Shandong
Shandong is a coastal province of the People's Republic of China, is part of the East China region. Shandong has played a major role in Chinese history since the beginning of Chinese civilization along the lower reaches of the Yellow River, it has served as a pivotal cultural and religious center for Taoism, Chinese Buddhism, Confucianism. Shandong's Mount Tai is the most revered mountain of Taoism and one of the world's sites with the longest history of continuous religious worship; the Buddhist temples in the mountains to the south of the provincial capital of Jinan were once among the foremost Buddhist sites in China. The city of Qufu is the birthplace of Confucius, was established as the center of Confucianism. Shandong's location at the intersection of ancient as well as modern north–south and east–west trading routes have helped to establish it as an economic center. After a period of political instability and economic hardship that began in the late 19th century, Shandong has emerged as one of the most populous and most affluent provinces in the People's Republic of China with a GDP of CNY¥5.942 trillion in 2014, or USD$967 billion, making it China's third wealthiest province.
Individually, the two Chinese characters in the name "Shandong" mean "mountain" and "east". Shandong could hence be translated as "east of the mountains" and refers to the province's location to the east of the Taihang Mountains. A common nickname for Shandong is Qílǔ, after the States of Qi and Lu that existed in the area during the Spring and Autumn period. Whereas the State of Qi was a major power of its era, the State of Lu played only a minor role in the politics of its time. Lu, became renowned for being the home of Confucius and hence its cultural influence came to eclipse that of the State of Qi; the cultural dominance of the State of Lu heritage is reflected in the official abbreviation for Shandong, "鲁". English speakers in the 19th century called the province Shan-tung; the province is on the eastern edge of the North China Plain and in the lower reaches of the Yellow River, extends out to sea as the Shandong Peninsula. Shandong borders the Bohai Sea to the north, Hebei to the northwest, Henan to the west, Jiangsu to the south, the Yellow Sea to the southeast.
With its location on the eastern edge of the North China Plain, Shandong was home to a succession of Neolithic cultures for millennia, including the Houli culture, the Beixin culture, the Dawenkou culture, the Longshan culture, the Yueshi culture. The earliest dynasties exerted varying degrees of control over western Shandong, while eastern Shandong was inhabited by the Dongyi peoples who were considered "barbarians". Over subsequent centuries, the Dongyi were sinicized. During the Spring and Autumn period and the Warring States period, regional states became powerful. At this time, Shandong was home to two major states: the state of Qi at Linzi and the state of Lu at Qufu. Lu is noted for being the home of Confucius; the state was, comparatively small, succumbed to the larger state of Chu from the south. The state of Qi, on the other hand, was a major power throughout the period. Cities it ruled included Jimo and Ju; the Qin dynasty conquered Qi and founded the first centralized Chinese state in 221 BCE.
The Han dynasty that followed created a number of commanderies supervised by two regions in what is now modern Shandong: Qingzhou in the north and Yanzhou in the south. During the division of the Three Kingdoms, Shandong belonged to the Cao Wei, which ruled over northern China. After the Three Kingdoms period, a brief period of unity under the Western Jin dynasty gave way to invasions by nomadic peoples from the north. Northern China, including Shandong, was overrun. Over the next century or so Shandong changed hands several times, falling to the Later Zhao Former Yan Former Qin Later Yan Southern Yan the Liu Song dynasty, the Northern Wei dynasty, the first of the Northern dynasties during the Northern and Southern dynasties Period. Shandong stayed with the Northern dynasties for the rest of this period. In 412 CE, the Chinese Buddhist monk Faxian landed at Laoshan, on the southern edge of the Shandong peninsula, proceeded to Qingzhou to edit and translate the scriptures he had brought back from India.
