SUMMARY / RELATED TOPICS

Spinal cord

The spinal cord is a long, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. It encloses the central canal of the spinal cord; the brain and spinal cord together make up the central nervous system. In humans, the spinal cord begins at the occipital bone, passing through the foramen magnum and entering the spinal canal at the beginning of the cervical vertebrae; the spinal cord extends down to between the second lumbar vertebrae, where it ends. The enclosing bony vertebral column protects the shorter spinal cord, it is around 45 cm in men and around 43 cm long in women. The diameter of the spinal cord ranges from 13 mm in the cervical and lumbar regions to 6.4 mm in the thoracic area. The spinal cord functions in the transmission of nerve signals from the motor cortex to the body, from the afferent fibers of the sensory neurons to the sensory cortex, it is a center for coordinating many reflexes and contains reflex arcs that can independently control reflexes.

It is the location of groups of spinal interneurons that make up the neural circuits known as central pattern generators. These circuits are responsible for controlling motor instructions for rhythmic movements such as walking; the spinal cord is the main pathway for information connecting the brain and peripheral nervous system. Much shorter than its protecting spinal column, the human spinal cord originates in the brainstem, passes through the foramen magnum, continues through to the conus medullaris near the second lumbar vertebra before terminating in a fibrous extension known as the filum terminale, it is about 45 cm long in men and about 43 cm in women, ovoid-shaped, is enlarged in the cervical and lumbar regions. The cervical enlargement, stretching from the C5 to T1 vertebrae, is where sensory input comes from and motor output goes to the arms and trunk; the lumbar enlargement, located between L1 and S3, handles sensory input and motor output coming from and going to the legs. The spinal cord is continuous with the caudal portion of the medulla, running from the base of the skull to the body of the first lumbar vertebra.

It does not run the full length of the vertebral column in adults. It is made of 31 segments from which branch one pair of sensory nerve roots and one pair of motor nerve roots; the nerve roots merge into bilaterally symmetrical pairs of spinal nerves. The peripheral nervous system is made up of these spinal roots and ganglia; the dorsal roots are afferent fascicles, receiving sensory information from the skin and visceral organs to be relayed to the brain. The roots terminate in dorsal root ganglia, which are composed of the cell bodies of the corresponding neurons. Ventral roots consist of efferent fibers that arise from motor neurons whose cell bodies are found in the ventral gray horns of the spinal cord; the spinal cord are protected by three layers of tissue or membranes called meninges, that surround the canal. The dura mater is the outermost layer, it forms a tough protective coating. Between the dura mater and the surrounding bone of the vertebrae is a space called the epidural space; the epidural space is filled with adipose tissue, it contains a network of blood vessels.

The arachnoid mater, the middle protective layer, is named for its spiderweb-like appearance. The space between the arachnoid and the underlying pia mater is called the subarachnoid space; the subarachnoid space contains cerebrospinal fluid, which can be sampled with a lumbar puncture, or "spinal tap" procedure. The delicate pia mater, the innermost protective layer, is associated with the surface of the spinal cord; the cord is stabilized within the dura mater by the connecting denticulate ligaments, which extend from the enveloping pia mater laterally between the dorsal and ventral roots. The dural sac ends at the vertebral level of the second sacral vertebra. In cross-section, the peripheral region of the cord contains neuronal white matter tracts containing sensory and motor axons. Internal to this peripheral region is the grey matter, which contains the nerve cell bodies arranged in the three grey columns that give the region its butterfly-shape; this central region surrounds the central canal, an extension of the fourth ventricle and contains cerebrospinal fluid.

The spinal cord is elliptical in cross section, being compressed dorsolaterally. Two prominent grooves, or sulci, run along its length; the posterior median sulcus is the groove in the dorsal side, the anterior median fissure is the groove in the ventral side. The human spinal cord is divided into segments. Six to eight motor nerve rootlets branch out of right and left ventro lateral sulci in a orderly manner. Nerve rootlets combine to form nerve roots. Sensory nerve rootlets form off right and left dorsal lateral sulci and form sensory nerve roots; the ventral and dorsal roots combine to form one on each side of the spinal cord. Spinal nerves, with the exception of C1 and C2, form inside the intervertebral foramen; these rootlets form the demarcation between the peripheral nervous systems. The grey column, in the center of the cord, is shaped like a butterfly and consists of cell bodies of interneurons, motor neurons, neuroglia cells and unmyelinated axons; the anterior and posterior grey column present as projections of the grey matter and are known as the horns of the spinal cord.

Together, the grey columns and the gray commissure fo

Royal court in Sutjeska

Royal Court in Sutjeska was a medieval Bosnian court and administrative seat of the Bosnian king, from mid-fourteenth to mid-fifteenth century, located in present-day Kraljeva Sutjeska and Herzegovina. In its close proximity is the location of medieval royal castle of Bobovac, the crown jewels of Bosnia were held; the royal chapel in Bobovac consisted the burial chamber of several Bosnian queens. Nine skeletons have been found in the five tombs located in the mausoleum; the identified skeletons belong to kings Dabiša, Ostojić, Tvrtko II and Thomas. It is assumed that one of the remaining skeletons belongs to the last king, Tomašević, decapitated in Jajce on the order of Mehmed the Conqueror. Only one of the skeletons, found next to that of King Tvrtko II, is female and assumed to belong to Tvrtko II's wife, Queen Dorothy; the court in Trstionica was established by Ban of Bosnia, Stjepan II Kotromanić. The compound consisted of several buildings and the nucleus of what will become Kraljeva Sutjeska Franciscan Monastery.

Bobovac List of National Monuments of Bosnia and Herzegovina The Royal Court in Kraljeva Sutjeska, photos at alltravels.com

Mosquito-borne disease

Mosquito-borne diseases or mosquito-borne illnesses are diseases caused by bacteria, viruses or parasites transmitted by mosquitoes. Nearly 700 million people get a mosquito-borne illness each year resulting in over one million deaths. Diseases transmitted by mosquitoes include malaria, West Nile virus, yellow fever, tularemia, Japanese encephalitis, Saint Louis encephalitis, Western equine encephalitis, Eastern equine encephalitis, Venezuelan equine encephalitis, Ross River fever, Barmah Forest fever, La Crosse encephalitis, Zika fever, as well as newly detected Keystone virus and Rift Valley fever; the female mosquito of the genus Anopheles may carry the malaria parasite. Four different species of protozoa cause malaria: Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale and Plasmodium vivax. Worldwide, malaria is a leading cause of premature mortality in children under the age of five, with an estimated 207 million cases and more than half a million deaths in 2012, according to the World Malaria Report 2013 published by WHO.

The death toll increased to one million as of 2018 according to the American Mosquito Control Association. Botflies are known to parasitize humans or other mammalians, causing myiasis, to use mosquitoes as intermediate vector agents to deposit eggs on a host; the human botfly Dermatobia hominis attaches its eggs to the underside of a mosquito, when the mosquito takes a blood meal from a human or an animal, the body heat of the mammalian host induces hatching of the larvae. Some species of mosquito can carry the filariasis worm, a parasite that causes a disfiguring condition characterized by a great swelling of several parts of the body; the viral diseases yellow fever, dengue fever, Zika fever and chikungunya are transmitted by Aedes aegypti mosquitoes. Other viral diseases like epidemic polyarthritis, Rift Valley fever, Ross River fever, St. Louis encephalitis, West Nile fever, Japanese encephalitis, La Crosse encephalitis and several other encephalitic diseases are carried by several different mosquitoes.

Eastern equine encephalitis and Western equine encephalitis occur in the United States where they cause disease in humans and some bird species. Because of the high mortality rate, EEE and WEE are regarded as two of the most serious mosquito-borne diseases in the United States. Symptoms range from mild flu-like illness to encephalitis and death. Viruses carried by arthropods such as mosquitoes or ticks are known collectively as arboviruses. West Nile virus was accidentally introduced into the United States in 1999 and by 2003 had spread to every state with over 3,000 cases in 2006. Other species of Aedes as well as Culex and Culiseta are involved in the transmission of disease. Myxomatosis is spread by biting insects, including mosquitoes. A mosquito's period of feeding is undetected; when a mosquito bites a human, it injects saliva and anti-coagulants. For any given individual, with the initial bite there is no reaction but with subsequent bites the body's immune system develops antibodies and a bite becomes inflamed and itchy within 24 hours.

This is the usual reaction in young children. With more bites, the sensitivity of the human immune system increases, an itchy red hive appears in minutes where the immune response has broken capillary blood vessels and fluid has collected under the skin; this type of reaction is common in older adults. Some adults can become desensitized to mosquitoes and have little or no reaction to their bites, while others can become hyper-sensitive with bites causing blistering and large inflammatory reactions, a response known as skeeter syndrome. Symptoms of illness are specific to the type of viral infection and vary on severity, based on the individuals infected. Symptoms vary on severity, from mild unnoticeable symptoms to more common symptoms like fever, headache, achy muscle and joints, conjunctivitis. Symptoms can last several days to weeks. Most people infected with the West Nile virus do not develop symptoms. However, some individuals can develop cases of severe fatigue, headaches, body aches and muscle pain, vomiting and rash, which can last for weeks or months.

More serious symptoms have a greater risk of appearing in people over 60 years of age, or those suffering from cancer, diabetes and kidney disease. Dengue fever is characterized by high fever, joint pain, rash. However, more severe instances can lead to hemorrhagic fever, internal bleeding, breathing difficulty, which can be fatal. People infected with this virus can develop sudden onset fever along with debilitating joint and muscle pain, headache and fatigue. Symptoms can be prolonged to weeks and months. Although patients can recover there have been cases in which joint pain has persisted for several months and can extend beyond that for years. Other people can develop heart complications, eye problems, neurological complications. Mosquitoes carrying such arboviruses stay healthy because their immune systems recognizes the virions as foreign particles and "chop off" the virus' genetic coding, rendering it inert. Human infection with a mosquito-borne virus occurs when a female mosquito bites someone while its immune system is still in the process of destroying the virus's harmful coding.

It is not known how mosquitoes handle eukaryotic parasites to carry them without being harmed. Data has shown tha