1. ESS 303 – Biomechanics
Levers and Joints

2. Lever Components Lever Fulcrum Effort Resistance
MAE: Moment Arm of Effort
MAR: Moment Arm of Resistance
Three types of levers

3. Levers (Type I) E
MAE
MAR R F

5. Levers (Type II)
MAE E R
MAR F

7. Levers (Type III)
MAR R E
MAE F

9. Equilibrium of a Lever Formula
E * MAE = R * MAR
Question: Two children are sitting on opposite sided of a balanced sea-saw. One child’s body mass is 50 Kilograms and he/she is seated 1.5 meters from the fulcrum. How far from the fulcrum is the other child if his/her body mass is 40 Kilograms?
Answer: 50 Kg * 1.5 M = 40 Kg * X M
X = Meters

10. Articulations Synarthrodial (Sutures of skull)
Amphiarthrodial (Between vertebrae)
Diarthrodial (Common)

11. Joints Articulations Connection point between two bones
Six basic types of joints in the body

12. #1 – Hinge

13. #2 – Gliding or Plane

14. #3 – Condyloid

16. #4 – Pivot

17. #5 – Ball & Socket

18. #6 – Saddle