. A text-book of human physiology . vesicle (hind-brain) inclusive of the diencephalon (tweenbrain), were formerly describedcollectively as the brain-stem in contradistinction to the endbrain (telen-cephalon). In presenting the subject of the brain functions it seems advisablefor several reasons to continue as formerly the use of this division and toapply the name cerebrum only to the parts developed from the endbrain. * This classification has been very slightly modified in accordance with more modernusage in English.—Ed. 602 PHYSIOLOGY OF THE BRAIX-STEM § 2. THE MEDULLA OBLONGATA, OR AFTERBR
. A text-book of human physiology . vesicle (hind-brain) inclusive of the diencephalon (tweenbrain), were formerly describedcollectively as the brain-stem in contradistinction to the endbrain (telen-cephalon). In presenting the subject of the brain functions it seems advisablefor several reasons to continue as formerly the use of this division and toapply the name cerebrum only to the parts developed from the endbrain. * This classification has been very slightly modified in accordance with more modernusage in English.—Ed. 602 PHYSIOLOGY OF THE BRAIX-STEM § 2. THE MEDULLA OBLONGATA, OR AFTERBRAIN The medulla oblongata extends from the upper end of the spinal cord tothe lower edge of the pons, its upper border being just a little dorsal to thelateral recess of the fourth ventricle. Its length on the ventral side is from20 to 24 mm. and on the dorsal from 2-i to 26 mm. The physioJogicnJ significance of the medulla consists chiefly m this, thatwithin its borders the afferent and efferent pathways of the cord are brought. Fig. 268.—Transverse section of the medulla oblongata, after Edinger. into much more intimate relationships with each other and with the cranialnerves and pathways than is the case in the cord itself. By this means theefferent nerves from the cord can act together for a common purpose in amuch more orderly manner than would be possible on the basis of theirconnections in the spinal cord alone, a thing of profound importance for theunity of the bodily functions. The centers which exemplify this influence of the medulla in the highestdegree are the vasomotor and respiratory centers, the physiologicaL purposeand mode of action of which have been discussed at pages 237 and may also be mentioned as an instance of coordination of manydifferent muscles to a common end, the center for which is probably situatedalso in the medulla (cf. page 286). It is very probable that the centers for several other geuoral functions, which,like vasodilatatio
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