front matter 1

Sp

in

oc

ep

ha

li

c

tr

a

c

ts

?

Sp

in

oc

ep

ha

li

c

tr

a

c

ts

?

VVentral funiculusentral funiculus

VVentral grayentral gray

Intermediate grayIntermediate gray

Dorsal root bifurcation zone

Superficial fasciculus cuneatus

Deep fasciculus cuneatus

Superficial fasciculus gracilis

Deep fasciculus gracilis

Dorsal root collateralization zone

Lissauer's tract

Lateral

funiculus

Lateral

funiculus

Tectospinal tract?

Medial longitudinal fasciculus?

Vestibulospinal tract?

Dorsal grayDorsal gray

Myelinated

ventral rootlets

Myelinated

ventral rootlets

Dorsal root

Myelinating terminals

of dorsal root collaterals

Dorsal median septum

Dorsal intermediate septum

Ventral median fissure

Dorsal funiculus

VVentral white commissureentral white commissure

VVentral gray commissureentral gray commissure

Ventral

corticospinal

tract

Ventral

corticospinal

tract

Lateral

corticospinal tract

Lateral

corticospinal tract

Spinal canal with

surrounding ependyma

Spinal canal with

surrounding ependyma

Int

ra

sp

in

al

tr

a

c

ts

?

Int

ra

sp

in

al

tr

a

c

ts

?

Sp

in

o

c

e

re

b

e

l

la

r

tr

a

c

ts

?

Sp

in

o

c

e

re

b

e

l

la

r

tr

a

c

ts

?

Examples of myelination

and concentrations

of reactive glia

Examples of myelination and

concentrations of reactive glia

Myelinated

Many

myelinated

fibers

Some myelinated fibers

Very dense reactive glia

Very sparse

reactive glia

Incipient

subgelatinosal

plexus

Incipient

subgelatinosal

plexus

Reticulated

area

Reticulated

area

Myelinated proximal

axons of ventral horn

motoneurons

Myelinated proximal

axons of ventral horn

motoneurons

Lateral
reticulospinal
tract?

Lateral
reticulospinal
tract?

See the matched cell body stained section in Plates 64A and B

The fi ne lines in the lateral and ventral funiculi segregate regions of differing densities of the myelin stain, not the borders of fi ber

tracts. These lines may correspond to the borders of some fi ber tracts, such as the spinocerebellar and the lateral corticospinal tracts.

Other lines run across fi ber tracts, such as the area surrounding the ventral horn that includes the medial and central parts of the

intraspinal tracts, and the internal fi bers of the spinocephalic tracts. Most tracts in the ventral and lateral funiculi overlap and do

not have distinct borders. The ventral part of the spinocephalic tracts overlaps with the vestibulospinal tract; its central part includes

fi bers in the ventrolateral reticulospinal tract (not labeled), the spinotectal tract (not labeled), and the spino-olivary tract (not labeled).

The intraspinal tracts overlap with the medial longitudinal fasciculus, the tectospinal tract, and the lateral reticulospinal tract.

PLATE 63B