Volume rendering of a mouse skull

The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.

The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates. The skull is a part of the skeleton.

Functions of the skull include protection of the brain, fixing the distance between the eyes to allow stereoscopic vision, and fixing the position of the ears to help the brain use auditory cues to judge direction and distance of sounds. In some animals, the skull also has a defensive function (e.g. horned ungulates); the frontal bone is where horns are mounted.

The English word "skull" is probably derived from Old Norse "skalli" meaning bald, while the Latin word cranium comes from the Greek root κρανίον (kranion).

The skull is made of flat bones.

Fish skulls[link]

The skull of fishes is formed from a series of only loosely connected bones. lampreys and sharks only possess a cartilaginous endocranium, with both the upper and lower jaws being separate elements. Bony fishes have additional dermal bone, forming a more or less coherent skull roof in lungfish and holost fish. The lower jaw defines a chin.

The simpler structure is found in jawless fish, in which the cranium is represented by a trough-like basket of cartilaginous elements only partially enclosing the brain, and associated with the capsules for the inner ears and the single nostril. Distinctively, these fish have no jaws.^[1]

Skeleton of Dalatias licha, the kitefin shark, in the Hall of Bones of the Smithsonian National Museum of Natural History

Cartilaginous fish, such as sharks, have also simple, and presumably primitive, skull structures. The cranium is a single structure forming a case around the brain, enclosing the lower surface and the sides, but always at least partially open at the top as a large fontanelle. The most anterior part of the cranium includes a forward plate of cartilage, the rostrum, and capsules to enclose the olfactory organs. Behind these are the orbits, and then an additional pair of capsules enclosing the structure of the inner ear. Finally, the skull tapers towards the rear, where the foramen magnum lies immediately above a single condyle, articulating with the first vertebra. There are, in addition, at various points throughout the cranium, smaller foramina for the cranial nerves. The jaws consist of separate hoops of cartilage, almost always distinct from the cranium proper.^[1]

Fish head parts, 1889, Fauna of British India, Sir Francis Day

Anarhichas lupus skull, a fish species

In the ray-finned fishes, there has also been considerable modification from the primitive pattern. The roof of the skull is generally well formed, and although the exact relationship of its bones to those of tetrapods is unclear, they are usually given similar names for convenience. Other elements of the skull, however, may be reduced; there is little cheek region behind the enlarged orbits, and little, if any bone in between them. The upper jaw is often formed largely from the premaxilla, with the maxilla itself located further back, and an additional bone, the symplectic, linking the jaw to the rest of the cranium.^[2]

Skull of Tiktaalik, a genus of extinct sarcopterygian (lobe-finned "fish") from the late Devonian period

Although the skulls of fossil lobe-finned fish resemble those of the early tetrapods, the same cannot be said of those of the living lungfishes. The skull roof is not fully formed, and consists of multiple, somewhat irregularly shaped bones with no direct relationship to those of tetrapods. The upper jaw is formed from the pterygoids and vomers alone, all of which bear teeth. Much of the skull is formed from cartilage, and its overall structure is reduced.^[2]

Tetrapod skulls[link]

The skulls of the earliest tetrapods closely resembled those of their ancestors amongst the lobe-finned fishes. The skull roof is formed of a series of plate-like bones, including the maxilla, frontals, parietals, and lacrimals, among others. It is overlaying the endocranium, corresponding to the cartilaginous skull in sharks and rays. The various separate bones that compose the temporal bone of humans are also part of the skull roof series. A further plate composed of four pairs of bones forms the roof of the mouth; these include the vomer and palatine bones. The base of the cranium is formed from a ring of bones surrounding the foramen magnum and a median bone lying further forward; these are homologous with the occipital bone and parts of the sphenoid in mammals. Finally, the lower jaw is composed of multiple bones, only the most anterior of which (the dentary) is homologous with the mammalian mandible.^[2]

In living tetrapods, a great many of the original bones have either disappeared, or fused into one another in various arrangements.

Amphibians skulls, Hans Gadow, 1909 Amphibia and Reptiles

Living amphibians typically have greatly reduced skulls, with many of the bones either absent or wholly or partly replaced by cartilage.^[2]

Scheme of Spinosaurus skull

In mammals and birds, in particular, modifications of the skull occurred to allow for the expansion of the brain. The fusion between the various bones is especially notable in birds, in which the individual structures may be difficult to identify.

