Anatomy of Joints and Connective Tissues Explained
Anatomy of Joints and Connective Tissues
Glenoid
A complex joint features a meniscus (fibrocartilage) between the articular surfaces (bone). This can be complete or incomplete, depending on whether the meniscus is perforated.
Fascia
Fascia is a sheath of connective tissue that performs several important functions, including acting as a jacket and insulator for one or more muscles. By extension, it applies to any structural envelope that provides support and protection.
Tendon
A tendon is a part of a striated muscle; it is white, strong, and non-contractile. It comprises fibers and connective tissue grouped into bundles.
Aponeurosis
Similar to fascia, an aponeurosis is a flat, sheet-shaped tendon. Its connective tissue fibers are white and bright, histologically similar to common tendons, but with lower innervation and blood supply.
Joint Capsule
The joint capsule is a fibrous membrane that covers the entire joint, preventing excessive movement of bone segments. Together with ligaments, it ensures contact between articular surfaces. It is inserted into the bone near the lining of the articular cartilage. Some joints are fixed at a distance from the articular surfaces and may have a recurrent path to the edge of the articular cartilage. The capsule forms an enclosed space containing the lower end of the femur, the patella, and the upper tibia. The inner lining of this capsule is the synovial membrane, which produces synovial fluid.
Synovial Fluid
Synovial fluid is a clear, viscous substance found in joints, with a consistency similar to egg white. Its composition is that of a plasma ultrafiltrate with an identical ionic makeup. The fluid contains few proteins and cells but is rich in hyaluronic acid synthesized by type B synoviocytes. It reduces friction between cartilage and other tissues, providing lubrication and cushioning during movement.
Rotator Cuff
The rotator cuff is a group of muscles and tendons that provide stability to the shoulder. These muscles connect to the humeral head, maintaining its position within the glenoid fossa of the scapula. This sleeve is continuous with the shoulder joint capsule.
Ligaments
A ligament is an anatomical structure composed of tough fibers that connect bones at the joints. These fibrous bands provide essential stability and facilitate bone movement. Consisting of fibrous connective tissue similar to tendons, ligaments function to unite anatomical structures and provide stabilization between bones and cartilage. They are traditionally classified as straps or cords.