1

A&P 1 Brain & Cranial Nerves Guide -

Lab Exercises Have someone in your group read the following out loud, while the others read along:

In this "Lab Guide", we will be looking at the brain & cranial nerves. This guide should only be attempted after reading the correct sections in either the lab or lecture book, or watching any videos that have been assigned. The First 2 Parts must be done in lab, with the dissections and other lab materials. Parts 3 & 4 can be done outside of lab.

2

#1

Part 1. Review Key Concepts from the book and videos

Have someone in your group read this, while the others follow along: Look over the list of regions and sub regions is below. Make sure you understand this outline, and write down any individual structures you can think of. For example, you could write “corpus callosum” under “inner white matter” and “pituitary” under “hypothalamus”. You might want to come back and complete this after the next section!

A. Cerebrum (telencephalon)

1. cerebral cortex (outer gray matter) 2. inner white matter (inner tracts, nuclei, etc.)

B. Diencephalon

1. epithalamus 2. thalamus 3. hypothalamus

C. Brain Stem

1. midbrain 2. pons 3. medulla oblongata

D. Cerebellum

Read Me

#1

Pm

H GY

W

Part 2. Findmodels and

Have someo

Get a dissectYour group s

1. Hu2. Sh3. Sh4. Sh

We will be co

Human

Sheep bra

d the Regiod the sheep

one in your g

ting pan, 1 should have t

uman Brain heep Brain -heep Brain Wheep Brain F

omparing the

n brain mo

ain without

ons and Stp brain.

group read

calpel, 1 pathe following

Model - Whole, witWhole - withFrontal Sec

ese four at th

del

meninges

tructures o

d this, while

ir scissors, ag in front of y

th Dura Mathout dura mtion

he same time

s

of the Brai

the others

and some layou:

ter (you willmater (you w

e.

Shee

Sheep

n you need

follow alon

tex-free surg

l be dissectwill not be d

ep brain w

brain - Fro

d, on both

ng:

gical gloves

ting this!) dissecting t

with mening

ontal sectio

3

the

.

this)

ges

on

T

#2 M

Omd W

Eco

Do his!

Do This!

Meninges

Obtain one ofmembranes k

ura mater, a

While lookin

Examine the onnective tis

f the preservknown as thea middle arac

ng at the "sh

dura matessue. Descr

Co

ved sheep be meninges.chnoid, and

heep brain w

er, a protectivribe the appe

ntinued

rains that is . The meninan internal p

with mening

ve outer meearance and

on next

still encasenges consistpia mater.

ges":

embrane comd feel of this

t page

d within the t of three lay

mposed of a membrane.

protective yers; an oute

tough dense

4

er

e

T

#3

Efilahd

S

A EceceT

Do This!

Examine thelmy membrarachnoid aere and therirectly attach

Study the ex

On thHowedura "hum

A fissure is a

Examine the erebral hemerebral hem

The cerebrum

e surface of ane coveringand pia mare...you mayhed to the ne

xternal featu

his guide, wever, find almater", the

man brain mo

deep groov

sheep brainispheres thaispheres are

m and cerebe

the "sheepg over the acater. The ary not really seural tissue.

ures of the b

e will use iml of the follodissected

odel". Use

ve that goes

n from a supeat constitute e almost comellum is sep

p brain whoctual brain tisrachnoid willee it. The p

brain.

mages fromowing on th“Sheep Brathe images

deep and se

erior view (sthe cerebru

mpletely separated by th

le - withoutssue. This il only look lik

pia mater wil

m either thehe surface oain - Whole,s in your lab

eparates big

see figure beum and enveparated by a he transvers

t dura mateis more delicke a film witl look like a

model or sof the "shee, with Dura b book as n

g regions.

elow). Note elop most of

deep longitse fissure.

r". Note thecate tissue oh dark patchshiny coat

heep brain.ep brain witMater” and

needed.

the two largthe brain. Ttudinal fiss

5

e thin of the hes

. thout the

e The ure.

