Gross Anatomy of the Brain and Cranial Nerves

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Gross Anatomy of the Brain and Cranial Nerves

Time Allotment: 2 hours.

Multimedia Resources: See Appendix B for a list of multimedia resource distributors.

Anatomy of the Human Brain (FHS: 35 minutes, DVD, 3-year streaming webcast)Animated Neuroscience and the Action of Nicotine, Cocaine, and Marijuana in the Brain (FHS: 25 minutes, DVD, 3-year streaming webcast)The Brain (FHS: 20 minutes, DVD, 3-year streaming webcast)The Brain (NIMCO: 30 minutes, DVD)Brain and Nervous System: Your Information Superhighway (FHS: 31 minutes, DVD, 3-year streaming webcast)The Human Brain in Situ (FHS: 19 minutes, DVD, 3-year streaming webcast)Practice Anatomy Lab 3.0 (PAL) (PE: DVD, Website)Sheep Brain Dissection (WNS: 22 minutes, DVD)

Advance Preparation 1. Make arrangements for appropriate storage, disposal, and cleanup of dissection materials. Check with

the Department of Health or the Department of Environmental Protection, or their counterparts, for state regulations.

2. Designate a disposal container for organic debris and a dishwashing area with hot soapy water, sponges, and a lab disinfectant such as Wavicide-01 (Carolina) for washing down the lab benches.

3. Set out disposable gloves and safety glasses.

4. Set out dissectible human brain models (ideally one per group) and preserved human brains.

5. Set out dissection kits, dissection trays, and sheep brains with meninges and cranial nerves intact.

6. For testing cranial nerve function, set out dropper bottles of oil of cloves and vanilla; an eye chart; an ophthalmoscope; a penlight; safety pins; mall probes (hot and cold); cotton; salty, sweet, sour, and bitter solutions; cotton swabs; ammonia; tuning forks; and tongue depressors. Set out an autoclave bag for disposables.

Comments and Pitfalls 1. Students who are not careful readers confuse or do not distinguish between cerebellar and cerebral.

2. Hasty removal of the meninges removes the pituitary gland before its connection to the brain by the infun-dibulum can be established; occasionally even the optic chiasma is lost. Encourage students to go slowly and use the scalpel sparingly.

3. The arachnoid meninx may be hard to identify, as it is usually poorly preserved.

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Answers to Activity Questions

Dissection: The Sheep Brain (pp. 171–172)

1. The sheep’s cerebral hemispheres are smaller than those of the human.

Ventral Structures

1. The olfactory bulbs are larger in the sheep. The sense of smell is more important to the sheep than it is to humans for both protection and locating food.

Dorsal Structures

1. The cerebrum is not as deep.

3. The corpora quadrigemina are reflex centers for visual and auditory stimuli.

Exercise 14 71


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Lab Time/Date E X E R C I S E14Gross Anatomy of the Brain and Cranial Nerves

3. Which of the following structures are not part of the brain stem? (Circle the appropriate response or responses.)

cerebral hemispheres pons midbrain cerebellum medulla

4. Complete the following statements by writing the proper word or phrase in the corresponding blank at the right.

1. gyrus

2. fissures

3. sulci

4. cell bodies of neurons or unmyelinated neurons

5. fiber tracts or myelinated neurons

6. association

7. commissure

8. basal nuclei (ganglia)

A(n) 1 is an elevated ridge of cerebral tissue. Inward folds of cerebral tissue are called 2 or 3 . Gray matter is composed of 4 . White matter is composed of 5 . A fiber tract that provides for communication between different parts of the same cerebral hemisphere is called a(n) 6 , whereas one that carries impulses from one cerebral hemisphere to another is called a(n) 7 . Nuclei deep within the cerebral hemisphere white matter are collectively called the 8 .

The Human Brain 1. In which of the cerebral lobes (frontal, parietal, occipital, or temporal) would the following functional areas be found?

primary auditory cortex Temporal primary olfactory cortex Temporal

primary motor cortex Frontal primary visual cortex Occipital

primary somatosensory cortex Parietal Broca’s area Frontal

2. Using the terms from the key, identify the structures of the brain.

Key:

a. brain stem

b. central sulcus

c. cerebellum

d. frontal lobe

e. lateral sulcus

f. occipital lobe

g. parietal lobe

h. parieto-occipital sulcus

i. postcentral gyrus

j. precentral gyrus

k. temporal lobe

l. transverse cerebral fissure

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5. Using the terms from the key, identify the structures on the following midsagittal view of the human brain.

