a reservoir on Campden Hill near Notting Hill capable of containing 6 million gallons.

text: In 1841 the East London Waterworks Company was supplying 36,916 houses.[14]

text: On 10 January 1845 the Southwark Waterworks Company and the Vauxhall Waterworks Company submitted a memorandum to the Health of Towns Commissioners proposing amalgamation. A consequent bill successfully passed through parliament, and the Southwark and Vauxhall Waterworks Company was formed later that year.[10] The area supplied by the SVWC was centred on the Borough of Southwark, reaching east to Rotherhithe, south to Camberwell and in the west including Battersea and parts of Clapham and Lambeth.[15] The amalgamated company established waterworks at Battersea Fields with two depositing reservoirs with a capacity of 32 million gallons; and two filtering reservoirs holding 11 million gallons.[15] In 1850 the company's treated water was described by the microbiologist Arthur Hassall as "the most disgusting which I have ever examined".[10]

text: In 1845 the limits of supply of the East London Waterworks Company were described as "all those portions of the Metropolis, and its suburbs, which lie to the east of the city, Shoreditch, the Kingsland Road, and Dalston; extending their mains even across the river Lea into Essex, as far as West Ham."[14] The water supplied by the company was taken from the Lea, with waterworks on 30 acres (0.12 km2) of land at Old Ford.

text: Metropolis Water Act[edit]

text: The companies often provided inadequate quantities of water which was often contaminated, as was famously discovered by John Snow during the 1854 cholera epidemic. Population growth in London had been very rapid (more than doubling between 1800 and 1850) without an increase in infrastructure investment. The Metropolis Water Act 1852 was enacted in order to "make provision for securing the supply to the Metropolis of pure and wholesome water." Under the Act, it became unlawful for any water company to extract water for domestic use from the tidal reaches of the Thames after 31 August 1855, and from 31 December 1855 all such water was required to be "effectually filtered".[16] The Metropolitan Commission of Sewers was formed, water filtration was made compulsory, and new water intakes on the Thames were established above Teddington Lock.

text: The Chelsea Waterworks Company and the Lambeth Waterworks Company, who shared the services of James Simpson, established the reservoirs and filtration plants at Seething Wells along part of the riverside of Thames Ditton and Surbiton. The Chelsea's former central site was taken over by railway companies to make space for Victoria Station. The 'Grand Junction', 'West Middlesex' and 'Southwark and Vauxhall' Waterworks Companies built the works above Molesey Lock at Hampton designed by Joseph Quick. The Stain Hill Reservoirs and Sunnyside Reservoir were constructed in Hampton by the SVWC in 1855, with a 36-inch (910 mm) diameter main to Battersea. A third reservoir was opened later in the year between Nunhead Cemetery and Peckham Rye.[10]

text: In the mid 19th century the East London Waterworks Company purchased the Coppermill at Walthamstow and modified it to drive a water pump to assist in the building of reservoirs on nearby marshland in the Lea Valley .[17] The company built a series of reservoirs which were High Maynard Reservoir, Low Maynard Reservoir, five linked numbered reservoirs making the Walthamstow Reservoirs, the East Warwick Reservoir and the West Warwick Reservoir.

text: In 1872 the Lambeth Waterworks Company moved upstream on the Thames to Molesey, followed by the Chelsea Waterworks Company. They built the Molesey Reservoirs there in 1872.

text: The East London Waterworks Company replaced their reservoir at Clapton by a reservoir at Stamford Hill in 1891.[18]

text: In 1897 the New River Company started developing the treatment works spanning Kempton Park and Hanworth to supply more water than their facilities at Cricklewood drawing on the River Brent.

text: In 1898 the SVWC started work on the Bessborough Reservoir and the Knight Reservoir across the Thames from Hampton at Molesey. By 1903 the SVWC supplied a population of 860,173 in 128,871 houses of which 122,728 (95.3%) had a constant supply.[19] The Lambeth Waterworks company started work on Island Barn Reservoir at Molesey in 1900.