DTh

If hed Tupanincobe Nthcetrsu Cosp FKse

Do his!

you gently spemispheres missect the bra

he surface ofpward folds ond shallow gr

ncrease the suortex to allowetween neuro

Next locate thehe cerebrum. erebral hemisransverse fisulci) and lobe

Caudal and infblongata whpinal cord.

ind these struKeep in mind tensory cortice

pread the hemmedially. Thisain.

f each hemispof nervous tissrooves called urface area o

w more compleons.

e cerebellum It is separate

spheres by thssure. Like thes (see image

ferior to the ceich tapers out

uctures on thethat you havees on your wo

mispheres aps is the corpu

phere consistssue called gysulci. Thesef the cerebralex interaction

m just caudal ted from the e deep he cerebrum, e below).

erebellum nott to form the m

e model and s to locate anyordlist:

art, you can ss callosum. W

s of yri e l

to

the cerebellu

te the medulmore slender

sheep brain. y motor and

see a band ofWe will be cu

um has a high

la r

f tissue that cutting through

hly convoluted

connects the tthis when we

d surface (gyr

6

two e

ri and

Texfis(stharthcotis Ebeothfr Cthth Cenp Tmh

Note: Thmamillarbody is very defor clear the sheebrain!!

he dorsal porxamined by cssure on the “see figure). The corpora qure larger than

he midline betolliculi you wissue called th

xamine the below). At thelfactory bulb

he cerebrum. om these bul

Caudal to the ohe two optic nhat extend ba

Caudal and infndocrine glanituitary gland

he infundibulumammillary bo

ypothalamus

he ry NOT

fined on

ep

rtion (or "roof"carefully sprea“whole sheep

This exposes fuadrigemina

n the two infertween and jusll see a smallhe pineal bod

rain from an i cranial end o

bs that lay ag The band of bs are the olf

olfactory bulbnerves from thck to the visu

ferior to the ond and is attacmay be miss

um is rooted ody and the nes. A portion o

") of the midbading apart thp brain withoufour rounded

a. The two surior colliculi. Ist above the s fingerlike extdy or gland.

inferior view (of the brain nogainst the undf tissue extendfactory tracts

bs and tracts ihe eyes meet ual area of the

ptic chiasma ched to the bing from som

in a bulge of ervous tissueof the pituitary

brain can be he transverse ut meninges”

bulges calleduperior collicuIf you look onsuperior tension of

(see Figure ote the two dersurface of ding caudally s.

s the X-shapeand partially

e cerebrum.

is a small bearain by a slen

me of the prese

nervous tissue superior to ity gland is act

d li

n

y

ed optic chiacross over be

an shaped pinder stalk callerved brains,

ue called the mt comprise thetually an exten

asma. This isefore forming

ituitary glandled the infund leaving only

mammillary e brain regionnsion of this h

s the point whg the optic trac

d. This is a mdibulum. Ththe infundibu

body. This n known as thhypothalamus

7

here cts

major he ulum.

he s.

Tneth CT

Now it isstructurehalves, abucket a Determilobe. If separatedura. Exbulbs weattachm Also, theyour eyeto look li Lay the Always uknife; netissue. passes tEach timthrough previouscenter oWATCH Use the on the bneed. Mthe shee

he ventral poervous tissue

he hypothalam

Caudal to the mhe nervous ti

s time to dises. You will and any preat the front

ne if your sthe bone ise the bone xamine theere sitting, ent of the m

e optic nerveball. Usingike the one

brain, upsid

use a scalpever “saw” tIt will take yto get throu

me you slidethe brain, t

s slice. Staof the pituitaH YOUR FIN

following imbrain model Make sure yep brain.

Do This!

rtion (or "flooe connect the mus.

midbrain is thssue then tap

ssect the “Sbe compar

e-sectionedof the room

specimen sts present, saway from

e removed eand the cris

meninges.

ve may still g the scisso in the imag

de down, o

pel like a buthrough theyou severalugh the brae the scalpetry to stay in

ay as close ary as possNGERS!

mages to gand dissec

you find eve

r") of the midcerebrum wit

he hindbrain wpers to form th

Dissec

Sheep Brainring this witd preservedm).

till has a paslip a blunt p

the specimethmoid bosta galli: cre

be attacheors, cut thege below.

n the disse

utter e l in. el n the to ible.

uide you thcted sheep erything ind

brain consiststh other regio

which consistshe spinal cord

cting the Sh

n - Whole, wth the braind sheep bra

art of the ethprobe betw

men. Then, ne and idenest of bone

ed to 2 largee optic nerve

ecting tray.

hrough the pbrain, usin

dicated on y

s of the cerebns of the brai

s of the ponsd.

