Saturday, July 29, 2006

 

DIVERSE SCANS

  • x-ray - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film; to determine bone changes.
  • computed tomography scan (Also called a CT or CAT scan.) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.
  • magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.
  • radionuclide bone scan - a nuclear imaging technique that uses a very small amount of radioactive material, which is injected into the patient's bloodstream to be detected by a
  • scanner. This test shows blood flow to the bone and cell activity within the bone.
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Positronemissietomografie

(Doorverwezen vanaf PET-scan)
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Positronemissietomografie (PET) is een beeldvormende techniek waarbij een radioactieve isotoop (een radionuclide) wordt ingebracht bij de patiënt. Deze isotoop produceert tijdens zijn verval positronen, oftewel elektronen met positieve lading (anti-elektronen). Daarmee kan een driedimensionaal beeld worden gevormd van de verdeling in het lichaam van deze radionucliden.

Deze techniek bestaat sinds de jaren zeventig.

Inhoud

[Niet tonen]

Werking van PET

Productie van de radioactieve stof

Omdat de radionuclide een korte halfwaardetijd heeft, moet hij kort voor de toepassing worden geproduceerd. Een radionuclide wordt gemaakt met een cyclotron. Aangezien het om een isotoop gaat, kan deze ook in een willekeurige verbinding "geplakt" worden, die selectief door de aan te tonen afwijking in het lichaam wordt opgenomen, zodat bijvoorbeeld glucosetransport in weefsel zichtbaar wordt.

Toediening van de radioactieve stof

Patiënten krijgen bijvoorbeeld een injectie met de radionuclide. Deze stof verspreidt zich in eerste instantie door het bloed, zodat het bloed zichtbaar kan worden gemaakt. Als de radionuclide gekoppeld zit aan een stof die door bepaalde cellen wordt opgenomen, kunnen ook die cellen zichtbaar gemaakt worden.

Detectie

De radionuclide vervalt spontaan onder het uitzenden van een positron. Elk positron zal binnen een millimeter in aanraking komen met een elektron, waarbij annihilatie optreedt. De gehele energie van zowel positron als elektron komt hierbij vrij in de vorm van twee gammafotonen die in precies tegengestelde richting uitgezonden worden, omdat er geen massa meer is, waardoor de resulterende totale impuls 0 moet zijn.

Deze gammastralen worden gedetecteerd door een detectorring of twee zich aan weerszijden van de patiënt bevindende roterende gammacamera's. Als twee fotonen tegelijk worden gedetecteerd door twee detectoren zijn ze afkomstig van het verval van hetzelfde positron, dat zich dus op een rechte lijn tussen de detectiepunten moet hebben bevonden.

Beeldvorming

Een groot aantal van dergelijke vervalgebeurtenissen samen, geobserveerd vanuit verschillende richtingen door een ring van detectoren kan door een computer worden samengesteld tot een driedimensionaal beeld, bijvoorbeeld door een terugprojectie - algoritme.

Het oplossend vermogen is vrij hoog (enige mm).

Beperkingen van PET

De PET-techniek wordt vooral beperkt door drie factoren:

  • De te gebruiken radionucliden moeten een korte halfwaardetijd hebben om de patiënt niet te veel met straling te belasten; meestal gaat het om uren, zodat voor de bereiding van het nuclide een cyclotron ter plaatse of op geringe afstand beschikbaar moet zijn;
  • Het nuclide moet kunnen worden ingebouwd in de te gebruiken stof binnen die tijd.
  • Er moet een stof bekend zijn die de gewenste afwijking aantoont.

Dit alles maakt de techniek bewerkelijk en kostbaar.

Toepassing van PET

De toepassing van PET is afhankelijk van de beschikbaarheid van een stof die specifiek doordringt in het weefsel dat zichtbaar gemaakt moet worden.

Zo kan PET bijvoorbeeld worden gebruikt om te onderzoeken hoeveel bloed er op elk moment van de hartslag in een bepaalde slagader zit.