Fenestrae[link]

The fenestrae in the skull of the dinosaur Massospondylus.

The fenestrae (from Latin, meaning windows) are openings in the skull.

• Antorbital fenestra
• Mandibular fenestra
• Palatal fenestra, as found in Marsupials
• Quadratojugal fenestra
• Subsquamosal fenestra, an opening between two parts of the squamosal bone in some rodents
• Temporal fenestra

A centrosaurus skull

Ceratopsia dinosaurs may have fenestrae in their frills.

Temporal fenestrae[link]

The temporal fenestrae are anatomical features of the skulls of several types of amniotes, characterised by bilaterally symmetrical holes (fenestrae) in the temporal bone. Depending on the lineage of a given animal, two, one, or no pairs of temporal fenestrae may be present, above or below the postorbital and squamosal bones. The upper temporal fenestrae are also known as the supratemporal fenestrae, and the lower temporal fenestrae are also known as the infratemporal fenestrae. The presence and morphology of the temporal fenestra are critical for taxonomic classification of the synapsids, of which mammals are part.

Physiological speculation associates it with a rise in metabolic rates and an increase in jaw musculature. The earlier amniotes of the Carboniferous did not have temporal fenestrae but two more advanced lines did: the Synapsids (mammal-like reptiles) and the Diapsids (most reptiles and later birds). As time progressed, diapsids' and synapsids' temporal fenestrae became more modified and larger to make stronger bites and more jaw muscles. Dinosaurs, which are sauropsids, have large advanced openings and their descendants, the birds, have temporal fenestrae which have been modified. Mammals, which are synapsids, possess no fenestral openings in the skull, as the trait has been modified. They do, though, still have the temporal orbit (which resembles an opening) and the temporal muscles. It is a hole in the head and is situated to the rear of the orbit behind the eye.

Classification based on fenestrae[link]

Chimpanzee skull

There are four types of amniote skull, classified by the number and location of their fenestra. These are:

• Anapsida - no openings
• Synapsida - one low opening (beneath the postorbital and squamosal bones)
• Euryapsida - one high opening (above the postorbital and squamosal bones); euryapsids actually evolved from a diapsid configuration, losing their lower temporal fenestra.
• Diapsida - two openings

Evolutionarily, they are related as follows:

• Amniota
  • Class Synapsida
    • Order Therapsida
      • Class Mammalia - mammals
  • (Unranked)Sauropsida - reptiles
    • Subclass Anapsida
    • (unranked) Eureptilia
      • Subclass Diapsida
        • (unranked) Euryapsida
        • Class Aves - birds

Human skull[link]

Model of a male human skull in the collections of the Museum of Osteology

For details and the constituent bones, see human skull, neurocranium and viscerocranium.

In humans, as in other mammals, the aforementioned division of the skull into the cranium and mandible is not usually followed. Instead, for the purposes of describing their anatomy and enumerating their bones, mammalian and human skulls are divided differently: They are deemed to consist of two categorical parts, the neurocranium and the viscerocranium. The neurocranium (or braincase) is a protective vault surrounding the brain. The viscerocranium (also splanchnocranium or facial skeleton) is formed by the bones supporting the face. Both parts have different embryological origins.

Except for the mandible, all of the bones of the skull are joined together by sutures, rigid articulations permitting very little movement.^[3]

Bones[link]

The jugal is a skull bone found in most reptiles, amphibians, and birds. In mammals, the jugal is often called the malar or zygomatic.

The prefrontal bone is a bone separating the lacrimal and frontal bones in many tetrapod skulls.

