( 
H NERVOUS CENTRES. (Human Anatomy. Tae Encepnaton.) 
A 
_allongée, bulbe rachidien. Germ. das Verlan- 
= gerte Mark. Ital. midollo allungato.)—We 
; Récin with the description of this segment be- 
cause of its immediate connection with the 
Spinal cord, for it is plain, since this is the 
connecting link between that centre and the 
intra-cranial mass, that whatever influence the 
latter may exercise upon the former, must be 
conveyed or propagated by the medulla ob- 
longata. 
It is proper to notice that the term medulla 
_ oblongata has not been employed in a uniform 
_ sense by all anatomists. Willis and Vieussens 
_ comprehended under this title all the parts 
_ from the corpora striata and optic thalami 
(both Ghdinded): doven to the commencement 
_ 0f the spinal cord.* The same signification 
was adopted by the writers who immediately 
followed these great anatomists. Winslow con- 
siders the medulla oblongata as “ one middle 
“medullary basis common to both cerebrum and 
cerebellum, by the reciprocal continuity of 
‘their medullary substances.”+ The crura, or 
pedunculi cerebri, constitute its anterior part : 
se seem to be lost in the corpora striata, as 
_ Winslow states, and therefore they are looked 
upon as the peduncles of the cerebrum. Its 
posterior portion is called the extremity or 
_ cauda of the medulla oblongata (queue de la 
As 2 allongée ). It is to this latter portion that 
_ Haller restricted the term medulla oblongata, 
and most modern anatomists follow his example. 
_ Rolando, however, still applies the term in its 
_ more extended sense. 
Inthe nang article, we adopt the phrase- 
blogy of Haller as far as regards the term me- 
- dulla oblongata. It seems to form an upper 
‘ portion of the medulla spinalis, to 
_ which it stands in somewhat the same relation as 
__ thecapital to the shaft of a column. Its superior 
___ limit is indicated by the posterior edge of the 
___ pons Varolii; its inferior is denoted by a horizon- 
. &. ah ge extended between the occipital foramen 
i 
' , the first vertebra. A more natural line of 
demarcation, however, between this part and 
3 
e< 
decussating fibres which are seen crossing the 
anterior median fissure of the former at its infe- 
rior extremity. No such limit as this, however, 
is found on the posterior surface (fig. 383). 
The medulla oblongata has somewhat of a 
_ @onical shape, its base being situate above at 
the posterior margin of the pons. It is slightly 
flattened on both anterior and posterior sur- 
faces, more so on the latter than on the former. 
__ _Themedulla oblongata admits of the same pri- 
__ marysubdivisionas the medulla spinalis, namely, 
into two equal and symmetrical portions sepa- 
rated from each other by an anterior and a poste- 
Tior median fissure. e former is wide but not 
| of greatdepth. Itis occupied bya fold of pia 
| mater. Its floor is formed by a layer of fibrous 
| Matter which has the same cribriform appear- 
} ance as that of the anterior spinal fissure. 
These fibres are commissural, connecting the 
_ the medulla spinalis may be found in certain 
* See the quotation from the English editi f 
Willis, at p. 669. i he 
+ Winslow’s Anatomy, 
translated by Douglas, 
— vol. ii. p.316. Edin. 1763. om 
679 
Fig. 383. 
Anterior view of the medulla oblongata and pons 
Varolit. (After Arnold.) 
a, anterior extremity of the pons. 
p» anterior pyramids. ; 
d, decussating fibres of anterior pyramids. 
0, olivary bodies. 
A, arciform fibres. 
D, portio dura lager pair 
I, portio intermedia of Wrisberg of Sareal: 
M, portio mollis 
G, glosso-pharyngeal nerve ee pair 
V, par vagum of nerves. 
S, spinal accessory 
two portions of the medulla oblongata. The 
posterior fissure is very deep and narrow. It is 
not limited in front by a grey commissure as the 
posterior spinal fissure is, but by the posterior 
surface of the white commissure just described. 
A single layer of the pia mater passes. into it. 
The continuity of the anterior fissure of the me- 
dulla oblongata and of that of the spinal cord is 
interrupted by the decussating fibres of the py- 
ramids, (fig. 383, d,) but the posterior fissures 
are distinctly continuous with each other. 
On either side of the median plane there are 
indications on the surface of the medulla ob- 
longata, which suggest a subdivision of each 
half of the organ into four columns of nervous 
matter, through the medium of which it forms 
its connection with certain parts of the cere- 
brum and cerebellum on the one hand, and of 
the spinal cord on the other. These columns 
are the anterior pyramidal, the olivary, the 
restiform, and the posterior pyramidal. 
The anterior pyramidal columns, or anterior 
pyramids, (figs. 383, 384, 385, p,) are two 
prismatic bundles of fibrous matter which 
extend between the antero-lateral columns of 
the spinal cord and the lateral hemispheres 
of the brain. In the medulla oblongata 
each of these columns forms a compact body, 
which, when cut transversely, exhibits a tri- 
angular outline in its central portion, but that 
of a cylinder at either extremity. Each pyramid 
is limited on the outside by a superficial groove, 
which separates it from the olivary column, 
and on the inside by the anterior median fis- 
