The human knee joint is a diarthrosis, or synovial joint, made up of multiple different tissues that work together to provide function. Everything from the outer layer of the skin to the core of the bone is necessary for the joint to articulate properly.
The most superficial layer of the knee is the skin, which is the largest organ of the human body and is made up of the epidermis and dermis, which in turn are made up of keratinized stratified squamous epithelium as well as dense, irregular collagenous connective tissue and glands, respectively (4). The most important function of the skin at the knee joint is to provide the first line of defense from the external environment (4). It is also interesting to note that the skin around the knee …show more content…
Skeletal muscle tissue is a voluntary striated muscle tissue that consists of bundles of muscle fibers; each muscle fiber is a long, multi-nucleated cell that contains myofibrils, which account for the visual striations as well as the contractile force of muscular tissue. Myofibrils are made up of a thick filament and a thin filament; the thick filament is myosin and the thin filament is a complex of actin, troponin, and tropomyosin (3)(4). Using calcium and ATP, the thick and thin filaments interact with each other resulting in a power stroke and a shortening of the sarcomere, the skeletal muscle fiber's contractile unit (4). The shortening of multiple sarcomeres in multiple muscle fibers results in the overall contraction of the muscle. Due to the origin and insertion of the muscles around the knee joint, this contractile force allows extension and flexure of the bones that meet at the knee …show more content…
The previously mentioned periosteum is a layer of dense fibrous connective tissue on the outside that is contiguous with the fibrous layer of the joint capsule (4). The inner layer of the periosteum is composed of osteoprogenitor cells that give rise to osteoblasts that create bone matrix (4). Bone matrix is a solid, calcified tissue that provides support for the body and, in conjunction with skeletal muscles, allows for motion (3)(4). At the knee, the epiphyses of the femur, tibia, and fibula meet to form the joint (3). These epiphyses are made of a layer of compact bone just superficial to a deeper layer of spongy bone, also known as cancellous bone (4). Compact bone is a dense system of osteons, which in turn are made up of concentric sheets of lamellae (1)(4). Spongy bone is a less dense web of bone tissue that includes trabeculae and spicules but lack the Haversian systems of compact bone, and the organization and orientation of spongy bone depends on the mechanical stress placed upon it (1)(4). The solid nature of bone tissue also leads to the important function of the patella in preventing hyperextension of the leg by limiting the movement at the knee joint
The most superficial layer of the knee is the skin, which is the largest organ of the human body and is made up of the epidermis and dermis, which in turn are made up of keratinized stratified squamous epithelium as well as dense, irregular collagenous connective tissue and glands, respectively (4). The most important function of the skin at the knee joint is to provide the first line of defense from the external environment (4). It is also interesting to note that the skin around the knee …show more content…
Skeletal muscle tissue is a voluntary striated muscle tissue that consists of bundles of muscle fibers; each muscle fiber is a long, multi-nucleated cell that contains myofibrils, which account for the visual striations as well as the contractile force of muscular tissue. Myofibrils are made up of a thick filament and a thin filament; the thick filament is myosin and the thin filament is a complex of actin, troponin, and tropomyosin (3)(4). Using calcium and ATP, the thick and thin filaments interact with each other resulting in a power stroke and a shortening of the sarcomere, the skeletal muscle fiber's contractile unit (4). The shortening of multiple sarcomeres in multiple muscle fibers results in the overall contraction of the muscle. Due to the origin and insertion of the muscles around the knee joint, this contractile force allows extension and flexure of the bones that meet at the knee …show more content…
The previously mentioned periosteum is a layer of dense fibrous connective tissue on the outside that is contiguous with the fibrous layer of the joint capsule (4). The inner layer of the periosteum is composed of osteoprogenitor cells that give rise to osteoblasts that create bone matrix (4). Bone matrix is a solid, calcified tissue that provides support for the body and, in conjunction with skeletal muscles, allows for motion (3)(4). At the knee, the epiphyses of the femur, tibia, and fibula meet to form the joint (3). These epiphyses are made of a layer of compact bone just superficial to a deeper layer of spongy bone, also known as cancellous bone (4). Compact bone is a dense system of osteons, which in turn are made up of concentric sheets of lamellae (1)(4). Spongy bone is a less dense web of bone tissue that includes trabeculae and spicules but lack the Haversian systems of compact bone, and the organization and orientation of spongy bone depends on the mechanical stress placed upon it (1)(4). The solid nature of bone tissue also leads to the important function of the patella in preventing hyperextension of the leg by limiting the movement at the knee joint