Terminology[link]

• Chondrocranium, a primitive cartilagionous skeletal structure
• Endocranium
• Epicranium
• Pericranium, a membrane that lines the outer surface of the cranium

Gallery[link]

Paracyclotosaurus davidi skull, a prehistoric amphibian species   Tyrannosaurus rex skull, a dinosaur species   Alligator skull, a reptile species   An elephant skull, a mammal species   A lion's skull, a typical carnivore   A hippopotamus' skull   Killer whale (Orcinus orca) skull   A bulldog skull   A Grizzly bear skull   A coypu skull, a typical rodent   A gerbil skull, another typical rodent   Cervocerus novorossiae skull   A Four-horned antelope skull drawing   Skull of a multi-horned Jacob sheep   A Vulture skull, a typical bird species

See also[link]

• Bucranium, the Greek word for the skull of an ox

Notes[link]

External links[link]

Wikimedia Commons has media related to: Animal skulls

Look up skull in Wiktionary, the free dictionary.

• Anatomy of cranial cavity.
• Dept of Anth Skull Module
• Skull Anatomy Tutorial.
• Bird Skull Collection Bird skull database with very large collection of skulls (Agricultural University of Wageningen)

The Edge
Background information
Birth name	David Howell Evans
Born	(1961-08-08) 8 August 1961 (age 50) Barking, Essex, England, United Kingdom
Origin	County Dublin, Ireland
Genres	Rock, post-punk, alternative rock
Occupations	Musician, songwriter, activist
Instruments	Guitar, vocals, keyboards, piano, bass guitar
Years active	1976–present
Labels	Island, Mercury
Associated acts	U2, Passengers
Website	www.u2.com
Notable instruments
Gibson Explorer Fender Stratocaster Gibson Les Paul Fender Telecaster Gretsch Country Gentleman Gretsch White Falcon Rickenbacker 330/12

David Howell Evans (born 8 August 1961), more widely known by his stage name The Edge (or just Edge),^[1] is a musician best known as the guitarist, backing vocalist, and keyboardist of the Irish rock band U2. A member of the group since its inception, he has recorded 12 studio albums with the band and has released one solo record. As a guitarist, The Edge has crafted a minimalistic and textural style of playing. His use of a rhythmic delay effect yields a distinctive ambient, chiming sound that has become a signature of U2's music.

The Edge was born in England to a Welsh family, but was raised in Ireland after moving there as an infant. In 1976, at Mount Temple Comprehensive School, he formed U2 with his fellow students and his older brother Dik. Inspired by the ethos of punk rock and its basic arrangements, the group began to write its own material. They eventually became one of the most popular acts in popular music, with successful albums such as 1987's The Joshua Tree and 1991's Achtung Baby. Over the years, The Edge has experimented with various guitar effects and introduced influences from several genres of music into his own style, including American roots music, industrial music, and alternative rock. With U2, The Edge has also played keyboards, co-produced their 1993 record Zooropa, and occasionally contributed lyrics. The Edge met his second and current wife, Morleigh Steinberg, through her collaborations with the band.

As a member of U2 and as an individual, The Edge has campaigned for human rights and philanthropic causes. He co-founded Music Rising, a charity to support musicians affected by Hurricane Katrina. He has collaborated with U2 bandmate Bono on several projects, including songs for Roy Orbison and Tina Turner, and the soundtracks to the musical Spider-Man: Turn Off the Dark and the Royal Shakespeare Company's London stage adaptation of A Clockwork Orange. In 2011, Rolling Stone magazine placed him at number 38 on its list of "The 100 Greatest Guitarists of All Time".

Personal life[link]

The Edge at a U2 concert in Anaheim (2005)

David Howell Evans was born at the Barking Maternity Hospital,^[2] Essex, England to Welsh parents Garvin and Gwenda Evans.^[1] When he was one, his family moved to County Dublin, Ireland where he attended St Andrew's National School. He received piano and guitar lessons and often performed with his brother Dik Evans before they both answered an advertisement posted by Larry Mullen, Jr. at their school, Mount Temple Comprehensive School, seeking musicians to form a band.^[3] The band accepted both of them. This band went through several incarnations before emerging as U2 in March 1978 (Dik Evans left the band just before the name change).^[3] U2 began performing in various venues in Ireland and eventually began developing a following. Their debut album, Boy, was released in 1980.

