LAB - CHICKEN LEG DISSECTION

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 looks white, silky, fatty and a little stretchy like elastic. It is fibrous connective tissue.

Removing the Chicken Skin

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 muscles bundles are skeletal muscles tissues. They are long, fibrous groups of cells with connecting fibrous tissue called fascia. The end is joined with the tendon that joins it to the bone.

Separating the muscles

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 made of tough, connective tissue which joins bones to muscles.

Finding the Tendons

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?

It is skeletal muscle because it connects to tendons which attach to bone.

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? ___Yes

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

A tendon is broader where it attaches to the bone at the origin, but it is compact and narrower at insertion where it is attached to moveable bone.

Tendon shapes differ at origin and insertion points

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 Yellow bone marrow.

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

Three types of cells present here are dense, compact bone, spongy bone and the central cavity with yellow bone marrow inside it.

c.       Name three functions of bone.

Three functions of bone are support, allows movement and the formation of blood cells.



Looking inside the bone joints



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?

Denser fibrous is what ligaments is made up of to attach bone to bone.

Figure 2 is provided in a separate document.

b.      Label Figure 2 with the names of the joints you observed and the motion they make.

c.       On Figure 2, sketch one muscle origin (the name of the bone indicates the insertion) and one muscle insertion you can see in the leg.

Labeling the joints and drawing in a muscle

14.       Dispose of materials as directed.  Make sure to wash your hands, tools, and work station with plenty of soap and water.