Factors that determine a joint’s range of motion.
Check all that apply.
A Tendons limit a joint’s range of motion, but muscles play a minor role.
B In many cases, joint movement is limited by the shapes of the bone surfaces.
C Bones are joined by ligaments that limit their movement.
D In many joints, pairs of muscles oppose each other and moderate the speed and range of joint motion.
E The articular surfaces of bones are designed in such a way as to always permit the greatest range of motion at a joint.
The correct answer and explanation is :
The correct answers are:
B. In many cases, joint movement is limited by the shapes of the bone surfaces.
C. Bones are joined by ligaments that limit their movement.
D. In many joints, pairs of muscles oppose each other and moderate the speed and range of joint motion.
Explanation:
1. Bone Surface Shapes (B)
The shape of the bone surfaces within a joint plays a significant role in determining the range of motion (ROM). For example, ball-and-socket joints, like the shoulder and hip, allow a wide range of motion due to their spherical shapes that fit into corresponding shallow sockets. In contrast, hinge joints, such as the knee and elbow, have a more limited range of motion because their bone surfaces are shaped to only allow movement in one plane (flexion and extension).
2. Ligaments (C)
Ligaments are tough, fibrous tissues that connect bones to one another at joints. They provide stability and restrict excessive movement, ensuring the joint does not move beyond its functional range. For example, the knee joint has cruciate ligaments that prevent overextension or excessive rotation, which could lead to injury. Thus, ligaments play a major role in limiting the range of motion to prevent damage and maintain joint stability.
3. Muscle Pairs (D)
Many joints have muscles that work in opposition to each other, which helps control the speed and range of movement. For example, the biceps and triceps work together to control the flexion and extension of the elbow. This balanced muscular activity helps moderate the ROM, ensuring that the joint moves within safe and controlled limits. Without this balance, joints could either overextend or fail to fully extend.
Incorrect Answers:
A. Tendons limit a joint’s range of motion, but muscles play a minor role.
This statement is incorrect. While tendons connect muscles to bones and can influence joint movement, muscles themselves play a much more significant role in joint movement. Muscles generate the force necessary to move joints, and the range of motion depends heavily on muscle flexibility and strength.
E. The articular surfaces of bones are designed in such a way as to always permit the greatest range of motion at a joint.
This is incorrect. While the articular surfaces (the parts of the bones that come into contact in a joint) are designed to facilitate movement, they do not always permit the greatest range of motion. The design of these surfaces can limit movement based on the type of joint and its specific function, as seen in hinge joints and ball-and-socket joints.