Quadriceps femoris muscle
The quadriceps femoris is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the great extensor muscle of the knee, forming a large fleshy mass which covers the front and sides of the femur; the name derives from Latin four-headed muscle of the femur. It is subdivided into four separate portions or'heads', which have received distinctive names: Rectus femoris occupies the middle of the thigh, covering most of the other three quadriceps muscles, it originates on the ilium. It is named from its straight course; the other three lie deep to rectus femoris and originate from the body of the femur, which they cover from the trochanters to the condyles: Vastus lateralis is on the lateral side of the femur. Vastus medialis is on the medial side of the femur. Vastus intermedius lies between vastus lateralis and vastus medialis on the front of the femur, but deep to the rectus femoris, it cannot be seen without dissection of the rectus femoris. All four parts of the quadriceps muscle insert into the tuberosity of the tibia via the patella, where the quadriceps tendon becomes the patellar ligament.
There is a fifth muscle of the quadriceps complex, forgotten and taught called articularis genus. In addition, recent cadaver studies have confirmed the presence of a sixth muscle, the tensor vastus intermedius. While the muscle has variable presentations, it originates at the proximal femur, runs between the vastus lateralis and vastus intermedius muscles, inserts distally at the medial aspect of the patellar base. Considered a part of the vastus lateralis, the tensor vastus intermedius muscle is innervated by an independent branch of the femoral nerve and its tendinous belly can be separated from the vasti lateralis and intermedius muscles in most cases. Femoral nerve. All four quadriceps are powerful extensors of the knee joint, they are crucial in walking, running and squatting. Because the rectus femoris attaches to the ilium, it is a flexor of the hip; this action is crucial to walking or running as it swings the leg forward into the ensuing step. The quadriceps the vastus medialis, play the important role of stabilizing the patella and the knee joint during gait.
In strength training, the quadriceps are trained by several leg exercises. Effective exercises include the leg press; the isolation movement is the leg extension exercise. In body building communities, this muscle is colloquially referred to as the "leg triceps"; the proper Latin plural form of the adjective quadriceps would be quadricipites. In modern English usage, quadriceps is used in both plural; the singular form quadricep, produced by back-formation, is used. Hamstring Quadriceps_muscle at the Duke University Health System's Orthopedics program Muscles/Quadriceps at exrx.net "Anatomy diagram: 39960.000-1". Roche Lexicon - illustrated navigator. Elsevier. Archived from the original on 2014-01-01
Fibular collateral ligament
The fibular collateral ligament is a ligament located on the lateral side of the knee, thus belongs to the extrinsic knee ligaments and posterolateral corner of the knee. Rounded, more narrow and less broad than the medial collateral ligament, the fibular collateral ligament stretches obliquely downward and backward from the lateral epicondyle of the femur above, to the head of the fibula below. In contrast to the medial collateral ligament, it is fused with neither the capsular ligament nor the lateral meniscus; because of this, the lateral collateral ligament is more flexible than its medial counterpart, is therefore less susceptible to injury. Both collateral ligaments are taut. With the knee in flexion, the radius of curvatures of the condyles is decreased and the origin and insertions of the ligaments are brought closer together which make them lax; the pair of ligaments thus stabilize the knee joint in the coronal plane. Therefore and rupture of these ligaments can be diagnosed by examining the knee's mediolateral stability.
Below its origin is the groove for the tendon of the popliteus. The greater part of its lateral surface is covered by the tendon of the biceps femoris. Deep to the ligament are the tendon of the popliteus, the inferior lateral genicular vessels and nerve; the LCL is injured as a result of varus force across the knee, a force pushing the knee from the medial side of the joint, causing stress on the outside. An example of this would be a direct blow to the inside of the knee; the LCL can be injured by a noncontact injury, such as a hyperextension stress, again causing varus force across the knee. An LCL injury occurs as the other ligaments of the knee are injured. Multiple knee ligament tears and stresses can result from a significant trauma that includes direct blunt force to the knee, such as an automobile crash. Symptoms of a sprain or tear of the LCL includes pain to the lateral aspect of the knee, instability of the knee when walking and ecchymosis at the site of trauma. Direct trauma to the medial aspect of the knee may affect the peroneal nerve, which could result in a foot drop or paresthesias below the knee which could present itself as a tingling sensation.