The Sui dynasty reestablished unity in 589, the Tang dynasty presided over the next golden age of China. For the earlier part of this period Shandong was ruled as part of Henan Circuit, one of the circuits. On China splintered into warlord factions, resulting in the Five Dynasties and Ten Kingdoms period. Shandong was part of all based in the north; the Song dynasty reunified China in the late tenth century. The classic novel Water Margin was based on folk tales of outlaw bands active in Shandong during the Song dynasty. In 1996, the discovery of over two hundred buried Buddhist statues at Qingzhou was hailed as a major archaeological find; the statues included early examples of painted figures, are thought to have been buried due to Emperor Huizong's repression of Buddhism. The Song dynasty was forced to cede northern China to the Jurchen Jin dynasty in 1142. Shandong was administered by the Jin as Shandong East Circuit and Shandong West Circuit – the first use of its current name; the modern provinc
Cambrian
The Cambrian Period was the first geological period of the Paleozoic Era, of the Phanerozoic Eon. The Cambrian lasted 55.6 million years from the end of the preceding Ediacaran Period 541 million years ago to the beginning of the Ordovician Period 485.4 mya. Its subdivisions, its base, are somewhat in flux; the period was established by Adam Sedgwick, who named it after Cambria, the Latin name of Wales, where Britain's Cambrian rocks are best exposed. The Cambrian is unique in its unusually high proportion of lagerstätte sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells; as a result, our understanding of the Cambrian biology surpasses that of some periods. The Cambrian marked a profound change in life on Earth. Complex, multicellular organisms became more common in the millions of years preceding the Cambrian, but it was not until this period that mineralized—hence fossilized—organisms became common; the rapid diversification of life forms in the Cambrian, known as the Cambrian explosion, produced the first representatives of all modern animal phyla.
Phylogenetic analysis has supported the view that during the Cambrian radiation, metazoa evolved monophyletically from a single common ancestor: flagellated colonial protists similar to modern choanoflagellates. Although diverse life forms prospered in the oceans, the land is thought to have been comparatively barren—with nothing more complex than a microbial soil crust and a few molluscs that emerged to browse on the microbial biofilm. Most of the continents were dry and rocky due to a lack of vegetation. Shallow seas flanked the margins of several continents created during the breakup of the supercontinent Pannotia; the seas were warm, polar ice was absent for much of the period. Despite the long recognition of its distinction from younger Ordovician rocks and older Precambrian rocks, it was not until 1994 that the Cambrian system/period was internationally ratified; the base of the Cambrian lies atop a complex assemblage of trace fossils known as the Treptichnus pedum assemblage. The use of Treptichnus pedum, a reference ichnofossil to mark the lower boundary of the Cambrian, is difficult since the occurrence of similar trace fossils belonging to the Treptichnids group are found well below the T. pedum in Namibia and Newfoundland, in the western USA.
The stratigraphic range of T. pedum overlaps the range of the Ediacaran fossils in Namibia, in Spain. The Cambrian Period was followed by the Ordovician Period; the Cambrian is divided into ten ages. Only three series and six stages are named and have a GSSP; because the international stratigraphic subdivision is not yet complete, many local subdivisions are still used. In some of these subdivisions the Cambrian is divided into three series with locally differing names – the Early Cambrian, Middle Cambrian and Furongian. Rocks of these epochs are referred to as belonging to Upper Cambrian. Trilobite zones allow biostratigraphic correlation in the Cambrian; each of the local series is divided into several stages. The Cambrian is divided into several regional faunal stages of which the Russian-Kazakhian system is most used in international parlance: *Most Russian paleontologists define the lower boundary of the Cambrian at the base of the Tommotian Stage, characterized by diversification and global distribution of organisms with mineral skeletons and the appearance of the first Archaeocyath bioherms.
