CHAPTER III.

THE COLUMNS OF THE SPINAL CORD.

Having given a general sketch of the regions of the model and
shown how its principal structures are related to the central fibre
mass, each of the structures of the spinal cord may next be traced
into the medulla oblongata. Starting with the central canal its en-
tire course is not shown in any one plate, but it can be traced as
follows:—In Plate v the canal is shown within the cord. In en-
tering the medulla oblongata it curves dorsalward along the border
of the medulla sheet until it opens out into the fourth ventricle as
seen in Plate m1. The relation of the aqueeductus cerebri to the
third ventricle can be traced in Plate nm.

A view of the lateral surface of the model gives the best idea of
its relations to the spinal cord (Plate 1). The ventral funiculus is
not seen, but the lateral and dorsal funiculi are plain.

On the distal edge of the model (Plate 11) is a shallow groove
which divides the lateral funiculus into two parts. This groove cor-
responds to the line on Text-Fig. 1. The ventral portion is the
fasciculus ventrolateralis, which, as the model will show, is sub-
divided in the medulla oblongata into four definite bundles and
certain scattered fibres. The dorsal part, or funiculus lateralis,
is divided into two parts, (1) the fasciculus cerebellospinalis, or
direct cerebellar tract, which occupies the lateral surface at the
distal end of the model, and (2) a mass of fibres concealed from the
surface which enters into the formation of the formatio reticularis
area of the medulla oblongata. The fasciculus cerebellospinalis
lies near the surface and joins with a bundle belonging to the
system of the dorsal funiculi to make the corpus restiforme
(Plate 1).

The dorsal funiculi of the spinal cord are shown in Plates m to vit
(omitting v1).

In entering the medulla oblongata the fasciculi gracilis and cu-
neatus (Goll and Burdach) slant dorsalward and spread out into a
nuclear capsule (Plate 1). This capsule is continuous with the
corpus restiforme. The nuclei of the dorsal funiculi can be seen
in Plates rv and vi.

Structures in
the spinal cord
traced into the
Medulla.
36 VENTROLATERAL CoLUMN or THE Sprnat Corp

The dorsal horn is visible in the surface view in the model, for
the fasciculus of Lissauer has been removed. At the beginning of
the medulla oblongata, the dorsal horn, swollen into a large sub-
stantia gelatinosa, becomes continuous with the nucleus of the
tractus spinalis nervi trigemini (Plates m and iv). A full discus-
sion of the gray matter of the cord in relation to the model is left
for Chapters v and vt.

A.-- VENTROLATERAL FUNICULI.

Ventrolateral (@) Pars Ventralis of the Ventrolateral Funiculi.—The separate
colum®. tuniculi of the spinal cord will now be considered in detail, begin-
ning with the ventrolateral fasciculus. This column includes all

Dorsal columns

Direct cerebellar tract

\ ‘Lateral ground bundle
Ventro-lateral column
Fia, 1.—Transverse section of the Spinal Cord at the level of the distal end of the
model.

of the white matter below the transverse line in Text-Fig. 1, for
the pyramidal tracts are not yet medullated. It will be clear that
the ventrolateral column as seen in Text-Fig. 1, is a cross-section
of the trough at the distal end of the model (Plates v and vm). As
has been said, the walls of the trough are divided in the medulla
into four definite bundles, and certain scattered fibres.
Fibres to posterior The first group includes the most medial and ventral fibres
bundle. (Plates v and vr). They have already been described as turning
dorsalward along the border of the medulla sheet to make the
fasciculus longitudinalis medialis.
In the transverse sections they are visible in Figs. 27 and 28, (F. v. 1.
oF F, v. p.), both of which give a cross-section of the trough where it

is opening out onto the medulla sheet. Fig. 20 shows these fibres in
longitudinal sections. The trough is lettered F. 1.
VENTROLATERAL CoLuMN oF THE Spinat Corp 37

The second bundle leaves the lateral funiculus a little farther
cerebralward (Plate v, Fasciculus lateralis [2]). It passes obliquely
toward the midline and is represented in the model as stopping
abruptly against the root of the N. hypoglossus. In reality the
fibres pass on between the root bundles of the nerve adjacent to the
medial lemniseus (Fig. 19, F. 1.). In some of the sections it is
possible to trace the fibres of this bundle through the parts of the
medial accessory olive into the lemniscus medialis. Other fibres
pass out into the proximal lobe of the nucleus olivaris inferior, the
wall of which they do not appear to penetrate.

