THE NERVOUS SYSTEM 

 THE ANATOMY OF THE MEDULLA OBLONGATA 



At its rostral end the spinal cord increases in size and goes over without 

 sharp line of demarcation into the medulla oblongata, or myelencephalon, which, 

 as we learned in Chapter II, is derived from the posterior part of the third brain 

 vesicle. The medulla oblongata may be said to begin just rostral to the high- 

 est rootlet of the first cervical nerve at about the level of the foramen magnum ; 



Marginal part of sukus cinguli 



Sulcus of corpus callosum \ 



Splenium of corpus callosum \ ;' 



Precuneux 

 Sub parietal sulcus \ 

 Parieto-occipital fissure\ 



Lamina quadrigemina 



Cuneus 

 Superior vermis^ 



Calcarinefissure f\ 



Occipital pole f 



Lingual gyrus 

 Transverse fissure 



Cerebellar hem. 

 Medullary substance 

 of vermis 



Inferior vermis'' 

 Calamus scriptorius'' 

 Central canal \ 



Spinal cord , , 

 Tela chorioidea of fourth ventricle f 



Fourth ventricle ; 

 Medulla oblongata 

 Anterior medullary velum 



Cerebral aqueduct ! 



Pans ! ; 



Posterior perforated substance , 

 Oculomotor nerve 



Central sulcus in paracentral lobule 

 Pineal body 

 I Pineal recess 

 ! ', Posterior commissure 

 I I 1 Tela chorioidea of third ventricle 

 Massa intermedia 

 . Gyrus cinguli 

 Thalamus 



Body of corpus callosum 

 Body offornix 

 Septum pellucidum 

 ' Sulcus cinguli 

 Interventric. foramen 

 Column offornix 

 Anterior commis- 



;> Superior frontal 

 gyrus 



'-Frontal pole 

 Cenu of cor pus callosum 

 Nostrum of cor p. callosum 

 -- Parolfactory area and sulci 

 , X X X X X \ % \ \ s- Subcallosal gyrus 

 X X X X X \ \ \ Hypothalamic sulcus 

 X X X X \ \ X ^Lamina terminal is 

 X X X X \ X Optic recess 

 X X X X \ "Optic nerve 

 X X X \ Optic chiasma 

 X X X Infundibulum 

 X \ "Anterior lobe\ , 



Posterior lobe 

 "Mammillary body 





Fig. 85. Medial sagittal section of the human brain. (Sobotta-McMurrich.) 



and at the opposite extremity it is separated from the pons by a horizontal groove 

 (Figs. 81, 85). Its ventral surface rests upon the basilar portion of the occipital 

 bone; while its dorsal surface is in large part covered by the cerebellum. The 

 shape of the medulla oblongata is roughly that of a truncated cone, the smaller 

 end of which is directed caudally and is continuous with the spinal cord. In 

 man it measures about 3 cm., or a little more than 1 inch, in length (Fig. 86). 

 Like the spinal cord, the medulla oblongata presents a number of more or 



