HBS 4.2.1

Essential Question How do muscles assist with movement of the body and of substances around the body?

Learning Objectives You will understand that there are three types of muscle tissue that differ in structure and function.

Success Criteria After researching the three types of muscles and viewing them under a microscope: Write a compare and contrast composition distinguishing between the three types of muscles.

4.2.1 Intro All movement in the human body, from wiggling a toe or swimming a mile to eating and digesting a sandwich, is the result of muscle action.

In previous lessons, you have learned about connective and nervous tissue. In this unit, you will explore the structure and function of another incredible tissue -- the muscle.

When we think of muscles, we usually focus on the muscles that move our bones and allow us to move about the Earth; the tissues we see from the outside.

But inside the amazing human, you will find other types of muscle tissue that work silently to move substances around the body.

Your heart keeps beating and your food continues to digest even when you fall fast asleep and close your conscious mind for the day.

Without muscle moving blood or distributing nutrients from food, the human machine would power down.

There are 206 bones in the human body, but over 600 skeletal muscles allow our bodies to move in different directions.  

Over sixty of these muscles are found in your face alone Over sixty of these muscles are found in your face alone. You use forty of these muscles every time you frown, but only twenty muscles when you smile. The human body is even built to make it easier to be happy than to be sad.

Skeletal muscles are attached to bones with tough cords or sheets called tendons and these bones meet other bones at junctions called joints. The contraction or shortening of muscles pulls on bone and moves the body.

In this activity, you will observe and compare the structure and function of the three types of muscle tissue. You will explore the structure of skeletal muscle both by looking at slides and by creating a model of a muscle unit. Before you move on to building actual muscle groups, a series of demonstrations will help you see that the placement of muscles on bones follows specific patterns and rules. These rules will later help you construct specific muscle groups on your Maniken®.

Complete part 1 of 4.2.1 Research 3 types of muscle- Create a comparison table for your information. Use microscope on low and high power to view prepared slides – Use colored pencils to sketch. Be prepared to write a compare and contrast composition on the three types of muscle tissue. Type of muscle Striations? (Y/N) Voluntary? (Y/N) Location in Body Function in Body Histology Skeletal Muscle Smooth Muscle Cardiac Muscle

Wrap-up Concept map pieces! Put it together.

4.2.1 Day 2 Review your notes from yesterday. Write a compare and contrast paragraph about the three types of muscles. You have ten minutes! ☺

Learning Essential Question – How do muscles function to help us move and move substances within our bodies? Today’s objective: Understand the structure of muscle tissue. Success criteria: Illustrate and label a muscle fiber with the key terms: fascicle, endomysium, perimysium, AND epimysium

Flip book Follow the instructions to create a flip book. Title the Flip book – Muscle fibers and Muscle Rules

Muscle cell Pick up one piece of spaghetti. Each piece of spaghetti will represent one skeletal muscle cell or fiber

Each muscle fiber is enclosed by a delicate membrane called the endomysium. For the purposes of this activity, the yellow outer coating of the spaghetti represents this membrane.

Lay the piece of spaghetti along your arm Do you think if it was a muscle cell it would be strong enough to lift your arm.

Have one member of your maniken pair pick up a bundle of spaghetti This bundle of fibers represents a fascicle.

Place the bunch of spaghetti on the end of a piece of plastic wrap Each fascicle, however, is covered by a membrane called the perimysium.

Roll the spaghetti up in the plastic to represent the perimysium. Do not worry about making it perfectly smooth. The wrinkles in the plastic wrap can be used to represent the dense irregular tissue that makes up this layer.

Hold up the completed fascicle. When you pull the ends taut, they will notice that this tissue has little to no bumps. These ends represent dense regular connective tissue. Notice that connective tissue covers the entire fascicle. It is not just found at the ends.

You are not done…. Fascicles group together to form a skeletal muscle. Several groups can combine their fascicles to form a whole muscle. Four to five fascicles works well. These fascicles are bound together by an even tougher outer membrane called the epimysium. One member of the team for each muscle should wrap the combined fascicles in another piece of plastic wrap. This layer of wrap will represent the epimysium.

Twist the plastic wrap on each end of the completed muscle. At the ends of the muscle, the epimysia blend together to form tendons, cordlike structures that attach muscle to bone, cartilage or other connective tissue.

Unwrap the muscle and return a fascicle to each student pair Review key anatomy as the muscles are unwrapped. Refer to your spaghetti muscle and to a reliable website, textbook page or other diagram as they sketch basic muscle anatomy in your flip book. Illustrate and label a muscle fiber with the key terms: fascicle, endomysium, perimysium, AND epimysium Each pair should keep your fascicle on your desk. This model will be used later in the activity to discuss striations and the rules of muscle attachment.

Building muscle on your Maniken We are going to learn the Muscle Rules! First, lets review the terms VENTRAL and DORSAL

Locate the ventral side and use a pencil to place a dot on the lateral and medial side of the radial groove (about halfway up the humerus).

Locate the ulna just below the fold of the elbow Locate the ulna just below the fold of the elbow. Do you see the hollowed out area in the antecubital region? Place a pencil dot above this area.