text: Twentieth century[edit]

text: The private water companies were nationalised at the beginning of the 20th century. The Metropolis Water Act 1902 (2 Edw.7, c.41) created the Metropolitan Water Board. It was founded in 1903 and as originally constituted in the Act had 67 members; 65 of these were nominated by local authorities, who appointed a paid chairman and vice-chairman. The board compulsorily acquired the following water companies:

text:
The New River Company
The East London Waterworks Company
The Southwark and Vauxhall Waterworks Company
The West Middlesex Waterworks Company
The Lambeth Waterworks Company
The Chelsea Waterworks Company
The Grand Junction Waterworks Company
The Staines Reservoirs Joint Committee
The Kent Waterworks Company

text: Also acquired at no cost were the water undertakings of Tottenham and Enfield Urban District Councils. The supply pipes stretch a similar distance to sewerage pipes which extend 13,000 miles in Greater London.[20]

text: The MWB opened the East London Waterworks reservoirs Banbury Reservoir and Lockwood Reservoir, and the Bessborough Reservoir, Knight Reservoir and Island Barn Reservoirs at Molesey. It also opened the Kempton Park Reservoirs in around 1907.

text: In 1910, extraction facilities were opened at Hythe End and the Staines Reservoir Aqueduct was built to supply water to Hampton. The Metropolitan Water Board Railway was opened in 1916 to carry coal from the river at Hampton to Kempton Park. An engine house with powerful steam engines was opened at Kempton Park in 1929, which has now become Kempton Park Steam Engines museum.

text: The MWB opened a succession of reservoirs - King George V Reservoir, (Lea Valley) in 1912, Queen Mary Reservoir (Ashford) in 1925, King George VI Reservoir (Stanwellmoor) in 1947 William Girling Reservoir (Lea Valley) in 1951, Queen Elizabeth II Reservoir (Molesey) 1962, Wraysbury Reservoir 1967, and Queen Mother Reservoir (Staines) 1976.

text: The Metropolitan Water Board and other local Water Boards were later combined into the Thames Water Authority, which was later privatized as Thames Water, a state-regulated private company which currently provides London's water supply.

text: Present day[edit]

text: Greater London is currently supplied by four companies: Thames Water (76% of population), Affinity Water (14%), Essex and Suffolk Water (6.6%) and Sutton and East Surrey Water (3.7%).[21]

text: Most of London's water comes from non-tidal parts of the Thames and Lea, with the remainder being abstracted from underground sources.[22]

text: Much of the water piping in London is still cast iron piping which dates back to the nineteenth century and is slowly deteriorating. This has led to widespread criticism of Thames Water for the amount of water lost to leaks in its distribution network.[23] As of 2007, Thames Water is still in the process of a rolling programme of upgrading the water supply network to use modern plastic piping.[24]

text: A major 21st large infrastructure investment has been the creation of the Thames Water Ring Main, a "backbone network" for London's water supply. This period also saw contingency planning reserve facilities used mostly in times of drought built at Beckton.[25][26] This connects all the waterworks, and pumping stations.

text: Water Treatment Works[edit]

text: The Water treatment works on the Ring Main are:

text:
Ashford Common
Kempton Park, Hanworth
Walton
Hampton
Coppermills Water Treatment Works

text: Pumping stations[edit]

text: The pumping stations on the ring main are:

text:
Surbiton PS
Merton PS
Streatham PS
Brixton PS
Battersea PS
Park Lane PS
Kew PS
Holland Park Avenue PS
Barrow Hill PS
New River Head PS
Stoke Newington PS

text: Access[edit]

text:
Hogsmill — Access
Raynes Park — Access
Mogden — Access

text: Storage[edit]

text:
Honor Oak — Underground Storage
Barnes — balancing storage


document_title: Vertebral column

question_text: division of the back contains the neck vertebrae

root

text: Vertebral column

text: Structure[edit]

text: In humans vertebral column there are normally thirty-three vertebrae;[3] the upper twenty-four are articulating and separated from each other by intervertebral discs, and the lower nine are fused in adults, five in the sacrum and four in the coccyx or tailbone. The articulating vertebrae are named according to their region of the spine. There are seven cervical vertebrae, twelve thoracic vertebrae and five lumbar vertebrae. The number of vertebrae in a region can vary but overall the number remains the same. The number of those in the cervical region however is only rarely changed.[4]

tag: p

text: There are ligaments extending the length of the column at the front and the back, and in between the vertebrae joining the spinous processes, the transverse processes and the vertebral laminae.