The International Commission on Stratigraphy list the Cambrian period as beginning at 541 million years ago and ending at 485.4 million years ago. The lower boundary of the Cambrian was held to represent the first appearance of complex life, represented by trilobites; the recognition of small shelly fossils before the first trilobites, Ediacara biota earlier, led to calls for a more defined base to the Cambrian period. After decades of careful consideration, a continuous sedimentary sequence at Fortune Head, Newfoundland was settled upon as a formal base of the Cambrian period, to be correlated worldwide by the earliest appearance of Treptichnus pedum. Discovery of this fossil a few metres below the GSSP led to the refinement of this statement, it is the T. pedum ichnofossil assemblage, now formally used to correlate the base of the Cambrian. This formal designation allowed radiometric dates to be obtained from samples across the globe that corresponded to the base of the Cambrian. Early dates of 570 million years ago gained favour, though the methods used to obtain this number are now considered to be unsuitable and inaccurate.
A more precise date using modern radiometric dating yield a date of 541 ± 0.3 million years ago. The ash horizon in Oman from which this date was recovered corresponds to a marked fall in the abundance of carbon-13 that correlates to equivalent excursions elsewhere in the world, to the disappearance of distinctive Ediacaran fossils. There are arguments that the dated horizon in Oman does not correspond to the Ediacaran-Cambrian boundary, but represents a facies change from marine to evaporite-dominated strata — which w
Silurian
The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago, to the beginning of the Devonian Period, 419.2 Mya. The Silurian is the shortest period of the Paleozoic Era; as with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by several million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when 60% of marine species were wiped out. A significant evolutionary milestone during the Silurian was the diversification of jawed fish and bony fish. Multi-cellular life began to appear on land in the form of small, bryophyte-like and vascular plants that grew beside lakes and coastlines, terrestrial arthropods are first found on land during the Silurian. However, terrestrial life would not diversify and affect the landscape until the Devonian; the Silurian system was first identified by British geologist Roderick Murchison, examining fossil-bearing sedimentary rock strata in south Wales in the early 1830s.
He named the sequences for a Celtic tribe of Wales, the Silures, inspired by his friend Adam Sedgwick, who had named the period of his study the Cambrian, from the Latin name for Wales. This naming does not indicate any correlation between the occurrence of the Silurian rocks and the land inhabited by the Silures. In 1835 the two men presented a joint paper, under the title On the Silurian and Cambrian Systems, Exhibiting the Order in which the Older Sedimentary Strata Succeed each other in England and Wales, the germ of the modern geological time scale; as it was first identified, the "Silurian" series when traced farther afield came to overlap Sedgwick's "Cambrian" sequence, provoking furious disagreements that ended the friendship. Charles Lapworth resolved the conflict by defining a new Ordovician system including the contested beds. An early alternative name for the Silurian was "Gotlandian" after the strata of the Baltic island of Gotland; the French geologist Joachim Barrande, building on Murchison's work, used the term Silurian in a more comprehensive sense than was justified by subsequent knowledge.
He divided the Silurian rocks of Bohemia into eight stages. His interpretation was questioned in 1854 by Edward Forbes, the stages of Barrande, F, G and H, have since been shown to be Devonian. Despite these modifications in the original groupings of the strata, it is recognized that Barrande established Bohemia as a classic ground for the study of the earliest fossils; the Llandovery Epoch lasted from 443.8 ± 1.5 to 433.4 ± 2.8 mya, is subdivided into three stages: the Rhuddanian, lasting until 440.8 million years ago, the Aeronian, lasting to 438.5 million years ago, the Telychian. The epoch is named for the town of Llandovery in Wales; the Wenlock, which lasted from 433.4 ± 1.5 to 427.4 ± 2.8 mya, is subdivided into the Sheinwoodian and Homerian ages. It is named after Wenlock Edge in England. During the Wenlock, the oldest-known tracheophytes of the genus Cooksonia, appear; the complexity of later Gondwana plants like Baragwanathia, which resembled a modern clubmoss, indicates a much longer history for vascular plants, extending into the early Silurian or Ordovician.