These dots each represent an attachment point for a muscle. Note that there are at least two attachments (in this case three) and the muscle will cross a joint at the elbow. You just discovered rule #1.

Rule #1: Muscles must have at least two attachments and must cross at least one joint. To build the brachialis muscle on the ventral forearm of the Maniken®…. Using terra cotta clay, form two balls about the diameter of a nickel Rolling the clay between the tabletop and a palm, roll each ball into a long carrot. The total length of the carrots should stretch from the humeral attachment to the ulnar attachment. Keep rolling if the carrot is too short or pinch some off if the carrot is too long. Bring the fat part of the carrots together, leaving the tops free (rabbit ears).

Attach the two free ends to the humeral attachments. Place the combined fat end across the elbow and attach the end to the ulnar attachment. Pinch off any extra clay. Use your thumb to press the clay muscle onto the arm. All of the muscles in the room do not have to look identical.

Explore the motion of the muscle Using your left thumb to represent the humeral attachments and your left middle finger to represent the ulnar attachment, place your left hand on your right arm where the attachments would be. “Pull” your forearm towards your heart and watch the position of your fingers. You should notice that your index finger and thumb are closer together than when you started. You just discovered rule #2!

Rule #2: Muscles always “pull” and get shorter. Repeat the motion and identify which attachment is “pulling” or moving closer to the other attachment. Is the ulnar attachment is being pulled (and moved forward), while the humeral attachment stays stationary?

The attachment that moves is known as the insertion of the muscle. The insertion is usually the distal attachment. The attachment that does not move and pulls the other attachment toward it is referred to as the origin. The origin is usually the proximal attachment If you combine these ideas, you discover Rule #3.

Rule #3: The attachment that moves is known as the insertion and the attachment that remains stationary is known as the origin.

Extend your arms out in front of your bodies. 180◦

Show the movement of the muscle you have built. This time pay attention to what happens to this angle when the muscle shortens. Do the angle decrease? What do we call motion at a joint that decreases the angle between articulating bones. We call this movement flexion and thus a muscle such as this is referred to as a flexor.

For every muscle you put on your manikens, you should list the origin and the insertion as well as the action of the muscle in your lab journals. Look at the brachialis muscle you have built and identity each location or action. Muscle Location of origin Location of insertion Action of muscle Brachialis

For every muscle you put on your manikens, you should list the origin and the insertion as well as the action of the muscle in your lab journals. Look at the brachialis muscle you have built and identity each location or action. Muscle Location of origin Location of insertion Action of muscle Brachialis halfway down the humerus (both medial and lateral of the radial groove) proximal ulna flexes elbow

Flex your arms one more time, but stop at the end of the movement. If muscles only pull, then how can the arm be straightened? Is there another muscle must pull to get the arm back to 180°? Where do you think this muscle would be placed? Act out the action of this muscle.

What do we call motion at a joint that increases the angle between articulating bones? We call this movement extension and thus a muscle that controls this movement is referred to as an extensor. If we combine this information, you will discover Rule #4.  

Rule #4: Muscles that decrease the angle between ventral surfaces of the body are known as flexors. Muscles that increase the angle between ventral surfaces of the body are known as extensors

Create an extensor: the triceps medial head, on the maniken arm.  Place a pencil dot halfway up the dorsal side of the humerus. Place another dot just distal of the elbow onto the ulna. Remember Rule #1???

Using terra cotta clay, form a ball the diameter of a nickel. Roll the ball into an even tube. Again, check to make sure this tube reaches from attachment to attachment. Attach the ends of the clay tube to dots on the humerus and on the ulna. Since the back of the humerus is flat, the muscle shapes to the bone and is also flat. Use your thumbs to flatten the clay. Remove any clay that makes its way to the ventral side.

Act out the action of this muscle With your right arm in the flexed position, place your left thumb on the back of the humerus and your left index finger on the back of your elbow. “Pull” with your index fingers and the angle should increase to 180°. Repeat the motion and relate the position of your fingers to Rules 2, 3 and 4. Since the angle in this motion increases, the muscle is an extensor.

List the origin, insertion and action of the muscle Location of origin Location of insertion Action of muscle Triceps Medial head

Triceps Medial head Muscle Location of origin Location of insertion Action of muscle Triceps Medial head proximal half of dorsal humerus distal of elbow on the ulna extends elbow

Where are flexors and extensors? ______________ are on the ventral side of the body and ____________ are located dorsally.

For smooth movements to occur, can both extensors and flexors be contracting at the same time? When the flexors are pulling, the extensors are relaxing. Once you get that, You’ve figured out Rule #5

Rule #5: Muscles work in opposing pairs.

Pick up your spaghetti fascicles. Remember that muscle fibers are parallel and all pull in the same direction. Place your spaghetti fascicle on the dorsal section of your arm representing the brachialis muscle that you built on your maniken. Do you see how the muscle fibers point towards the point of insertion?

Use a pencil or a wire tool to add striations to the clay muscles they have built. Remember: these striations run in the direction in which the muscle moves. Now you know rule number 6

Rule #6 Rule #6: Muscle striations point to the attachments and show the direction of pull.