Neuroanatomy
Purves et al. part of Chapter 1, Appendix, the Sylvius CD, Box A in Chapter
19 for prions, Figure from chapter 22
Resources
Here is a site I found on mouse brain
anatomy
(might not work on Netscape)
(unfortunately, some of the links are dead)
I found these pictures of stereotactic
apparatus at the Kopf Instrument site. (might not work on Netscape)
Sutures in bones are landmarks for surgery, Bregma is the anterior square
one, and Lambda is the posterior V shaped one, and here
is a picture from a site where you can buy a rat skull on a chain.
Using these landmarks, a rat brain atlas, and a drill, electrodes can be
placed into specified locations for stimulating or lesioning.
Here is a site
for sheep brain dissection.
Acknowledgements
In 1970-1971, I was assigned to be a teaching assistant (TA) in Physiological
Psychology at the University of Wiscconsin - Madison for Prof. Richard Keesey.
Without the help of the senior TA, Norm Ferguson, I do not know how I would
have survived. A few years later, Norm published "Neuropsychology Laboratory
Manual" (Norman B. L. Ferguson, San Francisco, Albion Publishing Company,
1977), with good coverage on anatomy. The slide
collection I present to you is mostly the slide collection I was given to
use as a TA. For the first time in recent years, a student dissection of
the sheep brain is being incorporated into this course. The dissection
guide, which we will follow, and the glossary
of neuroanatomical terms, which is entertaining and informative, is from
the course I TAed. This lab was prepared and added to the Neuro curriculum
for Spring 2005 mostly from the efforts of Christine Zelle, Lab coordinator
for upper division biology labs. 2006 revisions included (1) labeling the
slides, (2) simplifying the dissection guide from its original version,
and (3) hyperlinking to slides from the guide; some of these revisions were
suggested by 2005 students in their course assessment.
The Prion Lecture
Chapter 18 Box A
Prion diseases - this is in the cerebellum chapter because cerebellar ataxia
is one of the characteristics of the diseases; I put it here as a warning
for obvious reasons.
Creutzfeldt - Jakob Disease (CJD) "Spongiform" (brain turns to
sponge) degeneration.
There were seemingly esoteric* cases of spongiform encephalitis.
* for instance afflicting Jews in Lybia who thought raw sheep eyeballs were
a delicacy.
Kuru was a disease in New Guinea among cannibals.
D. Carleton Gadjusek (1976 Nobel
Prize) thought it was a slow virus.
Scrapie in sheep so named because they roll around with intense itching.
Personal reflection. Since we did a sheep brain dissection in physiological
psychology lab at Hopkins, I wondered if rubber gloves were necessary. Since
Baltimore was close to Bethesda, I called. Gadjusek was away, studying some
remote tribe, but I spoke with his coworker (Gibbs) who thought formaldehyde
might not kill the virus. Then I got on their mailing list and, once a month
or so, got an inch thich envelope full of case studies of diseases in far
away places. I had to move to Missouri (in 1979) to make it stop.
Stanley Pruisinger 1980's proposes "prion" (protenaceous infectious
particle).
That a disease could be transmitted without virus or bactera was heresy
at the time.
But he had strong evidence and won the 1997 Nobel
Prize.
Normal protein (PrP-C [control]) is altered by altered form (PrP-Sc [scrapie])
In the 1990s when the term "mad cow disease," was applied to observations
in Britain, it seemed like a joke.
Now "BSE" (bovine spongiform encephalitis) is no laughing matter.
In meat industry, having matter from other animals in the feed is really
bad.
Can disease spread from animal to animal? (probably)
Can disease spread from animal to human? (probably)
Cases in Canida, mainland Europe, and even in the US are in the news.
Should "downers" ("cows" that have dropped to the ground)
be slaughtered for food?
How is it that meat from one downer can be sold in many different states
and, only later, the announcement is made that it had BSE?
To supplement the above material, please view the 2006
graduate student presentation on prions.
Background
big area of cerebral cortex (2.2 square meters) from folding into sulci
and gyri
Fig. 1.6 FG
cellular cytoarchitecture - 2 mm thick cerebral cortex
6 layers, top (I) = molecular (without cells)
Brodman made areas (from cytoarchitecture), famous:
4 motor
17 vision
Fig. A1 [A,B] (Appendix)
Review (already covered in first lecture) and terminology:
Rostral - caudal
Medial - lateral
Ipsilateral - contralateral
Sagittal - coronal - horizontal
also:
gray matter, cortex, nucleus and ganglion
substantia (ex. substantia nigra) like nucleus but less distinct
locus (l. coeruleus) small distinct group
nerve, white matter, tract
bundle (medial forebrain bundle) go together but unrelated
capsule (internal c.) cerebrum - brainstem connection
commisure - one side to another
lemniscus (medial l.) - like ribbon
Fig. A10
Overall external anatomy viewed laterally
Shows brains of mammals (cortex = "bark")
cerebrum senses - hemisphere controls contralateral
cerebellum (little brain) - hemisphere controls ipsilateral
Landmarks:
Central Sulcus divides
postcentral gyrus (primary sensory projection)
17 vision
precentral gyrus (primary motor area) Brodman made area 4 motor
Lateral (Sylvian) fissure
Brainstem
Fig. A3
frontal lobe - planning behavior
parietal lobe - attending to stimuli
temporal lobe - recognition
occipital lobe - visual analysis
Figure, (not in book anymore, but relates to Fig. 22.5)
Developmental introduction to neuroanatomy
(there is also a development chapter, chapter 21)
Prosencephalon
Mesencephalon
Rhombencephalon
Each of the above develops further. note (especially):
Telencephalon -olfactory bulbs, cerebral cortex, basal ganglia, hippocampus,
etc.