An isolated LCL tear or sprain requires surgery. If the injury is a Grade 1 or Grade II, microscopic or partial macroscopic tearing the injury is treated with rest and rehabilitation. Ice, electrical stimulation and elevation are all methods to reduce the pain and swelling felt in the initial stages after the injury takes place. Physical therapy focuses on regaining full range-of-motion, such as biking and careful applications of pressure on the joint. Full recovery of Grade I or Grade II tears should take between 3 months. Continued pain and instability to the joint after this time period may require surgical repair or reconstruction to the ligament. Posterolateral knee injuries This article incorporates text in the public domain from page 341 of the 20th edition of Gray's Anatomy lljoints at The Anatomy Lesson by Wesley Norman
Skin is the soft outer tissue covering of vertebrates with three main functions: protection and sensation. Other animal coverings, such as the arthropod exoskeleton, have different developmental origin and chemical composition; the adjective cutaneous means "of the skin". In mammals, the skin is an organ of the integumentary system made up of multiple layers of ectodermal tissue, guards the underlying muscles, bones and internal organs. Skin of a different nature exists in amphibians and birds. All mammals have some hair on their skin marine mammals like whales and porpoises which appear to be hairless; the skin is the first line of defense from external factors. For example, the skin plays a key role in protecting the body against pathogens and excessive water loss, its other functions are insulation, temperature regulation and the production of vitamin D folates. Damaged skin may heal by forming scar tissue; this is sometimes depigmented. The thickness of skin varies from location to location on an organism.
In humans for example, the skin located under the eyes and around the eyelids is the thinnest skin in the body at 0.5 mm thick, is one of the first areas to show signs of aging such as "crows feet" and wrinkles. The skin on the palms and the soles of the feet is the thickest skin on the body; the speed and quality of wound healing in skin is promoted by the reception of estrogen. Fur is dense hair. Fur augments the insulation the skin provides but can serve as a secondary sexual characteristic or as camouflage. On some animals, the skin is hard and thick, can be processed to create leather. Reptiles and fish have hard protective scales on their skin for protection, birds have hard feathers, all made of tough β-keratins. Amphibian skin is not a strong barrier regarding the passage of chemicals via skin and is subject to osmosis and diffusive forces. For example, a frog sitting in an anesthetic solution would be sedated as the chemical diffuses through its skin. Amphibian skin plays key roles in everyday survival and their ability to exploit a wide range of habitats and ecological conditions.
Mammalian skin is composed of two primary layers: the epidermis, which provides waterproofing and serves as a barrier to infection. It forms a protective barrier over the body's surface, responsible for keeping water in the body and preventing pathogens from entering, is a stratified squamous epithelium, composed of proliferating basal and differentiated suprabasal keratinocytes. Keratinocytes are the major cells, constituting 95% of the epidermis, while Merkel cells and Langerhans cells are present; the epidermis can be further subdivided into the following strata or layers: Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum germinativum Keratinocytes in the stratum basale proliferate through mitosis and the daughter cells move up the strata changing shape and composition as they undergo multiple stages of cell differentiation to become anucleated. During that process, keratinocytes will become organized, forming cellular junctions between each other and secreting keratin proteins and lipids which contribute to the formation of an extracellular matrix and provide mechanical strength to the skin.
Keratinocytes from the stratum corneum are shed from the surface. The epidermis contains no blood vessels, cells in the deepest layers are nourished by diffusion from blood capillaries extending to the upper layers of the dermis; the epidermis and dermis are separated by a thin sheet of fibers called the basement membrane, made through the action of both tissues. The basement membrane controls the traffic of the cells and molecules between the dermis and epidermis but serves, through the binding of a variety of cytokines and growth factors, as a reservoir for their controlled release during physiological remodeling or repair processes; the dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis provides tensile strength and elasticity to the skin through an extracellular matrix composed of collagen fibrils and elastic fibers, embedded in hyaluronan and proteoglycans. Skin proteoglycans are varied and have specific locations.
