CHICKEN LEG DISSECTION LAB An incredible amount of information can be found by examining a chicken leg! Please read all the details of this fun project. In preparation for the lab exercise, I have provided the format for posting to your blog: Use headings to identify these components of your project. 1. Introduction. Just a few sentences introducing the objective. 2. Procedure. a. A step-­‐by-­‐step description of your process with at least six photos. b. Answers for the questions corresponding to each step. Please write question number and a, b, c designation for each answer. 3. Conclusion. Summarize what your experiment demonstrated and what you learned from it. The Lab Exercise Objectives: To identify and describe the structure and function of tendons, ligaments, and cartilage; identify muscles and their function; observe bone and its components; gain experience dissecting fresh biological material. THIS LAB EXERCISE REQUIRES CAREFUL USE OF SCISSORS AND KNIFE. USE EXTREME CAUTION WITH THESE SHARP OBJECTS. THE CHICKEN LEG IS SLIPPERY! YOU MIGHT WANT TO ENLIST A FRIEND OR FAMILY MEMBER TO HELP HOLD WHILE YOU CUT. Materials: Chicken leg (thigh + drumstick) a. If you do not normally keep these around or would not be likely to purchase for food, try asking at the meat department of your favorite store, they might give you one or sell you just one really cheaply. b. If you absolutely cannot (for whatever reason) perform the dissection on a chicken leg, just let me know, and I will give you alternative project. Examination gloves, if available Tray or plate Scissors Knife Paper towels, soap Procedure: Please document your work in photos and take notes as you proceed. 1 1. Put on gloves, if you have them. 2. Thoroughly rinse and dry one chicken leg. Place it on a plate or tray. 3. Examine the outside skin tissue. 4. Using scissors and a sharp knife, begin to work slowly and carefully to cut the skin and peel it away from the muscle below. Notice the clear connective tissue that holds the skin to the muscles. As you peel off the skin, you may need to cut away some of this connective tissue. Work slowly and carefully with scissors and knife until all skin is removed. 5. Connective tissue appearance. a. Describe the appearance of the connective tissue. b. What type of connective tissue is this? 6. Observe the yellowish clumps of fat tissue found outside the skin. a. Describe the fat. b. What are at least two of its functions? c. Give the biological term for the type of cells that store fat. 7. Observe bundles of pale, pink muscle tissue surrounding the bones. 8. Observe, with your naked eye bundles of muscle tissue surrounding the bones. Separate the bundles of muscles by separating them out with your fingers. Begin by inserting your thumb into the muscle of the lower leg. You will need to push forcefully through the connective tissue covering the muscle, but it will give way at the natural separations between the muscle bundles. Continue separating the muscle into bundles by forcing your thumb and fingers through the muscle until you are able to distinguish several separate bundles. a.
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Describe the arrangement of the muscle bundles. Do you see just one muscle, or are there many muscles present? How can you tell? Describe any patterns or arrangements you observe such as bundles surrounded by connective tissue. 9. The strong, shiny, white cords, called tendons, hold the muscle to the bones. Some of these tendons will pull away from the bone as you separate the muscle bundles. Find the tendons of the chicken leg. Using the dissection scissors, cut across the tendons at Line A (Figure 1). Observe the numerous tendons and pull the freed muscles down and away from the bone, as 2 if you were peeling a banana. Be careful you don't cut any ligaments that attach bone to bone. Look closely at the ligaments. Examine the two bones in the lower leg. The large bone (Bone A) is the tibia. The small, toothpick-­‐like bone (Bone B) is the fibula. Figure 1. From: Mrs. Gillum Science. http://www. mrsgillumscience.com. Accessed 4/6/13. a. What sort of connective tissue are tendons composed of? 10. Skeletal muscle function. a. What are skeletal muscles? b. What are their functions? 11. Remove a single muscle by cutting the tendons and peeling the muscle away from the bone. Nerves are generally thin, threadlike white strands found between the muscle and the nearest bone. Look for the nerve in your specimen. The texture is much different from a tendon or bone. It is rather slippery. a. Did you find it? 12. Remove the muscle that covers Joint B by cutting parallel to the femur, upward toward the backbone. Remove pink muscle tissue until you see a shiny white sheet of ligament that covers the joint. Present is an exterior ligament that holds the femur in the hip socket a. What type of connective tissue composes the ligaments? 13. Remove all remaining muscle to expose the bones of the chicken leg. 3 14. Cut onto the hinge joint by cutting into the top of the covering of the joint from the femur side. It will become apparent that you must remove the kneecap area to expose the menisci and ligaments within. Pull up on the kneecap 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. 15. Pull the covering back and look into the inside of the joint. You will see more white bands of ligaments holding the bones together. Observe the shiny, white layer covering the ends of the bones is cartilage. It helps the bones slide smoothly when the leg bends. 16. Bend the specimen at Joint B (Figure 1) and rotate the femur in all directions. Refer to pages 113-­‐115 in your textbook and answer these questions. a. What type of joint is this? b. What type of movement is being demonstrated? 17. Cut the ligaments at the joint between the upper and lower leg. Examine how the bones fit into each other. a. Describe the texture of the ends of the bones at the joint. b. What is the specific name of this type of connective tissue? c. What occurs when the cartilage at joints wears away? d. How is a joint of this type built to delay this event? 18. DO NOT BREAK THE RAW CHICKEN BONE. THERE IS DANGER FROM BONE FRAGMENTS FLYING OUT. If you could see inside the bone a. What soft material would you find? b. Name three specific types of cells present here. We will not break it open. c. Name three functions of bone. 19. Explore and examine all the parts before cleaning the area. 20. Dispose of materials as directed. Using warm water and soap thoroughly wash all tools and materials, including your hands and the surface you worked upon. 4