Diencephalon is thalamus (sensory & motor "relay") and hypothalamus
(visceral function)
Mesencephalon - tectum -> superior and inferior colliculi (vision and
audition respectively)
Metencephalon - cerebellum, pons
Myelencephalon - medulla - auditory, somatic, gustatory
Table A2 (appendix)
and
Fig. A7 (appendix)
and figure
from sheep brain dissection
another figure
from sheep
yet another
ventral view of brain
cranial nerves.(some are tracts)
sensory vs. motor, somatic vs. visceral (autonomic)
I olfactory
II optic
III occulomotor - goes to 4 external eye muscles, pupil, accomodation, eyelids
IV trochlear - to superior oblique muscle
V trigeminal - somatic from face, chewing
VI abducens - to external rectus muscle of eye
VII facial - facial muscles, lacrimal and salivary glands, taste
VIII auditory / vestibular
IX glossopharyngeal - taste from back of tongue, sense from pharynx, carotid
baroreceptors
X vagus - autonomic, sensation, vocal cords, swallowing
XI accessory - shoulder & neck muscles
XII hypoglossal - tongue movements
some other ventral landmarks:
pyramids- of pyramidal (corticospinal tract) (decussation is caudal to this)
(vs. extrapyramidal)
mammallary body, pons, inferior olive (motor control), rhinal fissure, etc
optic nerve, chiasm and tract
cerebral peduncles - axons between brainstem and cortex
Fig. A14
neocortex (found only in mammals),
hippocampus (archipallium) (one cell layer) (seahorse shaped)
and olfactory cortex
Fig A12
human midsagittal
sheep
close up
tract dissection
thalamus, hypothalamus, midbrain, pons, medulla
(subthalamus is between, concerned with motor function)
corpus callosum, anterior commisure, cingulate sulcus and gyrus, etc.
optic chiasm, infundibular stalk, pituitary, mammallary body, pineal, colliculi,
etc.
some of these are in limbic system (chapter 29)
Fig. A8
sheep
dorsal view of midbrain and brainstem
Cerebellum has 3 peduncles
superior and inferior colliculi
many important nuclei, principally of cranial nerves, are drawn in
Fig. A14A
coronal section
this view is especially good for the basal ganglia and internal capsule
striatum = caudate + putamen
sheep
horizintal section
Prep for dissection
A
B
C
D
E
F
G
Fig. A2A
spinal cord - cervical thoracic lumbar and sacral nerves
Cauda equina branches out toward bottom
Fig. A19
meninges (as in meningitis)
(1) dura (2) arachnoid (3) pia
subarachnoid space has cerebrospinal fluid (CSF)
So do ventricals.
sheep
Fig. A21
ventricles
the CSF is "isolated" by the blood-brain-barrier (BBB)
and is secreted by the choroid plexus
Exam questions from 2005 - 2007 relating to this outline (plus dissection
guide and slides)
For 1-16, refer to Figs 1st
p, 2nd p,
3rd p, 4th
p,
1. The name of this bulge.
pons
2. The name of this blood vessel feeding the circle of Willis.
internal carotid artery
3. The name of this ventricle.
3rd
4. The name of this nucleus. Its function. (two points)
caudate, motor (extrapyramidal
5. The name of this tract.
fornix
6. What big tract is being ripped here?
internal capsule
7. The name of this structure.
hippocampus
8. What part of the thalamus is this?
lateral geniculate
9. The name of this whole tract that is teased into 3 components on the
other side.
cerebellar peduncle
10. Name one of the two nuclei that form this lens-shaped nucleus.
ptuamen, glogus pallidus
11. The name of this bulge. The name of the equivalent structure in the
frog. (2 points)
superior colliculus, optic tectum
12. The name of this big bundle of cross over axons.
corpus callosum
13. The name of this bulge. Its function. (2 points)
precentral gyrus, motor
14. The name of this major subdivision of the brain.
cerebellum
15. The name of this small bundle of cross over axons.
anterior commisure
16. The name of this major subdivision of the brain.
medulla
Using a stereotaxic atlas of the rat brain and a stereotaxic apparatus,
what do you measure from on the rat's head to find a defined brain location
like the ventromedial nucleus of the
hypothalamus?
bone sutures bregma and lambda
Why do they call part of the basal ganglia the "striatum?"
brances off the internal capsule make these nuclei look striped
Only one of the cranial nerves for eye movements is also part of the parasympathetic
nervous system. Which?
occulomotor (III)
When you remove the cerebellum, you are looking at the floor of which ventricle?
