Meniscus of the Knee Essay Example | Topics and Well Written Essays - 1000 words

Meniscus of the Knee - Essay Example The menisci also cup the joint surfaces of the femur and therefore provide some degree of stabilization to the knee. The meniscus itself is for the most part avascular that is it doesn't bleed if cut and doesn't have blood vessels inside. The exception to this is at the periphery where it joins to the vascular knee lining providing the outermost 20% of the meniscus with a blood supply. As a result of this avascularity a torn meniscus doesn't have the ability to heal itself unless there is just a small tear confined to the peripheral vascular zone. Similarly the nerve supply providing pain and sensation to the meniscus is for the most part limited to the zone where the blood vessels are located. In terms of descriptive terminology orthopaedic surgeons divide the meniscus into thirds with three geographical zones;the front third is referred to as the anterior horn, the back third the posterior horn, and the middle third the body. Some people think that only athletes can tear a meniscus. This is not true. Even people who do not consider themselves "athletes" can tear a meniscus. Some menisci (plural) tear during activities of daily living such as getting in and out of a car or squatting. Menisci also tear during participation in recreational activities such as skiing, dancing, or racquetball. There are two different mechanisms for tearing a meniscus. Traumatic tears result from a sudden load being applied to the meniscal tissue which is severe enough to cause the meniscal cartilage to fail and let go. These usually occur from a twisting injury or a blow to the side of the knee that causes the meniscus to be levered against and compressed. Degenerative meniscal tears are best thought of as a failure of the meniscus over time. There is a natural drying-out of the inner centre of the meniscus that can begin in the late 20's and progresses with age. The meniscus becomes less elastic and compliant and as a result may fail with only minimal trauma (such as just getting down into a squat). Sometimes there are no memorable injuries or violent events which can be blamed as the cause of the tear. The association of these tears with aging makes degenerative tears in a teenager almost unheard of. There are many techniques for meniscal repair and these will depend on the location of the tear. The techniques include an open procedure (following arthroscopic examination of the joint) or the arthroscopic 'inside-out', 'outside-in' and 'all-inside' procedures. The open technique has been advocated for vertical tears of the posterior horn of the lateral and medial menisci within 1-2 mm of the meniscosynovial junction, where visualisation with the arthroscopy is difficult. In all cases the torn surfaces of the meniscus are derided of scar tissue and fibrin clot can be placed in situ before the sutures are tied to enhance healing. Repaired meniscal tears heal if there is adequate blood supply and tissue stability. A stable knee is therefore important and increased

Economics, Goods and Services, Firms, Production, Supply and Demand Essay

Economics, Goods and Services, Firms, Production, Supply and Demand - Essay Example The essay shall focus on how goods and services’ supply and demand is influenced by consumers, how the changing needs and wants of consumer are met and how the different types of resources are used by firms for the production of goods and services. A market is a place where buyers and sellers meet in order to exchange goods and services. Market structure is comprised of buyers, sellers, buyer and seller entry barriers, size of the firm, product differentiation, market share and competition. With the above characteristics, one is able to determine where a particular firm is classified. Some examples of market structure are; Monopoly-here, companies are owned by the state, and other partner entry is not allowed. Oligopoly-here, the number of buyers is high than the number of sellers, thus competition is high. Monopolistic competition-here there is many buyers and many sellers for same products, different branding and very high competition. Perfect competition-an example is betwe en food bought in the stores and those from the market. The following are other market definitions: Economics is concerned with production, allocation and utilization of goods and services. Economics can be divided into; microeconomics and macroeconomics. Microeconomics deals with firms, buyers, and markets. Macroeconomics deals with growth, inflation and policies that affect economy (Wessels, 16, 2006). Consumers are those who benefit from goods and services. They are the users of produced products (Houghton, 20, 2009). Goods are useful items that are required and useful to individuals to satisfy their needs or wants. They can also be classified as tangible, since they can be touched unlike services, and can be stored for the future (Houghton, 15, 2009).  There are three types; inferior goods, which decrease in demand as consumer income increases; normal goods, which demand increase as consumer income increases; and luxury goods, which are non essential and are mostly considered an influence. Services are intangible, cannot be stored and are an activity that is done to an individual from another. Services are the other alternatives to goods. Services are done in order to provide help or as a profession (Houghton, 15, 2009).   Firms are organizations that deal with goods and services and their production to cater for the needs and wants of consumers. Firms can be businesses, corporations, or partnerships that have the main aim of producing goods and services for consumption (Rugraff & Hansen, 119, 2011). Production is the process of manufacturing goods from raw materials. Production is transforming raw materials that in their natural form do not have any benefits to consumers. After processing these raw materials, the products that come out can be used by consumers (Menger, Klein, Hayek, Dingwall & Hoselitz, 161, 2007). Supply is the distribution of goods and services to consumers. Supply is influenced by the demand for goods and services (Adil, 4, 2006).à ‚   Demand is the desire for a certain good or service by a consumer(s) who is willing to buy the good or service at a certain set price. Factors that influence demand are like price; of the good and other related goods (substitute), and also the price of the good and other goods (complementary) (Adil, 5, 2006).   Resources are the sources that products are extracted from. In economics, there are four main types of resources namely; land, labor, capital and entrepreneurship (Mankiw, 538, 2011).