PET wordt vooral gebruikt om sommige tumoren en uitzaaiingen aan te tonen. Dat is mogelijk door chemische koppeling van radioactief fluor-18 aan glucose. Patiënten krijgen een injectie met dit mengsel. Na drie kwartier inwerking is op de scan te zien welke cellen veel actiever zijn en de meeste suiker opnemen. De cellen die verkwistend omgaan met energie vormen de indicatie voor de aanwezigheid van tumorcellen. De scan duurt ongeveer 45 minuten. Het radioactieve fluor is slechts korte tijd te gebruiken. Het wordt aangemaakt in een cyclotron en moet op dezelfde dag gebruikt worden voor de scan.

De PET-scan-techniek wordt in Nederland en België steeds vaker toegepast voor onderzoek bij de verdenking van lymfklier-, borst-, darm-, huid-, en longkanker. De PET-scan geeft bij een vermoeden van longkanker 96 % zekerheid.

Verwante technieken

Een verwante techniek is de SPECT-scan, (Single Photon Emission Computed Tomography) die van een ander type radionucliden gebruikt maakt om ongepaarde gammafotonen aan te tonen; de houdbaarheid van de diagnostische isotoopverbindingen is groter. Omdat plaatsbepaling van de ongepaarde gammafotonen slechts mogelijk is met een collimator heeft een SPECT scan in het algemeen een wat slechtere ruimtelijke nauwkeurigheid (circa 0.5-1 cm) en bevatten SPECT afbeeldingen meer ruis.



 

synovial cysts in spine

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Pain from a synovial cyst in the lumbar spine
> Introduction
Symptoms and diagnosis
Treatment options


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Fig 1: Synovial cyst in the lumbar spine
(larger view)
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Lumbar spinal stenosis and treatment

Pain from a synovial cyst in the lumbar spine

A synovial cyst is a relatively uncommon cause of spinal stenosis in the lumbar spine (lower back). It is a benign condition, and the symptoms and level of pain or discomfort may remain stable for many years.

A synovial cyst is a fluid-filled sac that develops as a result of degeneration in the spine. Because a synovial cyst develops from degeneration it is not often seen in patients younger than 45 and is most common in patients older than 65 years old.

The fluid-filled sac creates pressure inside the spinal canal and this in turn can give a patient all the symptoms of spinal stenosis. Spinal stenosis is a condition that occurs when degeneration in the facet joints causes pressure on the nerves as they exit the spine (see Figure 1).

Causes of a synovial cyst
Synovial cysts develop as a result of degeneration in the facet joint in the lumbar spine. It is typically a process that only happens in the lumbar spine, and it almost always develops at the L4-L5 level (rarely at L3-L4).

The pain probably comes from the venous blood around the nerves not being able to drain and this leads to pain and irritation of the nerves. Sitting down allows the blood to drain and relieves the pressure.

The facet joint of the lumbar spine is just like any other joint in the body (such as the hips or knees):

  • It is composed of two opposing surfaces that are covered with cartilage

  • The cartilage is the smooth, very slippery surface that allows a joint to move

  • A thick capsule surrounds the entire joint, and within this is the synovium

  • The synovium is a thin film of tissue that generates fluid within the joint that helps further lubricate the joint

  • As the joint degenerates it can produce more fluid.

As it degenerates, the cartilage looses its smooth, frictionless surface and the extra fluid can help by adding extra lubrication.

It is thought that the synovial cyst develops in response this extra fluid. The fluid escapes out of the joint capsule through a one-way ball valve type hole, but stays within a synovial covering. This functionally pumps fluid one way into the fluid sac. The fluid, however, is not under a lot of pressure, as neurological deficits or cauda equina syndrome (loss of bowel and bladder control) is extremely uncommon even for very large cysts.


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Tuesday, July 11, 2006

 

micro-cephaly

Monday, September 26, 2005


Microcefalie (bovenste plaatje)

