Nathan Niec
Bio 156 Online
4-16-13
LAB
Chicken Leg Dissection
Procedure:
Put on gloves and collect your
tools.
Thoroughly rinse and dry one
chicken leg. Place it in the dissecting tray.
Examine the outside skin tissue.
This is the epidermis and the dimples are where feathers emerged.
Using scissors and forceps.
Cut the skin and peel it away from
the muscle.
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.
Describe how the connective
tissue looks and feels. What type of connective tissue is this?
The connective tissue appears to be slightly yellow/white, smooth,
and thin. The connective tissue surrounding the muscle fibers between
the skin in muscle is fascia and fat tissue.
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.
Describe the arrangement of
the muscle bundles.
The individual muscle fibers seem to stick together, takes quite a
bit of force when from the fingers considering the surface area of
the muscle fibers. The bundles separate, but in different size
bundles depending on which ones continue to connect. They are a
bright red color and from what I already know about muscle fibers
they had a hefty blood supply.
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.
What sort of connective
tissue are tendons composed of?
Tendons are dense connective tissue.
Remove a single muscle by cutting
the tendons and peeling the muscle away from the bone.
What sort of muscle tissue
is represented? How do you know?
Skeletal muscle tissue is represented, which is obvious due to the
origin of the muscles and their connection to the bone sections via
tendons and ligaments. The muscle fibers run parallel to the bones.
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?
There are several small white strands within the muscle fibers,
however it is hard to differentiate the nerves from the different
small deposits of fat.
What is the physical
difference in the tendon of the insertion when compared to the
origin?
The origin seems to be a thicker tissue than the insertion. The
origin is more stationary therefore I believe that the insertion has
to be thinner in order to have the ability to stretch towards the
origin.
Remove all remaining muscle to
expose the bones of the chicken leg.
What is the soft material
inside a bone?
The soft material inside a bone is called bone marrow.
Name three specific types of
cells present here. Do not break the bone; it is sharp!
The cells inside the bone are osteocytes, osteoclasts and
osteoblasts.
Name three functions of
bone.
The
functions of bone are to protect, blood cell production, support,
shape and storing calcium.
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.
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.
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
What type of connective
tissue composes the ligaments?
Ligaments are made up of collagen fiber bundles.
Figure 2 is provided in a
separate document.
Label Figure 2 with the
names of the joints you observed and the motion they make.
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.
Dispose of materials as directed.
Make sure to wash your hands, tools, and work station with plenty of
soap and water.
(Tiger Cubs, National Geographic Society)
