Central nervous system

The central nervous system is the part of the nervous system consisting of the brain and spinal cord. The CNS is so named because it integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric animals—i.e. All multicellular animals except sponges and radially symmetric animals such as jellyfish—and it contains the majority of the nervous system. Many consider the retina and the optic nerve, as well as the olfactory nerves and olfactory epithelium as parts of the CNS, synapsing directly on brain tissue without intermediate ganglia; as such, the olfactory epithelium is the only central nervous tissue in direct contact with the environment, which opens up for therapeutic treatments. The CNS is contained within the dorsal body cavity, with the brain housed in the cranial cavity and the spinal cord in the spinal canal. In vertebrates, the brain is protected by the skull, while the spinal cord is protected by the vertebrae; the brain and spinal cord are both enclosed in the meninges.

Within the CNS, the interneuronal space is filled with a large amount of supporting non-nervous cells called neuroglia or glia from the Greek for "glue". The CNS consists of the two major structures: spinal cord; the brain is encased in the skull, protected by the cranium. The spinal cord lies caudally to the brain, it is protected by the vertebrae. The spinal cord reaches from the base of the skull, continues through or starting below the foramen magnum, terminates level with the first or second lumbar vertebra, occupying the upper sections of the vertebral canal. Microscopically, there are differences between the neurons and tissue of the CNS and the peripheral nervous system; the CNS is composed of gray matter. This can be seen macroscopically on brain tissue; the white matter consists of axons and oligodendrocytes, while the gray matter consists of neurons and unmyelinated fibers. Both tissues include a number of glial cells, which are referred to as supporting cells of the CNS. Different forms of glial cells have different functions, some acting as scaffolding for neuroblasts to climb during neurogenesis such as bergmann glia, while others such as microglia are a specialized form of macrophage, involved in the immune system of the brain as well as the clearance of various metabolites from the brain tissue.

Astrocytes may be involved with both clearance of metabolites as well as transport of fuel and various beneficial substances to neurons from the capillaries of the brain. Upon CNS injury astrocytes will proliferate, causing gliosis, a form of neuronal scar tissue, lacking in functional neurons; the brain consists of a cortex, composed of neuron-bodies constituting gray matter, while internally there is more white matter that form tracts and commissures. Apart from cortical gray matter there is subcortical gray matter making up a large number of different nuclei. From and to the spinal cord are projections of the peripheral nervous system in the form of spinal nerves; the nerves connect the spinal cord to skin, muscles etc. and allow for the transmission of efferent motor as well as afferent sensory signals and stimuli. This allows for involuntary motions of muscles, as well as the perception of senses. All in all 31 spinal nerves project from the brain stem, some forming plexa as they branch out, such as the brachial plexa, sacral plexa etc.

Each spinal nerve will carry both sensory and motor signals, but the nerves synapse at different regions of the spinal cord, either from the periphery to sensory relay neurons that relay the information to the CNS or from the CNS to motor neurons, which relay the information out. The spinal cord relays information up to the brain through spinal tracts through the "final common pathway" to the thalamus and to the cortex. Apart from the spinal cord, there are peripheral nerves of the PNS that synapse through intermediaries or ganglia directly on the CNS; these 12 nerves are called cranial nerves. Cranial nerves bring information to the CNS to and from the face, as well as to certain muscles. Two pairs of cranial nerves; this is. The olfactory epithelium is significant in that it consists of CNS tissue expressed in direct contact to the environment, allowing for administration of certain pharmaceuticals and drugs. Rostrally to the spinal cord lies the brain; the brain makes up the largest portion of the CNS.

It is the main structure referred to when speaking of the nervous system in general. The brain is the major functional unit of the CNS. While the spinal cord has certain processing ability such as that of spinal locomotion and can process reflexes, the brain is the major processing unit of the nervous system; the brainstem consists of the pons and the midbrain. The medulla can be referred to as an extension of the spinal cord, which both have similar organization and functional properties; the tracts passing from the spinal cord to the brain pass through here. Regulatory functions of the medulla nuclei include control of blood breathing. Other nuclei are involved in balance, taste and control of muscles of the face and neck; the next structure rostral to the medulla is the pons, which lies on the ventral anterior side of the brainstem. Nuclei in the

Battle of Silva Litana

The Battle of Silva Litana was an ambush during the Second Punic War that took place in a forest 75 miles northwest of the Roman city of Ariminum in 216 BC. The Gallic Boii surprised and destroyed a Roman army of 25,000 men under the consul-elect Lucius Postumius Albinus. Only ten men escaped the ambush, few prisoners were taken and Postumius was killed and his skull covered with gold by the Boii. News of the military disaster, coming either several days or months after the defeat at Cannae, triggered a renewed panic in Rome and the Romans postponed military operations against the Gauls until the conclusion of the Second Punic War. In 216 BC, the Romans elected Lucius Aemilius Paullus and Gaius Terentius Varro as consuls; the consuls gave a legion to Lucius Postumius Albinus to punish the Gallic tribes in Cisalpine Gaul that had supplied troops to Hannibal's Carthaginian army. After Hannibal's crushing victory at the Battle of Cannae, Postumius was elected Roman consul for the third time and in absentia, since he was in command of the Roman legion in Cisalpine Gaul.

Postumius' army strength was increased to two Roman legions and he raised allied troops along the Adriatic coast, raising the number of his soldiers to 25,000. Postumius' army marched through a large forest called Litana by the Gauls; the Boii had cut the trees so that unsupported, they would remain standing, but if given a slight push would topple over. As the Romans went along a road in the forest, the Boii secured a perimeter outside it and pushed over the trees on the outer edges; the trees fell on each other and crashed onto the road from both sides, killing Roman soldiers and horses and destroying equipment. Most of the soldiers died under the weight of the trees trunks and branches and the panicked survivors were slaughtered by the Boii waiting outside the forest. A party of Romans tried to escape across a river, but were captured by the Boii who had taken the bridge over it. Few Roman prisoners only ten men survived the disaster. Postumius fought to avoid capture but was killed and his head taken to a Boii sacred temple, where the skin was scraped off and the bare skull covered with gold.

It was used as a cup for drinking by the Boii high priest. The Boii took a vast amount of loot, with the Roman goods handily concentrated along the forest road. A panic hit the city of Rome upon arrival of the news; the Roman Senate ordered aediles to patrol the streets, open shops and disperse any sign of defeatism. Tiberius Sempronius Gracchus, master of horse and consul-elect for 215 BC, consoled the Senate by emphasizing the importance of defeating Hannibal, with the Gauls only a secondary priority for Roman strategy. Livius, Titus. Hannibal's War: Books Twenty-One to Thirty. Translated by J. C. Yardley and notes by Dexter Hoyos. Oxford: Oxford University Press. ISBN 0-19-283159-3

Battle of Panjwaii

The Battle of Panjwaii was fought in mid-2006 between Canadian and Afghan soldiers, supported by small elements of Dutch and British forces, the Taliban. There were two separate times; the first phase was fought in July 2006, the second encounter lasted from September to October 2006. Prior to the summer upsurge of violence and fighting, there were limited contacts in the Panjwai district. On May 17 there were a number of battles between Taliban fighters. One of the contacts claimed the life of Captain Nichola Goddard, Canada's first female combat arms casualty. In another contact on the same day, Sergeant Michael Thomas Victor Denine's acts of heroism resulted in him being awarded the Medal of Military Valour. After this initial fighting Task Force Orion operated as a Battle Group in Panjway and Zharie Districts from 23 May until June 14, were involved in a classic "running fight" with numerous Taliban groups; the Task Force recorded 37 firefights in that period. Between June 14 and July 7, 2006, B Company of 2 PPCLI remained in Panjwyai to keep the Taliban from seizing the initiative there while the remainder of the Task Force operated in Northern Kandahar.

In mid July 2006, Canadian and Afghan forces involved in Operation Mountain Thrust came into the Panjwaii area to help clear the area of Taliban strongholds. On July 8 heavy fighting broke out in the mud wall complexes where Taliban forces decided to dig in and fight for control of this area of Panjwaii. Canadian and Afghan forces on the offensive gained control of the battlefield while heavy fighting was still ongoing. One complete Taliban group was destroyed in this fighting, another received casualties. Taliban groups in Pashmul and eastern Panywayi were forced to withdraw by July 12, when fighting waned. During the following day Canadian forces were called to support Operation Hewad – a combined endeavour by a complete brigade attempting to clear Taliban from Sangin in Helmand. Canadians were tasked to relieve British soldiers besieged in Sangin district centre, at the same time pressure Taliban command and control throughout the lower Sangin and Gereshk districts of Helmand, operations that again involved multiple firefights each day with dozens of Taliban casualties, but no Canadian deaths.

On July 17 Task Force Orion was ordered to retake the captured towns of Nawa and Garmsir, which they did after intense fighting on July 18. They stayed for another week in Helmand. All these operations affected Canadian operations in the area of the Panjwaii region; the Canadians were assisted by three US special forces teams. B company continued operations in Panjwayi; the task force began concerted operations in Panjwayi again on August 2, fought fierce battles in Pashmul again on August 3, resulting in 4 Canadians killed and 11 wounded. This battle resulted in numerous Canadian personnel earning Medals of Valour and decorations of Mentioned in Dispatches. Sgt William MacDonald received the Star of Military Valour and Cpl Bryce Keller, one of the soldiers killed on August 3, received the Medal of Military Valour; this marked the first time in Canadian history. Sgt Vaughn Ingram, Cpl Christopher Reid and Pte Kevin Dallaire all received Mentioned in Dispatches decorations posthumously. An estimated 90 Taliban -- included three commanders -- were wounded in this fighting.

The action arrested Taliban plans to launch attacks upon Kandahar City in August. Instead they attacked Panjwayi District Centre on August 19. A tough defensive fight by Afghans and soldiers from A Company 2 PPCLI held the enemy at bay, causing up to 70 Taliban casualties. There was a lull before fighting recommenced in September. After the fighting in July and Afghan forces left the Panjwaii region and it once again became a Taliban stronghold and a thorn in the side of Canadian forces in Kandahar province when the Taliban poured back into the deserted district; the beginning of September saw the beginning of much more intense fighting in the Panjwaii region again. And once again it was Canadians spearheading the Operation. Canadian forces on the first day strategically surrounded the Taliban and called in heavy artillery and air strikes while taking no casualties themselves. On the second day, company-sized elements of the Canadian forces moved in to directly challenge the Taliban. Four soldiers were killed in two attacks.

Three were killed while assaulting one was killed in a bomb attack. The day after was another deadly day, a Canadian soldier was killed and more than thirty others were wounded when an American A-10 accidentally strafed Canadian troops who had called in air support while fighting the Taliban. For the next few weeks there was more heavy fighting on a daily basis and the Taliban who had begun fighting the battle in a conventional way of trenches started to retreat from the battlefield. Canadian forces faced sporadic resistance until Canadian forces gained the upper hand. Reconstruction efforts began and small cells of Taliban fighters returned to their deadly tactics of suicide and roadside bombings. After major combat operations of Operation Medusa had ceased, the reconstruction efforts began. One project in particular has become a dangerous effort to help the local economy grow. Canadian Forces began the construction of a road, code-named "Summit", from the Panjwaii area to outlying areas including Kandahar city.

The purpose of this road was to improve security in the region by providing a paved route into otherwise difficult and close terrain. Further the road helped the local economy