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: Understanding the Concept:
In a third class lever the effort acts between the fulcrum and the load. It gives speed and range of movement, and it is the most common lever in the human body.

Step 2: Check statement A:
Triceps causing extension at the elbow is a first class lever. The elbow joint is the fulcrum between the triceps pull and the weight of the forearm. So A is not third class.

Step 3: Check statement B:
In the V sit-up position, the trunk and legs are lifted together and balance on the hips. The hip is the fulcrum and it sits between the two raised ends, so it acts as a first class lever. So B is not third class.

Step 4: Check statement C:
Biceps causing flexion at the elbow: the elbow is the fulcrum, the biceps pulls near the elbow, and the load is in the hand. Effort is between fulcrum and load, so C is a third class lever.

Step 5: Check statement D:
In sit-ups, the hip flexors pull the trunk up. The effort acts between the fulcrum at the hip and the load of the upper body. So D is a third class lever.

Step 6: Compare with options:
Only C and D are correct. This is option (4).

Final Answer:
Biceps flexion and sit-ups are third class levers. This is option (4). \[ \boxed{\text{C and D only}} \]