The first terrestrial animals appear in the Wenlock, represented by air-breathing millipedes from Scotland. The Ludlow, lasting from 427.4 ± 1.5 to 423 ± 2.8 mya, comprises the Gorstian stage, lasting until 425.6 million years ago, the Ludfordian stage. It is named for the town of Ludlow in England; the Přídolí, lasting from 423 ± 1.5 to 419.2 ± 2.8 mya, is the final and shortest epoch of the Silurian. It is named after one locality at the Homolka a Přídolí nature reserve near the Prague suburb Slivenec in the Czech Republic. Přídolí is the old name of a cadastral field area. In North America a different suite of regional stages is sometimes used: Cayugan Lockportian Tonawandan Ontarian Alexandrian In Estonia the following suite of regional stages is used: Ohessaare stage Kaugatuma stage Kuressaare stage Paadla stage Rootsiküla stage Jaagarahu stage Jaani stage Adavere stage Raikküla stage Juuru stage With the supercontinent Gondwana covering the equator and much of the southern hemisphere, a large ocean occupied most of the northern half of the globe.
The high sea levels of the Silurian and the flat land resulted in a number of island chains, thus a rich diversity of environmental settings. During the Silurian, Gondwana continued a slow southward drift to high southern latitudes, but there is evidence that the Silurian icecaps were less extensive than those of the late-Ordovician glaciation; the southern continents remained united during this period. The melting of icecaps and glaciers contributed to a rise in sea level, recognizable from the fact that Silurian sediments overlie eroded Ordovician sediments, forming an unconformity; the continents of Avalonia and Laurentia drifted together near the equator, starting the formation of a second supercontinent known as Euramerica. When the proto-Europe coll
Chordate
A chordate is an animal constituting the phylum Chordata. During some period of their life cycle, chordates possess a notochord, a dorsal nerve cord, pharyngeal slits, an endostyle, a post-anal tail: these five anatomical features define this phylum. Chordates are bilaterally symmetric; the Chordata and Ambulacraria together form the superphylum Deuterostomia. Chordates are divided into three subphyla: Vertebrata. There are extinct taxa such as the Vetulicolia. Hemichordata has been presented as a fourth chordate subphylum, but now is treated as a separate phylum: hemichordates and Echinodermata form the Ambulacraria, the sister phylum of the Chordates. Of the more than 65,000 living species of chordates, about half are bony fish that are members of the superclass Osteichthyes. Chordate fossils have been found from as early as the Cambrian explosion, 541 million years ago. Cladistically, vertebrates - chordates with the notochord replaced by a vertebral column during development - are considered to be a subgroup of the clade Craniata, which consists of chordates with a skull.
The Craniata and Tunicata compose the clade Olfactores. Chordates form a phylum of animals that are defined by having at some stage in their lives all of the following anatomical features: A notochord, a stiff rod of cartilage that extends along the inside of the body. Among the vertebrate sub-group of chordates the notochord develops into the spine, in wholly aquatic species this helps the animal to swim by flexing its tail. A dorsal neural tube. In fish and other vertebrates, this develops into the spinal cord, the main communications trunk of the nervous system. Pharyngeal slits; the pharynx is the part of the throat behind the mouth. In fish, the slits are modified to form gills, but in some other chordates they are part of a filter-feeding system that extracts particles of food from the water in which the animals live. Post-anal tail. A muscular tail that extends backwards behind the anus. An endostyle; this is a groove in the ventral wall of the pharynx. In filter-feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus.