text: Vertebrae[edit]

text: The vertebrae in the human vertebral column are divided into different regions, which correspond to the curves of the spinal column. The articulating vertebrae are named according to their region of the spine. Vertebrae in these regions are essentially alike, with minor variation. These regions are called the cervical spine, thoracic spine, lumbar spine, sacrum and coccyx. There are seven cervical vertebrae, twelve thoracic vertebrae and five lumbar vertebrae. The number of vertebrae in a region can vary but overall the number remains the same. The number of those in the cervical region however is only rarely changed.[4] The vertebrae of the cervical, thoracic and lumbar spines are independent bones, and generally quite similar. The vertebrae of the sacrum and coccyx are usually fused and unable to move independently. Two special vertebrae are the atlas and axis, on which the head rests.

text: A typical vertebra consists of two parts: the vertebral body and the vertebral arch. The vertebral arch is posterior, meaning it faces the back of a person. Together, these enclose the vertebral foramen, which contains the spinal cord. Because the spinal cord ends in the lumbar spine, and the sacrum and coccyx are fused, they do not contain a central foramen. The vertebral arch is formed by a pair of pedicles and a pair of laminae, and supports seven processes, four articular, two transverse, and one spinous, the latter also being known as the neural spine. Two transverse processes and one spinous process are posterior to (behind) the vertebral body. The spinous process comes out the back, one transverse process comes out the left, and one on the right. The spinous processes of the cervical and lumbar regions can be felt through the skin.

text: Above and below each vertebra are joints called facet joints. These restrict the range of movement possible, and are joined by a thin portion of the neural arch called the pars interarticularis. In between each pair of vertebrae are two small holes called intervertebral foramina. The spinal nerves leave the spinal cord through these holes.

text: Individual vertebrae are named according to their region and position. From top to bottom, the vertebrae are:

text:
Cervical spine: 7 vertebrae (C1–C7)
Thoracic spine: 12 vertebrae (T1–T12)
Lumbar spine: 5 vertebrae (L1–L5)
Sacrum: 5 (fused) vertebrae (S1–S5)
Coccyx: 4 (3–5) (fused) vertebrae (Tailbone)

tag: ul

text: Shape[edit]

text: The upper cervical spine has a curve, convex forward, that begins at the axis (second cervical vertebra) at the apex of the odontoid process or dens, and ends at the middle of the second thoracic vertebra; it is the least marked of all the curves. This inward curve is known as a lordotic curve.

text: The thoracic curve, concave forward, begins at the middle of the second and ends at the middle of the twelfth thoracic vertebra. Its most prominent point behind corresponds to the spinous process of the seventh thoracic vertebra. This curve is known as a kyphotic curve.

text: The lumbar curve is more marked in the female than in the male; it begins at the middle of the last thoracic vertebra, and ends at the sacrovertebral angle. It is convex anteriorly, the convexity of the lower three vertebrae being much greater than that of the upper two. This curve is described as a lordotic curve.

text: The sacral curve begins at the sacrovertebral articulation, and ends at the point of the coccyx; its concavity is directed downward and forward as a kyphotic curve.

text: The thoracic and sacral kyphotic curves are termed primary curves, because they are present in the fetus. The cervical and lumbar curves are compensatory or secondary, and are developed after birth. The cervical curve forms when the infant is able to hold up its head (at three or four months) and to sit upright (at nine months). The lumbar curve forms later from twelve to eighteen months, when the child begins to walk.

