Joints and Body movements Exercise 10

Joints are essential structures in the human body that enable us to move and manipulate objects around us. They provide a stable base for supporting our body weight while allowingfor flexibility and movement. This exercise review sheet covers some key concepts related to joints and body movements, including the different types of joints, examples of body movements, and the role of muscular contractions.

Types of Joints

There are several types of joints, each with unique characteristics that allow for different movements. Below are some of the main types of joints:

1. Hinge Joints: These joints allow for flexion and extension movements in a single Plane. They are located at the knee, elbow, and ankle.

2. Pivot Joints: These uniaxial joints allow for rotational movement around a single axis. An example is the atlantoaxial joint.

3. Condyloid Joints: These biaxial joints allow for flexion, extension, abduction and adduction in various planes. Examples include the metacarpophalangeal joints of fingers and the radiocarpal joint of the wrist.

4. Saddle Joints: Similar to condyloid joints, these biaxial joints allow for flexion, extension, abduction, and adduction. The first carpometacarpal joint of the thumb is a common example.

5. Ball-and Socket Joints: These multiaxial joints allow for a wide range of movements including flexion, extension, abduction, adduction, circumduction, and medial and lateral rotation. The shoulder and hip joints are examples of ball-and-socket joints.

Body Movements

Body movements refer to the various ways in which our bodies change position or orientation. These movements can be categorized into two main types: open-chain movements and closed-chain movements. Open-chain movements involve moving one end of the body (the prime mover) relative to the other end (the fulcrum), while closed-chain movements involve moving the entire body as a single unit around a fixed point (the center of rotation).

Muscular Contractions

Muscle contractions are necessary to move the body's joints and bones. Skeletal muscle works in concert with the nervous system to produce movement. The process of generating force and movement involves the nervous system sending signals to the muscles, which then respond by contracting and moving the骨骼.

Example: Flexion and Extension at the Elbow

Let's consider an example of how elbow flexion and extension are accomplished. Flexion occurs when the bicep muscles contract and the upper arm moves towards the body's midline. This action decreases the angle between the humerus and radius. Extension occurs when the triceps muscles contract and the upper arm moves away from the body's midline. This action increases the angle between the humerus and radius.

Muscle Action During Motion

As the joint moves through its range of motion, muscles act in various ways to produce movement. For example, during arm extension at the shoulder joint, the latissimus dorsi muscle performs a reverse pupose, helping to abduct the arm. Additionally, the pectoralis major and minor muscles work together to medially rotate the arm.

Review Questions

1. What are the three most common types of joints in the body?

2. How many degrees of freedom does a hinge joint have?

3. What is the difference between a pivot joint and a condyloid joint?

4. Name two muscles that work together to cause flexion of the knee joint.

5. During an ankle sprain, which muscle group is typically affected?

Glossary

• Synovial Joints: Joints that allow for considerable freedom of movement, characterized by a fluid-filled gap between the articular surfaces.

• Ball-and-Socket Joints: Joints that have a round head that fits into a cup-like socket, allowing for extensive movements in multiple directions.

• Hinge Joints: Joints that allow for flexion and extension around a single axis, such as at the knee, elbow, and ankle.

• Pivot Joints: Uniaxial joints that allow for rotation around a single axis, such as the Atlantoaxial joint.

• Condyloid Joints: Biaxial joints that allow for flexion/extension, abduction/adduction, and circumference movements, such as the metacarpophalangeal joints of fingers.

• Saddle Joints: Biaxial joints that allow for flexion/extension, abduction/adduction, and circumference movements, such as the first carpometacarpal joint of the thumb.

• Open-Chain Movement: A movement in which one end of the body moves relative to the other, without moving the whole body as a single unit.

• Closed-Chain Movement: A movement in which the entire body moves as a single unit around a fixed point, such as the center of rotation at the knee joint.

• Muscles: Organized tissues responsible for movement, responsible for pulling on bones to produce force and movement.

##Understanding the different types of joints and movements performed by the body is crucial for mastering various physical activities and maintaining good health. Exercise and physical therapy can help improve strength, flexibility, and coordination, leading to better overall movement and performance.