It stores iodine, may be a precursor of the vertebrate thyroid gland. There are soft constraints that separate chordates from certain other biological lineages, but are not part of the formal definition: All chordates are deuterostomes; this means. All chordates are based on a bilateral body plan. All chordates are coelomates, have a fluid filled body cavity called a coelom with a complete lining called peritoneum derived from mesoderm; the following schema is from the third edition of Vertebrate Palaeontology. The invertebrate chordate classes are from Fishes of the World. While it is structured so as to reflect evolutionary relationships, it retains the traditional ranks used in Linnaean taxonomy. Phylum Chordata †Vetulicolia? Subphylum Cephalochordata – Class Leptocardii Clade Olfactores Subphylum Tunicata – Class Ascidiacea Class Thaliacea Class Appendicularia Class Sorberacea Subphylum Vertebrata Infraphylum incertae sedis Cyclostomata Superclass'Agnatha' paraphyletic Class Myxini Class Petromyzontida or Hyperoartia Class †Conodonta Class †Myllokunmingiida Class †Pteraspidomorphi Class †Thelodonti Class †Anaspida Class †Cephalaspidomorphi Infraphylum Gnathostomata Class †Placodermi Class Chondrichthyes Class †Acanthodii Superclass Osteichthyes Class Actinopterygii Class Sarcopterygii Superclass Tetrapoda Class Amphibia Class Sauropsida Class Synapsida Craniates, one of the three subdivisions of chordates, all have distinct skulls.
They include the hagfish. Michael J. Benton commented that "craniates are characterized by their heads, just as chordates, or all deuterostomes, are by their tails". Most craniates are vertebrates; these consist of a series of bony or cartilaginous cylindrical vertebrae with neural arches that protect the spinal cord, with projections that link the vertebrae. However hagfish have incomplete braincases and no vertebrae, are therefore not regarded as vertebrates, but as members of the craniates, the group from which vertebrates are thought to have evolved; however the cladistic exclusion of hagfish from the vertebrates is controversial, as they ma
Autapomorphy
In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not those most related to the focal taxon, it can therefore be considered an apomorphy in relation to a single taxon. The word autapomorphy, first introduced in 1950 by German entomologist Willi Hennig, is derived from the Greek words αὐτός, aut- = "self"; because autapomorphies are only present in a single taxon, they do not convey information about relationship. Therefore, autapomorphies are not useful to infer phylogenetic relationships. However, like synapomorphy and plesiomorphy is a relative concept depending on the taxon in question. An autapomorphy at a given level may well be a synapomorphy at a less-inclusive level. An example of an autapomorphy can be described in modern snakes. Snakes have lost the two pairs of legs that characterize all of Tetrapoda, the closest taxa to Ophidia - as well as their common ancestors - all have two pairs of legs.
Therefore, the Ophidia taxon presents an autapomorphy with respect to its absence of legs. The autapomorphic species concept is one of many methods that scientists might use to define and distinguish species from one another; this definition assigns species on the basis of amount of divergence associated with reproductive incompatibility, measured by number of autapomorphies. This grouping method is referred to as the "monophyletic species concept" or the "phylospecies" concept and was popularized by D. E. Rosen in 1979. Within this definition, a species is seen as "the least inclusive monophyletic group definable by at least one autapomorphy". While this model of speciation is useful in that it avoids non-monophyletic groupings, it has its criticisms as well. N. I. Platnick, for example, believes the autapomorphic species concept to be inadequate because it allows for the possibility of reproductive isolation and speciation while revoking the "species" status of the mother population. In other words, if a peripheral population breaks away and becomes reproductively isolated, it would conceivably need to develop at least one autapomorphy to be recognized as a different species.
If this can happen without the larger mother population developing a new autapomorphy the mother population cannot remain a species under the autapomorphic species concept: it would no longer have any apomorphies not shared by the daughter species. Phylogenetic similarities: These phylogenetic terms are used to describe different patterns of ancestral and derived character or trait states as stated in the above diagram in association with synapomorphies. Homoplasy in biological systematics is when a trait has been gained or lost independently in separate lineages during evolution; this convergent evolution leads to species independently sharing a trait, different from the trait inferred to have been present in their common ancestor. Parallel Homoplasy – derived trait present in two groups or species without a common ancestor due to convergent evolution. Reverse Homoplasy – trait present in an ancestor but not in direct descendants that reappears in descendants. Apomorphy – a derived trait. Apomorphy shared by two or more taxa and inherited from a common ancestor is synapomorphy.
