; 
i 
MEDULLA OBLONGATA OR BULB. 449 
the posterior column of the cord. In the cervical part of the cord the posterior 
column is divided by the paramedian septum of pia mater into an inner column 
of Goll and an outer column of Burdach. 
These are prolonged upwards into the 
medulla, and in the lower part of the 
posterior area they stand out distinctly, 
and are separated from each other by a | 
continuation upwards from the cord of the | 
paramedian groove. In the medulla the 
inner of these strands is called the funiculus 
gracilis, whilst the outer one is designated 
the funiculus cuneatus. Each of these 
strands, when it reaches the level of the 
lower part of the floor of the fourth ven- 
tricle, ends in a slightly expanded bulb- 
ous prominence. The swollen extremity of 
the funiculus gracilis is called the clava. 
This is thrust aside from its neighbour of eZ 
the opposite side by the opening up of the . 
medulla to form the floor of the fourth 
ventricle, and the central canal of the cord 
opens on the surface in the angle between 
the two clave. The bulbous end of the 
fasciculus cuneatus receives the name of : 
the cuneate tubercle (tuberculum cinereum), a Te EA VSG ELIE ULE 
ae é ONS, AND MESENCEPHALON OF A FULL-TIME 
but it is only in the foetal or very young Te Ler eT 
brain that it is well marked. 
The elongated prominences formed on the surface of the medulla by these two 
strands and their enlarged extremities are, in a great measure, due to the presence 
of two elongated nuclei or collections of gray matter which make their appearance 
subjacent to the strands, and which gradually increase in bulk as they are traced 
upwards. These are termed respectively the gracile (nucleus funiculi gracilis) and 
cuneate (nucleus funiculi cuneati) nuclei, and it can be easily shown that as the 
gray matter increases in quantity the fibres of the two corresponding strands 
diminish in number by coming to an end in connexion with the cells of the 
subjacent nuclei. Indeed, it is doubtful if any of the fibres of the gracile and 
cuneate strands extend upwards beyond these nuclei. 
But a third longitudinal elevation is also apparent in the lower part of the 
posterior area of the medulla. This is placed on the outer side of the funiculus 
cuneatus—between it and the posterior row of nerve-roots—and it has no counter- 
part in the posterior column of the cord. It is called the funiculus of Rolando, 
because it is produced by the substantia gelatinosa Rolandi, which caps the 
posterior horn, coming close to the surface and forming a bulging in this situation. 
The funiculus of Rolando is wedge-shaped in outline. Extremely narrow below, it 
widens as it is traced upwards, and finally ends in an expanded extremity called 
the tubercle of Rolando (tuberculum Rolandi). A thin layer of white matter, com- 
posed of longitudinally arranged fibres, is spread over this district, and separates the 
substantia Rolandi from the surface. These fibres constitute the spinal root of the 
fifth or trigeminal nerve, which here assumes a superficial position as it descends 
in the medulla. 
The restiform body (corpus restiforme) forms the upper part of the posterior 
area of the medulla. It les between the floor of the fourth ventricle and the 
roots of the vagus and glosso-pharyngeal nerves. It is a large and prominent 
rope-like strand, which inclines upwards and outwards, and then finally takes 
a tum backwards and enters the cerebellum. It forms the great link of 
connexion between the cerebellum on the one hand and the medulla and spinal 
cord on the other, and consequently it also receives the name of the inferior cere- 
bellar peduncle. At the same time it must be understood that it is not formed 
by fibres which are prolonged into it from the funiculus cuneatus and funiculus 
29 
_ Optic tract 
i ‘ 
ee cerebri 
Corpus geniculatum 
pace oe Veneer 
—Pulvinar 
‘!Corpus geniculatum 
internum 
SA Superior brachium 
~—Inferior brachium 
g—Inferior quadrigeminal body 
Lateral fillet 
Superior cerebellar peduncle 
Tenia pontis 
Middle peduncle of 
cerebellum 
Restiform body 
Ligula 
Olive 
Arcuate fibres (anterior superficial) 
Clava 
Cuneate tubercle 
Rolandic tubercle 
Lateral district of medulla 
-Anterior column of cord 
