7.3.3 Synovial Joints

• They are freely moveable joints.
• The ends of bones are covered with hyaline cartilage and held together by a surrounding, tube like capsule of dense fibrous tissue.
• The joint capsule is composed of an outer layer of ligaments and an inner lining of synovial membrane, which secretes synovial fluid.

• Hinge joints — elbow, knee, and finger joints.
• Ball-and-socket joints — shoulder and hip joints.
• Pivot joints — between the first two vertebrae in the neck.
• Gliding joints — carpal joints in the wrist, tarsal joints in the ankle, and facet joints in the spine.

Summary Table of Joints

Science, Technology and Society Connections

Name the techniques for joint replacement.

• Many joints of the body can be replaced by artificial joints.
• Joint replacement is called arthroplasty.
• Artificial joints are usually composed of metal, such as stainless steel, titanium alloys, in combination of modern plastics, such as high-density polythene, silastic or elastomer.
• The bone of the articular area is removed on one side.
• This procedure called partial joint replacement or hemi-replacement technique.
• When both sides of the articular area are removed it is called total joint replacement technique.
• The artificial articular areas are glued to the bone with a synthetic adhesive, such as methyl methacrylate.

Relate the bipedal posture of man with his skeleton and musculature.

• Curvatures of vertebral column help to balance the body for bipedal stance.
• The intervertebral discs lend flexibility to the vertebral column and absorb vertical shock.
• The structure of the pelvis, in its attachment to the vertebral column, permits upright posture and locomotion on two appendages (bipedal locomotion).
• Certain muscles are active posture muscles, whose primary function is to work in opposition to gravity.
• For example, the strong, complex muscles of the vertebral column are adapted to provide support and movement in resistance to the effect of gravity.
• Thus, the skeleton and muscular systems maintain the bipedal posture of man.

Intermediate Level

Types of Joints

Types of Synovial Joints

Joint Replacement

Formula / Mathematical Form

Not applicable to this topic.

Solved Example

Not applicable to this topic (descriptive topic).

Important Points

• 1. Joint is a place where two bones or bone and cartilage come together.
• 2. Study of joints is called arthrology.
• 3. Joints are classified as fibrous, cartilaginous, and synovial.
• 4. Fibrous joints are immoveable.
• 5. Fibrous joints have no joint cavity.
• 6. Examples of fibrous joints: sutures of skull, tooth socket.
• 7. Cartilaginous joints are slightly moveable.
• 8. Cartilaginous joints have no joint cavity.
• 9. Examples of cartilaginous joints: pubic symphysis, intervertebral disc.
• 10. Synovial joints are freely moveable.
• 11. Synovial joints have hyaline cartilage and joint capsule.
• 12. Synovial fluid is secreted by synovial membrane.
• 13. Examples of synovial joints: hinge, ball-and-socket, pivot, gliding.
• 14. Hinge joints: elbow, knee, finger joints.
• 15. Ball-and-socket joints: shoulder, hip.
• 16. Pivot joints: between first two vertebrae.
• 17. Gliding joints: carpal, tarsal, facet joints.
• 18. Joint replacement is called arthroplasty.
• 19. Partial joint replacement: one side removed.
• 20. Total joint replacement: both sides removed.

Remember

• - **Joint** = articulation
• - Arthrology = study of joints
• - Fibrous joints = immoveable
• - Cartilaginous joints = slightly moveable
• - Synovial joints = freely moveable
• - Suture = fibrous joint in skull
• - Pubic symphysis = cartilaginous joint
• - Hinge joint = synovial joint (elbow, knee)
• - Ball-and-socket joint = synovial joint (shoulder, hip)
• - Pivot joint = between first two vertebrae
• - Gliding joint = carpal, tarsal, facet joints
• - Arthroplasty = joint replacement

Common Mistakes

• 1. Confusing the types of joints — Fibrous (immoveable), cartilaginous (slightly moveable), synovial (freely moveable).
• 2. Mixing up the examples — Sutures = fibrous; pubic symphysis = cartilaginous; elbow = synovial.
• 3. Forgetting the role of synovial fluid — Lubricates the joint.
• 4. Confusing arthrology and arthroplasty — Arthrology = study of joints; arthroplasty = joint replacement.
• 5. Mixing up the types of synovial joints — Hinge, ball-and-socket, pivot, gliding.
• 6. Forgetting the structure of synovial joints — Hyaline cartilage, joint capsule, synovial membrane.
• 7. Believing fibrous joints are moveable — Fibrous joints are immoveable.
• 8. Mixing up cartilaginous and synovial joints — Cartilaginous = slightly moveable; synovial = freely moveable.
• 9. Forgetting the role of ligaments — Ligaments connect bones.
• 10. Mixing up partial and total joint replacement — Partial = one side; total = both sides.

Quick Revision

A joint or articulation is a place where two bones or bone and cartilage come together. The scientific study of the structure and function of joints is called arthrology. The joints are classified as fibrous joints (immoveable), cartilaginous joints (slightly moveable) and synovial joints (freely moveable). When the adjacent bones are directly connected to each other by fibrous connective tissue consisting mainly of collagen, it is called fibrous joint. Examples: Most bones of the skull called suture; the shaft regions of the long bones in the forearm and in the leg; the root of a tooth and the socket in the maxilla or mandible. At a cartilaginous joint, the adjacent bones are united by cartilage, a tough but flexible type of connective tissue. Examples: Costal cartilages that attach ribs to the sternum; Pubic symphysis and intervertebral disc. Synovial joints are freely moveable joints. The ends of bones are covered with hyaline cartilage and held together by a surrounding, tube like capsule of dense fibrous tissue. The joint capsule is composed of an outer layer of ligaments and an inner lining of synovial membrane, which secretes synovial fluid. Examples: Hinge Joints (elbow, knee, and finger joints), Ball-and-Socket Joints: (shoulder and hip joints), Pivot Joints (between the first two vertebrae in the neck), Gliding joint (carpal joints in the wrist, tarsal joints in the ankle, and facet joints in the spine).

60-Second Revision

• Joint = articulation
• Arthrology = study of joints
• Fibrous joints = immoveable
• Cartilaginous joints = slightly moveable
• Synovial joints = freely moveable
• Suture = fibrous joint in skull
• Pubic symphysis = cartilaginous joint
• Hinge joint = synovial joint (elbow, knee)
• Ball-and-socket joint = synovial joint (shoulder, hip)
• Pivot joint = between first two vertebrae
• Gliding joint = carpal, tarsal, facet joints
• Arthroplasty = joint replacement
• Warning: Fibrous joints are immoveable; cartilaginous joints are slightly moveable; synovial joints are freely moveable

NEXT TOPIC

• Chapter:
• 7. Support and Movement

• Topic:
• 7.4 DISORDERS OF SKELETON

Source: