Anatomy - Central Catholic High School



Anatomy

Lab 2 - Chicken Leg Dissection

Name_______________________Date_______

INTRODUCTION: Similar in some respects to the human leg, the chicken leg and thigh are composed of numerous different cells, tissues and organs. These body parts interact and cooperate to allow the chicken to perform a variety of activities such as walking, hopping, sitting, and standing. In this investigation the various tissues and structures of the leg and thigh of a chicken will be located and described. Refer to your text book frequently.

MATERIALS:

• Chicken leg with thigh

• Blunt and sharp dissecting probes

• Scalpel

• Paper towels

• Forceps

• Dissecting pan

• Scissors

• Plastic baggie with tie-wrap

• 10cm of small and large dental floss

PROCEDURE:

1. Become oriented with your particular chicken leg. Identify if it is a right or left leg by deciding lateral, medial, dorsal and ventral regions based on the cut of the lower abdominal/pelvic area. First locate the spine, the rest should be self explanatory. Which leg do you have, right or left? (circle one)

2. Place a chicken leg/thigh in your dissecting pan, medial side up.

CAUTION: Scalpels are very sharp. Use extreme care. Only cut downward and away from your body.

3. Carefully remove the skin and subcutaneous fat. Use fingers, blunt probe, and scalpel. Do not cut any muscle fiber. Where is the fat more numerous, in the thigh or leg? more medial, lateral, anterior, or posterior?

4. You may be able to pull the skin off of the end of the drumstick. When through, be sure to return the leg to the medial side.

5. Now that the skin and fat are off, you can more easily see the muscle fibers. List the different kinds of muscle fiber arrangements can you identify:

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6. Beginning with the lower leg, separate the epimysium from each muscle. Use your fingers, the blunt probe. Dental floss may be helpful in this process. Locate the insertion points of each muscle at the tibia/tarsus joint. What is the purpose of the thin epimysium?

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7. What is the physical difference in the tendon of the insertion when compared to the origin? ___________________________________________________________________

8. Look in your text book for the muscles, tendons, and ligaments of the foot. What page is it found on? ______ Find the band of tough fibrous tissue that acts as a band around the tendons of the lower leg called the INFERIOR EXTENSOR RETINACULUM. There is a similar band around the tendons of the hamstrings on the chicken. It is located on the distal and posterior area of the tibiofibula. Count the number of insertion tendons that are attached through this tissue. How many tendons are attached through this band of connective tissue?________________.

9. Remove the insertion tendons that are attached distally to the tibiofibula.

10. How many different insertions did you find?_____________

11. Now separate the muscles that are attached to the femur as you did with the muscles of the tibiobula. Begin you work carefully on the medial side.

12. You will notice that there are a number of blood vessels deep within the mass of muscles. They probably will be found 2-3cm, posterior to the femur with fat and nerves near by. Describe the physical difference in the artery, compared to the tendons. _______________________________________________

13. Look your text book for the veins & arteries fo the lower limb (leg and foot). What page are they found on? ______ What is the name of the artery that you have just found?

__________________________

14. Are your sure that you found an artery and not a vein?___________ Carefully examine the differences in your book. Can you see any physical difference between the two?____________. If so, What is the difference? ______________________________. Arteries are generally more muscular (thicker) than veins. Follow the artery superiorly as far as you can and locate as many branches as possible.

15. Nerves are generally thin, threadlike white strands found between the muscle and the nearest bone. Look for the nerve in your specimen.

16. Find an image of the nerves of the lower limb or leg & foot in your text book. What page is it found on? ______ What is the name of the nerve that you may have found?___________________

17. Next, remove all of the muscles from the lower leg (tibiofibula) at there origins. Be careful to not cut the ligaments around the knee joint. Scissors may prove to be the most appropriate instrument. Why is this called the tibiofibula and not the tibia and fibula?________________________________________________

18. Now remove the muscles of the femur to expose the knee joint. This need not be a delicate and time consuming task. Be aggressive, as we have seen most of the important tissues already. You will be able to see the “sleeves” that the tendons move through as they contract. Again, try to remove as much of the muscle tissue as possible, without disturbing the knee structure.

19. It will become apparent that you must remove the knee cap area to expose the menisci and ligaments within. Pull up on the knee cap area and cut through it with the scissors. You will have cut through the bursa, a sac that acts as a shock absorber for the knee joint. These are found in every joint.

20. Find images of the knee with the tendons and ligaments. What pages are they found on? ______ Locate the collateral ligaments (medial and lateral). Move the lower leg and gently twist it to see how they act to stabilize the joint. Now carefully remove the lateral and medial collateral ligaments.

21. Locate the medial and lateral menisci and the anterior and posterior cruciate ligaments. Move the bone around to understand their functions more clearly.

22. Flex and extend the lower leg to find the range of motion (R.O.M.) Draw the bones in each case below:

MAXIMUM FLEXION ..........................................................................MAXIMUM EXTENSION

[pic]

23. Now cut, with the scissors, the anterior cruciate ligament. Again, Draw the bones in each case below:

MAXIMUM FLEXION ............................................................................MAXIMUM EXTENSION

24. What is the purpose of these two ligaments? ___________________________________________________________________

• IF TIME RUNS OUT: Place your specimen in a baggie and wrap it up tight with the twist-wrap tie. Write your name on a piece of tape and place the tape on the baggie.

• BE SURE TO WASH (with soap) AND DRY ALL INSTRUMENTS.

• WHEN THIS LAB IS COMPLETED: Write a comprehensive conclusion about what you've learned. Do not simply recap the lab, I know what went on. Discuss what insights you learned and apply this knowledge to this class as well as anything else that is applicable. Discuss errors, and suggest improvements.

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