In 1981, leading up to the October tour, Evans came very close to leaving U2 for religious reasons, but he decided to stay.^[3] During this period, he became involved with a group called Shalom Tigers, in which bandmates Bono and Larry Mullen Jr. were also involved.^[4] Shortly after deciding to remain with the band, he wrote a piece of music that later became "Sunday Bloody Sunday".^[3] The Edge married his high school girlfriend Aislinn O'Sullivan on 12 July 1983.^[5] The couple had three daughters together: Hollie in 1984, Arran in 1985 and Blue Angel in 1989.^[4] The couple separated in 1990, but were unable to get officially divorced because of Irish laws regarding marriage annulment; divorce was legalised in 1995 and the couple were legally divorced in 1996.^[4]

In 1993, The Edge began dating Morleigh Steinberg, a professional dancer and choreographer employed by the band as a belly dancer during the Zoo TV Tour. They had a daughter, Sian (born 1997), and a son, Levi (born 25 October 1999),^[4] before marrying on 22 June 2002.^[4] He appeared in the 2009 music documentary film It Might Get Loud.^[6] The Edge has been criticized for his efforts to build five luxury mansions on a 156 acre plot of land in Malibu, California.^[7] The California Coastal Commission voted 8-4 against the plans, with the project described by the commission's executive director, Peter Douglas, as "In 38 years...one of the three worst projects that I've seen in terms of environmental devastation...It's a contradiction in terms – you can't be serious about being an environmentalist and pick this location."^[7] The Santa Monica Mountains Conservancy agreed to remain neutral on the issue following a $1 million donation from The Edge and a commitment from The Edge to designate 100 acres of the land as open space for public footpaths.^[7]

Music style[link]

Guitar playing[link]

As a guitar player, The Edge has a sound typified by a low-key playing style, a chiming, shimmering sound (thanks in part to the sound of VOX AC-30s) that he achieves with extensive use of delay effects and reverb. The feedback delay is often set to a dotted eighth note (3/16 of a measure), and the feedback gain is adjusted until a note played repeats two or three times.^{[citation needed]}

On 1987's The Joshua Tree, The Edge often contributes just a few simple lead lines given depth and richness by an ever-present delay. For example, the introduction to "Where the Streets Have No Name" is simply a repeated six-note arpeggio, broadened by a modulated delay effect. The Edge has said that he views musical notes as "expensive", in that he prefers to play as few notes as possible. He said in 1982 of his style,

"I like a nice ringing sound on guitar, and most of my chords I find two strings and make them ring the same note, so it's almost like a 12-string sound. So for E I might play a B, E, E and B and make it ring. It works very well with the Gibson Explorer. It's funny because the bass end of the Explorer was so awful that I used to stay away from the low strings, and a lot of the chords I played were very trebly, on the first four, or even three strings. I discovered that through using this one area of the fretboard I was developing a very stylized way of doing something that someone else would play in a normal way."^[9]

Many different influences have shaped The Edge's guitar technique.^{[citation needed]} His first guitar was an old acoustic guitar that his mother bought him at a local flea market for only a few pounds; he was nine at the time. He and his brother Dik Evans both experimented with this instrument.^[9] He said in 1982 of this early experimentation, "I suppose the first link in the chain was a visit to the local jumble sale where I purchased a guitar for a pound. That was my first instrument. It was an acoustic guitar and me and my elder brother Dik both played it, plonking away, all very rudimentary stuff, open chords and all that."^[9] The Edge has stated that many of his guitar parts are based around guitar effects. This is especially true from the Achtung Baby era onwards, although much of the band's 1980s material made heavy use of echos.

Vocals[link]

The Edge in June 2005

The Edge also supplies the backing vocals for U2. U2's 1983 live album and video release, Under a Blood Red Sky and Live at Red Rocks: Under a Blood Red Sky are good reference points for his singing (as are the live DVDs from the Elevation Tour, U2 Go Home: Live from Slane Castle and Elevation 2001: Live from Boston). For example, he sings the chorus to "Sunday Bloody Sunday" (Bono harmonizes on the final 'Sunday'). U2 used this tradeoff technique later in "Bullet the Blue Sky" as well. His backing vocals are sometimes in the form of a repeated cry; examples of songs that use this approach include "Beautiful Day", "New Year's Day" and "Stay (Faraway, So Close!)". Another technique he uses in his backing vocals is the falsetto, in songs such as "Stuck in a Moment You Can't Get Out Of", "Sometimes You Can't Make It on Your Own", "A Man and a Woman", "The Wanderer", live versions of "The Fly", and "Window in the Skies".

