THE PAETS OF THE BRAIN BELOW CEREBRAL 

 CORTEX, VIZ. MEDULLA OBLONGATA, PONS, 

 CEREBELLUM, CORPORA QUADRIGEMINA, AND 

 REGION OF THALAMUS. 



BY C. S. SHERRINGTON. 



CONTEXTS. THE MYELENCEPHALON OR REGION OF THE MEDULLA OBLOXGATA, 

 p. 884 The Root Cell Systems in, p. 884 The Bulbo-spinal Frog, p. 886 The 

 Bulbo-spinal Mammal, p. 886 " Centres " in the Bulb, p. 887 Conduction 

 Paths in the Bulb, p. 888 THE METENCEPHALON OR REGION OF THE PONS 

 VAROLII AND CEREBELLUM, p. 890 Reactions in the Frog, p. 890 And Rabbit, 

 p. 890 THE PONS, p. 891 The Root Cell Systems in, p. 891" Centres " in, 

 p. 891 Conduction Paths in, p. 893 THE CEREBELLUM, p. 893 Excitation of, 

 p. 893 LESIONS OF, Unilateral Ablation, p. 895 Ablation of the whole 

 Cerebellum, p. 897 Destruction of the Middle Lobe, p. 898 Longitudinal 

 Bisection, p. 898 Ablation in the Bird, p. 898 -Ablation in Lower Verte- 

 brates, p. 899 Phenomena caused by Section of the Cerebellar Peduncles. 

 Section of Anterior Peduncle, p. 900 Section of Middle Peduncle, p. 900 

 Section of the Posterior Peduncle, p. 901 Bilateral Section of the Peduncles, 

 p. 901 Phenomena of Cerebellar Origin in Human Disease, p. 901 

 Inferences drawn from Comparative Anatomy, p. 902 Functions of the 

 Cerebellum, p. 903 THE MESENCEPHALON OR REGION OF THE CORPORA 

 QUADRIGEMINA, p. 911 The Root Cell Systems in, p. 911 Excitation of the 

 Corpora Quadrigemina, p. 912 Reactions of Animals after Ablation of all the 

 Encephalic Regions in front of the Mesencephalon, p. 912 Lesions of the 

 Corpora Quadrigemina, p. 912 Decerebrate Rigidity, p. 913 Conduction 

 Paths through the Mesencephalon, p. 915 THE DIENCEPHALON OR REGION OF 

 THE OPTIC THALAMUS, p. 916 Visual Connections of, p. 916 Excitation of, 

 p. 917 Destructive'Lesions of, p. 917. 



THE MYELENCEPHALON OR REGION OF THE MEDULLA OBLONGATA. 



THE roof of this portion of the encephalon contains neither nerve 

 cells nor nerve fibres. From the present point of view, therefore, it is 

 functionless. The floor, on the other hand, forms the bulb, and exercises 

 manifold neural functions. 



Belonging to the afferent root cell system of this part are the ganglion cells 

 of the nervus intermedius (geniculate ganglion), receiving impulses, perhaps 

 gustatory, from the tongue region ; the ganglion cells of the cochlear and vesti- 

 bular nerves, conducting impulses from the organs for hearing, geotropism and 

 space-relations of the head ; the ganglion cells of glosso-pharyngeal and vagus 

 nerves, conducting impulses from alimentary and respiratory mucous mem- 

 branes and from heart ; and occasionally ganglion cells belonging to the hypo- 

 glossal nerve, their distribution being unknown. The afferent root cell system 

 of this region brings no impulses from skin, except from a tiny patch at the 