Apomorphy unique to a given taxon is autapomorphy. Synapomorphy/Homology – a derived trait, found in some or all terminal groups of a clade, inherited from a common ancestor, for which it was an autapomorphy. Underlying synapomorphy – a synapomorphy, lost again in many members of the clade. If lost in all but one, it can be hard to distinguish from an autapomorphy. Autapomorphy – a distinctive derived trait, unique to a given taxon or group. Symplesiomorphy – an ancestral trait shared by two or more taxa. Plesiomorphy – a symplesiomorphy discussed in reference to a more derived state. Pseudoplesiomorphy – is a trait that cannot be identified as neither a plesiomorphy nor an apomorphy, a reversal. Reversal – is a loss of derived trait present in ancestor and the reestablishment of a plesiomorphic trait. Convergence – independent evolution of a similar trait in two or more taxa. Hemiplasy
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype. Under the International Code of Zoological Nomenclature, a holotype is one of several kinds of name-bearing types. In the International Code of Nomenclature for algae and plants and ICZN the definitions of types are similar in intent but not identical in terminology or underlying concept. For example, the holotype for the butterfly Lycaeides idas longinus is a preserved specimen of that species, held by the Museum of Comparative Zoology at Harvard University. An isotype is a duplicate of the holotype and is made for plants, where holotype and isotypes are pieces from the same individual plant or samples from the same gathering. A holotype is not "typical" of that taxon, although ideally it should be. Sometimes just a fragment of an organism is the holotype in the case of a fossil.
For example, the holotype of Pelorosaurus humerocristatus, a large herbivorous dinosaur from the early Jurassic period, is a fossil leg bone stored at the Natural History Museum in London. If a better specimen is subsequently found, the holotype is not superseded. Under the ICN, an additional and clarifying type could be designated an epitype under Article 9.8, where the original material is demonstrably ambiguous or insufficient. A conserved type is sometimes used to correct a problem with a name, misapplied. In the absence of a holotype, another type may be selected, out of a range of different kinds of type, depending on the case, a lectotype or a neotype. For example, in both the ICN and the ICZN a neotype is a type, appointed in the absence of the original holotype. Additionally, under the ICZN the Commission is empowered to replace a holotype with a neotype, when the holotype turns out to lack important diagnostic features needed to distinguish the species from its close relatives. For example, the crocodile-like archosaurian reptile Parasuchus hislopi Lydekker, 1885 was described based on a premaxillary rostrum, but this is no longer sufficient to distinguish Parasuchus from its close relatives.
This made. Texan paleontologist Sankar Chatterjee proposed that a new type specimen, a complete skeleton, be designated; the International Commission on Zoological Nomenclature considered the case and agreed to replace the original type specimen with the proposed neotype. The procedures for the designation of a new type specimen when the original is lost come into play for some recent, high-profile species descriptions in which the specimen designated as the holotype was a living individual, allowed to remain in the wild. In such a case, there is no actual type specimen available for study, the possibility exists that—should there be any perceived ambiguity in the identity of the species—subsequent authors can invoke various clauses in the ICZN Code that allow for the designation of a neotype. Article 75.3.7 of the ICZN requires that the designation of a neotype must be accompanied by "a statement that the neotype is, or upon publication has become, the property of a recognized scientific or educational institution, cited by name, that maintains a research collection, with proper facilities for preserving name-bearing types, that makes them accessible for study", but there is no such requirement for a holotype.
