Sheep Brain Dissection Guide
Sheep Brain Dissection Guide
Sheep Brain Dissection Guide
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<strong>Sheep</strong> <strong>Brain</strong> <strong>Dissection</strong><br />
<strong>Guide</strong><br />
Good<br />
Luck!!<br />
Laurie Hayes
To begin<br />
• Get gloves and a rubber apron or lab coat.<br />
Goggles are available if you would like<br />
them.<br />
• Pick up dissection tray, dull probe, pins<br />
and labels<br />
• Obtain a sheep brain and share this with a<br />
partner (or 2)<br />
• Rinse the sheep brain to remove<br />
preservative
Meninges of the <strong>Brain</strong><br />
<strong>Brain</strong> is protected by the skull and 3 layers of membranes called<br />
meninges
Observe Meninges<br />
• Examine the brain to see if there is a tough outer<br />
coat…This is the DURA MATER (literally means “tough<br />
mother”)<br />
• Now look for the stringy, web-like ARACHNOID MATER<br />
(literally means spider mother) beneath and stuck to the<br />
dura mater. The space under the arachnoid, the<br />
subarachnoid space, is filled with cerebrospinal<br />
fluid and contains blood vessels.<br />
• Look deeper and see an thin transparent membrane that<br />
follows the contour of the ridges (gyri) and valleys (sulci)<br />
of the brain. This is the PIA MATER ( means tender<br />
mother)
Questions<br />
• What is the function of the meninges<br />
• Describe the following meninges:<br />
Dura mater, Arachnoid mater, and Pia<br />
mater<br />
• What is meningitis
Main <strong>Brain</strong> Regions<br />
• Identify the cerebrum,<br />
brain stem) and<br />
cerebellum on your<br />
brain<br />
• Draw picture of sheep<br />
brain and label<br />
structures<br />
Cerebrum<br />
Cerebellum<br />
<strong>Brain</strong> stem
Questions<br />
• Which part of the brain allows for<br />
1) Balance<br />
2) Breathing<br />
3) Hearing and Vision
Human vs <strong>Sheep</strong><br />
• Compare the various<br />
areas of the sheep<br />
brain (cerebrum, brain<br />
stem, cerebellum) to<br />
the human brain.<br />
#4. How is it the same<br />
and How is it different<br />
Human brain
Identify Dorsal Structures<br />
• With the dorsal<br />
side up, identify<br />
the cerebral<br />
hemispheres, gyri,<br />
sulci,and<br />
longitudinal fissure<br />
on your sheep<br />
brain
Questions<br />
• What does the<br />
longitudinal fissure<br />
divide<br />
• What is the difference<br />
between gyri and<br />
sulci<br />
• What is the purpose<br />
of the gyri and sulci
Lobes of the Cerebrum<br />
• Find the 4<br />
lobes of the<br />
brain-frontal,<br />
parietal,<br />
occipital,<br />
and temporal<br />
• Using pins<br />
label each lobe<br />
• Teacher check
Questions<br />
• Name the lobe that functions in<br />
a) Hearing<br />
b) Vision<br />
c) Touch<br />
d) Movement
Corpus Callosum<br />
• At the longitudinal fissure, gently separate<br />
the two hemispheres and look down<br />
between them for the thick band of white<br />
fibers. This is the corpus callosum<br />
• What is its function
Identify Ventral Structures<br />
• Place the sheep brain<br />
ventral side up.<br />
• Identify the olfactory<br />
bulb, optic nerve,<br />
optic chiasm<br />
• Using pins label each<br />
structure.<br />
• Draw and label the<br />
structures in lab<br />
writeup
Questions<br />
• How does the human brain’s olfactory<br />
bulb differ from the sheeps<br />
• Which is able to smell more odors<br />
• Look at the optic chiasma. What happens<br />
to the optic nerve (vision) at the optic<br />
chiasma<br />
• Which side of the occipital lobe (right or<br />
left) “sees” for the right eye
<strong>Brain</strong> Stem<br />
• Look at the three<br />
parts of the brain<br />
stem-the midbrain<br />
(cerebral peduncle<br />
and mammilary<br />
body), pons and<br />
medulla oblongata<br />
• Pin and label parts<br />
• Teacher check
Function<br />
• Mammillary bodies<br />
serve as relay<br />
stations for reflexes<br />
related to sense of<br />
SMELL<br />
• Cerebral Pedunclegroup<br />
of myelinated<br />
nerves
Questions<br />
• Label your diagram with parts of midbrain<br />
and brain stem<br />
• What is the function of the medulla<br />
oblongata and pons<br />
• Could you survive without them<br />
• Why or Why not
Identify dorsal structures<br />
• Carefully pull the<br />
cerebellum away from<br />
the cerebrum. Don’t<br />
break any structures<br />
off.<br />
• Identify the pineal<br />
body, superior<br />
colliculi, and inferior<br />
colliculi.
Functions-Reflex Centers<br />
• Inferior Colliculimovement<br />
of head<br />
and trunk in response<br />
to sound stimuli<br />
• Superior Colliculimovement<br />
of eyes,<br />
head and neck in<br />
response to visual<br />
stimuli
Pineal Gland<br />
• Produces the<br />
hormone melatonin at<br />
night<br />
• Melatonin is the sleep<br />
hormone
• What is the function<br />
of the Pineal body<br />
Questions
Midsagittal Section<br />
• Obtain a brain the has been cut in half<br />
• Locate the brain stem parts: the medulla<br />
oblongata, the pons, cerebrum, and cerebellum
Cerebellum<br />
• Look at the cross section of the<br />
cerebellum. The inner structure is called<br />
the arbor vitae (living tree).<br />
Why is this a good name for it
Midsagittal Section<br />
• Locate the corpus callosum, thalamus,lateral<br />
ventricle, fourth ventricle and cerebral aqueduct
Questions<br />
– What is the function of the ventricles<br />
– The cerebral aquaduct allows for the<br />
circulation of the cerebral spinal fluid through<br />
the ventricles. What do you think would<br />
happen if the duct became blocked<br />
– How would that affect brain tissue
The End!!<br />
Good bye or in sheep language<br />
BAA BAA
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