For example, hyaluronan and decorin are present throughout the dermis and epidermis extracellular matrix, whereas biglycan and perlecan are only found in the epidermis. It harbors many mechanoreceptors that provide the sense of touch and heat through nociceptors and thermoreceptors, it contains the hair follicles, sweat glands, sebaceous glands, apocrine glands, lymphatic vessels and blood vessels. The blood vessels in the dermis provide nourishment and waste removal from its own cells as well as for the epidermis; the dermis is connected to the epidermis through a basement membrane and is structurally divided into two areas: a superficial area adjacent to the epidermis, called the papillary region, a deep thicker area known as the reticular region. The papillary region is composed of loose areolar connective tissue; this is named for its fingerlike projections called papillae. The papillae provide the dermis with a "bumpy" surface that interdigitates with the epidermis, strengthening the connection between the tw
The vastus medialis is an extensor muscle located medially in the thigh that extends the knee. The vastus medialis is part of the quadriceps muscle group; the vastus medialis is a muscle present in the anterior compartment of thigh, is one of the four muscles that make up the quadriceps muscle. The others are vastus intermedius and rectus femoris, it is the most medial of the "vastus" group of muscles. The vastus medialis arises medially along the entire length of the femur, attaches with the other muscles of the quadriceps in the quadriceps tendon; the vastus medialis muscle originates from a continuous line of attachment on the femur, which begins on the front and middle side on the intertrochanteric line of the femur. It continues down and back along the pectineal line and descends along the inner lip of the linea aspera and onto the medial supracondylar line of the femur; the fibers converge onto the inner part of the quadriceps tendon and the inner border of the patella. The obliquus genus muscle is the most distal segment of the vastus medialis muscle.
Its specific training plays an important role in maintaining patella position and limiting injuries to the knee. With no clear delineation, it is the most distal group of fibers of the vastus medialis; the vastus medialis is one of four muscles in the anterior compartment of the thigh. It is involved in knee extension, along with the other muscles the quadriceps muscle; the vastus medialis contributes to correct tracking of the patella. A division of the vastus medialis muscle into two groups of fibers has been hypothesized, a long and inline group of fibres with the quadriceps ligament, the vastus medialis longus. There is as yet insufficient evidence to conclusively deny this hypothesis. Knee pain is thought to be associated with specific quadriceps muscle weakness or fatigue in the vastus medialis obliquus, it is known that fatigue can be caused by many different mechanisms, ranging from the accumulation of metabolites within muscle fibers to the generation of an inadequate motor command in the motor cortex.
Characteristics of the vastus medialis, including its angle of insertion, correlate with presence of knee joint pain. However, this syndrome is complex and definitive evidence of causality has not yet been published. Misfiring and fatiguing of the VMO causes mal-tracking of the patella and subsequent damage to surrounding structures creating increased force on the knees resulting in injuries such as patellofemoral pain syndrome, anterior cruciate ligament rupture and tendinitis. Through the use of electromyography, researchers can evaluate and record the electrical activity produced by the skeletal muscle of the VMO to analyze the biomechanics and detect any possible abnormalities, weakness, or fatigue. With an analysis of muscle activity of the VMO through the use of electromyography, proper rehabilitative plans and goals can be established to not only correct the established abnormality, but prevent such injuries if tested sooner. Preventing injuries is crucial as well as teaching proper training techniques to ensure there are no valgus collapse forces causing unplanned stress on other structures of the knee, causing asymmetry, predisposing that individual for injury.
Medial patellofemoral ligament This article incorporates text in the public domain from page 471 of the 20th edition of Gray's Anatomy Cross section image: pembody/body18b—Plastination Laboratory at the Medical University of Vienna PTCentral
The NewYork–Presbyterian Hospital is a 501 nonprofit university hospital in New York City affiliated with two Ivy League medical schools: Columbia University Vagelos College of Physicians and Surgeons and Weill Cornell Medical College. It is composed of two distinct medical centers, Columbia University Medical Center and Weill Cornell Medical Center; as of August 2017, the hospital is ranked as the 8th best hospital in the United States and 1st in the New York City metropolitan area by U. S. News & World Report; the hospital has 2,478 beds in total, is one of the largest hospitals in the United States and one of the world's busiest. The New York Hospital was founded in 1771 by Edinburgh graduate Samuel Bard, it received a Royal Charter granted by King George III of Great Britain and became associated with Weill Cornell Medical College upon the latter institution's founding in 1898. It is the third oldest hospital in the United States, after NYC Health + Hospitals/Bellevue in New York and Pennsylvania Hospital.
