Chapter 8: The Skeletal System - Articulations

Joints, also known as articulations, are defined as connections between bones.
These connections can either permit movement or be entirely immovable.
Joints are typically held together by various tissues, including cartilage, fluid, or dense connective tissues.
The functional classification of joints is based on the amount of movement they allow.
- Immovable or slightly movable joints (e.g., in the axial skeleton) are designed for stability.
- Freely movable joints (e.g., in the appendicular skeleton) are more common and allow a wide range of motion.

These joints allow no movement and are characterized by very strong connections between bones.
Structural Categories within Synarthroses:
- Fibrous Joints:
  - Suture: Found exclusively in the skull, where bony edges interlock tightly and are held by short, dense connective tissue fibers. (Example: Between bones of the skull)
  - Gomphosis: A specialized joint formed by the insertion of a tooth into the alveolar fossa of the maxillae or mandible. Held in place by periodontal ligaments. (Example: Periodontal ligaments between teeth and jaws)
- Cartilaginous Joints:
  - Synchondrosis: A joint where hyaline cartilage separates the ends of the bones involved. (Example: Epiphyseal cartilages, such as the growth plates in long bones, or the articulation of the first rib with the sternum)
- Bony Fusion:
  - Synostosis: Occurs when bones fuse together to form a single, solid mass of bone, typically resulting from the ossification of other articular forms. (Example: Portions of the adult skull, such as along the frontal suture; epiphyseal lines after the fusion of epiphyseal cartilages)

These joints permit limited movement, offering a balance between stability and flexibility.
Structural Categories within Amphiarthroses:
- Fibrous Joints:
  - Syndesmosis: Bones are connected by relatively long connective tissue ligaments, allowing for some