text: Surfaces[edit]

text: When viewed from in front, the width of the bodies of the vertebrae is seen to increase from the second cervical to the first thoracic; there is then a slight diminution in the next three vertebrae; below this there is again a gradual and progressive increase in width as low as the sacrovertebral angle. From this point there is a rapid diminution, to the apex of the coccyx.[5]

text: From behind, the vertebral column presents in the median line the spinous processes. In the cervical region (with the exception of the second and seventh vertebrae) these are short, horizontal and bifid. In the upper part of the thoracic region they are directed obliquely downward; in the middle they are almost vertical, and in the lower part they are nearly horizontal. In the lumbar region they are nearly horizontal. The spinous processes are separated by considerable intervals in the lumbar region, by narrower intervals in the neck, and are closely approximated in the middle of the thoracic region. Occasionally one of these processes deviates a little from the median line — which can sometimes be indicative of a fracture or a displacement of the spine. On either side of the spinous processes is the vertebral groove formed by the laminae in the cervical and lumbar regions, where it is shallow, and by the laminae and transverse processes in the thoracic region, where it is deep and broad; these grooves lodge the deep muscles of the back. Lateral to the spinous processes are the articular processes, and still more laterally the transverse processes. In the thoracic region, the transverse processes stand backward, on a plane considerably behind that of the same processes in the cervical and lumbar regions. In the cervical region, the transverse processes are placed in front of the articular processes, lateral to the pedicles and between the intervertebral foramina. In the thoracic region they are posterior to the pedicles, intervertebral foramina, and articular processes. In the lumbar region they are in front of the articular processes, but behind the intervertebral foramina.[5]

text: The sides of the vertebral column are separated from the posterior surface by the articular processes in the cervical and thoracic regions, and by the transverse processes in the lumbar region. In the thoracic region, the sides of the bodies of the vertebrae are marked in the back by the facets for articulation with the heads of the ribs. More posteriorly are the intervertebral foramina, formed by the juxtaposition of the vertebral notches, oval in shape, smallest in the cervical and upper part of the thoracic regions, and gradually increasing in size to the last lumbar. They transmit the special spinal nerves and are situated between the transverse processes in the cervical region, and in front of them in the thoracic and lumbar regions.[5]

text: Ligaments[edit]

text: There are different ligaments involved in the holding together of the vertebrae in the column, and in the column's movement. The anterior and posterior longitudinal ligaments extend the length of the vertebral column along the front and back of the vertebral bodies.[6] The interspinous ligaments connect the adjoining spinous processes of the vertebrae.[7] The supraspinous ligament extends the length of the spine running along the back of the spinous processes, from the sacrum to the seventh cervical vertebra.[8] From there it is continuous with the nuchal ligament.

text: Development[edit]

text: The striking segmented pattern of the spine is established during embryogenesis when somites are rhythmically added to the posterior of the embryo. Somite formation begins around the third week when the embryo begins gastrulation and continues until around 52 somites are formed. The somites are spheres, formed from the paraxial mesoderm that lies at the sides of the neural tube and they contain the precursors of spinal bone, the vertebrae ribs and some of the skull, as well as muscle, ligaments and skin. Somitogenesis and the subsequent distribution of somites is controlled by a clock and wavefront model acting in cells of the paraxial mesoderm. Soon after their formation, sclerotomes, which give rise to some of the bone of the skull, the vertebrae and ribs, migrate, leaving the remainder of the somite now termed a dermamyotome behind. This then splits to give the myotomes which will form the muscles and dermatomes which will form the skin of the back. Sclerotomes become subdivided into an anterior and a posterior compartment. This subdivision plays a key role in the definitive patterning of vertebrae that form when the posterior part of one somite fuses to the anterior part of the consecutive somite during a process termed resegmentation. Disruption of the somitogenesis process in humans results in diseases such as congenital scoliosis. So far, the human homologues of three genes associated to the mouse segmentation clock, (MESP2, DLL3 and LFNG), have been shown to be mutated in cases of congenital scoliosis, suggesting that the mechanisms involved in vertebral segmentation are conserved across vertebrates. In humans the first four somites are incorporated in the base of the occipital bone of the skull and the next 33 somites will form the vertebrae, ribs, muscles, ligaments and skin.[9] The remaining posterior somites degenerate. During the fourth week of embryogenesis, the sclerotomes shift their position to surround the spinal cord and the notochord. This column of tissue has a segmented appearance, with alternating areas of dense and less dense areas.