A 1927 endowment of more than $20 million by Payne Whitney expanded the hospital and the Payne Whitney Psychiatric Clinic is named in his honor. Other prominent donors have included Edward S. Harkness and Anna Harkness, Howard Hughes, William Randolph Hearst and Leona Helmsley, Maurice R. Greenberg, the Baker, Whitney and Payson families; the Presbyterian Hospital was founded in 1868 by James Lenox, a New York philanthropist and was associated with Columbia University College of Physicians and Surgeons founded by Samuel Bard in 1767. In 1925 the Sloane Hospital for Women, a leader in obstetrics and gynecology, founded in 1886, was incorporated. New York Hospital was the subject of a lawsuit from the family of Libby Zion, a young woman admitted in 1984 who died while under the care of overworked hospital residents. An investigation by the New York state Health Commissioner, the Bell Commission, led to restrictions on the number of hours residents could work and required oversight of their care by accredited physicians.
These reforms have since been adopted nationwide. On January 1, 1998, The New York Hospital announced its merger with The Presbyterian Hospital to create New York–Presbyterian Hospital. New York–Presbyterian Hospital, chartered as The New York and Presbyterian Hospital by the State of New York in 1996, was formed in 1998 with the merger of two large independent hospitals, the New York Hospital and Presbyterian Hospital. In the 2010s, the hospital began to supplement its physical presence with remote and online services. A telemedicine service allows patients to receive follow-up care remotely, a CAT-equipped ambulance allows stroke care to take place outside the hospital, a remote second opinion program uses Grand Rounds technology; the NYP system includes a variety of outlying hospitals, affiliates of NYH or Presbyterian. The hospital, along with Weill Cornell Medical College and Columbia University College of Physicians & Surgeons, runs the NewYork-Presbyterian Healthcare System, a network of independent, acute-care and community hospitals, continuum-of-care facilities, home-health agencies, ambulatory sites, specialty institutes in the New York metropolitan area.
The two medical schools remain autonomous, though there is increasing cooperation and coordination of clinical and residency training programs. The hospitals have merged administrations, with Herb Pardes, MD, leading the combined hospitals from 2001 to 2011. Steven Corwin, MD is now the Hospital system CEO; the institution's facilities are: NewYork-Presbyterian/Columbia University Irving Medical Center NewYork-Presbyterian/Weill Cornell Medical Center NewYork-Presbyterian/Allen Hospital NewYork-Presbyterian/Morgan Stanley Children's Hospital NewYork-Presbyterian/Westchester Division the Payne Whitney Psychiatric Clinic, before that Bloomingdale Insane Asylum NewYork-Presbyterian/Lower Manhattan Hospital NewYork-Presbyterian/Lawrence Hospital NewYork-Presbyterian/Hudson Valley Hospital NewYork-Presbyterian/New York Hospital Queens NewYork-Presbyterian/New York Methodist Hospital As of 2018, the U. S. News and World Report rankings place NYPH overall as the sixth-best hospital in the United States.
Every specialty was ranked in the top 50 by US News, the following were ranked in the top 10 of hospitals around the country: neurology and neurosurgery. New York–Presbyterian Emergency Medical Services is a hospital-based ambulance service that has operated since 1981. NYP-EMS operates critical care transport ambulances throughout the New York City Metropolitan Area; the service is licensed to operate in the 5 counties of New York City, Westchester and Dutchess counties in New York, in the state of New Jersey for Basic Life Support and Specialty Care Transport. In addition to providing emergency and non-emergency ambulance services, either through the New York City 911 system or through the NYP-EMS Communications Center at Weill Cornell Medical Center, NYP-EMS provides stand-by EMS services for events throughout the New York City area, including the Avon Walk for Breast Cancer and the NYC Triathlon. NYP-EMS is a New York State Department of Health-approved training center for EMT and Paramedic programs, several of which are approved for college-level credit by the New York State Department of Education.