The shape of this second bundle in the model is peculiar, for the
dorsal fibres do not appear to come from the lateral funiculus at all.
They represent a little group of fibres which come from the forma-
tio reticularis and pass with the bundle in question toward the area
of the medial lemniscus. As the bundle is crossing from the lateral
funiculus toward the middle line a small group of fibres becomes
separated from the mesial surface of the main mass, passes parallel
to it for a short distance and then joins with it again. It cannot be
seen in the lateral views given in the plates, but it shows in Figs.
19 and 28. It is not labeled in either section but is a small bundle
of fibres within the trough. (In Fig. 19 the line F. a. i. passes
through it.) Its meaning I do not know. To return to the main
bundle, the model shows the following points: (1) The bundle is
connected with the lateral funiculus of the cord; (2) it does not
decussate in the medulla oblongata; (3) it runs parallel to the
medial lemniscus at the level of the inferior olive; (4) its fibres
appear to join the lemniscus in part and in part to turn toward the
olive, beyond which they cannot be traced in these preparations.
If this bundle joins the lemniscus medialis it may represent, a sen-
sory path from the lateral funiculi which does not decussate in the
medulla oblongata.

The two bundles just described receive the medial and ventral
fibres of the fasciculus ventrolateralis (Text-Fig. 1). The lateral
fibres pass onward to a point opposite the distal end of the inferior
olive, where the bundle divides into two parts (Plates 1v and v).
This statement is made without regard to the direction of the
axones of the fibres. The larger and medial of these two bundles
extends between the lateral funiculus of the cord and the lemniscus
lateralis (Plates Iv and v). It does not joi the lemniscus, but

Fibres to medial
lemniscus.

Fibres from
Deiter’s nucleus
to the spinal cord.
88 VENTROLATERAL CotuMN oF THE Sprnat Corp

rather passes beyond the point of meeting; its fibres, however,
could not be traced farther in the longitudinal series. The lateral
lemniscus leaves the trapezoid body just dorsal to the nucleus
olivaris superior which lies embedded within the trapezoid body.
The bundle connected with the cord touches the lemniscus lateralis
just dorsal to the medial border of the superior olive. The two
bundles make a slight angle in which lies the nucleus of the facial
nerve. The bundle will be traced spinalward inasmuch as this
is the direction taken by at least a portion of the axones of its
constituent fibres. Starting from the point where it touches the
lemniscus, it passes at once ventralward, lateralward and spinal-
ward. The bundle spreads out in its course and sweeps around the
surface of the inferior olive to join the lateral funiculus of the
cord (Plates rv and v).

This bundle must be studied carefully in both series of sections. In
the longitudinal series, a considerable portion of the bundle can be seen
in one section (Fig. 13, Tr. fr. Nu. D.). Its approach to the faseiculus
lateralis of the spinal cord can be seen in Fig. 16. I wish to emphasize
two points shown in Fig. 13: (1) that though the bundle adjoins the
lateral lemniscus, its fibres are cut at a different angle, that is, more
obliquely (compare Plate v), (2) that the bundle can be recognized
from its relation to the nucleus of the facial nerve.

Turning to the transverse series the bundle is determined readily by
this relation. In Fig. 38 the bundle corresponds with the tract described
as passing from Deiters’ nucleus to the spinal cord. It can be seen in
Figs. 36 to 38, in which its fibres are passing dorsalward through the
formatio reticularis. These sections include the area between the pars
prima and pars secunda of the N. facialis (Plate v); hence the bundle
scatters in its dorsal course so that it is not strange to lose it in the
longitudinal sections, in which its fibres must be cut across. Even in

the transverse series I cannot demonstrate the connection of the bundle
with Deiters’ nucleus.’

