The =spinal cord= resembles that of the horse in conformation and
structure. In cattle of medium size its length is about 165 to 170 cm.
(ca. 65 to 67 inches) and its weight about 240 to 250 grains (ca. 8
ounces).
In a cow 140 cm. in height Dexler found the weight of the cord
(including the intradural nerve-roots) to be 260 g. and the length 162
cm. The lengths of the regions were: cervical 41 cm., thoracic 72 cm.,
lumbar 32 cm., sacral 7 cm.
The =brain= has an average weight of about 500 grams (ca. 16 to 17
ounces). Its differences in general form are correlated with those noted
in the consideration of the cranial cavity.
The =medulla= is short, wide, and thick. Its ventral face is strongly
convex. The pyramids are narrow, short, and close together in front.
Near the decussation there is a well defined oval prominence on either
side which indicates the position of the posterior olive. The corpus
trapezoideum is large; it has no central part between the pyramids. The
external arcuate fibers are distinct. The restiform bodies are short and
thick and diverge more strongly than in the horse. The floor of the
fourth ventricle is only about two-thirds as long as in the horse. The
area acustica is a well-marked oval prominence lateral to the middle
part of the limiting sulcus. The tuberculum acusticum at the origin of
the auditory nerve is very large. The anterior fovea is distinct. The
posterior recess of the fourth ventricle communicates through the
foramen of Magendie (Apertura mediana) with the subarachnoid space.
[Illustration: