Final Answer:
Synovial joints are characterized by the presence of a joint cavity filled with synovial fluid, allowing for free movement. This distinguishes them from other types of joints. Therefore, the correct option is b. All synovial joints are freely movable.
Step-by-step explanation:
In the classification of joints, it's crucial to understand the characteristics of each type. Synarthrotic joints are immovable, amphiarthroses are slightly movable, and diarthroses are freely movable. Synovial joints fall under the diarthroses category. These joints have a joint cavity filled with synovial fluid, providing lubrication and allowing for a wide range of movements. Therefore, the correct answer is b, stating that all synovial joints are freely movable.
Amphiarthroses, mentioned in option c, actually refer to slightly movable joints, not immovable ones. This is an important distinction in joint classification. Cartilaginous joints, mentioned in option d, do not typically have a joint cavity, and their movement is more restricted compared to synovial joints. Hence, option d is incorrect.
Understanding these distinctions is crucial in anatomy and physiology. Synovial joints play a pivotal role in the body's movement, enabling actions like flexion, extension, and rotation. The synovial fluid within the joint cavity reduces friction, allowing for smooth motion. In summary, the classification of joints is based on their structure and degree of movement, and the correct identification aids in comprehending the body's biomechanics.
Therefore, the correct option is b. All synovial joints are freely movable.