4th
The hippocampus looks white because of axons of the fimbria that form what
major tract?
fornix
Among the meninges (brain membranes), which is the toughest?
dura mater
When Stanley Pruisinger, who eventually won a Nobel Prize, proposed the
prion theory for spongiform encephalitis, how was he disagreeing with the
Nobel Prize winning work
of D. Carleton Gadjusek?
SP said a protein could be infectious while DCG thought more traditionally
that it was a virus (a slow one)
For questions # 1 - 4, refer to this
figure.
1. This gray matter. Note that it is covered with white matter. Also note
its location between the white matter of the cerebral cortex and the thalamus.
hippocampus
2. This thin midsagittal structure blocks your view into the lateral ventricle
and the head of the caudate nucleus.
septum pellucidum
3. Part of the mesencephalon, this part of the lamina quadrigemina is a
visual area related to the optic tectum of the frog.
superior colliculus
4. This bulge, white matter, leads to the brachium pontis of the cerebellar
pecuncle. On the ventral view of the brain, it blocks your view of the pyramidal
tract.
pons
for 5-8, see this
figure
5. If you started cutting into the longitudinal fissure, what is the first
white matter you would cut?
corpus callosum
6. This visual structure blocks your view to the supraoptic nucleus of the
hypothalamus.
optic chiasm
7, Many of the brains we had for dissection showed this ribbon-shaped cranial
nerve.
oculomotor nerve (III)
8. This tract is named for its connection from the thalamus to what specific
portion of the hypothalamus, a body which would be conspicuous on the ventral
view.
mammillary body
for 9-12, see this
figure
9. This portion of the cerebellar peduncle has axons that are seen in what
ventral structure?
pons
10. What commisure is here? (The arrow does not point to the corpus callosum.)
hippocampal commisure
11. What major subdivision of the brain is this?
cerebellum
12. Why is the hippocampus white?
its output axons, the fimbria, are on the surface
"Each picture in a stereotactic atlas of the rat brain is a coronal
section with its distance anterior or posterior of bregma indicated."
Translate.
coronal is dorsal-ventral, lateral-contralateral plane, and bregma is a
landmark on the sutures of the bones
Why did I decide to tell the prion story in the neuroanatomy lecture before
the brain dissection?
to give you a cautious appreciation for how contact with neural tissue,
in the case of scrapie, might be dangerous
The pons covers up a white matter that goes from the cerebral peduncles
through the pyramids. What is this tract (not the pons, rather the tract
covered by the pons) used for?
motor output
The most obvious of the "membranes" (meninges) of an "un-peeled"
brain is a very thick and tough one called the (what)?
dura mater
"Bundle," "capsule,""commisure," and "lemniscus"
are all terms referring to what specific type of tissue?
tracts
Toward the bottom of the spinal cord, there are many parallel tracts. What
is this called?
cauda equina
Sometimes caudate plus putamen is called striatum. Why?
looks striated from branches of white matter off the internal capsule
What vascular tissue, seen dark in dissection, secretes cerebrospinal fluid?
choroid plexus
For 1-3, see here
1. In some brains, this was intact, in others, it was damaged, revealing
a fluid-filled compartment. What is it?
olfactory bulb
2. Hardly anybody had this good of a view of this pair of laterally projecting
nerves found near the stump of this obvious rostrally projecting nerve.
Give the name or number of one of them.
Facial (7) or auditory (8)
3. If this tract is followed laterally and superiorally, with the cerebellum
removed, it is part of a huge structure of white matter. What is this white
matter called?
cerebellar peduncle
For 4-8, see here
4. Here is white matter (covered by the pons). What is the function of this
white matter tract?
motor (pyramidal [corticospinal] tract)
5. Between the two lines (and just on the other side of the optic chiasm)
lies what structure, important in motivation?
hypothalamus
6. With the cerebellum removed, what are the midbrain structures seen
superior (and inferior) colliculi,, lamina (corpora) quadrigemina
7. and what would the visual counterpart be called in the frog?
optic tectum
8. What ventricle is this?
4th
For 9-12, see here
9. What motor nucleus is right on the other side of the septum?
caudate
10. What is the name of this huge area of white matter?
internal capsule
11. Covered by the hippocampus, what is the specific function of this part
of the thalamus?
vilson (lateral geniculate nucleus [body])
12. The fimbria fibers that make this structure white are bundled together
in what tract that can be seen in mid-sagittal section?
fornix
What distinguishes a bundle (like the medial forebrain bundle) from a tract?
several unrelated tracts travel together
What are the diencephalic structures that would be seen in the neighborhood
of the third ventricle?
thalamus and hypothalamus
The surface of the hippocampus is white. How, during the dissection, would
you ascertain the direction that these axons go?
stroke with the grain and across the grain with the cuticle stick
Starting at the lumbar area and going through the sacral area, describe
the spinal cord.
cauda equina, a bunch of nerves
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