Sheep Brain Dissection
Quarter 2 Project
Andrew Ruiz
Andrew Ruiz
John Horton
Science Class
1-2-13
Sheep Brain Dissection Report
A one in a lifetime experience presented itself recently in my Biology
Class. I got a chance to dissect a sheep brain and get up close and
personal with the structure of its unique design. With each type of brain
there will be differences in size, structure, and brain regions, but the
general structures and their area of location are relatively the same or very
similar. During this lab I cut open a sheep brain and labeled all the divided
structures that allow a sheep to survive and sustain life when everything
worked as one. Taking part in this experiment helped me better understand
how the brain works and what makes the human brain stand out from all
the rest.
Before taking part in this experiment I had to prepare myself with the
necessary materials to dissect this sheep brain such as.
- Gloves
- Goggles
- Toothpicks/Labels
- Pointers
- Scissors
- Tweezers
- Scalpel
Sheep Brain Dissection Guide and Steps when completing this
procedure.
1. Place the brain on a dissection tray, dorsal side up
2. Observe the structure of the of the sheep brain
3. Identify the cerebrum and the medial longitudinal fissure which separates
the right and left hemispheres of the cerebral cortex
4. Locate the four lobes of the cerebrum. At the anterior portion of the brain
is the frontal lobe, which controls motor functions. Dorsal to this side is the
parietal lobe, which receives and processes somatic sensory information.
Inferior to the parietal lobe are the temporal lobes that take care of
receiving and processing auditory sensations. The dorsal portion of the
cerebrum makes up the occipital lobe, which receives and processes
sensations from the eyes.
5. Locate the cerebellum, which is inferior to the occipital lobe of the
cerebrum. The cerebellum has an outer cortex and is folded it controls
muscle coordination.
6. Place the brain on the dissecting tray, ventral surface up. Locate the
medulla, pons, brain stem and spinal cord.
7. Next identify the olfactory bulb, which lies below the frontal lobe of the
cerebrum and the optic chiasma. The optic chiasma looks like an x-shape
structure that is formed by the crossover of the right and left optic nerves.
8. Place the brain on a dissection tray, dorsal side up. Using your fingers,
gently widen that medial longitudinal fissure. Insert a scalpel into the fissure
and cut through the corpus callosum connecting the two cerebral
hemispheres. Continue to cut, dividing the cerebrum, cerebellum, and
brainstem into two longitudinal halves.
9. Each hemisphere contains a lateral ventricle, referred to as the first and
second ventricles. Locate the third and fourth ventricles. The fourth
ventricle connects to the central canal of the spinal cord and also connects
to the third ventricle by a cerebral aqueduct.
10. With the cut side facing up, locate the following parts: thalamus,
hypothalamus, pineal body, pons, and medulla.
11. Observe the cut surface of the cerebrum. In medial section, the white
matter of the cerebellum forms a branched like pattern.
12. Locate the midbrain region, located inferiorly between the thalamus and
pons. This area contains important nerve tracts. Dorsal areas of the
midbrain are concerned with response to visual and auditory stimuli.
13. Make a cross section through a cerebral hemisphere just anterior to the
thalamus. Examine the cross section and identify the inner white matter
and outer gray matter.
14. Remove the cerebellum and the remainder of the cerebral hemisphere
by dissecting away everything dorsal to the floor of the lateral ventricle.
This will expose an unfolding of the cerebral cortex, called the
hippocampus which is involved with emotion and memory.
15. Remove the hippocampus to locate the remainder of the thalamus.
16. Once you have observed all the structures of the brain, dispose of the
specimen in accordance with your teacher’s instructions.
After completing this dissection lab I realized many things that I didn’t
know before about the brain. For example where structures are like the
pons, medulla, and four lobes and how they help assist the brain in its
everyday activity. I even discovered what the difference is between white
matter and gray matter. The difference is white matter is located in the
center on the brain and gray matter is located on the outside layer of the
brain so they are fairly close but in different locations. Also that gray matter
can gather more information and can hold it longer than white matter can.
Taking part in this opportunity taught me what makes the human brain
stand out in comparison to the sheep brain. An example can be we are
considered smarter than a sheep because our brain is several times larger
than a sheep’s brain which allows us to do many more special things that is
not possible for any other organism on this planet. Also we have more folds
in our brain that allows us to carry a lot more information compared to a
sheep brain with much less. Lastly one key ability the human brain has that
makes us different from any other species is our ability to talk and to think
before we act likes most organisms that react off instinct. Many of these
reason are why I recommend learning more about the brain because it can
help you understand what makes our brain and other creatures brain
function in the way they do in each of are similar but very different ways of
life and help you know what affects your brain for better or for worse and
how you can improve as a person based off this information.