Question

How many saddle joints can be traced in the human body?

A. 2

B. 4

C. 8

D. 10

Answer 1

Hint: Meeting point of two bones is called a joint. There are different types of joint in the human body and the saddle is one such joint. It is present at the carpal bone of thumb and tarsal bone of the foot.

Complete answer:

A joint is a point where two or more bones meet. Based on its mobility joints can be immovable, slightly movable and freely movable.  Freely movable joints are also called synovial joints. In the synovial joints two bones consisting of a cartilage lined cavity filled with fluid called synovial fluid. Due to the presence of synovial fluid, all parts of the joint move smoothly against each other. These are the most common joints in the human body and Knees, elbows and shoulders are examples of synovial joints.

On the basis of the shape and structure of the joint, synovial joints are classified into six different types of joints. These are ball-and-socket joints, hinge, pivot, condyloid, saddle joint and planar joint. 

Saddle joint is a type of synovial joint in which the surface of the opposite bones form concave-convex structure to form a saddle.  The two bones fit together and it provides flexibility. In humans, saddle joints are only found in two joints, one the carpal bone of thumb and the second is the tarsal bone of the foot.

Thus, option (B) is the correct answer. 

Note: Synovial joints are the only joints that have a space between the two bones. This space is called the synovial cavity which is filled with synovial fluid. Synovial fluid reduces friction between the bones and allows for greater movement. Saddle joint allows greater movement than hinge joint.