Question

From the following, select the examples of the 3rd class lever-
A. Triceps causing extension at elbow
B. V Sit-Up position
C. Biceps causing flexion at the elbow
D. Sit-Ups
Choose the correct answer from the options given below:

• A. A, B and D only
• B. A, and C only
• C. A, B and C only
• D. C and D only

Hint:

In a third class lever, effort lies between the fulcrum and the load. Biceps curl is the classic example.

Answer 1

The Correct Option is D

Step 1: Test used:
For each example, ask where the effort acts. If it acts between the pivot and the load, the lever is third class.

Step 2: Elbow flexion:
The biceps attaches close to the elbow, and the hand carries the load far from it. Effort is in the middle. So C is third class.

Step 3: Sit-up:
The stomach and hip flexor muscles pull the trunk about the hip joint with the load at the upper body. Effort is in the middle, so D is third class.

Step 4: Elbow extension and V sit-up:
Triceps extension and the V sit-up balance position each have the pivot between the two forces. That is a first class lever, so A and B are out.

Step 5: Result:
Only C and D are third class levers, option (4).

Final Answer:
C and D only. \[ \boxed{\text{Option 4}} \]