Dissection: Sheep Brain
Overview: The nervous system is the control center for the entire human
body and all of its processes, with the central nervous system being the
headquarters of the control center. The brain and spinal cord are the two
structures that make up the central nervous system. Today you will be
dissecting a sheep brain, which although is much smaller than a human
brain, has many of the same structures organized in the same way.
Procedures:
1. Review lab safety procedures, appropriate use of dissection tools, and proper dissection etiquette prior to
beginning. Make sure you have all of the protective safety gear and dissecting instruments you will
need prior to getting started.
2. Remove the packaging and place the sheep brain in the center of the dissection tray. There may be a
thick layer of tissue, called the meninges, surrounding the brain. The outermost layer is the dura
matter. You will need to carefully remove this layer in order to observe the brain more clearly.
3. Once the dura matter is removed, observe the brain from several angles. Locate the cerebrum,
cerebellum, brain stem, and spinal cord. Notice the how the cerebrum is divided into left and right
hemispheres. The cleft between the two sides is the longitudinal fissure. The nerve fibers that connect
these hemispheres are the corpus callosum.
4. Notice another cleft between the cerebrum and the cerebellum. This is the transverse fissure.
5. See if you can locate the four lobes of the cerebrum – the frontal, parietal, occipital, and temporal
lobes.
6. Notice the folds and grooves of the brain. Each fold is called a gyrus, and each groove is called a
sulcus.
7. Now carefully make a sagittal cut along the midline of the brain. With the two sides open now and
mirroring each other, see if you can locate all of the same parts you were able to find externally.
8. Look at the cerebellum. The different branches you see are called the arbor vitae, which means tree of
life. They are essentially white matter that brings sensory and motor information to and from the
cerebellum.
9. Identify the various cavities in the brain. These are called ventricles. They contain choroid plexus,
which makes the cerebrospinal fluid that the brain and spinal cord are surrounded by.
10. You should now be able to see the different sections of the brain stem (the midbrain, pons, and
medulla oblongata) as well as the diencephalon, which is posterior to the forebrain and surrounded by
cerebrum (which is why you couldn’t see it externally), between the cerebrum and the brainstem. The
diencephalon has three key parts: the thalamus, hypothalamus (that contains the pituitary gland), and
the epithalamus (that contains the pineal gland.) Locate each structure.
11. Make any more observations you need. Before you clean up, make one last transverse cut across the
frontal lobe of the cerebrum. This will allow you to see the difference between the gray and white
matter that compose the brain. The gray matter is mostly composed of nonmyelinated neurons. The
white matter is mainly composed of myelinated axons that form connections among the gray matter.
© It’s Not Rocket Science® 2019 1
Overview: The nervous system is the control center for the entire human
body and all of its processes, with the central nervous system being the
headquarters of the control center. The brain and spinal cord are the two
structures that make up the central nervous system. Today you will be
dissecting a sheep brain, which although is much smaller than a human
brain, has many of the same structures organized in the same way.
Procedures:
1. Review lab safety procedures, appropriate use of dissection tools, and proper dissection etiquette prior to
beginning. Make sure you have all of the protective safety gear and dissecting instruments you will
need prior to getting started.
2. Remove the packaging and place the sheep brain in the center of the dissection tray. There may be a
thick layer of tissue, called the meninges, surrounding the brain. The outermost layer is the dura
matter. You will need to carefully remove this layer in order to observe the brain more clearly.
3. Once the dura matter is removed, observe the brain from several angles. Locate the cerebrum,
cerebellum, brain stem, and spinal cord. Notice the how the cerebrum is divided into left and right
hemispheres. The cleft between the two sides is the longitudinal fissure. The nerve fibers that connect
these hemispheres are the corpus callosum.
4. Notice another cleft between the cerebrum and the cerebellum. This is the transverse fissure.
5. See if you can locate the four lobes of the cerebrum – the frontal, parietal, occipital, and temporal
lobes.
6. Notice the folds and grooves of the brain. Each fold is called a gyrus, and each groove is called a
sulcus.
7. Now carefully make a sagittal cut along the midline of the brain. With the two sides open now and
mirroring each other, see if you can locate all of the same parts you were able to find externally.
8. Look at the cerebellum. The different branches you see are called the arbor vitae, which means tree of
life. They are essentially white matter that brings sensory and motor information to and from the
cerebellum.
9. Identify the various cavities in the brain. These are called ventricles. They contain choroid plexus,
which makes the cerebrospinal fluid that the brain and spinal cord are surrounded by.
10. You should now be able to see the different sections of the brain stem (the midbrain, pons, and
medulla oblongata) as well as the diencephalon, which is posterior to the forebrain and surrounded by
cerebrum (which is why you couldn’t see it externally), between the cerebrum and the brainstem. The
diencephalon has three key parts: the thalamus, hypothalamus (that contains the pituitary gland), and
the epithalamus (that contains the pineal gland.) Locate each structure.
11. Make any more observations you need. Before you clean up, make one last transverse cut across the
frontal lobe of the cerebrum. This will allow you to see the difference between the gray and white
matter that compose the brain. The gray matter is mostly composed of nonmyelinated neurons. The
white matter is mainly composed of myelinated axons that form connections among the gray matter.
© It’s Not Rocket Science® 2019 1