A joint or articulation is the connection made between bones in the body which link the skeletal system into a functional whole. They are constructed to allow for different types of movement; some joints, such as the knee and shoulder, are self-lubricating frictionless, are able to withstand compression and maintain heavy loads while still executing smooth and precise movements. Other joints such as sutures between the bones of the skull permit little movement in order to protect the brain and the sense organs; the connection between a tooth and the jawbone is called a joint, is described as a fibrous joint known as a gomphosis. Joints are classified both functionally. Joints are classified structurally and functionally. Structural classification is determined by how the bones connect to each other, while functional classification is determined by the degree of movement between the articulating bones. In practice, there is significant overlap between the two types of classifications. Monoarticular – concerning one joint oligoarticular or pauciarticular – concerning 2–4 joints polyarticular – concerning 5 or more joints Structural classification names and divides joints according to the type of binding tissue that connects the bones to each other.
There are four structural classifications of joints: fibrous joint – joined by dense regular connective tissue, rich in collagen fibers cartilaginous joint – joined by cartilage. There are two types: primary cartilaginous joints composed of hyaline cartilage, secondary cartilaginous joints composed of hyaline cartilage covering the articular surfaces of the involved bones with fibrocartilage connecting them. Synovial joint – not directly joined – the bones have a synovial cavity and are united by the dense irregular connective tissue that forms the articular capsule, associated with accessory ligaments. Facet joint – joint between two articular processes between two vertebrae. Joints can be classified functionally according to the type and degree of movement they allow: Joint movements are described with reference to the basic anatomical planes. Synarthrosis – permits little or no mobility. Most synarthrosis joints are fibrous joints. Amphiarthrosis – permits slight mobility. Most amphiarthrosis joints are cartilaginous joints.
Synovial joint – movable. Synovial joints can in turn be classified into six groups according to the type of movement they allow: plane joint and socket joint, hinge joint, pivot joint, condyloid joint and saddle joint. Joints can be classified, according to the number of axes of movement they allow, into nonaxial, monoaxial and multiaxial. Another classification is according to the degrees of freedom allowed, distinguished between joints with one, two or three degrees of freedom. A further classification is according to the number and shapes of the articular surfaces: flat and convex surfaces. Types of articular surfaces include trochlear surfaces. Joints can be classified based on their anatomy or on their biomechanical properties. According to the anatomic classification, joints are subdivided into simple and compound, depending on the number of bones involved, into complex and combination joints: Simple joint: two articulation surfaces Compound joint: three or more articulation surfaces Complex joint: two or more articulation surfaces and an articular disc or meniscus The joints may be classified anatomically into the following groups: Joints of hand Elbow joints Wrist joints Axillary articulations Sternoclavicular joints Vertebral articulations Temporomandibular joints Sacroiliac joints Hip joints Knee joints Articulations of footUnmyelinated nerve fibers are abundant in joint capsules and ligaments as well as in the outer part of intraarticular menisci.
These nerve fibers are responsible for pain perception. Damaging the cartilage of joints or the bones and muscles that stabilize the joints can lead to joint dislocations and osteoarthritis. Swimming is a great way to exercise the joints with minimal damage. A joint disorder is termed arthropathy, when involving inflammation of one or more joints the disorder is called arthritis. Most joint disorders involve arthritis, but joint damage by external physical trauma is not termed arthritis. Arthropathies are called polyarticular when involving many joints and monoarticular when involving only a single joint. Arthritis is the leading cause of disability in people over the age of 55. There are many different forms of arthritis; the most common form of arthritis, occurs following trauma to the joint, following an infection of the joint or as a result of aging and the deterioration of articular cartilage. Furthermore, there is emerging evidence that abnormal anatomy may contribute to early development of osteoarthritis.
