Rebekah BIO 156: Chicken Legs

LAB

Chicken Leg Dissection

Image Taken from: http://www.123rf.com/photo_15498129_yellow-chicken-in-green-grass.html. on April 14, 2013

Procedure:

1. Put on gloves and collect your tools.

2. Thoroughly rinse and dry one chicken leg. Place it in the dissecting tray.

3. Examine the outside skin tissue. This is the epidermis and the dimples are where feathers emerged. Using scissors and forceps.

4. Cut the skin and peel it away from the muscle.

5. 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 forceps until all skin is removed.

6. Describe how the connective tissue looks and feels. What type of connective tissue is this?

The connective tissue under the skin, which was holding the skin to the muscle, is areolar connective tissue. It was not very dense, but it did require the use of scissors during the removal process in some areas. It felt slimy and stringy.

7. 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 shiny lining (called fascia) over 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. Describe the arrangement of the muscle bundles.

The muscle bundles seemed to be small groups of long bundles connected together. The bundles did not have breaks in them… meaning that they went from one connection to the other as a continuous structure.

8. 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. Use a probe, if needed, to 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 if you were peeling a banana. 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.

a. What sort of connective tissue are tendons composed of?

Tendons are composed of dense fibrous connective tissue.

9. Remove a single muscle by cutting the tendons and peeling the muscle away from the bone.

a. What sort of muscle tissue is represented? How do you know?

The muscle tissue that is represented is skeletal muscle tissue. I know this because it is connected to the skeleton. The muscles also seem to be composed of long, continuous fibers, which is characteristic of skeletal muscle. It may also be suggested that this muscle is composed of slow-twitch fibers based on the very red appearance.

b. Nerves are generally thin, threadlike white strands found between the muscle and the

nearest bone. Look for the nerve in your specimen. Did you find them?

Not sure if I found them or not. I am sure it was there but I am unclear if I identified it correctly.

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

At the intersection the tendon was more narrow but also more dense. At the origin, it was wide and less dense.

10. Remove all remaining muscle to expose the bones of the chicken leg.

a. What is the soft material inside a bone?

The soft material inside a bone is called marrow.

b. Name three specific types of cells present here. Do not break the bone; it is sharp!

Bones contain osteocytes, osteoblasts, and osteoclasts.

c. Name three functions of bone.

Three functions of bone are support, movement, and protection. Two other functions are mineral storage and blood cell formation.

11. 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 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.

12. 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.

13. Bend the specimen at Joint B (Figure 1) and rotate the femur in all directions. 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?

Ligaments are composed of dense fibrous connective tissue.

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