text: As the sclerotome develops, it condenses further eventually developing into the vertebral body. Development of the appropriate shapes of the vertebral bodies is regulated by HOX genes.

text: The less dense tissue that separates the sclerotome segments develop into the intervertebral discs.

text: The notochord disappears in the sclerotome (vertebral body) segments, but persists in the region of the intervertebral discs as the nucleus pulposus. The nucleus pulposus and the fibers of the anulus fibrosus make up the intervertebral disc.

text: The primary curves (thoracic and sacral curvatures) form during fetal development. The secondary curves develop after birth. The cervical curvature forms as a result of lifting the head and the lumbar curvature forms as a result of walking.

text: Function[edit]

text: Spinal cord[edit]

text: The vertebral column surrounds the spinal cord which travels within the spinal canal, formed from a central hole within each vertebra. The spinal cord is part of the central nervous system that supplies nerves and receives information from the peripheral nervous system within the body. The spinal cord consists of grey and white matter and a central cavity, the central canal. Adjacent to each vertebra emerge spinal nerves. The spinal nerves provide sympathetic nervous supply to the body, with nerves emerging forming the sympathetic trunk and the splanchnic nerves.

text: The spinal canal follows the different curves of the column; it is large and triangular in those parts of the column which enjoy the greatest freedom of movement, such as the cervical and lumbar regions; and is small and rounded in the thoracic region, where motion is more limited.[citation needed]

text: The spinal cord terminates in the conus medullaris and cauda equina.

text: Clinical significance[edit]

text: Disease[edit]

text: Spina bifida is a congenital disorder in which there is a defective closure of the vertebral arch. Sometimes the spinal meninges and also the spinal cord can protrude through this, and this is called Spina bifida cystica. Where the condition does not involve this protrusion it is known as Spina bifida occulta. Sometimes all of the vertebral arches may remain incomplete.[10] Another, though rare, congenital disease is Klippel-Feil syndrome which is the fusion of any two of the cervical vertebrae.

text: Spondylolisthesis is the forward displacement of a vertebra and retrolisthesis is a posterior displacement of one vertebral body with respect to the adjacent vertebra to a degree less than a dislocation.

text: Spinal disc herniation, more commonly called a "slipped disc", is the result of a tear in the outer ring (anulus fibrosus) of the intervertebral disc, which lets some of the soft gel-like material, the nucleus pulposus, bulge out in a hernia.

text: Spinal stenosis is a narrowing of the spinal canal which can occur in any region of the spine though less commonly in the thoracic region. The stenosis can constrict the spinal canal giving rise to a neurological deficit.

text: Pain at the coccyx (tailbone) is known as coccydynia.[11]

text: Spinal cord injury is damage to the spinal cord that causes changes in its function, either temporary or permanent.

text: Curvature[edit]

text: Excessive or abnormal spinal curvature is classed as a spinal disease or dorsopathy and includes the following abnormal curvatures:

text:
Kyphosis is an exaggerated kyphotic (concave) curvature in the thoracic region, also called hyperkyphosis. This produces the so-called "humpback" or "dowager's hump", a condition commonly resulting from osteoporosis.
Lordosis as an exaggerated lordotic (convex) curvature of the lumbar region, is known as lumbar hyperlordosis and also as "swayback". Temporary lordosis is common during pregnancy.
Scoliosis, lateral curvature, is the most common abnormal curvature, occurring in 0.5% of the population. It is more common among females and may result from unequal growth of the two sides of one or more vertebrae, so that they do not fuse properly. It can also be caused by pulmonary atelectasis (partial or complete deflation of one or more lobes of the lungs) as observed in asthma or pneumothorax.
Kyphoscoliosis, a combination of kyphosis and scoliosis.