Links: Jane Goodall met chimp





Er wordt door weinigen betwijfeld, dat elke vorm van leven, gedurende een zeer lange periode van meer dan een miljard jaar, door evolutie is ontstaan. Volgens sommigen zou de evolutie puur van het toeval afhankelijk zijn geweest, terwijl anderen een intelligent designer (God ?) aannemen, die regulerend en sturend zou zijn opgetreden. Met deze veronderstelling worden meer vragen dan antwoorden gegeven. Zowel toeval als design kunnen geen bevredigende antwoorden op het verschijnsel evolutie geven. Evolutie door natuurlijke selectie over een tijdsbestek van meer dan een miljard jaar, zoals door Charles Darwin werd verondersteld is het enige voor de hand liggend antwoord. Dit wordt nog eens duidelijk nu het genoom van de chimpansee bekend is geworden en slechts voor ongeveer één procent van dat van de mens verschilt. Dit betekent immers dat kleine mutaties in de genen enorme veranderingen kunnen teweeg brengen. Enkele mutaties in het DNA, (zie ook 12 September) hebben onder druk van natuurlijke selectie, naast de chimpansee ook de mens, uit een gezamenlijke voorouder van ongeveer zes miljoen jaar geleden te voorschijn geroepen. Dan beseft men pas dat er slechts weinig in de genen hoeft te veranderen om enorme veranderingen tot stand te brengen. Gedurende enkele miljoenen jaren, waarin de mens evolueerde werd de inhoud van de hersenen ongeveer drie keer zo groot. Er moest steeds een compromis gevonden worden tussen schedel inhoud en geboorte moeilijkheden en het is het principe van natuurlijke selectie dat uiteindelijk dan de Homo Sapiëns te voorschijn bracht.

Ongeveer twee-honderd duizend jaar geleden traden zo mutaties op, die nog grotere en complexere hersenen tot gevolg hadden. In het Zuiden van Afrika, waar deze mutaties optraden, veranderde de Homo Erectus zo langzaam in de Homo Sapiëns, die zich vervolgens over de hele wereld verspreidde. Het was vanzelfsprekend een voordeel, dat men grotere en complexere hersenen kreeg, want het gevolg was dat men meer cognitieve mogelijkheden kreeg. Door natuurlijke selectie zullen de individuen, die de gemuteerde genen overerfden, in het voordeel zijn geweest en hen die deze genen misten, langzaamaan verdrongen hebben. Nu zijn er ook later nog mutaties opgetreden en in een publicatie van de geneticus Bruce Lahn en zijn collega's van de universiteit van Chicago in Science van 9 September (1en 2) worden twee mutaties van de genen die AASPM en Microcephalin genoemd worden beschreven. Er zijn volkeren waar het ASPM voorkomt, terwijl bij andere het Microcephalin overheerst. Het zou kunnen dat deze verschillen op een of andere wijze in de verschillende populaties tot uitdrukking komt, bijvoorbeeld wat het gedrag of intelligentie betreft en antropoloog John Howkins van de universiteit in Madison, Wisconsin zegt dan ook: “This has to be the worst nightmare of people who believe strongly there are no differences in brain function between groups”. (3)

Beide genen regelen specifiek de grootte van de hersenen en als mensen een niet functionerend mutatie van een van de twee genen dragen, lijden ze aan zogenaamde microcefalie. Dat wil zeggen de structuur van de hersenen is normaal maar de hersenen zij veel kleiner dan normaal ( zie plaatje microcefalie). De onderzoekers onderzochten eerst het gen Microcephalin, dat voorkomt bij 89 etnisch verschillend populaties en bij een enkele chimpansee. Ze vonden tal van variaties van het gen maar bepaalde varianten traden sterk naar voren, die verantwoordelijk zijn voor veranderingen in het eiwit waarvoor ze coderen. Ongeveer 70% van de mensen draagt het gen, waarvan de helft precies dezelfde variant. Dit verschijnsel maakt duidelijk dat deze mutatie van dit gen vrij recent is en de beste schatting is dat ze ongeveer 37,000 jaar geleden moet ontstaan zijn. Dit was de tijd dat symbolisch gedrag voor het eerst duidelijk werd, denk hierbij aan de oudste grottekeningen van de Cro-magnon in de Chauvet grotten van Pont- d'Arc, Ardeche in Zuid Frankrijk. Deze nieuwe mutatie komt veel voor bij volkeren in Europa, het Midden Oosten en Amerika en veel minder bij sub-Sahara populaties. Hetzelfde verhaal geldt voor het gen met de naam ASPM en men schat dat het ongeveer 5800 jaren geleden ontstaan is, dat overeen zou kunnen komen met de eerste stedenbouw in het Nabije Oosten. Ongeveer een kwart van de wereldbevolking heeft het gen maar het komt het meest frequent voor in Europa en het Midden Oosten.

