Levers | Skeletal System 09 | Anatomy & Physiology

Summary

This video introduces the concept of levers, focusing on the anatomy and physiology of lever systems in the human body. It explains key components of levers: fulcrum, load, effort, and lever arm. The video details the three types of levers—first, second, and third order—highlighting how each operates and providing real-life examples like neck movements, calf raises, and bicep curls. The presenter uses a simple mnemonic (FLE: Fulcrum, Load, Effort) to help viewers remember the order of the levers. The video encourages questions and engagement from viewers.

Takeaways

• 🔺 The fulcrum is the pivot point of a lever, often represented by a joint or contact point with the ground.
• 📦 The load, also called resistance, is the object or mass that the lever system is trying to move, such as a dumbbell or the body's weight.
• 💪 The effort refers to the force applied to the lever system, typically the muscular force in anatomy and physiology.
• 🦴 The lever arm is the bone on which the muscle exerts its force, acting as the lever in the system.
• 1️⃣ A first-order lever has the fulcrum between the load and the effort, like the neck lifting the head.
• 2️⃣ In a second-order lever, the load is between the fulcrum and the effort, such as in a calf raise where body weight is centered over the ankle.
• 3️⃣ A third-order lever places the effort between the fulcrum and the load, like a bicep curl where the muscle insertion is central to the movement.
• 🧠 First, second, and third-order levers can be remembered using 'FLE': fulcrum is central in first, load in second, and effort in third.
• 🧍 Most levers in the human body are third-order, where the effort is centrally located between the fulcrum and the load.
• 💡 Common examples in the body: first-order (neck), second-order (calf raise), and third-order (bicep curl).

Q & A

What is the fulcrum in a lever system, according to the script?

The fulcrum is the point at which the lever arm pivots. In anatomy, this is usually a joint or a contact point, such as where the feet or hands meet the ground.

How is the load defined in the context of a lever system?

The load, sometimes known as resistance, is the mass or object that the lever system is set up to move. In human anatomy, this can include items like a dumbbell, a football, or even the body’s own weight.

What does the red arrow represent in the script’s explanation of levers?

The red arrow represents the effort, which is the force applied to the lever system. In anatomy, effort refers to the muscular force that contracts to pull on a bone.

What is a lever arm in anatomical terms?

In anatomy, the lever arm is the bone or bones upon which the contracting muscles exert their force or effort.

How is a first-order lever defined in the script?

A first-order lever has the fulcrum positioned between the load and the effort. The fulcrum doesn't have to be in the exact center but must be between the other two components.

What is the difference between a second-order lever and a first-order lever?

In a second-order lever, the load is placed in the center, with the fulcrum at one end and the effort at the other. In contrast, a first-order lever has the fulcrum in the center.

What arrangement defines a third-order lever?

A third-order lever has the effort placed in the center, with the fulcrum and load at opposite ends. The effort is applied between the fulcrum and the load.

What is the memory tool suggested in the script to remember the types of levers?

The memory tool is '1-2-3 FLE,' which stands for fulcrum in the center for the first order, load in the center for the second order, and effort in the center for the third order.

Can you give an example of a first-order lever in the human body?

A good example of a first-order lever is in the neck, where the atlas vertebra acts as the fulcrum, the head’s weight is the load, and the posterior muscles of the neck provide the effort to lift the head.

What is an example of a second-order lever in human movement?

Standing on your tiptoes is an example of a second-order lever. The fulcrum is the contact point with the ground, the load is the body's weight, and the effort is provided by the calf muscles via the Achilles tendon.

What is the most common type of lever in the human body, and can you provide an example?

The most common type of lever in the human body is a third-order lever. An example is the bicep curl, where the elbow joint is the fulcrum, the dumbbell is the load, and the bicep's insertion point provides the effort.