Cartilage is a resilient and smooth type of connective tissue. It is a semi-transparent and non-porous type of tissue. It is usually covered by a tough and fibrous membrane called perichondrium. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck and the bronchial tubes, and the intervertebral discs. In other taxa, such as chondrichthyans, but also in cyclostomes, it may constitute a much greater proportion of the skeleton. It is not as hard and rigid as bone, but it is much stiffer and much less flexible than muscle. The matrix of cartilage is made up of glycosaminoglycans, proteoglycans, collagen fibers and, sometimes, elastin. It usually grows quicker than bone.
In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia, and one between the femur and patella. It is the largest joint in the human body. The knee is a modified hinge joint, which permits flexion and extension as well as slight internal and external rotation. The knee is vulnerable to injury and to the development of osteoarthritis.
In anatomy, the temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral synovial articulation between the temporal bone of the skull above and the mandible below; it is from these bones that its name is derived. This joint is unique in that it is a bilateral joint that functions as one unit. Since the TMJ is connected to the mandible, the right and left joints must function together and therefore are not independent of each other.
A joint or articulation is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole. They are constructed to allow for different degrees and types of movement. Some joints, such as the knee, elbow, and shoulder, are self-lubricating, almost frictionless, and 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 very little movement in order to protect the brain and the sense organs. The connection between a tooth and the jawbone is also called a joint, and is described as a fibrous joint known as a gomphosis. Joints are classified both structurally and functionally.
The synovial membrane is a specialized connective tissue that lines the inner surface of capsules of synovial joints and tendon sheath. It makes direct contact with the fibrous membrane on the outside surface and with the synovial fluid lubricant on the inside surface. In contact with the synovial fluid at the tissue surface are many rounded macrophage-like synovial cells and also type B cells, which are also known as fibroblast-like synoviocytes (FLS). Type A cells maintain the synovial fluid by removing wear-and-tear debris. As for the FLS, they produce hyaluronan, as well as other extracellular components in the synovial fluid.
The human musculoskeletal system is an organ system that gives humans the ability to move using their muscular and skeletal systems. The musculoskeletal system provides form, support, stability, and movement to the body.
The periosteum is a membrane that covers the outer surface of all bones, except at the articular surfaces of long bones. Endosteum lines the inner surface of the medullary cavity of all long bones.
Synovial fluid, also called synovia,[help 1] is a viscous, non-Newtonian fluid found in the cavities of synovial joints. With its egg white–like consistency, the principal role of synovial fluid is to reduce friction between the articular cartilage of synovial joints during movement. Synovial fluid is a small component of the transcellular fluid component of extracellular fluid.
Hyaline cartilage is the glass-like (hyaline) and translucent cartilage found on many joint surfaces. It is also most commonly found in the ribs, nose, larynx, and trachea. Hyaline cartilage is pearl-gray in color, with a firm consistency and has a considerable amount of collagen. It contains no nerves or blood vessels, and its structure is relatively simple.
Synovitis is the medical term for inflammation of the synovial membrane. This membrane lines joints that possess cavities, known as synovial joints. The condition is usually painful, particularly when the joint is moved. The joint usually swells due to synovial fluid collection.
The carpometacarpal (CMC) joints are five joints in the wrist that articulate the distal row of carpal bones and the proximal bases of the five metacarpal bones.
In anatomy, a joint capsule or articular capsule is an envelope surrounding a synovial joint. Each joint capsule has two parts: an outer fibrous layer or membrane, and an inner synovial layer or membrane.
The articular disc is a thin, oval plate of fibrocartilage present in several joints which separates synovial cavities. This separation of the cavity space allows for separate movements to occur in each space.
The articular capsule of the knee joint is the wide and lax joint capsule of the knee. It is thin in front and at the side, and contains the patella, ligaments, menisci, and bursae of the knee. The capsule consists of an inner synovial membrane, and an outer fibrous membrane separated by fatty deposits anteriorly and posteriorly.
The fat pad sign, also known as the sail sign, is a potential finding on elbow radiography which suggests a fracture of one or more bones at the elbow. It is may indicate an occult fracture that is not directly visible. Its name derives from the fact that it has the shape of a spinnaker (sail). It is caused by displacement of the fat pad around the elbow joint. Both anterior and posterior fat pad signs exist, and both can be found on the same X-ray.
The articular disk of the temporomandibular joint is a thin, oval plate made of non-vascular fibrous connective tissue located between the mandible's condyloid process and the cranium's mandibular fossa.
Proteoglycan 4 or lubricin is a proteoglycan that in humans is encoded by the PRG4 gene. It acts as a joint/boundary lubricant.
A rheumatoid nodule is a lump of tissue, or an area of swelling, that appears on the exterior of the skin usually around the olecranon or the interphalangeal joints, but can appear in other areas. There are four different types of rheumatoid nodules: subcutaneous rheumatoid nodules, cardiac nodules, pulmonary nodules, and central nervous systems nodules. These nodules occur almost exclusively in association with rheumatoid arthritis. Very rarely do rheumatoid nodules occur as rheumatoid nodulosis in the absence of rheumatoid arthritis. Rheumatoid nodules can also appear in areas of the body other than the skin. Less commonly they occur in the lining of the lungs or other internal organs. The occurrence of nodules in the lungs of miners exposed to silica dust was known as Caplan’s syndrome. Rarely, the nodules occur at diverse sites on body.
Fibroblast-like synoviocytes (FLS) represent a specialised cell type located inside joints in the synovium. These cells play a crucial role in the pathogenesis of chronic inflammatory diseases, such as rheumatoid arthritis.
Pain in the hip is the experience of pain in the muscles or joints in the hip/ pelvic region, a condition commonly arising from any of a number of factors. Sometimes it is closely associated with lower back pain.
