The Human Brain During the Third Trimester

Solitary nucleus and tract

Gracile nucleus

Gracile fasciculus

Cuneate nucleus

External cuneate nucleus

Dorsal sensory nucleus (X)

Dorsal motor nucleus (X)

Hypoglossal nucleus (XII)

Nucleus of Roller

Medial longitudinal fasciculus

and tectospinal tract

Fourth ve ntricle

Raphe nuclear complex Area postrema

Infer

iorc

ere

be

llar

peduncle

Infer

iorc

ere

be

llar

peduncle

F

ourth

v

entricl

e

F

ourth

ventricl

e

Nerve X

Solitary nucleus

and tract

Solitary nucleus

and tract

Nucleus

ambiguus

Nucleus

ambiguus

Cuneate

nucleus

Cuneate

nucleus

Cuneate

nucleus

Cuneate

nucleus

Dorsal sensory

nucleus (X)

Dorsal sensory

nucleus (X)

Dorsal motor nucleus (XDorsal motor nucleus (X))

Hypoglossal nucleus (XII)Hypoglossal nucleus (XII)

Inferior

olive

complex

Inferior

olive

complex

Medial longitudinal fasciculus

and tectospinal tract

Medial longitudinal fasciculus

and tectospinal tract

Dorsal longitudinal fasciculuDorsal longitudinal fasciculuss

Reticular

formation

Reticular

fo rmation

Nodulus

(X)

Nodulus

(X)

Uvula

(IX)

Uvula

(IX)

Raphe nuclear compleRaphe nuclear complexx

Spinal nucleus

and tract (V)

Spinal nucleus

and tract (V)

PONSPONS

Crus II,

ansi

form lo

b

ul

e

(HVIIA

)

Crus II,

ansif

orm lo

bu

le

(HVIIA

)

Crus II,

ansif

orm lob

ule

(HVIIA

)

Crus II,

ansif

orm lob

ul

e

(HVIIA

)

Vestibular

nuclear

complex

Vestibu lar

nuclear

complex

Choroid

plexus

Choroid

plexus

Flocculus

(HX)

Flocculus

(HX)

Flocculus

(HX)

Flocculus

(HX)

Paraflocculus

(HIX)

Paraflocculus

(HIX)

Paraflocculus

(HIX)

Paraflocculus

(HIX)

MEDULLAMEDULLA

PrPrepositus nucleuepositus nucleuss

P

aramedian lob

ule (HVIIB)

Paramedian lob

ule (HVIIB)

Param

edian

lob

ule

(H

VIIB

)

Param

ed

ian

lob

ule

(H

VIIB

)

Bi

ventral lo

bule (HVIII)

Biventral lo

bu

le (HVIII)

Bi

ven

tra

l lo

bu

le

(H

VI

II)

Biv

entr

al lo

bu

le

(H

VI

II)

Middle cerebellar

peduncle

Inferior

cerebellar

peduncle

Inferior

cerebellar

peduncle

Inf

erio

r^ c

ereb

ella

r

ped

unc

le

Inf

erio

r^ c

ereb

ella

r

ped

unc

le

Spinocerebellar

tracts

Basal pontine
gray

*Arcuate nucleus

(medulla) Medial lemniscuMedial lemniscuss

Principal nucleus

Medial accessory nucleus

Corticospinal tract

Spi

noc

ere

bel

lartracts

Spi

noc

ere

bel

lartracts

PyramidPyramid

Inferior

olive

complex

Inferior

olive

complex

Reticular

formation

Reticular

formation

Spinal nucleus and tract (V)

Crus II,

ansi

form lo

b

ul

e

(HVIIA

)

Crus II,

ansif

orm lo

bu

le

(HVIIA

)

Crus II,

ansif

orm lo

b

ul

e

(HVIIA

)

Crus II,

ansif

orm lo

bu

le

(HVIIA

)

Choroid

plexus

Choroid

plexus

Paraflocculus

(HIX)

Paraflocculus

(HIX)

Paraflocculus

(HIX)

Paraflocculus

(HIX)

MEDULLAMEDULLA

P

aramedian lob

ule (HVIIB)

Paramedian lob

ule (HVIIB)

P

a

ra

m

e

d

ia

n

lo

b

u

le

(H

V

II

B

)

P

a

ra

m

e

d

ia

n

lo

b

u

le

(H

V

II

B

)

Bi

ventral lo

bule (HVIII)

Biventral lo

bu

le (HVIII)

Bi

ventral lo

b

ul

e

Biventral lo(HVIII)

bu

le

(HVIII)

Spinocerebellar tracts

Lateral reticular nucleus

Nucleus ambiguus

*Arcuate nucleus

(medulla)

Medial lemniscuMedial lemniscuss

Medial lemniscuMedial lemniscuss

(arcuate fibers)

Principal nucleus

Medial accessory nucleus

Dorsal accessory nucleus

Corticospinal tract

PyramidPyramid

Inferior cerebellar peduncle

Germinal and transitional structuGerminal and transitional structurres ines in italicsitalics

C

E

R

E

B

E

L

L

U

M

CEREBELLUM

VVermisermis

HemispheHemispherree

HemispheHemispherree

External germinal layer

External germinal layer

External

germinal layer

External

germinal layer

Medullary glioepithelium/ependymaMedullary glioepithelium/ependyma

Medullary glioepithelium/ependymaMedullary glioepithelium/ependyma

Section 1201 Section 1241

*The arcuate nucleus in the medulla

may contain neurons

from the Raphe migration.

PLATE 149B