Als nu door omstandigheden tijdens de zwangerschap vooral op de 8-35 weken een virus, overmatig alcohol of roken, toxische stoffen of schadelijke straling, mutaties in de twee genoemde genen optreden wordt de baby vaak met microcefalie geboren. de hersen inhoud bedraagt soms slechts 400 cc. Dit komt overeen met de inhoud van de bekende Australopithicus genaamd Lucy, die ongeveer 3 miljoen jaren geleden leefde. Normale mensen van tegenwoordig, hebben een hersen-inhoud van 1200-1600 cc. Deze microcefale patiënten zijn meestal geestelijk gehandicapt, motorisch gestoord, vertonen vaak dwerg-groei en hebben problemen met het spreken. Soms vertonen ze hyperactief gedrag en epileptische aanvallen.

Heel duidelijk was dit in Japan in 1946 bij vrouwen die zwanger waren tussen 8 en 25 weken. De ontwikkelende hersenen van de vrucht zijn dan het meest gevoelig voor straling. De genoemde vrouwen die kort bij het hypo-centrum van de atoombom ontploffing waren en het overleefden en niet aborteerden, kregen meestal een microcefale baby.

1) Patrick Evans et al.
Microcephalin, a gene regulating brain size, continues to evolve adaptively in humans
Science vol: 309 9 Sept. 2005 p:1717

2) Nitzan Mekl-Bobrov et al.
Ongoing adaptive evolution of ASPM, a brain size determinant in Homo Sapiens.
Science Vol: 309 9 Sept. 2005 p: 1720

3) Mason Inman
Our brains they are a-changing
New Scientist vol:187 17 Sept. 2005 no: 2517




Friday, July 07, 2006

 

whiplash associated disorders



Whiplash and Whiplash Associated Disorders

What is it? How is it treated?


Anatomy of the Neck

The spine is a long chain of bones, discs, muscles and ligaments that extends from the base of the skull to the tip of the tailbone. The cervical spine (neck region) supports the head, protects the nerves and spinal cord, and allows for smooth function of the neck during activity. The major structural support is from the vertebrae (bone). Between two adjacent vertebrae is a disc. In the back of each vertebra are two facet joints, one on each side. The facet joints are designed to allow smooth motion for bending forward. backward and rotating, but also limit excess motion. Muscles and ligaments surround and support the spinal column. All of these structures have nerve supplies, and injury to any one can cause pain.

What Causes Chronic Neck Pain?

It is usually not possible to know the exact cause of neck pain in the days or weeks after a car accident. We know the muscles and ligaments get strained and are probably inflamed, but they usually heal within six to ten weeks. Pain that lasts longer is usually due to deeper problems such as injury to the disc or facet joint, or both.

  • Facet Joint Pain is the most common cause of chronic neck pain after a car accident. It may occur alone or along with disc pain. Facet joint pain is usually located to the right or left of the center back of the neck. The area might be tender to the touch, and facet pain may be mistaken for muscle pain. We cannot tell if a facet joint hurts by how it looks on an X-ray or MRI scan. The only way to tell if the joint is a cause of pain is to perform an injection called “medial branch block (MBB),” which is discussed below.
  • Disc Injury can also cause chronic neck pain. The disc allows motion of the neck, but at the same time keeps the neck from moving too much. The outer wall of the disc (called the anulus) can be torn by a whiplash injury. This usually heals, but in some people, the disc does not heal. In that case, it might get weaker and hurts when stressed during normal activities. The pain comes from the nerve endings in the anulus. The disc is the major cause of chronic neck pain in about 25% of patients, and there can be both disc pain and facet pain in some people. Less often, a disc can herniate and push on a nerve. This usually causes more arm pain than neck pain.
  • Muscle Strain of the neck and upper back can cause acute pain. However, there is no evidence that neck muscles are a primary cause of chronic neck pain, although muscles can hurt if they are working too hard to protect injured discs, joints, or the nerves of the neck or there is something else wrong that sustains the muscle pain, such as poor posture and work habits.
  • Spinal nerves and the spinal cord can be compressed by a Herniated Disc or Bone Spur. This usually causes arm pain, but there can also be neck pain. (If you are diagnosed with a herniated disc, see the NASS Patient Education Brochure on Cervical Herniated Disc for more information.)

