The Human Brain During the Third Trimester

GW26 Sagittal

CR 225 mm

Y147-63

Level 3: Section 461

Pontine gray

Olfactory peduncle

Transpontine corticofugal tract

Oculomotor nerve(III)

Primary fissure

Pyramid (corticospinal tract)

Pyramidal decussation

Medial lemniscus

Inferior olive complex

Anterior

commissure

Anterior

commissure

ThalamusThalamus

Gracile fasciculus and nucleus

Paraflocculus (HIX)

Orbital gyrusOrbital gyrus

Parietal

lobe

Parietal

lobe

Frontal

lobe

Frontal

lobe

Frontal

lobe

Frontal

lobe

Hypo-

thalamus

Hypo-

thalamus

Preoptic

area

Preoptic

area

GenuGenu

Sp

len

iu

m

Sp

len

iu

m

SeptuSeptumm

TTectuectumm

MidbraiMidbrainn

PPonsons

MedullaMedulla

Spinal cordSpinal cord

Occipital

lobe

Occipital

lobe

Cortical plate

White matter

Third

ventricle

Third

ventricle

Fourth

ventricle

Fourth

ventricl e

Cere bellum

(lateral vermis)

Anterior

lobe

Anterior

lobe

Central

lobe

Central

lobe

Posterior

lobe

Po sterior

lobe

Inferior

lobe

Inferior

lobe

TTe gmentumegmentum

Inferior

colliculus

Inferior

colliculus

Superior

colliculus

Superior

colliculus

11

22

22

44

33

55

88

77

66

Co

rpu

scal

losum

Co

rpu

scal

losum

Hippocampal

commissure

Pretectum

Cave of the

septum

Induseum griseum

Fasciola cinereum

Cingulate gyrusCingulate gyrus

Cin

gul

ate^

gyr

us

Cin

gul

ate^

gyr

Fornix us

(precom-

missural)

Fornix

(postcom-

missural)

Islands of Calleja and

medial nucleus accumbens

Islands of Calleja and

medial nucleus accumbens

9

9

10

10

10

Layer I

Remnants of the germinal matrix, migratory streams, and transitional fields

6 Mesencephalic glioepithelium/ependyma

5 Diencephalic (thalamic) glioepithelium/ependyma

3 Fo rnical glioepithelium

4 Strionuclear glioepithelium 9 External germinal layer (cerebellum)

1 Rostral migratory stream

2 Callosal glioepithelium 7 Pontine and medullary glioepithelium/ependyma

8 Germinal trigone (cerebellum)

10 Subpial granular layer (cortical)

See detail of brain core and

cerebellum in Plates 202A and B.

Paracentral

lobule

Paracentral

lobu le

PLATE 192