Why Do You Have a Kneecap?

Introduction

• Common belief: Kneecap (patella) protects the knee joint.
• This video explores another important function related to quadriceps muscles.

What is the Kneecap?

• Referred to as the patella, which translates to "little dish".
• Located on the anterior (front) surface of the knee.
• Embedded in a tendon connecting quadriceps muscles to the shin bone (tibia).
• Anatomy names: Pointy portion = apex; top portion = base.

Patella's Role in the Knee Joint

• Positioned in extended leg: Not over internal knee joint anatomy.
• Moves based on leg position: Slides upward when extended; downward when bent.
• Not primarily for protecting joint anatomy, especially since it ossifies (becomes bone) around ages 2-6.

Sesamoid Bones

• Sesamoid bones develop inside tendons subject to high friction, compression, and stresses.
• Common sesamoid bones: Base of thumb (metacarpal phalangeal joint) and big toe (metatarsal phalangeal joint).
• Patella is the largest and most consistent sesamoid bone.

Function of Sesamoid Bones

• Protect tendon from wear and tear.
• Improve mechanical advantage (leverage) of tendons and muscles.

Relationship to Quadriceps

• Quadriceps consist of four muscles: Vastus lateralis, vastus medialis, rectus femoris, and vastus intermedius.
• These muscles converge into the quadriceps tendon, which attaches to the tibial tuberosity.
• Quadriceps pull upward, extending the knee (e.g., standing up, kicking a ball).

Patella and Mechanical Advantage

• Patella creates a lever arm for the quadriceps, enhancing their leverage and strength by up to 30%.
• Leverage concept: Longer lever arm (like a wrench) makes it easier to apply more force.

Whiteboard Explanation

• Diagram: Represents femur, tibia, and patella, showing the lever arm created by the patella.
• Without patella: Decreased distance from axis = reduced leverage.
• Most mechanical advantage occurs in 20-60 degrees of knee flexion.

Biomechanical Importance

• Understanding biomechanics requires knowledge of anatomy, physics, and math.
• Encouragement to explore courses on platforms like Brilliant to deepen understanding.

Conclusion

• The patella is an essential structure for maximizing the strength and functionality of the quadriceps muscles.
• Appreciation for the complexity and efficiency of human anatomy.