Key:

6. Using the key from question 5, match the appropriate structures with the following descriptions:

hypothalamus 1. important autonomic center of brain involved in the regulation of body temperature

corpora quadrigemina 2. located in the midbrain; contains reflex centers for vision and hearing

cerebellum 3. coordinates complex muscular movements

medulla oblongata 4. contains autonomic centers regulating heart rate, respiration, and other visceral activities

corpus callosum 5. large fiber tract connecting the cerebral hemispheres

pituitary gland 6. the infundibulum connects this gland to the hypothalamus

cerebral aqueduct 7. canal that connects the third and fourth ventricles

thalamus 8. the interthalamic adhesion connects its two lobes

Review Sheet 14 73

a. anterior commissure

b. cerebellum

c. cerebral aqueduct

d. cerebral hemisphere

e. choroid plexus

f. corpora quadrigemina

g. corpus callosum

h. fornix

i. fourth ventricle

j. hypothalamus

k. interthalamic adhesion

l. mammillary body

m. medulla oblongata

n. midbrain

o. optic chiasma

p. pineal gland

q. pituitary gland

r. pons

s. septum pellucidum

t. thalamus

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74 Review Sheet 14

Meninges of the Brain 7. Identify the meningeal (or associated) structures described below.

dura mater 1. outermost meninx; composed of tough fibrous connective tissue

pia mater 2. innermost meninx covering the brain; follows every convolution

arachnoid villi 3. return cerebrospinal fluid to the venous blood in the dural venous sinuses

choroid plexus 4. structure that produces the cerebrospinal fluid

arachnoid mater 5. middle meninx; delicate with cottony fibers

falx cerebri 6. a dural fold that attaches the cerebrum to the crista galli of the skull

Cerebrospinal Fluid 8. Label the structures involved with circulation of cerebrospinal fluid on the accompanying diagram.

Lateral ventricles

Third ventricle

Cerebral aqueduct

Fourth ventricle

Lateral aperture

Median aperture

Interventricular foramen

Central canal


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Cranial Nerves 9. Using the terms below, correctly identify all structures indicated by leader lines on the diagram.

a. abducens nerve (VI)

b. accessory nerve (XI)

c. facial nerve (VII)

d. glossopharyngeal nerve (IX)

e. hypoglossal nerve (XII)

f. longitudinal fissure

g. mammillary body

h. medulla oblongata

i. oculomotor nerve (III)

j. olfactory bulb

k. olfactory tract

l. optic chiasma

m. optic nerve (II)

n. optic tract

o. pons

p. trigeminal nerve (V)

q. trochlear nerve (IV)

r. vagus nerve (X)

s. vestibulocochlear nerve (VIII)


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76 Review Sheet 14

Dissection of Sheep Brain 10. In your own words, describe the relative hardness of the sheep brain tissue as noticed when you were cutting into it.

The sheep brain tissue is fairly soft.

Formalin hardens all tissue. What conclusions might you draw about the relative firmness and texture of living

brain tissue? The human brain is a relatively soft tissue.

11. How does the relative size of the cerebral hemispheres compare in sheep and human brains?

The cerebral hemispheres in human brains are larger.

What is the significance of this difference? Humans have a more developed area for speech, language, conscious thought,

interpretation, and other functions associated with the cerebrum.

12. What is the significance of the fact that the olfactory bulbs are much larger in the sheep brain than in the human brain?

The sense of smell is more important as a protective and food-getting sense in sheep.

13. + Explain why trauma to the brain stem is often much more dangerous than trauma to the frontal lobes.

The brain stem controls many autonomic functions, such as respiration, heart rate, and blood pressure. The frontal lobes

are involved in thought and personality, rather than functions essential to life.

14. + Patients with unresponsive wakefulness syndrome (UWS) have lost awareness of self and their environment. In many cases, there is no damage to the cerebral cortex or the brain stem. If signal transmission to the cerebral cortex

is affected, what part of the brain is most likely to have been damaged? Thalamus

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Gross Anatomy of the Brain and Cranial Nerves

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