In anatomy, the term "articulation" refers to an arrangement of structures that keeps two or more contiguous bony surfaces together. Thus, articulation represents a set of elements (fibrous tissue and/or cartilage, ligaments, capsules, membranes) that regulate the connection between two skeletal segments.
A joint is a point in the body where bones meet. They make movement possible by making the skeleton flexible. The main bones that form the joints include the following:
- Synovial joints: knee, wrist, shoulder, elbow, ankle, and hip joints (freely movable)
- Semi-mobile joints: articulation of the spine (restricted flexibility)
- Fixed joints: joints of the bones of the skull or pelvis (immovable)
Joints are classified by how much movement they allow (function) or what they are made of (structure). Most allow free movement, some only allow movement in certain ways and others allow no movement. By use of scientific terminology, we speak respectively of synovial joints, synarthrosis joints and amphiarthrosis joints.
In regards to joint disorders, the three most common types include: osteoarthritis, arthritis, and traumatic injuries. Osteoarthritis is the most common joint disorder and occurs when the joints become swollen and more difficult to move. Arthritis refers to a joint condition that causes inflammation of one or more joints. Traumatic injuries are characterized by two bones separating from their meeting point. They may caused by a fall, sudden impact or other form of trauma. Other disorders may involve cancers and birth defects (such as hip dislocation). Seeking medical attention is essential in order to verify the cause of the disorder and determine the most appropriate form of treatment. Most treatment options tend to depend greatly on the disorder in question, its severity and an individual’s condition. They may include antibiotic treatment and physical therapy, however in more severe cases, surgery may be necessary.
What are semi-mobile joints?
Semi-mobile joints, also known as amphiarthrosis joints, refer to the joints that are characterized by limited movement. Such examples include the vertebra, ribs and spine. In the spine articulation, the bones that form the joints are coated with cartilage and joined together by interosseous and peripheral ligaments that only allow the execution of some movements. Slightly movable joints are a part of the skeletal system and include the joints between the vertebrae and pubic symphysis. There are two types of semi-mobile joints:
- Symphysis: A slightly moveable joint in which the articulating surfaces of the articulating bones are covered with hyaline cartilage and the bones are attached together by a layer called fibrocartilage. Ex: the pubic symphysis and the sacrococcygeal symphysis
- Synchondrosis: An immovable joint in which the material connecting the articulating surfaces is hyaline cartilage. Ex: the first sternocostal joint
What function do semi-mobile joints serve?
The main function of the joints is to allow both movement and flexibility. They tend to be classified by the degree of their possible movement, the number of bones involved and the complexity of the joint.
The main function of the semi-mobile joints is to allow certain movements of the body to be made, as well as act as supporting structures.
