BA Nervous System Lab
Part I: Sheep Brain Dissection
Objectives:
1. List and describe the principal structures of the sheep brain
2. Identify important parts of the sheep brain in a preserved specimen
Materials:
Dissection tools and tray, lab gloves, preserved sheep brain specimen, goggles
Procedure:
A. External Sheep Brain:
1. What are the 4 main parts of the brain that we learned about
previously?
2. Turn your sheep brain so that you are viewing its left lateral
aspect. Compare the various areas of the sheep brain
(cerebrum, brain stem, cerebellum) to the picture at right.
Relatively speaking, which of these structures is obviously
larger in humans? Why do you think this is?
3.
Place the sheep brain ventral surface down and identify the following structures:
a. dura mater: the sac-like outermost layer of meninges, may not be present in your specimen.
b. arachnoid mater: the middle layer of the meninges, appears on the brain surface as a delicate “cottony”
material spanning the fissures (you may not be able to locate the arachnoid mater since this layer does not
withstand preservation well).
c. pia mater: the innermost layer of the meninges, tightly adheres to the sulci and gyri of the brain.
a. What is the purpose for the meninges?
b.
What layers of the meninges are visible on your specimen? Describe what they look like.
4. Examine the superior surface of the brain. Notice that, like the human brain, its surface is thrown
into convolutions (fissures/sulci and gyri). Describe how these terms differ.
5. Use the photo at right to help you locate olfactory
bulbs.
a. What are these nerves used for?
b. Why do you think they are larger in sheep
than in humans?
6. Locate the optic chiasma (this is the point where the
two optic nerves cross over each other). What lobe
of the cerebrum will the optic nerve travel to?
7.
Turn the brain so that it is dorsal side up and identify the following structures. Pin these structures with different
colored pins (include key below) and insert a completed picture of the pinned brain below.
a. cerebrum (cerebral cortex ) b. frontal lobe c. parietal lobe d. occipital lobe e. temporal lobe f. cerebellum g. brain stem h. longitudinal fissure -
8.
Turn the brain so that it is ventral side up and identify the following structures. Pin these structures with different
colored pins (include key below) and insert a completed picture of the pinned brain below.
a. olfactory bulb (CN I) b. optic nerve (CN II) c. pons d. medulla oblongata e. spinal cord -
B. Internal Sheep Brain:
9. Use a knife or long-bladed scalpel to cut the specimen along a midsagittal plane. Use the
longitudinal fissure as a cutting guide.
10. The corpus callosum had been connecting the two cerebral hemispheres and can now be
clearly seen. You may be able to see a hollow cavity just ventral to the corpus callosum in each
brain half. These cavities are the lateral ventricles.
a. What substance is found within the ventricles?
b. What neuroglia cells line the ventricles? Why?
11. Place the brain ventral side down, slice the entire brain into two halves (midsagittal). Cut through the longitudinal
fissure, corpus callosum, and midline of the cerebellum. Now examine the brain from a midsagittal view. Identify the
following internal structures. Pin these structures with different colored pins (include key below) and insert a completed
picture of the pinned brain below.
a. cerebrum b. corpus callosum c. cerebellum d. arbor vitae e. lateral ventricle f. 4th ventricle g. thalamus h. hypothalamus i. pineal gland j. pons k. medulla oblongata l. midbrain m. spinal cord -
Part 2: Spinal Cord Structure
12. Where is grey matter and white matter found in the spinal cord?
13. Describe where grey matter and white matter are primarily located in the brain.
14. Observe the ventral root of the spinal nerves that come off the spinal cord cross-section model. Are these
nerves sensory or motor in nature? _________________ Are they afferent or efferent nerves?________________
15. How many pairs of spinal nerves project off of the spinal cord? _____________________________
16. What is the main motor tract within the spinal cord called? ________________________________
17. Insert a picture of the spinal cord cross section model below. Label the following structures - grey matter, white
matter, spinal nerves, ventral (motor) root, dorsal (sensory) root, dorsal ganglion, central canal
18. Take a picture of the spinal cord/vertebrae model and insert below. Label the following structures: spinal cord,
conus medullaris, cauda equina.