What are the Symptoms?

What are the symptoms of whiplash and WAD?

  • Headache due to neck problems is called cervicogenic or neck-related headache. It may be due to injury to an upper cervical disc, facet joint or higher joints called the atlanto-occipital or atlanto-axial joints. Cervicogenic headache can also make migraines worse.
  • Arm pain and heaviness may be due to nerve compression from a herniated disc, which is easy for your health care professional to diagnose. More commonly, arm pain is “referred” from other parts of the neck. “Referred pain” is pain that is felt at a place away from the injured areas, but not due to pressure on a nerve.
  • Pain between the shoulder blades is usually a type of referred pain.
  • Low back pain is occasionally seen and is quite common after whiplash and may be due to injury to the discs, facet joints of the low back or sacroiliac joints.
  • Difficulties with concentration or memory can be due to pain itself, medications you are taking for the pain, depression or mild brain injury. You might also experience irritability and depression.
  • Sleep disturbance can be due to pain or depression.
  • Other symptoms might include blurry vision, ringing in the ears, tingling in the face and fatigue.

How is Whiplash Diagnosed?

Your health care professional ask you about your symptoms and how the injury occurred, and then perform a physical examination. This will allow the health care professional to know if you need any tests immediately or if they can wait, and also how to best treat your problem. In patients who do not get better after about 12 weeks, more detailed evaluation might be needed and some of the tests are described below. Not all patients need all tests.

  • X-rays are used right after injury if the health care professional suspects there may be a fracture or that the spine is not stable. X-rays also show disc height and bone spurs. Otherwise they are often used in patients who do not get significantly better by about 12 weeks. If an MRI is performed, X-ray examination is usually also done to look at the bone anatomy.
  • MRI scan is necessary if the health care professional suspects a disc herniation, disc injury or compression of a nerve or the spinal cord. (See the NASS Patient Education brochure on Magnetic Resonance Imaging for more information if this test is prescribed for you.)
  • Medial branch block (MBB) is an injection done to determine whether a facet joint is contributing to neck pain.
  • Discography is an injection into the disc itself to determine if a disc may be contributing to the pain. Discography is only used for patients with severe pain that has not improved with good treatment, and for whom surgery is being considered. (See the NASS Patient Education brochure on Discography for more information if this test is prescribed for you.)
  • Computed tomography (CT scan), usually combined with myelogram (dye or contrast injected into the spinal canal) can also be used to help diagnose neck pain that does not respond to treatment.
  • Electromyography and nerve conduction velocity (EMG/NCV) might be used if there is suspicion that a nerve is being trapped (such as in carpal tunnel syndrome) or there is nerve damage. (See the NASS Patient Education brochure on EMG for more information if this test is prescribed for you.)

Treatment of Whiplash

The treatment of whiplash in the first few weeks and months usually involves strength training and body mechanics instruction. Patients who do not get better after about 12 weeks require specialized treatment, often from a spine specialist, based on the cause of the pain.

  • Strength training is necessary to develop sufficient muscle strength to be able to hold the head and neck in positions of good posture at rest and during activity. Strengthening the muscles will also improve their range of motion.
  • Body mechanics describes the interrelationship between the head, neck, upper body and low back during movement and at rest. Training in proper posture decreases the stress on muscles, discs and vertebrae, giving damaged tissue the chance to heal. Poor posture and body mechanics unbalances the spine and creates high stress on the neck, which may impede healing.
  • Medications are helpful for symptom control. They never solve the problem and should be used as just one part of a total treatment program. There is no best medicine for neck pain. The choice of medication depends on the type, severity and duration of the pain as well as the general medical condition of the patient. Types of medications that are most often prescribed for acute neck pain include antiinflammatory drugs and opioid (narcotic) pain relievers. Additionally, your health care professional may prescribe the use of muscle relaxants. For chronic and severe neck pain, the opioid analgesics and antidepressants are generally most helpful.
  • Spinal Injections can be helpful in carefully selected patients. Again, injections do not cure the problem and should be only one part of a comprehensive treatment program. Epidural injections into the spinal canal can provide short-term relief in cases of nerve compression with arm pain, but are rarely effective for pure disc pain without radiating symptoms. Facet (zygopophyseal) injections may help temporarily with neck pain and are usually tried before radiofrequency neurotomy. Radiofrequency neurotomy (RFN) is a procedure that heats the nerves to stop them from conducting pain signals but is only useful for facet joint pain. It can help for about nine to 18 months and then can be repeated if needed and should only be considered in chronic situations with significant pain.
  • Spinal manipulative therapy (SMT) is usually provided by chiropractors, osteopaths or specially trained physical therapists. SMT can provide relief from symptoms for many patients, and is generally safe. SMT should be combined with strength training and body mechanics instruction.
  • Surgery for chronic neck pain is hardly ever necessary. However, surgery can be helpful when there is severe pain arising from one or two discs and the patient is very disabled, psychologically healthy and has not gotten better with nonoperative care. Surgery is done more often when there is pressure on a nerve or the spinal cord.

