Textbook of normal histology: including an account of the development of the tissues and of the organs . somewhat higher level, lateral groups of pigmented nerve-cells occupy the floor of the fourth ventricle ; these cells are sodark that they collectively present an area visible to the unaided eye,the substantia ferruginea ; seen through the stratum of whitefibres forming the immediate floor of the ventricle, this area appearsof a bluish-gray or slate-color and constitutes the locus cceru-leus. Close to this pigmented area, lying to its mesial side and nearthe raphe, an angular tract, known a
Textbook of normal histology: including an account of the development of the tissues and of the organs . somewhat higher level, lateral groups of pigmented nerve-cells occupy the floor of the fourth ventricle ; these cells are sodark that they collectively present an area visible to the unaided eye,the substantia ferruginea ; seen through the stratum of whitefibres forming the immediate floor of the ventricle, this area appearsof a bluish-gray or slate-color and constitutes the locus cceru-leus. Close to this pigmented area, lying to its mesial side and nearthe raphe, an angular tract, known as the posterior longitudinalbundle, extends beneath the gray matter of the ventricle, just at thedorsal border of the reticular formation. This fasciculus, also prom- THE CENTRAL NERVOUS SYSTEM. 303 inent at higher levels, is the continuation of fibres from the anteriorground-bundle of the cord. THE CRURA. The crura cerebri, or cerebral peduncles, resemble the ponsin general arrangement, since they consist of a ventral portion, thecrusta pedunculi, or the cerebral peduncle proper, made up Fig. Section through human cerebral peduncles at point of emergence ofoculo-motor nerve: C, crusta, separated from tegmentum (Tg) by sub-stantia nigra (5) ; K, raphe dividing formaiio reticularis ; F, longitudinalbundles of latter ; O, groups cf nerve-cells connected with origin of oculo-motor fibres ( Gm) ; Tf. cells connected with origin of trifacial nerve ; A,aqueduct of Sylvius ; CQ, anterior corpora quadrigemina. (After Krause.) exclusively of ascending and descending fibre-tracts, and of a dorsalportion, the tegmentum, which contains the prolongation of theformatio reticularis and of the dorsal stratum of the gray substance ,04 NORMAL HISTOLOGY. of the medulla and the pons. On transverse section of the crura,it is seen that the tegmental halves are united, while the twopeduncular portions are widely separated and are attached tothe tegmentum alone ; the oblique line of this junctur
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Keywords: ., bookauthorpiersolgeorgeageorgea, bookcentury1800, bookdecade1890