Other forms of arthritis are rheumatoid arthritis and psoriatic arthritis, which are autoimmune diseases in which the body is attacking itself. Septic arthritis is caused by joint infection. Gouty arthritis is caused by deposition of uric acid crystals in the joint that results in subsequent inflammation. Additionally, there is a less common form of gout, caused by the formation of rhomboidal-shaped crystals of calcium pyrophosphate; this form of gout is known as pseudogout. Temporomandibular joint syndrome involves the jaw joints and can cause facial p
Poly known as acrylic, acrylic glass, or plexiglass as well as by the trade names Crylux, Acrylite and Perspex among several others, is a transparent thermoplastic used in sheet form as a lightweight or shatter-resistant alternative to glass. The same material can be used as a casting resin, in inks and coatings, has many other uses. Although not a type of familiar silica-based glass, the substance, like many thermoplastics, is technically classified as a type of glass hence its occasional historical designation as acrylic glass. Chemically, it is the synthetic polymer of methyl methacrylate; the material was developed in 1928 in several different laboratories by many chemists, such as William Chalmers, Otto Röhm, Walter Bauer, was first brought to market in 1933 by German Röhm & Haas AG and its partner and former U. S. affiliate Rohm and Haas Company under the trademark Plexiglas. PMMA is an economical alternative to polycarbonate when tensile strength, flexural strength, polishability, UV tolerance are more important than impact strength, chemical resistance and heat resistance.
Additionally, PMMA does not contain the harmful bisphenol-A subunits found in polycarbonate. It is preferred because of its moderate properties, easy handling and processing, low cost. Non-modified PMMA behaves in a brittle manner when under load under an impact force, is more prone to scratching than conventional inorganic glass, but modified PMMA is sometimes able to achieve high scratch and impact resistance; the first acrylic acid was created in 1843. Methacrylic acid, derived from acrylic acid, was formulated in 1865; the reaction between methacrylic acid and methanol results in the ester methyl methacrylate. Polymethyl methacrylate was discovered in the early 1930s by British chemists Rowland Hill and John Crawford at Imperial Chemical Industries in England. ICI registered the product under the trademark Perspex. About the same time and industrialist Otto Röhm of Rohm and Haas AG in Germany attempted to produce safety glass by polymerizing methyl methacrylate between two layers of glass.
The polymer separated from the glass as a clear plastic sheet, which Röhm gave the trademarked name Plexiglas in 1933. Both Perspex and Plexiglas were commercialized in the late 1930s. In the United States, E. I. du Pont de Nemours & Company subsequently introduced its own product under the trademark Lucite. In 1936 ICI Acrylics began the first commercially viable production of acrylic safety glass. During World War II both Allied and Axis forces used acrylic glass for submarine periscopes and aircraft windshields and gun turrets. Airplane pilots whose eyes were damaged by flying shards of PMMA fared much better than those injured by standard glass, demonstrating better compatibility between human tissue and PMMA than glass. Civilian applications followed after the war. Common orthographic stylings include polymethyl polymethylmethacrylate; the full IUPAC chemical name is poly. Although PMMA is called "acrylic", acrylic can refer to other polymers or copolymers containing polyacrylonitrile. Notable trade names include Acrylite, Lucite, R-Cast, Optix, Oroglas, Altuglas and Sumipex.
PMMA is produced by emulsion polymerization, solution polymerization, bulk polymerization. Radical initiation is used, but anionic polymerization of PMMA can be performed. To produce 1 kg of PMMA, about 2 kg of petroleum is needed. PMMA produced by radical polymerization is atactic and amorphous; the glass transition temperature of atactic PMMA is 105 °C. The Tg values of commercial grades of PMMA range from 85 to 165 °C. PMMA is thus an organic glass at room temperature; the forming temperature goes up from there. All common molding processes may be used, including injection molding, compression molding, extrusion; the highest quality PMMA sheets are produced by cell casting, but in this case, the polymerization and molding steps occur concurrently. The strength of the material is higher than molding grades owing to its high molecular mass. Rubber toughening has been used to increase the toughness of PMMA to overcome its brittle behavior in response to applied loads. PMMA can be joined using cyanoacrylate cement, with heat, or by using chlorinated solvents such as dichloromethane or trichloromethane to dissolve the plastic at the joint, which fuses and sets, forming an invisible weld.
Scratches may be removed by polishing or by heating the surface of the material. Laser cutting may be used to form intricate designs from PMMA sheets. PMMA vaporizes to gaseous compounds upon laser cutting, so a clean cut is made, cutting is performed easily. However, the pulsed lasercutting introduces high internal stresses along the cut edge, which on exposure to solvents produce undesirable "stress-crazing" at the cut edge and several millimetres deep. Ammonium-based glass-cleaner and everything short of soap-and-water produces similar undesirable crazing, sometimes over the entire surface of th