If You Have Whiplash ...

  • A spine care specialist can help relieve the pain of whiplash and regain range of motion. Follow your health care professional’s instructions carefully.
  • Remain active and do the exercises that you are taught to improve your posture and reduce the strain on your neck.
  • Remember that, with proper care and patience, you are likely to recover from whiplash.


Disclaimer: This information is for general information and understanding only and is not intended to represent official policy of the North American Spine Society. Please consult your physician for specific information about your condition.

Copies of this information in a glossy color brochure are available from the NASS Office by calling toll-free 1-877-SpineDr.

© 2002 North American Spine Society. Reprint with written permission only.


North American Spine Society
22 Calendar Court, 2nd Floor LaGrange, IL USA 60525
Toll-Free Telephone (877) 774-6337 E-mail: info@spine.org
Copyright © 2003, All Rights Reserved.



Thursday, July 06, 2006

 

THE CERVICAL SPINE



The Cervical Spine

HWS und KopfgelenkThe cervical spine is the most flexible, but also the weakest part of the entire spinal column. It is divided in

the “classic” cervical spine with five parts (C3-C7)


the head joint area consisting of the Atlas (C1),
the Axis (C2) and the moving segment C2/3

The head joint area

The head joint area is composed of the upper and lower head joint. The upper joint (Articulatio

Atlas
Taken from: Huch/Bauer: Mensch Körper Krankheit, 4.Aufl., 2003 Urban + Fischer Verlag, München, Jena

atlantooccipipitalis) is made up of the first cervical vertebra, the atlas (C1) and the articular surfaces of the occipital bone. The atlas is the only vertebra without a body. On the other hand this vertebra shows so-called outgrowths (Massa lateralis) on the right and left side which can be seen in the picture on the right with the blue kidney-shaped areas.
These outgrowths are connected via the front and rear atlas arch. The top of the outgrowths are formed by two sockets that are brought into contact with the so-called “condyles” of the occipital bone. The articular surfaces do not match exactly, which gives us the possibility to perform nodding (max. 30 degrees) and lateral declines (less than 20 degrees). You can say that the atlas “carries” the head, as the giant Atlas from Greek mythology carried the firmament on his shoulders. He also gave the vertebra its name. The atlas has to support the weight of the head with up to 7 kilograms.

Axis und das Querband des Dens
Taken from: Huch/Bauer: Mensch Körper Krankheit, 4.Aufl., 2003 Urban + Fischer Verlag, München, Jena

DThe axis is the second vertebra, also called C2, and it forms the lower head joint (Articulatio atlantoaxialis). The Axis is specialised on rotational movements. Thereby the round sockets at the bottom of the atlas get into contact with the corresponding articular surfaces of the axis. The axis already has a vertebral body and an arch, as well as strong transverse and spinal processes. The most outstanding characteristic of the axis is its dens axis. The dens is a strong outgrowth to the top and reaches up to the atlas. At its front side it is covered with cartilage and shows a flat socket on the inner side the atlas.. The rear side, also covered with cartilage, slides on a stable transverse ligament (Ligamenta transversa) which is tightened between the two outgrowths of the atlas (see above picture). That way a hollow space (similar to a fissure) is created between the front atlas arch and the transverse ligament. In this space the dens can move and perform rotations of 15° to 25° to the left or right. Minor stretching and nodding movements are also possible because once again the lateral angular surfaces do not match exactly.
Die Bänder des KopfgelenksThe
head joint is very flexible since it is rather “loose”. Yet to prevent uncontrolled stretching, bending and turning movements from injuring the spinal cord, several ligaments inhibit the movement types in the head joint. The Membrana atlantooccipitalis anterior reaches from between the front atlas arch to the occipital bone. This ligament prevents excessive stretching in the upper head joint. There are three other important ligaments which can be seen in the adjacent illustration. These run in a V-shape from the dens to the front and lateral margin of the foramen occipitale magnum. The lateral ligaments are called Ligamenta alaria, the ligament in the middle is called Ligamenta cruciforme. These ligaments prohibit inordinate turning and tilting movements in the lower head joint. A “complete” image of the head joint as a summary can be found here.

