Types of Joints — Class 12 Biology | Support & Movement

 

🦴 Joints

Definition:
Joints occur where bones meet. They not only hold the skeleton together but also provide mobility.

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🔹 Classification of Joints (Based on Movement)

Immovable Joints (Fixed Joints)

• No movement occurs.
• Example: Sutures in the skull

Slightly Movable Joints

• Allow limited movement.
• Example: Between vertebrae

Freely Movable Joints (Synovial Joints)

Allow a wide range of movements.

• Two main types:
• Hinge Joint
• Ball and Socket Joint

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🔹 Classification of Joints (Based on Structure)

1. Fibrous Joints

• Bones are held together by short collagen fibers embedded in connective tissue.

• No joint cavity present.

• Examples:

• Sutures in skull

• Teeth fixed into jaw

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2. Cartilaginous Joints

• Bones are connected by cartilage (either hyaline or fibrous).
• Allow little or no movement
• Examples:
• Between vertebrae (fibrocartilage)
• Where coxal bones meet in the pelvis (pubic symphysis)

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3. Synovial Joints

• Contain a joint cavity filled with synovial fluid to reduce friction.
• Enclosed by a fibrous capsule lined with a synovial membrane.
• Ligaments may be present to hold bones together.
• Allow free movement.

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🔹 Types of Synovial Joints (Based on Movement)

1. Hinge Joint

• Allows movement in one plane (like the opening and closing of a door).

• Examples: Elbow, Knee
• Muscles Arrangement:
• Each joint has a pair of muscles arranged in the same plane.

• One end (origin) is fixed to the immovable bone.

• Other end (insertion) is attached to the movable bone.

2. Ball and Socket Joint

• Allows movement in several directions (multiaxial movement).
• Consists of a ball-like head fitting into a socket-like cavity.
• Examples: Shoulder, Hip
• Muscles: At least two pairs of muscles act in perpendicular directions to provide maximum flexibility.

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🧩 Summary Diagram (for reference)

Three types of joints:

1. Fibrous – Immovable

2. Cartilaginous – Slightly movable

3. Synovial – Freely movable (hinge, ball & socket)

Interactive MCQ Quiz — Types of Joints (Class 11 Biology)

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