Sheep Brain Dissection Guide
Student’s Names:
Observations
1. Write down 5 physical characteristics of your sheep brain?
(example: how the brain feels, color of the brain)
a.
b.
c.
d.
e.
2. Take a picture of the LATERAL (outer side) view of your sheep brain; include the
cerebellum and brainstem and paste it here. Label the 4 cerebral lobes and the cerebellum
and brainstem. You can peel the covering halfway back.
Sheep Brain Dissection Guide
Student’s Names:
3. List one or more functions of each lobe.
Frontal Lobe
Parietal Lobe
Temporal Lobe
Occipital Lobe
4. Take a picture of the MEDIAL (inner side) view of the sheep brain and paste it here. Use
the following website to guide you:
http://www.gwc.maricopa.edu/class/bio201/brain/brshpx.htm Label the spinal cord,
medulla oblongata, pons, thalamus, hypothalamus, arbor vitae of the cerebellum,
fornix, lateral ventricle, corpora quadrigemina, corpus callosum, frontal lobe, parietal
lobe, and occipital lobe.
5. Look at your sheep brain and find out whether you have the right or left half
(hemisphere). I have the __________________ _____ half (hemisphere).
6. Find another group that has the half that is opposite to yours and put both halves
together. Describe how big or small the whole brain is compared to familiar object.
Coverings of the Brain
1
The dura mater (tough mother) is a protective covering of the brain. Does your sheep brain
have a dura mater? _________ (Hint: it looks white or purplish.)
2
To take the dura mater off, locate the ROSTRAL end of your sheep brain. Using your thumb
and index finger, peel the dura mater back towards the CAUDAL side. You might have to use the
scissors to snip part of the dura mater at the ROSTRAL end. Remove the dura mater. Take a picture
of the dura mater and paste it here.
3
Try pulling the dura mater apart. What do you notice? Does it rip like a piece of paper?
Sheep Brain Dissection Guide Student Name:
First Dissection Exploring the Neuron and its Parts
1. Place your sheep brain with the cut side (MEDIAL) down. Cut the brain about 1 inch from
the rostral end (where the dent is located).
2. Take a picture of the inside surface view of the piece cut off the brain and paste it here.
a. Label the light and dark areas with their official names
b. Using the probe stick, poke the dark area. How does it feel?
c. Using the probe stick, poke the light area. How does it feel?
Sheep Brain Dissection Guide
Student’s Names:
Comparing Sheep Brains to Human Brains
MEDIAL View of the Human Brain
MEDIAL View of the Sheep Brain
1.
Label the brain parts in both the human and sheep brain pictures.
2.
How are these brains similar?
3.
Why might both brains be similar?
4.
How are they different?
5.
Why would they be different?
DISSECTION OF THE SPINAL CORD
Students’ Names:
1. Examine the spinal cord section and observe the connective tissue and fat covering the
exit of the spinal nerves.
2. Carefully remove these tissues until the spinal nerves can be seen. They are typically
small, white, cylindrical, fibrous structures occurring in pairs about every 1.5' along the
length of the cord. If the cord were still encased within the vertebral column, one pair
of spinal nerves would extend outward between each two vertebrae. The dorsal
(sensory) root of each spinal nerve contains an enlarged segment (dorsal root
ganglion) which distinguishes it from the ventral (motor) root.
3. Use a sharp scalpel or single-edged razor blade to cut the spinal cord in cross section at
the point where a pair of spinal nerves originates. Look at the cut end and identify the
H-shaped inner core of gray mater (tan). The gray mater is composed of the cell bodies
of neurons. The surrounding white mater contains nerve fibers (axons) and owes its
whiteness to the myelin which ensheathes the axons. The white mater contains
bundles of nerve fibers called spinal tracts which conduct impulse to and from the
brain.
4. Observe the deep ventral (anterior) median fissure (mislabeled as tissue)which can be
used as a landmark to distinguish ventral from dorsal.
5. Carefully lift the outermost covering (the dura mater) from the main mass of tissue at
one end of the cord.
6. Cut the dura mater along the entire ventral side of the cord. Using fingers, carefully lay
the dura mater back, observing delicate strands of arachnoid mater and exposing the
roots of the spinal nerves.
7. Try to tear a piece of dura mater with your fingers.
8. Using fingers and forceps gently lift the delicate arachnoid mater which clings to the pia
mater covering the cord.
9. Stretch the arachnoid mater and observe its web like appearance. Notice that is also
envelops the roots of the spinal nerves.
10. Now lift the pia mater which covers the cord. Notice that it contains the blood vessels
of the cord's surface.
11. Take a picture and label the following:
Use the Dissection Guide included in your box to help identify these structures.
a.
b.
c.
d.
e.
f.
g.
h.
Dura mater
Dorsal nerve root
Ventral nerve root
Anterior gray horn
Posterior gray horn
White mater
Ventral (anterior) median fissure
Central canal