THE 
VETERINARIAN. 
VOL. VII, No. 75.] MARCH, 1834. [New Series, No. 15. 
MR. YOUATT’S VETERINARY LECTURES, 
DELIVERED AT THE UN 1VERS1TY OF LONDON. 
LECTURE XXXIX. 
The fifth Pair of Nerves , their double Origin and Function .— 
The Structure of the Spinal Marrow, and double Root of the 
Spinal Nerves— The Origin of the Fibres conveying Sensa¬ 
tion from the superior Surface of the Chord, and of those 
connected with muscular Motion from the inferior Surface. 
The Double Origin of the Fifth Pair of Nerves. —The Tri¬ 
geminus or fifth pair of nerves has been described by our ana¬ 
tomists as springing by a multitude of filaments from the crura 
cerebelli, and forthwith running for security into the cavernous 
sinuses, and there suddenly enlarging into or passing though a 
ganglion. Human anatomists, however, had long spoken ot the 
double origin of the fifth pair; and the researches of some mo¬ 
dern physiologists, and particularly of Sir Charles Bell and Mr. 
Mayo, have attached great importance to this double origin. The 
experiments were made on our patients, and therefore we have 
a legitimate right to refer to them, and to reason upon them. 
The Difference between the two Roots.— The double origin of the 
fifth pair is plain enough in this dissection, as well as the ine¬ 
quality in the size of the two roots, the inferior one being very 
much smaller than the superior; likewise the difference in the 
structure of the two, the fibres or fibriculi of the superior root 
being much larger than those of the inferior. On examining a 
brain that has been long macerated in alcohol, and thus more 
easily resolvable into its fibrous structure, the smaller portion can 
be traced through the pons varofii to the crura cerebri, a portion 
of the inferior surface of the brain, and also close to the medulla¬ 
ry track in which we have found the motor nerves. The larger 
portion springs from the lower part of the crura cerebelli, winding 
from that which answers to the superior surface. Again; we find 
that the fifth pair, or a portion of it, after entering the cavernous 
sinus, swells out into, or passes through, a ganglion, and, examin- 
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