The Human Brain During the Third Trimester

3 Glioepithelium (optic nerve and chiasm)

1

33

4

(^4444)
55
55
66
66
77
9
88
9
22
2 Preoptic glioepithelium/ependyma
1 Strionuclear glioepithelium
9 External germinal layer (cerebellum)
4 Thalamic glioepithelium/ependyma
5 Mesencephalic glioepithelium/ependyma
7 Medullary glioepithelium/ependyma
8 Germinal trigone (cerebellum)
6 Pontine glioepithelium/ependyma
Nodulus
X
Nodulus
X
Uvula
IX
Uvula
IX
Pyramis
VIII
Pyramis
VIII
Folium
VIIa
Fo lium
VIIa
Declive
VI
Declive
VI
Culmen
IV, V
Culmen
IV, V
Lingula
I, II
Lingula
I, II
Centralis
III
Centralis
III
Tuber
VIIb
Tuber
VIIb
Fastigial
nucleus
PPontine grayontine gray
Dorsomedial
nucleus
Dorsomedial
nucleus
A
n
te
ri
o
r
c
o
m
p
le
x
A
n
te
ri
o
r
c
o
m
p
le
x
Oculomotor nerve
Cerebral peduncle
Optic nerve
and chiasm
Ventromedial
nucleus
Ve ntro medial
nucleus
Dorsomedial
nucleus
Dorsomedial
nucleus
Mammillary
body
Mammillary
body
Lamina terminalis
PPerieriventricular prventricular preoptic nucleueoptic nucleuss
Third ve ntricle
(preoptic recess)
Third vThird ventricleentricle
Third ventricle
Diagonal band
of Broca
(vertical limb)
Diagonal band
of Broca
(vertical limb)
Medial
septal
nucleus
Medial
septal
nucleus
Anterior
commissure
Choroid
plexus
Choroid
plexus
Choroid
plexus
Subcallosal arSubcallosal areaea
Fornix
(postcommissural)
Fornix
(postcommissural)
Fo
rn
ix
(pr
ec
om
m
iss
ur
al
)
Fo
rn
ix
(pr
ec
om
m
iss
ur
al)
Fo
rn
ix
Fo
rn
ix
Hippoc
ampal
commi
ssure
Hippoc
ampal
commi
ssure
Hippocampal
commissure
Cor
pus callosu
m
Corpus callosu(body)
m
(body)
Induseum griseuInduseum griseumm
Corpus
callosum
(splenium)
Corpus
callosum
(splenium)
Cingulate gyrusCingulate gyrus
Corpus
callosum
(rostrum)
Corpus
callosum
(rostrum)
La
te
ra
l v
en
tr
ic
le
Fields of Fields of FForelorel
Mammillo-
thalamic
tract
Mammillo-
thalamic
tract
HYPO-
THALAMUS
HYPO-
THALAMUS
PREOPTIC
AREA
PREOPTIC
AREA
SEPTUMSEPTUM
THALAMUSTHALAMUS
MIDBRAIMIDBRAINN
PONSPONS
Central grayCentral gray
Su
pe
rio
r (^) c
ollic
ulu
s
Su
pe
rio
r (^) c
ollic
ulu
s
Inferior
colliculus
Inferior
colliculus
Red
nucleus
Red
nucleus
Ventral tegmental area
Superior cerebellar
peduncle
Superior cerebellar
peduncle
Oculomotor nuclear
complex (III)
Oculomotor nuclear
complex (III)
Reticular
formation
Reticular
fo rmation
Reticular
formation
Reticular
formatio n
Reticular
formation
Reticular
formatio n
TTr ochlear nucleus (IV)?rochlear nucleus (IV)?
Ceerebral
aqueduct
Ceerebral
aqueduct
Inferior
Olive
Inferior
Oliv e
Reticular
tegmental
nucleus
Reticular
tegmental
nucleus
Dorsal
tegmental
nucleus
Dorsal
tegmental
nucleus
Medial lemniscus (decussation)
Medial longitudinal fascuculus and tectospinal tract
Dorsal motor nucleus (X)
*Arcuate nucleus (medulla)
Transpontine corticofugal tract
(thick longitudinal bundles)
Pontocerebellar
fibers (thin trans-
verse bundles)
Corticofugal tract
Medial
habenular
nucleus
Gracile fasciculus
Cave of the
septum
Cave of th e
septum
C
e
n
tr
a
lc
omplex
C
e
n
tr
a
lc
omplex
P
er
iv
en
tric
ular comp
le
x
P
er
iv
en
tric
ular comp
le
x
Dorsa l
comple x
Dorsa l
comple x
Inter-
peduncular
nucleus
Inter-
peduncular
nucleus
Suprachiasmatic
nucleus
Hypoglossal
nucleus (XII)
Hypoglossal
nucleus (XII)
Fo urth
ventricl e
MEDULLAMEDULLA
R
a
ph
en
u
c
le
a
r
c
o
m
p
l
e
x
R
a
ph
en
u
c
le
a
r
c
o
m
p
l
e
x

M

ed

ia

ll

on

gi

tu

d

in

a

l

fa

sc

ic

u

lu

s

M

ed

ia

ll

on

gi

tu

d

in

a

l

fa

sc

ic

u

lu

s

SSttrriiaammeedduullllaarriiss

Dorsal

raphe

nuclei

Dorsal

raphe

nuclei

Gracile nucleus

Prepositus nucleus

M

e

d

ia

l

le

m

n

is

c

u

s

M

e

d

ia

l

le

m

n

is

c

u

s

TEGMENTUMTEGMENTUM

TECTUMTECTUM

Paraflocculus

(tonsil, extends from uvula

to hemisphere)

Paraflocculus

(tonsil, extends from uvula

to hemisphere )

Paramedian lo

bule

(extends fr

om tuber to hemisphe

re)

Paramedian lo

bu

le

(extends fr

om tuber to hemisphe

re

)

Trochlear

nerve

bundles?

Tr ochlear

nerv e

bundles?

Superior

medullary

velum

Superior

medullary

velum

Fa stigial

nucleus

AN

TE

RI

O

R^ L

OB

E

AN

TE

RI

O

R^ L

OB

E

CENTRAL

LOBE

CENTRAL

LOBE

INFERIOR

LOBE

INFERIOR

LOBE

POSTERIOR

LOBE

POSTERIOR

LOBE

V E R M I SV E R M I S

H

E M I S P

H

E

R

E

H

E M I S P

H

E

R

E

Preculminate fissure

A (separates centralis and culmen)

Primary fissure

(separates anterior and central lobes)

B

Secondary fissure

(separates central and posterior

lobes)

D

Prepyramidal fissure

C (separates tuber and pyramis)

Posterolateral fissure

(separates posterior and inferior

lobes)

E

Cerebellar fissures

CC

AA

AA

BB

BB

CC

DD

DD

EE

EE

Habenulo-

interpeduncular

tract

Habenulo-

interpeduncular

tract

Habenulo-

interpeduncular

tract

Posterior

commissure

Bed nucleus

of the stria

terminalis

Bed nucleus

of the stria

terminalis

La

ter

al^

sep

ta

l

nu

cle

us

La

ter

al^

sep

ta

l

nu

cle

us

Remnants of the germinal matrix

Parabrachial

nucleus

Parabrachial

nucleus

Arcuate

nucleus

Arcuate

nucleus

*Cells may be entering this nucleus

via the Raphe migration.

C E

R E B E L L U M

PLATE 55B