text: Anatomical landmarks[edit]

text: Individual vertebrae of the human vertebral column can be felt and used as surface anatomy, with reference points are taken from the middle of the vertebral body. This provides anatomical landmarks that can be used to guide procedures such as a lumbar puncture and also as vertical reference points to describe the locations of other parts of human anatomy, such as the positions of organs.

text: Other animals[edit]

text: Variations in vertebrae[edit]

text: The general structure of vertebrae in other animals is largely the same as in humans. Individual vertebrae are composed of a centrum (body), arches protruding from the top and bottom of the centrum, and various processes projecting from the centrum and/or arches. An arch extending from the top of the centrum is called a neural arch, while the haemal arch or chevron is found underneath the centrum in the caudal (tail) vertebrae of fish, most reptiles, some birds, some dinosaurs and some mammals with long tails. The vertebral processes can either give the structure rigidity, help them articulate with ribs, or serve as muscle attachment points. Common types are transverse process, diapophyses, parapophyses, and zygapophyses (both the cranial zygapophyses and the caudal zygapophyses). The centrum of the vertebra can be classified based on the fusion of its elements. In temnospondyls, bones such as the spinous process, the pleurocentrum and the intercentrum are separate ossifications. Fused elements, however, classify a vertebra as having holospondyly.

text: A vertebra can also be described in terms of the shape of the ends of the centrum. Centra with flat ends are acoelous, like those in mammals. These flat ends of the centra are especially good at supporting and distributing compressive forces. Amphicoelous vertebra have centra with both ends concave. This shape is common in fish, where most motion is limited. Amphicoelous centra often are integrated with a full notochord. Procoelous vertebrae are anteriorly concave and posteriorly convex. They are found in frogs and modern reptiles. Opisthocoelous vertebrae are the opposite, possessing anterior convexity and posterior concavity. They are found in salamanders, and in some non-avian dinosaurs. Heterocoelous vertebrae have saddle-shaped articular surfaces. This type of configuration is seen in turtles that retract their necks, and birds, because it permits extensive lateral and vertical flexion motion without stretching the nerve cord too extensively or wringing it about its long axis.

text: In horses, the Arabian (breed) can have one less vertebrae and pair of ribs. This anomaly disappears in foals that are the product of an Arabian and another breed of horse.[12]

text: Regional vertebrae[edit]

text: Vertebrae are defined by the regions of the vertebral column that they occur in, as in humans. Cervical vertebrae are those in the neck area. With the exception of the two sloth genera (Choloepus and Bradypus) and the manatee genus, (Trichechus),[13] all mammals have seven cervical vertebrae.[14] In other vertebrates, the number of cervical vertebrae can range from a single vertebra in amphibians, to as many as 25 in swans or 76 in the extinct plesiosaur Elasmosaurus. The dorsal vertebrae range from the bottom of the neck to the top of the pelvis. Dorsal vertebrae attached to the ribs are called thoracic vertebrae, while those without ribs are called lumbar vertebrae. The sacral vertebrae are those in the pelvic region, and range from one in amphibians, to two in most birds and modern reptiles, or up to three to five in mammals. When multiple sacral vertebrae are fused into a single structure, it is called the sacrum. The synsacrum is a similar fused structure found in birds that is composed of the sacral, lumbar, and some of the thoracic and caudal vertebra, as well as the pelvic girdle. Caudal vertebrae compose the tail, and the final few can be fused into the pygostyle in birds, or into the coccygeal or tail bone in chimpanzees (and humans).

text: Fish and amphibians[edit]

text: The vertebrae of lobe-finned fishes consist of three discrete bony elements. The vertebral arch surrounds the spinal cord, and is of broadly similar form to that found in most other vertebrates. Just beneath the arch lies a small plate-like pleurocentrum, which protects the upper surface of the notochord, and below that, a larger arch-shaped intercentrum to protect the lower border. Both of these structures are embedded within a single cylindrical mass of cartilage. A similar arrangement was found in the primitive Labyrinthodonts, but in the evolutionary line that led to reptiles (and hence, also to mammals and birds), the intercentrum became partially or wholly replaced by an enlarged pleurocentrum, which in turn became the bony vertebral body.[15] In most ray-finned fishes, including all teleosts, these two structures are fused with, and embedded within, a solid piece of bone superficially resembling the vertebral body of mammals. In living amphibians, there is simply a cylindrical piece of bone below the vertebral arch, with no trace of the separate elements present in the early tetrapods.[15]