Undetermined ‘The last and smallest of the four bundles from the ventral part
Pendle of the lateral funiculus maintains a lateral position throughout its
course. It passes along the surface through the entire length of
the medulla oblongata and joins the trapezoid body midway be-
tween its dorsal and ventral aspects (Plate v). In the trapezoid

body it is wholly lost from view.

The bundle is horizontal, so its complete course can be seen in one
section (Fig. 17). It can be followed as readily in the transverse series

 

* The position of the bundle corresponds with Ramén y Cajal’s descrip-
tion. Ramén y Cajal, S. Beitrag zur Studium der Medulla oblongata, des
Kleinhirns und des Ursprung der Gehirnnerven. Deutsche Uebersetz.
von Bresler, Leipzig (1896), S. 71.
Direct CerEBELLAR TRAcT of THE Sprvat Corp 39

(Figs. 30 to 35) (F.1.). This bundle is labeled the fasciculus anterior by
Edinger.

It may correspond to v. Bechterew’s’ aberrant bundle. As regards
Gowers’ tract the section in Taf. Ix of Hoche’s article,’ shows the fibres
of Gowers’ tract just ventral to the tractus spinalis N. trigemini. The
section is taken opposite the middle of the inferior olive proximal to the
passage of the fasciculus cerebellospinalis into the corpus restiforme.
In the series I have studied, a corresponding section has this area as a
non-medullated space, while ventral to it lies the bundle shown in the
model. A second section in my series, taken to correspond with Fig. 7,
Taf. 1x of Hoche’s paper, will show still more clearly the non-medulla-
tion of the fibres of Gowers’ bundle as described by Hoche (Fig. 38).
At this level Gowers’ tract cuts across the pars secunda of the facial
nerve, just as it plunges into the corpus trapezoideum and this area in
my series is non-medullated. At the level of Fig. 38, the fourth bundle
of the model is no longer visible.

These four bundles in the medulla oblongata contain all of the
fibres of the fasciculus ventrolateralis, medullated at this stage,
with the exception of certain fibres of the formatio reticularis.
These come from the mesial part of the lateral wall of the trough
(Plate vit). They spread out in the medulla oblongata and consti-
tute the ventral bundle of the formatio reticularis.* This bundle is
much smaller than the dorsal bundle of the formatio reticularis.

(b) Pars Dorsalis of the Funiculus Lateralis.—Turning now to Dorsal abres of
the dorsal part of the lateral funiculus of the cord, the section ‘“"™ °™™™
in Text-Fig. 1, shows that it contains two fibre masses; one lateral,
the fasciculus cerebellospinalis, or direct cerebellar tract, and one
more medial, a part of the fasciculus lateralis proprius (Flechsigi),
or the so-called lateral ground bundle.

At the distal edge of the model the direct cerebellar tract forms Direct cerebellar
a band or ribbon on the surface of the spinal cord (Plate m and Text- tracts
Fig. 1). In approaching the medulla oblongata the fibres con-
verge to form a compact bundle (Fig. 28). In this bundle the fibres

1 Edinger, L., Vorlesungen iiber den Bau der nervésen Centralorgane,
Leipzig (1893), S. 186.

2 Barker, L. F., op. cit. .

2 Hoche, A., Ueber secundire Degeneration, speciell des Gowers’...
schen Biindels, nebst Bemerkungen tiber das Verhalten der Reflexe bei
Compression des Riickenmarkes. Arch. f. Psychiat. u. Nervenkr., Berl.,
Bd. xxvuir (1896), S. 510-543.

*This is a part of the vordere genvischte Seitenstrangzone of Flechsig.
Flechsig, P., Die Leitungsbahnen im Gehirn und Riickenmark, Leipzig
(1876), S. 305.
Lateral ground
bundle.

