Sheep Brain Dissection And Comparative Anatomy Medical Detectives © 2013 Project Lead The Way, Inc.

Step 1: Working with a partner, obtain a dissection pan, a tool set, toothpicks, and adhesive labels from your teacher. Step 2: Use the toothpicks and folded adhesive labels to make 19 toothpick flags. Label the flags with the following terms: cerebrum, right frontal lobe, left frontal lobe, right parietal lobe, left parietal lobe, right occipital lobe, left occipital lobe, right temporal lobe, left temporal lobe, cerebellum, brain stem, olfactory bulb (two flags), optic nerve (two flags), optic chiasm, corpus callosum, thalamus, and hypothalamus.

Step 3: After your flags are made, put on your goggles, apron, and gloves. Step 4: Remove the rest of the materials from the tray. Spread out the wax paper on the tray. Step 5: I will bring a sheep brain to your group.

Step 6: As you first look at the sheep brain, notice the way the brain matter is folded. This folding increases the surface area of the brain and allows for more nerve cells to process information in the brain. The next 3 slides show views of the brain. Look at each view and turn the brain to see the same views.

Superior (Top) View With Dura matar Without Dura matar

Inferior (Bottom) View With Dura matar Without Dura matar

Sagittal (Side) View With Dura matar Without Dura matar

Step 7: Finding an existing hole, cut the dura mater off. Note how thick it is. Be careful not to cut anything else! It can be hard to remove. Cut and pull firmly but carefully.

Step 8: Place the brain in the tray top side up Step 8: Place the brain in the tray top side up. Use the following slides to help you locate the brain stem. In the sheep brain, the brain stem will exit the brain horizontally. Sheep are four legged animals, so their brain and spinal cord line up horizontally. Humans, on the other hand, are bipedal (two legged) animals. Therefore, the human spinal cord must exit the brain vertically to travel down the spinal column. Use a tape flag to label the brain stem.

Step 9: The structure connected to the brain stem is the cerebellum and will appear as a densely folded structure located at the base of the brain. Use a tape flag to label the cerebellum. Step 10: The largest portion of the brain is the cerebrum. This portion of the brain consists of four lobes. Use a tape flag to label the cerebrum. .

Superior View Cerebrum Cerebellum Brain Stem

Step 11: Place the brain in your dissecting tray with the frontal lobes facing away from you. This positioning will ensure that the right side of the brain is the same as the right side of your body as you continue the dissection. Step 12: Locate and use your tape flags to label the following lobes of the cerebrum: right and left frontal lobes, right and left parietal lobes, right and left occipital lobes, and right and left temporal lobes. Use the following slides to help you. Step 13: Have your teacher check your flag placement before moving to the next step.

Frontal Lobe Parietal Lobe Temporal Lobe Occipital Lobe Cerebrum Frontal Lobe Left Right Parietal Lobe Left Right Temporal Lobe Left Right Occipital Lobe Left Right Cerebellum Brain Stem

Step 13: Have your teacher check your flag placement before moving to the next step. Step 14: Remove the flags and place them to the side. You will use them again. Turn the brain over so that you are viewing the bottom, or ventral side, of the brain with the frontal lobes still facing away from you. Step 15: Label the brain stem, cerebellum and cerebrum. Step 16: Two nerves involved in sensing input from the environment are visible on the surface of the brain. Locate and use your tape flags to label the following structures: A pair of olfactory bulbs may be seen, one under each lobe of the frontal cortex. A pair of optic nerves may be seen as they meet in the optic chiasm, which is the X-shaped structure on the bottom surface of the cerebrum. It is named after the Greek letter chi, c, which it resembles As you work through the following slides, label all the parts it shows.

Inferior View Cerebrum Cerebellum Brain Stem

Step 16: Two nerves involved in sensing input from the environment are visible on the surface of the brain. Locate and use your tape flags to label the following structures: A pair of olfactory bulbs may be seen, one under each lobe of the frontal cortex. A pair of optic nerves may be seen as they meet in the optic chiasm, which is the X-shaped structure on the bottom surface of the cerebrum. It is named after the Greek letter chi, c, which it resembles As you work through the following slides, label all the parts it shows.

Cerebrum Cerebellum Brain Stem Frontal Lobe Left Right Olfactory Bulb Left Right Parietal Lobe Left Right Optic Nerve Left Right Optic Chiasma Temporal Lobe Left Right Occipital Lobe Left Right Cerebellum Brain Stem

Step 17: Stop and have your teacher check your work.

Step 18: Place the brain with the brain stem closest to you and carefully cut along the longitudinal fissure, the natural division between the left and right hemispheres of the cerebrum. Gently cut and separate the two hemispheres of the brain. Continue cutting the cerebellum and brain stem so you have two similar halves.

The cut should look like this The cut should look like this. You only need one side of the brain to finish but you can use both if it is easier.

Step 19: Locate and label with a tape flag the following structures: corpus callosum, thalamus, hypothalamus, brain stem, cerebellum, left frontal lobe, left parietal lobe, left temporal lobe, and left occipital lobe. Use the following slides to help you.

Cerebellum Cerebrum Brain Stem Parietal Lobe Corpus Callosum Frontal Lobe Occipital Lobe Thalamus Brain Stem Hypothalamus Optic Chiasma Olfactory Bulb Optic Nerve

Step 19: Stop and have your teacher come check your work. Step 20: Clean up. Put the wax paper with the brain in the trash. Put your gloves in the trash. Put the googles and aprons on the room table at the back. Put the scissors in the dissecting tray and put the tray on the long table at the back of the room. Let your teacher know you are finished and you may be dismissed to your next class.

COMPARATIVE ANATOMY HUMAN:SHEEP