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Topic 2: The skeletal and muscular systems
Topic 2: The skeletal and muscular systems
Biomechanics
Biomechanics
Objectives
Objectives
Define a joint and distinguish between fixed and flexible joints.
Describe different types of flexible joints (hinge, ball-and-socket, pivot), stating the type of movement they allow and where they are found in the body.
Identify the key structures within a flexible joint (cartilage, synovial fluid, ligaments) and explain their role in enabling smooth movement.
The function of joints
The function of joints
A joint is a place where two or more bones meet. Most joints:
Are flexible, allowing movement.
Are held tightly together but still allow motion.
Some joints, like those in the skull, are fixed and do not move at all.
Different types of joint
Different types of joint
Joints work in partnership with your muscles to make movement possible.
The type of joint determines the kind of movement that can occur:
Hinge Joints:
These allow movement back and forth in one direction, like a door opening and closing on its hinge.
Examples: Your knee and elbow.
Ball-and-Socket Joints:
These allow movement in almost all directions – forwards, backwards, sideways, and rotation.
The rounded end (ball) of one bone fits into a cup-shaped socket of another.
Examples: Your hip and shoulder.
Pivot Joints:
These allow a rotating or twisting movement.
One bone swivels around another.
Example: The joint in your neck that allows you to turn your head from side to side.
Fixed Joints:
These joints do not allow any movement.
Their main job is to connect bones firmly to provide protection or strength.
Example: The joints between the bones in your skull.
The structure of joints
The structure of joints
Movable joints (like your knees, elbows, and shoulders) have a special structure to ensure bones can move smoothly against each other without causing damage or pain.
Key parts include:
Cartilage:
This is a smooth, slippery, and tough protective tissue that covers the ends of the bones where they meet at a joint.
It acts like a cushion, reducing friction and preventing the bones from grinding directly against each other.
Synovial Fluid:
This is a lubricating (oily) fluid found within the joint cavity.
It acts like oil in a machine, keeping the joint well-oiled so it can move easily and smoothly.
Ligaments:
These are strong, slightly elastic bands of tissue that connect bones to other bones at the joint.
They are crucial for holding the joint together, providing stability, and preventing the bones from moving too far or in the wrong direction.
Key words
Key words
Joint: A place where two or more bones meet.
Flexible joint: A joint that allows movement.
Fixed joint: A joint that does not allow any movement.
Hinge joint: A flexible joint that allows movement back and forth (like a door).
Ball-and-socket joint: A flexible joint that allows movement in all directions.
Pivot joint: A flexible joint that allows a rotating and twisting motion.
Cartilage: Smooth, slippery tissue covering the ends of bones in a joint to prevent rubbing.
Synovial fluid: A lubricating fluid found in flexible joints that reduces friction.
Ligaments: Strong bands of tissue that hold bones together at a joint.
Extension ideas
Extension ideas
Investigate the effects of common joint injuries (like sprains or dislocations) or conditions (like arthritis) on the structure and function of a joint.
Research other types of flexible joints not mentioned (e.g., gliding, saddle) or build simple models of different joint types to demonstrate their range of motion.
Related topics
Related topics
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