The classical Cervical Spine

The classical cervical spine consists of five vertebrae C3 to C7

Bild eines Halswirbels

Halswirbel
taken from: Huch/Bauer: Mensch Körper Krankheit, 4.Aufl., 2003 Urban + Fischer Verlag, München, Jena

Halswirbelsäule The vertebrae do largely have the typical basic vertebral form, but they can be recognized by the Foramina transversaria as cervical vertebrae (this is a kind of canal for arteries). The cervical vertebrae are smaller compared to the ones of the remaining spinal column, increasing their size from cranial (top) to caudal (bottom). They are also diagonally wider than from the front to the rear.
The upper front surface of the vertebra is formed like a scoop. The margins of this area are accumulated, which is called Uncus corporis, the bottom however is bevelled and crenated. From time to time there are small outgrowths of bones coming from the Uncus corporis which can exercise pressure on the respective spinal nerves. The cervical holes are rather large because they absorb the cervical intumescence of the spinal cord (Intumenscentia cervicalis). With its upper process, also called Facies articularis superior, each cervical vertebra is in contact with the lower angular process of the vertebra above. That way the vertebral canal of the cervical spine is formed, which is as well known as Foramina intervertebralia.

The 7th cervical vertebra (Vertebra prominens) stands a bit apart from the other cervical vertebrae. Its very long spinal process ends in a distinct hunch. This hunch can be palpated quite easily at the lower end of the neck furrow. The 7th cervical vertebra sometimes lacks the Foramen transversarium on one or both sides.

The cervical spine accommodates as well part of the spinal cord, namely 8 spinal cord segments (cervical segments) that supply especially the respiratory musculature and the upper extremities.. Arterienverlauf in der HWS und im KopfBut not only nerve cords run through the cervical spine, there are also arteries using it as a “canal”. The most important arteries here are the two Arteria vertebralis. Both arteries emanate from the Arteria subclavia (Arteria is the Latin word for artery) and pass on the left and right of the cervical spine through the Foramina transversi (plural form of Foramina transversaria) of the 6th to the 2nd cervical vertebrae. After the passage through the 2nd vertebra each artery makes a dorsal bend (to the rear) and runs on the rear atlas arch, this is the atlas loop of the artery. Then the arteries enter the cranial cavity and then continue forward again (cranial). Both Arteria vertebralis merge into the Arteria basilaris.
These arteries supply the cerebellum, parts of the mesencephalon and of the brain stem, furthermore hearing and equilibrium organs and rear components of the cerebrum as well as cervical spinal nerves and ganglia (nerve roots). It has to be noticed that the artery has very little expansibility.

I hope I was able to explain you a bit the sophisticated and complicated structure of the cervical spine. In my opinion, these explanations are important in order to understand the consequences that injuries of the cervical spine can implicate. Unfortunately injuries of the cervical spine do often occur in our engineered world, just think of the whiplash injury.



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brain intelligence

For Immediate Use: Sunday, November 4, 2001, 11:00AM PST, 2:00PM EST

UCLA brain mapping researchers have created the first images to show how an individual's genes influence their brain structure and intelligence.

The findings, published in the November 5 issue of the journal Nature Neuroscience, offer exciting new insight about how parents pass on personality traits and cognitive abilities and how brain diseases run in families.

The team found that the amount of gray matter in the frontal parts of the brain is determined by the genetic make-up of an individual's parents, and strongly correlates with that individual's cognitive ability, as measured by intelligence test (IQ) scores.