text: In cartilaginous fish, such as sharks, the vertebrae consist of two cartilaginous tubes. The upper tube is formed from the vertebral arches, but also includes additional cartilaginous structures filling in the gaps between the vertebrae, and so enclosing the spinal cord in an essentially continuous sheath. The lower tube surrounds the notochord, and has a complex structure, often including multiple layers of calcification.[15]

text: Lampreys have vertebral arches, but nothing resembling the vertebral bodies found in all higher vertebrates. Even the arches are discontinuous, consisting of separate pieces of arch-shaped cartilage around the spinal cord in most parts of the body, changing to long strips of cartilage above and below in the tail region. Hagfishes lack a true vertebral column, and are therefore not properly considered vertebrates, but a few tiny neural arches are present in the tail.[15]

text: Other vertebrates[edit]

text: The general structure of human vertebrae is fairly typical of that found in mammals, reptiles, and birds. The shape of the vertebral body does, however, vary somewhat between different groups. In mammals, such as humans, it typically has flat upper and lower surfaces, while in reptiles the anterior surface commonly has a concave socket into which the expanded convex face of the next vertebral body fits. Even these patterns are only generalisations, however, and there may be variation in form of the vertebrae along the length of the spine even within a single species. Some unusual variations include the saddle-shaped sockets between the cervical vertebrae of birds and the presence of a narrow hollow canal running down the centre of the vertebral bodies of geckos and tuataras, containing a remnant of the notochord.[15]

text: Reptiles often retain the primitive intercentra, which are present as small crescent-shaped bony elements lying between the bodies of adjacent vertebrae; similar structures are often found in the caudal vertebrae of mammals. In the tail, these are attached to chevron-shaped bones called haemal arches, which attach below the base of the spine, and help to support the musculature. These latter bones are probably homologous with the ventral ribs of fish. The number of vertebrae in the spines of reptiles is highly variable, and may be several hundred in some species of snake.[15]

text: In birds, there is a variable number of cervical vertebrae, which often form the only truly flexible part of the spine. The thoracic vertebrae are partially fused, providing a solid brace for the wings during flight. The sacral vertebrae are fused with the lumbar vertebrae, and some thoracic and caudal vertebrae, to form a single structure, the synsacrum, which is thus of greater relative length than the sacrum of mammals. In living birds, the remaining caudal vertebrae are fused into a further bone, the pygostyle, for attachment of the tail feathers.[15]

text: Aside from the tail, the number of vertebrae in mammals is generally fairly constant. There are almost always seven cervical vertebrae (sloths and manatees are among the few exceptions), followed by around twenty or so further vertebrae, divided between the thoracic and lumbar forms, depending on the number of ribs. There are generally three to five vertebrae with the sacrum, and anything up to fifty caudal vertebrae.[15]

text: Dinosaurs[edit]

text: The vertebral column in dinosaurs consists of the cervical (neck), dorsal (back), sacral (hips), and caudal (tail) vertebrae. Saurischian dinosaur vertebrae sometimes possess features known as pleurocoels, which are hollow depressions on the lateral portions of the vertebrae, perforated to create an entrance into the air chambers within the vertebrae, which served to decrease the weight of these bones without sacrificing strength. These pleurocoels were filled with air sacs, which would have further decreased weight. In sauropod dinosaurs, the largest known land vertebrates, pleurocoels and air sacs may have reduced the animal's weight by over a ton in some instances, a handy evolutionary adaption in animals that grew to over 30 metres in length. In many hadrosaur and theropod dinosaurs, the caudal vertebrae were reinforced by ossified tendons. The presence of three or more sacral vertebrae, in association with the hip bones, is one of the defining characteristics of dinosaurs. The occipital condyle is a structure on the posterior part of a dinosaur's skull which articulates with the first cervical vertebra.[16]