Type Allotype Paratype Type species Genetypes- genetic sequence data from type specimens. BOA Photographs of type specimens of Neotropical Rhopalocera
Cervical vertebrae
In vertebrates, cervical vertebrae are the vertebrae of the neck below the skull. Thoracic vertebrae in all mammalian species are those vertebrae that carry a pair of ribs, lie caudal to the cervical vertebrae. Further caudally follow the lumbar vertebrae, which belong to the trunk, but do not carry ribs. In reptiles, all trunk vertebrae are called dorsal vertebrae. In many species, though not in mammals, the cervical vertebrae bear ribs. In many other groups, such as lizards and saurischian dinosaurs, the cervical ribs are large; the vertebral transverse processes of mammals are homologous to the cervical ribs of other amniotes. Most mammals have 7 cervical vertebrae. In humans, cervical vertebrae are the smallest of the true vertebrae, can be distinguished from those of the thoracic or lumbar regions by the presence of a foramen in each transverse process, through which the vertebral artery, vertebral veins and inferior cervical ganglion pass; the remainder of this article focuses upon human anatomy.
By convention, the cervical vertebrae are numbered, with the first one closest to the skull and higher numbered vertebrae proceeding away from the skull and down the spine. The general characteristics of the third through sixth cervical vertebrae are described here; the first and seventh vertebrae are extraordinary, are detailed later. The bodies of these four vertebrae are small, broader from side to side than from front to back; the anterior and posterior surfaces are flattened and of equal depth. The upper surface is concave transversely, presents a projecting lip on either side; the lower surface is concave from front to back, convex from side to side, presents laterally shallow concavities that receive the corresponding projecting lips of the underlying vertebra. The pedicles are directed laterally and backward, attach to the body midway between its upper and lower borders, so that the superior vertebral notch is as deep as the inferior, but it is, at the same time, narrower; the laminae are narrow, thinner above than below.
The spinous process is short and bifid, the two divisions being of unequal size. Because the spinous processes are so short, certain superficial muscles attach to the nuchal ligament rather than directly to the vertebrae; the superior and inferior articular processes of cervical vertebrae have fused on either or both sides to form articular pillars, columns of bone that project laterally from the junction of the pedicle and lamina. The articular facets are flat and of an oval form: the superior face backward and medially; the inferior face forward and laterally. The transverse processes are each pierced by the foramen transversarium, which, in the upper six vertebrae, gives passage to the vertebral artery and vein, as well as a plexus of sympathetic nerves; each process consists of a posterior part. These two parts are joined, outside the foramen, by a bar of bone that exhibits a deep sulcus on its upper surface for the passage of the corresponding spinal nerve; the anterior portion is the homologue of the rib in the thoracic region, is therefore named the costal process or costal element.
It arises from the side of the body, is directed laterally in front of the foramen, ends in a tubercle, the anterior tubercle. The posterior part, the true transverse process, springs from the vertebral arch behind the foramen, is directed forward and laterally; the anterior tubercle of the sixth cervical vertebra is known as the carotid tubercle or Chassaignac tubercle. This separates the carotid artery from the vertebral artery and the carotid artery can be massaged against this tubercle to relieve the symptoms of supraventricular tachycardia; the carotid tubercle is used as a landmark for anaesthesia of the brachial plexus and cervical plexus. The cervical spinal nerves emerge from above the cervical vertebrae. For example, the cervical spinal nerve 3 passes above C3; the atlas and axis are the two topmost vertebrae. The atlas, C1, is the topmost vertebra, along with the axis, its chief peculiarity is that it has no body because the body of the atlas has been fused with that of the axis. The axis, C2, forms the pivot.
The most distinctive characteristic of this bone is the strong odontoid process that rises perpendicularly from the upper surface of the body. The body is deeper in front than behind, prolonged downward anteriorly so as to overlap the upper and front part of the third vertebra; the vertebra prominens, or C7, has a distinctive long and prominent spinous process, palpable from the skin surface. Sometimes, the seventh cervical vertebra is associated with an abnormal extra rib, known as a cervical rib, which develops from the anterior root of the transverse process; these ribs are small, but may compress blood vessels or nerves in the brachial plexus, causing pain, numbness and weakness in the upper limb, a condition known as thoracic outlet syndrome. This rib occurs in a pair; the long spinous process of C7 is thick and nearly horizontal in dire
