How do joints form? Discuss in detail the types of joints and their functions.

(N/A) Joints are structural arrangements of tissues that connect two or more bones at the place of their articulation.
$\Rightarrow$ Joints are essential for all types of movements involving the bony parts of the body.
- Joints are points of contact between bones or between bones and cartilages. The force generated by the muscles is used to carry out movement through joints,where the joint acts as a fulcrum.
Joints are classified into $3$ major structural forms:
$(1)$ Fibrous joints,$(2)$ Cartilaginous joints,$(3)$ Synovial joints.
Fibrous joints: These are immovable joints that do not allow any movement. This type of joint is seen in the flat skull bones which fuse end-to-end with the help of dense fibrous connective tissues in the form of sutures to form the cranium.
$\Rightarrow$ Cartilaginous joints: The bones are joined together with the help of cartilages. The joint between adjacent vertebrae in the vertebral column follows this pattern. It permits limited movements.
Synovial joints: These joints are characterized by the presence of a fluid-filled synovial cavity between the articulating surfaces of the two bones. Such an arrangement allows considerable movement and helps in locomotion and other movements. Examples include:
$(i)$ Ball and socket joint (between humerus and pectoral girdle)
$(ii)$ Hinge joint (knee joint)
$(iii)$ Pivot joint (between atlas and axis vertebrae)
$(iv)$ Gliding joint (between carpals)
$(v)$ Saddle joint (between carpal and metacarpal of thumb)