The human skeletal system is a bodily system that functions as a framework which gives proper shape and protection to both the external and internal parts of the human body. The human skeletal system has six major functions in human anatomy including functions of support, movement, protection, blood cell production, storage and endocrine regulation.
Hence, in order to connect the whole skeletal system into one piece, joints or the association of two or more bones are needed. Joints give way to flexible movements and allow the skeletal system to make good on its intended purpose.
Basically, joints are classified structurally and functionally. Structural classification categorizes the joint based on how it connects the bones in the human skeletal system. On the other hand, functional classification is determined by the function which the joint serves.
Thus, joints are classified structurally as fibrous, cartilaginous and synovial while the functional classification includes synarthrosis, amphiarthrosis and dairthrosis.
Fibrous joints are connected by dense connective tissues known as fibrous connective tissue (FCT) which allows relatively rigid and stiff movement. Similarly, there are three sub-divisions of fibrous joints namely sutures, syndesmosis and gomphosis.
Connected entirely by cartilage, an immobile connective tissue composed of chondrocytes, a type of cell which produces collagen and fibers, cartilaginous joints are much more flexible and mobile compared to fibrous joints but are not as freewheeling as synovial joints. More so, cartilaginous joints form growth regions of bones in the human skeletal system.
Synovial joints are the most mobile and movable among the three structural classification of joints. Synovial joints allow bodily and joint movements such as abduction, adduction, extension, flexion and rotation.
Furthermore, there are seven types of synovial joints present in the human skeletal system such joints include, gliding or planar; hinge or the elbow joints; pivot joints; condyloid; saddle; ball and socket joints and compound or the knee joint.
In addition to the structural classification of joints, their are the functional classification as noted above. However, such classifications are similarly associated with the fibrous, cartilaginous and synovial – the structural classification.
Hence, most if not all synarthrosis joints are fibrous while the same can also be applied with amphiarthrosis and dairthrosis, having similar attributes with cartilaginous and synovial joints respectively.
Further classification of joints however, includes biochemical classification or the classification based on their biomechanical properties and anatomical classification which is grouped into 11 sub-classifications.