heep Brain

with Dura M model, wh

ains you wa

hmoid boneween the bo

using yourntify the cri

e where tha

e fat bodieses to remov

parts you ng the image

your wordlis

bral pedunclein and are loc

s and the me

ater”, as wehich you shoant for varia

e attached ne and the r scissors, sbriform platt serves as

s – these arve the pads

need to knowes in your tst indicated

s. These bancated just cau

dulla oblong

e want to seould now se

ability (avail

on the antedura to ca

snip away ates, where

s the surfac

re 2 pads ths, trying to g

w, finding ttext or lab bd with an As

8

nds of udal to

gata.

e internal eparate theable in a

erior frontalrefully any attachethe olfactore of

hat sit behinget the bra

he structurbook as yousterisk (*) o

e 2

ed ry

nd in

es u n

1. SpecifLocate theconnects band of tisfornix. Dcut you shand corpumembranfluid is pro Make surethe lateraFrontal S 2. Specif Before we The dienc

fic Parts of the corpus calthe two cerebssue below th

Depending on hould either sus callosum oe is the chorooduced and c

e you see thel ventricles onSection”.

fic Parts of th

e go on: A wo

cephalon is th

he Cerebrumlosum, the bbral hemisphehe corpus calthe exact pos

see a membraor a cavity betwoid plexus, whcirculated.

e corpus callon the “Sheep

he Dienceph

ord about the

he region that

m and of tissue eres. Also loclosum knownsition of the sane linking theween them. here cerebros

osum and p Brain

halon:

“diencephalo

surrounds th

that cate the as the ectioning e fornix The spinal

on” and its ind

e 3rd ventricle

4. FBrai Depyoustrunot

dividual “sub-

e. So a good

Find the diencepn Frontal Sectio

pending on wu may not seeuctures, on a “be on the Pra

regions”:

way to look a

phalon, and its son”.

where your froe exactly what“Sheep Brainactical!

at it is like a t

sub regions, on

ntal section wt is shown ben Frontal Sec

9

hick box:

n the “Sheep

was taken, elow! These ction”, will

Inferior tointermediathe two poeach cerea depressthe thalam 3. Specifthe midb Examine acorpora qventral ceparts of ththe cereb 4. Specif The whitevitae. Note that through thcerebellumventricle oaqueductcerebrospfourth vethe condit

the fornix is aate mass. Thortions of the ebral hemisphsed area aroumus, this will

fic Parts of thrain:

again the midquadrigeminerebral pedunhe hindbrain; bellum.

fic Parts of th

e matter struct

there is a slehe midbrain tom and the meof the brain ant. The cerebrpinal fluid fromntricle. Bloction known as

a round struchis is the medthalamus tha

here. If there und the interm

be the third v

he Brain Ste

dbrain structua and pineal cles. Also rethe pons, the

he Cerebellu

ture in the ce

ender canal tho the cavity beedulla. The cand the canal iral aqueduct cm the third veckage of this ps hydrocepha

cture called thdial portion of at lie within appears to be

mediate mass ventricle.

m, including

ures; the dorsbody, and thexamine the e medulla, an

um

nter is the arb

hat passes etween the avity is the fois the cerebracarries ntricle to the passage causlus.

e

e of

g

sal he

nd

bor

ourth al

ses

10

11 On the dissected ““Sheep Brain - Whole, with Dura Mater”, note the following structures, and how different they look on the dissected brain, versus the whole brain: Dura mater Pituitary gland (hypophysis) Optic chiasma Mamillary body (human brain model only) Central sulcus Midbrain and corpora quadrigemina Pons Pineal gland There are others, but these really stand out! Also notice how different these structures look on the shhep brain versus the human model, do to the fact that a sheep has a neck that goes straight out, whereas our has a 90 degree bend: Hypothalamus Midbrain

Clean Up Procedures

1. Replace the following back into the buckets from which they came: Sheep Brain Whole - without dura mater (you will not be dissecting this) Sheep Brain Frontal Section

2. Place the brain you dissected, and any parts, in the designated container. When you are ready, place your gloves in a regular trash can and NOT in the container with the dissected brains. 3. Take the dissection tray and all instruments to the sink to be washed. 4. Remove the pad from the dissection tray and wash them separately using the provided disinfectant and sponge. 5. Also spray the instruments with disinfectant and clean them using the provided toothbrushes. 6. Rinse the pad, dissecting tray, and all tools and place them in the drying tray. 7. Place the instruments SHARP END DOWN in the appropriate portion of the drying tray. 8. Spray down the area of the lab bench where the dissection was completed with disinfectant and dry using a paper towel.

Do This!

12

#1

Part 3. Identify and study the Cranial Nerves – Can be done out of lab!