Dorsal columns,

40 LatrraL Grounp Bunpie or tHe Sprrivat Corp

pass on to a point opposite the distal end of the inferior olivary
nucleus where the entire bundle turns dorsalward at almost a right
angle (Plates 11 and v with Fig. 30). The lines in Plate 1 of the
model showing this dorsal course are perhaps a little too abrupt.
They should follow the course of the lines of the transverse sec-
tions shown on Fig. 52. The fibres extend dorsalward beyond the
level of the tractus spinalis nervi trigemini; here they turn cere-
bralward again and join with the dorsal external arcuate fibres to
enter the corpus restiforme. This arcuate bundle shows in the
model as the direct continuation of the capsule of the nuclei of the
dorsal funiculi (Plate 1). The line in which the direct cerebellar
tract meets this arcuate bundle forms an arch, beneath which the
tractus spinalis nervi trigemini and its nucleus can be seen. The
corpus restiforme passes cerebralward, and at the same time
slightly lateralward, to a point opposite the level of the nucleus
N. abducentis. Here it turns dorsalward to enter the cerebellum
and hence is cut off in the model.

To return to the cross-section of the spinal cord shown in Text-
Fig. 1, all of the medullated fibres of the lateral funiculus have
been traced save the ground bundle, for at this stage the lateral
pyramidal tract is non-medullated. The model shows that the
ground bundle of the lateral funiculus has only to turn slightly
dorsalward, in agreement with the cervical curve in order to enter
the formatio reticularis of the medulla oblongata. (See the cross-
section of the cord in Plate v.) This formatio reticularis region
extends throughout the length of the medulla. It lies dorsal to the
nucleus olivaris inferior and lateral to the medulla sheet.

B.—FUNICULUS DORSALIS.

The dorsal funiculi of the spinal cord form a wedge-shaped mass
as seen in the cross-section (Text-Fig. 1). Each funiculus runs
to the beginning of the medulla oblongata without change of form
save that the groove between the fasciculus gracilis (Goll) and the
fasciculus cuneatus (Burdach) deepens (Plates m and mi). At
about the junction of the spinal cord and medulla oblongata, the
fasciculus gracilis becomes hollowed out to make a capsule for
its nucleus and a little farther cerebralward the fasciculus cuneatus
shows the same change. This capsule can be best understood after
the nucleus has been described.
DorsaLt Cotumys or tHE SprnaL Corp 41

The nucleus of the dorsal funiculus of the cord is seen best after Nuclei of the

removing the fibre capsule (Plates 1v and vi). It is an irregular
mass of cells, which is divisible into three parts; moreover, this divis-
ion, made from form alone is strengthened by the mode of dis-
tribution of the fibres. In general the distal portion of the nucleus
has a long diameter in a dorsoventral plane (Plate vir) at right
angles with the long axis of the proximal portion (Plate rv). The
three divisions, as seen from a lateral view, are (1) a distal, (2) a
middle and (8) a proximal part. The middle portion does not ex-
tend to the mesial surface of the nuclear mass and so may well be
called the lateral portion. (Nucleus funiculi cuneati lateralis,
Plate rv.)

The distal part or nucleus funiculi gracilis consists of a column
of cells placed in a dorsoventral direction. Its distal margin is
straight but the dorsal margin is eurved and raised above the rest
of the nuclear mass (Plate 1v). It is separated from the middle
nucleus by a deep groove but its surface is smooth, thereby contrast-
ing with the proximal portion. The rest of the mass has been
called the nucleus funiculi cuneati, but Blumenau has shown that
it consists of two distinct parts. The middle part, or nucleus of
Blumenau is a mass of cells projecting from the lateral surface
(Plate 1v. Nucleus funiculi cuneati lateralis). It is separated from
the distal nucleus by a deep groove but fades gradually into the

-proximal nucleus. Its distal border is about opposite the middle
of the nucleus funiculi gracilis, while its proximal limit is opposite
the lower part of the nucleus olivaris inferior, and the distal end of
the radix descendens nervi vestibuli.