The Edge sings the lead vocal on "Van Diemen's Land" and "Numb", the first half of the song "Seconds", dual vocals with Bono in "Discotheque", and the bridge in the song "Miracle Drug".^[4] He also sings the occasional lead vocal in live renditions of other songs (such as "Sunday Bloody Sunday" during the PopMart Tour and "Party Girl" during the Rotterdam Zoo TV show when it was Bono's birthday).^[10] He also plays a solo acoustic version of the song "Love is Blindness" that is featured in the documentary film From the Sky Down.

Other instruments[link]

He has played piano and keyboards on many of the band's songs, including "I Fall Down", "October", "So Cruel", "New Year's Day", "Running to Stand Still", "Miss Sarajevo", "The Hands that Built America", and "Original of the Species" and others. He plays the organ on "Please". In live versions of "New Year's Day", "The Unforgettable Fire", "Your Blue Room", and "Moment of Surrender", he plays both the piano and guitar parts alternately. In most live versions of "Original of the Species," piano is the only instrument played during the song. Although The Edge is the band's lead guitarist, he occasionally plays bass guitar, including the live performances of the song "40" where The Edge and bassist Adam Clayton switch instruments.

Solo recordings[link]

In addition to his regular role within U2, The Edge has also recorded with such artists as Johnny Cash, B. B. King, Tina Turner, Ronnie Wood, Jay-Z, and Rihanna. The Edge connected with Brian Eno and Lanois collaborator Michael Brook (the creator of the infinite guitar, which he regularly uses), working with him on the score to the film Captive (1986). From this soundtrack the song "Heroine", the vocal of which was sung by a young Sinéad O'Connor was released as a single.

He also created the theme song for season one and two of The Batman. He and fellow U2 member, Bono, wrote the lyrics to the theme of the 1995 James Bond film GoldenEye. The Edge, along with bandmate Bono, recently composed a musical adaptation of Spider-Man. On May 25, 2011, a single titled Rise Above 1: Reeve Carney Featuring Bono and The Edge was released digitally.^[11] The music video was released on July 28, 2011.^[12]

Musical equipment[link]

Edge's 1964 Vox AC30 on stage in Foxborough for the U2 360° Tour.

The Edge plays electric guitar, acoustic guitar, keyboards, piano, bass guitar (on "40" and "Race Against Time") and lap steel guitar. Compared to many lead guitarists, The Edge is known for using many more guitars during a show. According to his guitar tech Dallas Schoo, a typical lead guitarist uses four or five different guitars in one night, whereas The Edge takes 45 on the road, and uses 17 to 19 in one 2.5-hour concert. He is estimated to have more than 200 guitars in the studio.^{[citation needed]}

Philanthropy[link]

In 2005, The Edge along with Bob Ezrin and Henry Juszkiewicz co-founded Music Rising, a charity that helped provide replacement instruments for those that were lost in Hurricane Katrina. The instruments were originally only replaced for professional musicians but they soon realized the community churches and schools needed instruments as well. The charity's slogan is "Rebuilding the Gulf Region note by note" and has so far helped over a hundred musicians who were affected by Hurricane Katrina. The Edge also serves on the board of the Angiogenesis Foundation, a 501(c)(3) nonprofit organization dedicated to improving global health by advancing angiogenesis-based medicine, diets, and lifestyle.^[13]

See also[link]

• Timeline of U2
• List of people on stamps of Ireland

References[link]

Footnotes

Bibliography

External links[link]

This article's use of external links may not follow Wikipedia's policies or guidelines. Please improve this article by removing excessive or inappropriate external links, and converting useful links where appropriate into footnote references. (October 2011)

Wikimedia Commons has media related to: The Edge

Wikiquote has a collection of quotations related to: The Edge

• U2.com, official U2 site
• Music Rising
• The Edge at the Internet Movie Database
• The Edge – Album Credits
• A Study of The Edge's Guitar Delay
• The Edge: 'It's all about the vision'
• Food Bank For New York City public service announcement
• Comment on the mathematical analysis of The Edge's guitar sound