I2O 



THE NERVOUS SYSTEM 



decussation, crossing the median plane in large obliquely interdigitating bundles, 

 which fill up and almost obliterate the anterior median fissure in the caudal 

 part of the medulla oblongata. This is known as the decussation of the pyra- 

 mids (decussatio pyramidum). In the sheep these fibers pass into the opposite 

 posterior funiculus of the spinal cord. In man the crossing is incomplete, a 



Infundibidum 

 Orbital sulci of frontal 

 Orbital gyri of frontal lobe 



Hypophysis 

 Temporal pole 



Anterior perfor, substance 



Oculomotor nerve ^ 

 Uncus --, 

 Mammillary body 



Cerebral peduncle - 

 Pans - 



Trigeminal nerve - 



Temporal lobe 



Facial nerve 



Frontal pole olfadory sukus 



,. Olfactory bulb 



Olfactory tract 

 Optic nerve 



Nervus intermedius - 



Acoustic nerve." 



Flocculus of cerebellum^' 

 Cerebellum ' 



Chorioid plexus of ventricle IV 

 Glossopharyngeal nerve 



Vagus nerve' 

 Hypoglossal nerve 



Accessory nerve ' 

 Root filaments of cervical nerve I 



Decussation of pyramids 



.-Optic chiasma 

 - Lateral olfactory stria 

 Tuber cinereum 

 Maxillary nerve 



Ophthalmic nerve 

 Portia minor of trigem. 

 nerve 

 Mandibular nerve 



Semilunar ganglion 

 Trochlear nerve 



Inter peduncular fossa 



Abducens nerve 

 'Olive 

 Pyramid 



Medulla oblongata 

 Tonsil of cerebellum 

 * Occipital pole 

 Spinal cord 

 Vermis of cerebellum 



Fig. 86. Ventral view of the human brain. (Sobotta-McMurrich.) 



majority of the fibers descending into the lateral funiculus of the opposite side, 

 a minority into the anterior funiculus of the same side (Fig. 77). We are al- 

 ready acquainted with these bundles in the spinal cord as the ventral and lateral 

 corticospinal tracts (direct and crossed pyramidal tracts). In addition to the 

 pyramid the ventral area of the medulla also contains a bundle of fibers, the 