In the model, the nucleus cannot be traced as far cerebralward
as Blumenau was able to trace it from histological details. Blum-
enau’ places the proximal limit opposite the lowest plane of en-
trance of the fibres of the N. acusticus. The sections of both my
series show small, scattered masses of cells in the corpus restiforme,
and these can be traced even into the cerebellum itself. They are
considered by Blumenau to be part of the nucleus which bears his
name. As has been said, the nucleus of Blumenau does not reach
the mesial surface of the nuclear mass. The thin mesial zone con-

1Blumenau, L., Ueber den Ausseren Kern des Keilstranges im verlin-
gerten Mark. Neurol. Centralbl., Leipz., Bd. x (1891), S. 229.

dorsal columns.
42 Sensory Decussatrox

sists (1) of a small column of cells projecting parallel to the nucleus
funiculi gracilis, and (2) a layer of cells associated with the prox-
imal nucleus. This will be explained in connection with the course
of the fibres from these cells.

The proximal portion of the mass is oblong in shape. It is char-
acterized by the irregularity of its lateral surface which is broken
by fibre bundles. One deep depression is to be seen near its ventral
surface.

Internal arcuate Further evidence of the division of this nucleus into three parts
ren ousatio 18 seen in the course of the fibres from it. In Plate vu it will be
noted that, while both the distal and proximal divisions give bun-
dles of fibres that run toward the raphe, no such bundle comes
from the lateral nucleus. These two bundles of internal arcuate
fibres, distal and proximal, are wholly distinct from one another
in the longitudinal series. In the transverse series, on the other
hand, it can be made out that the thin medial border of the middle
zone makes a transition between the distal and proximal bundles.

The distal bundle leads to the decussatio lemniscorum. It is a
small, compact bundle, which comes (1) from the distal third of the
nuclear mass, the nucleus funiculi gracilis, and (2) from the distal
part of the thin middle zone of the mass, the nucleus funiculi eune-
ati. The bundle leaves the proximal border of the nucleus funi-
culus gracilis and hence appears in transverse section to arise wholly
from the nucleus funiculi cuneati (Fig. 28). It is found in the
distal part of the medulla oblongata, distal to the olive and oppo-
site the proximal end of the decussatio pyramidum.* The bundle
passes along the border of the central gray matter, to a point ven-
tral to the central canal, where it decussates in mass between the
medulla sheets of the two sides and joins the stratum interolivare
lemnisci (Plate viz).

The proximal bundle of internal arcuate fibres, on the other
hand, is different both in position and in form. It is related to the
proximal part of the nuclear mass and forms a broad band which
appears as a direct continuation of the entire proximal third of the
nucleus into a fibre bundle (Plates 1v and vm). This bundle
sweeps across the medulla in a curve, dorsal to the olive, pierces the
medulla sheet, turns ventralward to decussate in the raphe, and

*Ramén y Cajal, op. cit., 8. 52.
. Agcuate Fisres 43

joins the stratum interolivare lemnisci of the opposite side. This
bundle contrasts with the distal arcuate bundle: (1) in position, for
it lies opposite the middle of the nucleus olivaris inferior, while the
latter is distal to it; (2) in course, for its fibres arise far lateralward
and pass through the formatio reticularis instead of bordering upon
the central canal; and (3) in the arrangement of its fibres into a
broad band instead of a compact bundle (Figs. 28 and 31, F. a. i.).
According to v. Bechterew* the fibres from the fasciculi of Goll
and Burdach can be distinguished from each other throughout the
pons. The mesial border of the middle zone gives off a few fine
arcuate fibres which make a transition between the distal and prox-
imal bundles. At first they lie near the central gray matter after
the type of the distal bundle, but they gradually pass farther to the
side until the proximal bundle is reached.

