1. Muscle Arrangement

2. Fascicle Arrangement
Muscle fibers in skeletal muscle form bundles called fascicles
These single fibers are parallel to each other and end in a tendon
However the arrangement of the muscle fascicles will determine the type of muscle, the strength of the muscle and the function of the muscle

3. Fascicle Arrangement
In a parallel muscle the fascicles are parallel to the long axis of the muscle
Most of the muscles in the human body are parallel muscles
Some are broad and flat while others are long with a plump body
The biceps brachii are good examples of this

4. Fascicle Arrangement
Convergent muscles extend over a broad area and converge on a common attachment site
The fascicles often fan out from their attachment site where they cover a large area
The pectorals muscles are excellent examples of convergent muscles

5. Fascicle Arrangement
Pennate muscles form a common angle with the tendon
This means the tendon is straight, while all of the muscle fibers come off the tendon at a common angle
These muscles commonly contain more fascicles than skeletal muscle and can create more tension when they contract

6. Fascicle Arrangement
Circular muscles are fascicles that are contained around an opening
These fascicles will decrease the size of the opening when they contract
The fascicles will increase the size of the opening when they relax
These are more commonly called sphincters

7. Skeletal Muscle Levers
Skeletal muscles do not work in isolation
Muscles work in groups in order to help perform tasks that are essential to the body
For this we need to revisit physics…

8. Skeletal Muscle Levers
A lever is a bar that pivots at a fixed point
The fixed point that a lever pivots is called the fulcrum
The lever moves based on the application of force in a give direction

9. Skeletal Muscle Levers
A first class lever is seen when the fulcrum lies between the load and the applied load
This can be seen in a child’s seesaw
It can be seen in the muscles that control the head and neck

10. Skeletal Muscle Levers
A second class lever is seen when the load is applied between the force and the fulcrum
An example of this is the wheelbarrow
In humans we can see this in our legs when we walk

11. Skeletal Muscle Levers
A third class lever is seen when the force is seen between the load and the fulcrum
This is seen in a baseball bat
The fulcrum is the wrist, the force is the force of the bat and the load is the ball
In humans this is the most common type of lever, seen in the arm

12. The Origin of the Story…
Muscles have defined parts that dictate the job of the muscle
Each part of the muscle is located in a specific part of the body and had a specific function
These specific functions will be a great advantage to understanding the basics of the location of skeletal muscles

13. The Origin of the Story…
In a muscle fiber, both ends of the myofibril are able to contract and move together
You would think this would create a scenario where a skeletal muscle contracts evenly
This is not the case
Generally one end of the muscle is held in a fixed position
During a contraction, the other end of the muscle will move to the opposite end

14. The Origin of the Story…
The site where the end of the muscle attaches to in a fixed position is called the origin
The site where the moveable end attaches to another structure is called the insertion
Generally the origin is proximal to the insertion

15. Diagram

16. The Origin of the Story…
The actual movement of the muscle is defined as the action
The action of a muscle describes how it moves in the body and what end of the muscle manipulate the body
The action is different for every muscle

17. Muscle Groups
Muscles have the responsibility to move the skeleton around in the world
However, one muscle cannot move the body in all different directions
This is because one contraction can only shorten one muscle
To move the body in all different directions you need a complex series of muscles

18. Activity!
ourceid=chrome- instant&ion=1&espv=2&ie=UTF- 8#q=qwop%20unblocked
Pull out your chromebooks and go to the following link
This is a great simulator that shows how hard it is to make muscles work together
People who get over 5m can write their names and distances on the board
High Scores

19. Muscle Groups
Since each muscle group has different muscles that have different jobs
Each job in a muscle group is defined and has a specific purpose
A muscle agonist is a prime mover
Agonist is the primary muscle that produces the desired movement in a joint

20. Muscle Groups
An antagonist is a muscle whose action opposes that of the particular agonist
These muscles contract and produce the opposite movement of the agonist
A good example of this is the triceps brachii
Their contractions produce extension in the elbow
This is opposite of the biceps brachii

21. Muscle Groups
When a synergist muscle contracts it is helping move the agonist
These muscles are vitally important to moving the agonist
Many muscle groups contain multiple synergists
The hips and knees contain large amounts of strong synergists

22. Muscle Groups
Some muscle groups are designed to prevent the movement of joints
This can create a stable origin for other muscles
These muscles are often synergists
These muscles are called fixators