front matter 1

Floor plateFloor plate

VVentral funiculusentral funiculus

Ventral

corticospinal

tract

Ventral

corticospinal

Ventral horn tract

motoneurons

Ventral horn

motoneurons

Ventral horn

interneurons

Ventral horn

interneurons

Intermediate

interneurons

Intermediate

interneurons

Dorsal root bifurcation zone

Dorsal root collateralization zone

Lissauer's tract

Dorsal funiculus

Dorsal

horn Substantia

gelatinosa

Substantia

gelatinosa

Lateral

funiculus

Lateral

funiculus

EpendymaEpendyma

Central

autonomic

area

Central

autonomic

area

Lateral

cervical

nucleus

Lateral

cervical

nucleus

Lamina ILamina I

Dorsal root

Ventral root

Laminae

IV-V

Laminae

IV-V

corticospinalLateral

tract

corticospinalLateral

tract

Tectospinal tract?

Medial longitudinal fasciculus?

Vestibulospinal tract?

Roof plateRoof plate

Central canalCentral canal

shoulder?shoulder?

shoulder

and arm?

shoulder

and arm?

arm?arm?

forearm?forearm?

wrist?wrist?

digits?digits?

Deep fasciculus cuneatus

Superficial fasciculus cuneatus

Deep fasciculus gracilis

Superficial fasciculus gracilis

VVentral white commissureentral white commissure

VVentral gray commissureentral gray commissure

Dorsal median septum

Dorsal intermediate septum

Ventral

median

fissure

D

or

sa

lsp

inoc

er

e

b

e

ll

a

r

tr

a

c

t

D

or

sa

lsp

inoc

er

e

b

e

ll

a

r

tr

a

c

t

V

en

tr

a

l

s

p

in

o

c

e

r

e

b

e

ll

a

r

tr

a

c

t

V

en

tr

a

l

s

p

in

o

c

e

r

e

b

e

ll

a

r

tr

a

c

t

Spi

no

ce

ph

al

ic

tr

ac

ts

Spi

no

ce

ph

al

ic

tr

ac

Intraspin ts

al

tr

a

c

t

s

Intraspina

l

tr

a

c

t

s

Rubrospinal

tract?

Rubrospinal

tract?

Note the larger lateral and ventral corticospinal tracts on one side of the spinal cord and the smaller ones on the other (see

also Plates 39 and 41 ). Axons in the lateral corticospinal tract cross the midline, while axons in the ventral corticospinal

tract remain ipsilateral. The larger lateral corticospinal tract (crossed component) is linked to the smaller ventral corti-

cospinal tract (uncrossed component) and vice versa. It is unknown which is the true right or left side. This specimen is

the only one in the Atlas to show such a pronounced asymmetry.

PLATE 40B

See Table III B-1 for the list of glial densities in each fi ber tract.

Examples of glial densities in each category are labeled in the lower

left corner of Plate 39B.