More importantly, these are the first images to uncover how normal genetic differences influence brain structure and intelligence. Brain regions controlling language and reading skills were virtually identical in identical twins, who share exactly the same genes, while siblings showed only 60 percent of the normal brain differences. This tight structural similarity in the brains of family members helps explain why brain diseases, including schizophrenia and some types of dementia, run in families.

"We were stunned to see that the amount of gray matter in frontal brain regions was strongly inherited, and also predicted an individual's IQ score," said Paul Thompson, Ph.D., the study's chief investigator and an assistant professor of neurology at the UCLA Laboratory of Neuro Imaging. "The brain's language areas were also extremely similar in family members. Brain regions that were found to be most similar in family members may be especially vulnerable to diseases that run in families, including some forms of psychosis and dementia."

The scientists employed magnetic resonance imaging (MRI) technology to scan a group of 20 identical twins, whose genes are identical, and 20 same-sex fraternal twins, who share half their genes. Using a high-speed supercomputer, they created color-coded images showing which parts of the brain are determined by our genetic make-up, and which are more adaptable to environmental factors, such as learning and stress.

To make the maps of genetic influences on the brain, the UCLA scientists teamed up with the National Public Health Institute of Finland, and the Finnish Universities of Helsinki and Oulu. In a national initiative, the Finnish team tracked all the same-sex twins born in Finland between 1940 and 1957 -- 9,500 pairs of twins -- many of whom received brain scans and cognitive tests. Their genetic similarity was confirmed by analyzing 78 different genetic markers. These individual pieces of DNA match exactly in identical twins, and half of them match in siblings.

Recent research has shown that many cognitive skills are surprisingly heritable, with strong genetic influences on verbal and spatial abilities, reaction times, and even some personality qualities, including emotional reactions to stress. These genetic relationships persist even after statistical adjustments are made for shared family environments, which tend to make members of the same family more similar. Until this study, little was known about how much individual genotype accounts for the wide variations among individual brains, as well as individual's cognitive ability.

The UCLA researchers are also applying this new genetic brain mapping approach to relatives of schizophrenic patients, and individuals at genetic risk for Alzheimer's disease, to screen them for early brain changes, and help understand familial risk for inherited brain disorders where specific risk genes are unknown.

A copy of the full study is available here (Word .doc) and here (PDF).

Graphics related to the study can be found at http://www.loni.ucla.edu/~thompson/MEDIA/NN/IMAGES/images.html.

Nature Neuroscience Article:

[1] Paul M. Thompson, Tyrone D. Cannon, Katherine L. Narr, Theo G. M. van Erp, Veli-Pekka Poutanen, Matti Huttunen, Jouko Lönnqvist, Carl-Gustaf Standertskjöld-Nordenstam, Jaakko Kaprio, Mohammad Khaledy, Rajneesh Dail, Chris I. Zoumalan, Arthur W. Toga (2001). Genetic Influences on Brain Structure, Nature Neuroscience, vol. 4, no. 12, November 5, 2001. [Word .doc (59 KB)] [PDF (53 KB)] [PDF with images, 1.1 MB].

Media stories on other research projects can be found here (on brain growth) and here (on schizophrenia) and here (other topics). Contact Information:

Paul Thompson thompson@loni.ucla.edu
Laboratory of Neuro Imaging, UCLA School of Medicine
Phone: 310-206-2101
Fax: 310-206-5518




 

twins and cognition

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Substantial genetic influence on cognitive abilities in twins 80 or more years old.

McClearn GE, Johansson B, Berg S, Pedersen NL, Ahern F, Petrill SA, Plomin R.

Center for Developmental and Health Genetics, The Pennsylvania State University, University Park, PA 16802, USA.

General and specific cognitive abilities were studied in intact Swedish same-sex twin pairs 80 or more years old for whom neither twin had major cognitive, sensory, or motor impairment. Resemblance for 110 identical twin pairs significantly exceeded resemblance for 130 fraternal same-sex twin pairs for all abilities. Maximum-likelihood model-fitting estimates of heritability were 62 percent for general cognitive ability, 55 percent for verbal ability, 32 percent for spatial ability, 62 percent for speed of processing, and 52 percent for memory. There was also evidence for the significant influence of idiosyncratic experience as the environmental component that most determines individual differences in cognitive abilities late in life.

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PMID: 9171059 [PubMed - indexed for MEDLINE]

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