Lab Review Activity
MATCH THE BRAIN REGION WITH THE FUNCTION:
1. ______ BALANCE AND EQUILIBRIUM
2. ______ MENINGE LAYER ON BRAIN
3. ______ VISUAL CORTEX
4. ______ AUDITORY CORTEX
5. ______ OUTERMOST MENINGE
A. MEDULLA
B. HYPOTHALAMUS
C. PARIETAL LOBE
D. PIA MATER
E. FRONTAL LOBE
F. TEMPORAL LOBE
G. OCCIPITAL LOBE
H. DURA MATER
I. CEREBELLUM
J. INSULA
6. ______ BODY TEMPERATURE CONTROL
7. ______ EMOTIONAL RESPONSE, ANGER, RAGE, FEAR
8. ______ CARDIAC CENTER, VASOMOTOR CENTER, RESPIRATORY CENTER
9. ______ THINKING, PLANNING, PERSONALITY, INITIATES VOLUNTARY MOVEMENT
10.______ PRIMARY MOTOR CORTEX
11.______SOMATOSENSORY CORTEX
12.______OLFACTORY CORTEX
13.______BROCA’S AREA (MOTOR SPEECH)
14.______WERNICKE’S AREA (SENSORY SPEECH)
MATCH THE CRANIAL NERVE WITH THE FUNCTION:
1. ______ SEE A PICTURE
3. ______ SMELL PERFUME
4. ______ LISTEN TO THE RADIO
5. ______ STICK YOUR TONGUE OUT
6. ______ CHEW GUM
7. ______ SLOWING OF HEART BEAT
A. VESTIBULOCOCHLEAR
B. FACIAL
C. GLOSSOPHARYNGEAL
D. HYPOGLOSSAL
E. TRIGEMINAL
F. ABDUCENS
G. OLFACTORY
H. OPTIC
I. ACCESSORY
J. VAGUS
K.TROCHLEAR
L. OCULOMOTOR
8. ______ FEEL A TOOTHACHE
9. ______,______,______ THREE NERVES THAT MOVE THE EYEBALL
10. ______ SMILE AND TASTE FROM ANTERIOR 2/3 OF TONGUE
11. ______ SPEECH, SWALLOWING, AND TASTE FROM POSTERIOR 1/3 OF TONGUE
12. ______ MOVES TRAPEZIUS AND STERNOCLEIDOMASTOID MUSCLES
13. ______ MOVES EYEBALL LATERALLY ( ABDUCTS THE EYEBALL )
14. ______ CONTROLS 4 OF THE 6 EXTRINSIC EYE MUSCLES
15. ______ MOVES THE SUPERIOR OBLIQUE MUSCLE OF THE EYEBALL
Multiple Choice Questions
1. Which of the following is NOT part of the brainstem?
A. Thalamus
C. Medulla oblongata
B. Pons
D. Midbrain
2. The white matter of the cerebellum is called the
A. Epithalamus
C. Arbor vitae
B. Cerebellar peduncles
D. Ventricles
3. What divides the cerebrum into right and left hemispheres?
A. Central sulcus
C. Longitudinal fissure
B. Lateral fissure
D. Transverse fissure
4. Elevated regions on the surface of the cerebrum are called
A. Gyri
C. Fissures
B. Sulci
D. Commissures
5. Which lobe is NOT correctly matched with its general functions?
A. Frontal lobe - abstract thought and judgment
B. Parietal lobe - evaluation of sensory information
C. Temporal lobe - hearing
D. Occipital lobe - rage and anger
6. What are the CSF fluid-filled spaces of the brain called?
A. fissures
C. ventricles
B. gyri
D. sulci
7. The visual cortex is located in the _______ lobe.
A. Frontal
B. Occipital
C. Temporal
D. Parietal
E. Insula
8. The auditory cortex is located in the _____ lobe.
A. Frontal
B. Occipital
C. Temporal
D. Parietal
E. Insula
9. The primary motor cortex is located on the ________ of the ________ lobe.
A. Postcentral gyrus; parietal
B. Precentral gyrus; parietal
C. Medial gyrus; temporal
D. Precentral gyrus; frontal
10. Which cortical area initiates the movements needed for speech?
A. Wernicke's area
B. Arcuate fasciculus
C. Broca's area
D. Prefrontal cortex