Types of Joints

Joints

Types of Joints

Synarthroses (Immovable Joints)
- Definition: These joints have the surfaces of the bones in direct contact, connected by connective tissue or hyaline cartilage.
- Examples:
  - a) Synchondrosis:
  - A temporary joint where cartilage is converted to bone.
  - Example: Growth plate.
  - b) Suture:
  - The bones are connected by a thin layer of fibrous connective tissue.
  - Example: Sutures of the skull.
  - c) Gomphosis:
  - A conical process fits into a socket.
  - Example: Teeth in the jaw.
Amphiarthroses (Slightly Movable Joints)
- Definition: The bony surfaces are united by cartilage.
- Examples:
  - a) Syndesmosis:
  - Two bones united by an interosseous ligament.
  - Example: Distal tibio-fibular joint.
  - b) Symphysis:
  - Bony surfaces are connected by a piece of fibrocartilage disc.
  - Examples: Pubic symphysis, intervertebral discs.
Diarthroses (Freely Movable Joints)
- Definition: Most of the joints in the body. The bony surfaces are covered with hyaline cartilage, connected by ligaments, and lined by a synovial membrane (with fluid).
- Examples:
  - a) Ginglymus (Hinge Joint):
  - Articular surfaces molded together to permit motion in one plane only.
  - Example: Elbow.
  - b) Trochoid (Pivot Joint):
  - Allows for rotation only; a ring moves around a process.
  - Examples: Atlas rotating on dens, radial head articulating with the humerus.
  - c) Condyloid (Ellipsoidal Joint):
  - An ovoid surface fits into an elliptical cavity.
  - Examples: Temporomandibular joint (TMJ), knee joint.
  - d) Saddle Joint (Sellaris):
  - Opposing surfaces are concavo-convex.
  - Example: Carpo-metacarpal joint of the thumb (trapezium-1st metacarpal).
  - e) Spheroidal (Ball and Socket Joint):
  - A globular head fits into a socket.
  - Examples: Femur into acetabulum, humeral head into glenoid fossa.
  - f) Gliding Joint (Arthrodial):
  - Two planar surfaces articulate.
  - Example: Vertebrae articulating with each other (joint of Luschka, facet joint).