The model shows that the lateral nucleus of Blumenau’ is in the
‘exact position to send its fibres lateralward to the cerebellum rather
than medialward to the medial lemniscus on its way to the cerebrum.
This will appear clear by comparing Plates m, mt and tv.

The capsule of the nuclei of the dorsal funiculi of the cord is
continued directly into the corpus restiforme. This connection is
made by means of dorsal external arcuate fibres. These arcuates
come from two sources, (1) from the dorsal funiculi of the cord,
(2) from the nucleus of Blumenau.”

*¥. Bechterew, W., Ueber die Schleifenschicht auf Grund der Resultate
von nach der entwickelungsgeschichtlichen Methode ausgefiihrten
Untersuchungen. Arch. f. Anat. u. Phys., Anat. Abth., Leipz. (1895),
S. 379-395.

? Blumenau, op. cit., S. 226,

*In regard to the literature on this subject, Edinger, Flechsig, Hoche
and vy. Monakow say that fibres of the dorsal funiculi pass directly to
the corpus restiforme. Vejas on the ground of experimental degenera-
tion says that the dorsal funiculi and the corpus restiforme are con-
nected only by mediation of a nucleus.

(1). von Monakow, C., Arch. f. Psychiat. u. Nervenkr., Berl., Bd. xiv
(1883).

(2). Edinger, L., Neurol. Centralbl., Leipz., Bd. mr (1885), S. 73-76.

(3). Flechsig, P., Neurol. Centralbl., Leipz. (1885), No. 5.

(4). Vejas, P., Arch. f. Psychiat. u. Nervenkr., Berl., Bd. xvi (1885),
8. 200-214.

(5). Barker, L. F., Op. cit., p. 560 and p. 575.

Flechsig calls these fibres, “ Fibre transversales.” Die Leitungsbah-
nen im Gehirn und Riickenmark des Menschen, Leipzig, 1876.
Dorsal columns
of cord and their

nuclei in sections, |

44 Dorsat Cotvmys or tHE Sprvat Corp

The transverse series will be used first to illustrate the points of the
model (Figs. 25 to 31). Fig. 25 shows that the nucleus funiculi gracilis
is well developed at a level in which only the ventral part of the nucleus
funiculi cuneati is visible. Fig. 28 shows both the nuclei of the fasciculi
of Goll and Burdach, together with the nuclear capsules and the distal
bundle of internal arcuate fibres. The capsule of the nuclei of Bur-
dach’s fasciculus is dense, while that of the nucleus of Goll’s fasciculus
is delicate. The characteristics of the distal internal arcuate bundle
are evident in Fig. 28. The proximal bundle on the other hand is shown
in Fig. 31, while the transition between the two is represented by Fig.
29. Figs. 29 and 30 show the lateral nucleus of Blumenau (Nu. f. ¢. 1).
In the second section its close connection with the fibre eapsule and
the contrast of its cellular arrangement with that of the proximal
nucleus is evident,

The relative positions of the three parts of the nuclear mass are more
clearly made out in the longitudinal series (Figs. 5 to 17). The sections
in Figs. 5 to 7 illustrate these relations. The nucleus funiculi gracilis
and a small part of the nucleus funiculi cuneati form a common mass
that gives rise to the distal internal arcuate bundle. The middle, lat-
eral portion is the nucleus of Blumenau (Nu. f. c. 1, Fig. 5). At the
level of Fig. 7 it is separated from the proximal third by a band of
fibres entering the nucleus from the capsule. All three sections pass
through the corpus restiforme. The fibre bundle opposite the nucleus
of Blumenau is much broken, due to the entrance and exit of the fibres
of the capsule. .

In passing ventralward the internal arcuate fibres can be traced to
their decussations. On Fig. 9 the proximal third of the nucleus seems
to have been transformed into fibres. These fibres can be traced
through Figs. 12, 13 and 15. The distal bundle which lies farther ventral
is seen first on Fig. 15 and is traced to the decussatio lemniscorum in
Figs. 17 and 19.