Have someone in your group read this, while the others follow along: No two instructors are the same when it come to the cranial nerves. Some want you to know the names only, some want names and function, some want you to be able to ID them on images and models. You should confirm with your instructor what you need to know regarding the cranial nerves. Here, we will have you:

1. name all 12 in order, starting with the most anterior. 2. know something about their basic function. 3. ID the first 6, and number 10, on an image.

If you need to know more, your instructor can guide you.

Read Me

Continued on next page

13 #2

Fill out this table: Cranial Nerve: Major Functions:

I

Sensory only:

II

Sensory only:

III

Mainly Motor:

IV

Mainly Motor:

V

Motor & Sensory:

VI

Mainly Motor:

VII

Motor & Sensory:

VIII

Mainly Sensory:

IX

Motor & Sensory (only sense listed here):

X

Motor & Sensory:

XI

Mainly Motor:

XII

Mainly Motor:

#3 Label t

Larigthth

If

1

2

he Cranial

abel the cranght and left s

he nerve (for ehe structures t

your instructo

Nerves.

ial nerves listides. If you cexample, the that attach to

or wants you

ted below, ancannot directlyoptic and olfa them can be

VagusOlfactoTrochleOculomAbduceOptic Trigemi

to be able to

d number X, y label the neactory nervese).

ry ear motor ens

inal

ID the other

on this diagrerve, label thes cannot be di

5, label them

ram. Label the structure thairectly seen o

on the image

hem on both tat accommodon the image,

e now!

14

he ates but

15

#1

Part 4. Assess yourself using a series of thinking questions – Can be done out of lab!

Have someone in your group read this, while the others follow along: This will help in both lecture and lab. Answer these questions while identifying the structures on a model or image. You may do this exercise outside of lab if time is short. Answer them out loud, if you want to save time. Use a separate piece of paper if you need more space.

1. Beginning with the outside layer, the names of the three meninges that enclose the CNS. 2. Name the three major regions of the Diencephalon. 3. Name the three major regions of the midbrain.

Read Me

16 4. Name the two major regions of the cerebrum 5. Name the band of tissue at the base of the longitudinal or sagittal fissure that is the primary nerve pathway connecting right and left cerebral hemispheres. 5. Name of the brain region to which the pituitary gland is attached. Part of the pituitary (posterior lobe) is actually formed from tissue of this part of the brain. Also name the stalk that attached the gland. 6. Name of the small cavity around the thalamus which contains CSF. 7. Name of the point where the two optic nerves meet and partially cross over, before passing to the cerebrum.

17 8. Name of the outer layer of each cerebral hemisphere. (HINT: it is composed of grey matter) 9. The region of the brain consisting of two major hemispheres. 10. Name of the deep fissure that separates the cerebellum from the cerebral hemispheres. 11. Name of the grooves and folds of tissue characteristic of each cerebral hemisphere.

Groove - Fold -

18 12. What do we call the large, obvious sulcus running across the cerebral cortex? 13. Finish this sentence: All ___________________ functions of the brain are posterior to the Central Sulcus. 14. Finish this sentence: All ___________________ functions of the brain are anterior to the Central Sulcus. 15. Name the ridges of tissue anterior and posterior to the central sulcus of the cerebrum. What are their functions?

Anterior ridge - Posterior ridge -

16. Name the gland that is found in the epithalamus. What does it secrete?

19 17. Brain region that includes "vital centers" for involuntary control of heart function, respiratory function and vasomotor activity. 18. Brain center that functions as the "master gland" of the endocrine system. (HINT: fill in the blanks below):

"The ______________________ of the brain acts to control homeostasis of the visceral organs, mainly by controlling the output of the _________________gland, also known as the ___________________. "

19. Primary visual area of cerebrum are found where?

20 20. Brain center that acts as a primary organizational control center for all information entering the cerebrum. 21. Brain center that includes involuntary centers critical to maintenance of muscle tone, equilibrium and posture. 22. What is the white matter of the cerebellum called?

21 23. How do the relative sizes of the cerebral hemispheres compare in the sheep brain and the human brain? What conclusions can you draw from this? 24. How do the relative sizes of the olfactory bulbs compare in the sheep brain and the human brain? What conclusions can you draw from this? 25. What is the importance of the fact that the surface of the cerebral hemispheres is highly convoluted?

22 26. What is the importance of the corpus callosum? 27. What is the function or importance of the ventricles of the brain? How are they related to the central canal of the spinal cord, and the subarachnoid space?