ANATOMY IN A NUTSHELL. 



347 



LESSON C. 



Besides the gray matter of the cerebral hemispheres of the cerebellum and 

 the meddulla oblongata, and the ganglia at the base of the brain are: 



(a) Olfactory bulb which is the anterior enlargement of the olfactory- 

 tract from the which olfactory nerves are sent off. 



(b) Corpora striata (striped bodies) are large ganglia of the brain, of mixed 

 white and gray substance, situated beneath the anterior horn of each lateral 

 ventricle of the cerebrum. 



(c) Optic thalamus is a large ganglion of the thalamencephalon, situated 

 upon the crus and separated from the lenticular nucleus by the internal cap- 

 sule; also called thalamus. It gives origin to some of the fibers of the optic 

 nerve. 



(d) Tubercula quadrigemina are on the dorsal part of the mid-brain. 

 The lobes are paired, right and left, and hence called corpora bigemina in ani- 



PLATE CLXVII. 



PINEAL BODY fe 



CORPRA QUADRIGEMINA 

 CEREBELLUM 



%, 



MEDULLA OBLONGATA 



OLFACTORY DIVERTICULUM 



THALAMUS 



A Sagitaal Section of a Vertebrate Brain. 



mals below mammals. In man they are marked by a cross-furrow so they are 

 called corpora quadrigemina, and constitutute what are called the nates or 

 testes of the brain. The optic nerve arises in part from the optic lobes. 



(e) Tuber annulare is the annular tuber of the brain, the pons Varolii. 



The anterior commissure is white and situated directly in front of the an- 

 terior pillars of the fornix. (Plate CLXXX). It connects those parts of the 

 hemispheres not connected by the corpus callosum, viz., in man the temporal 

 lobes and in osmaties the entire rhinencephalon. It forms a curve with the 

 convexity forward and slightly upward and its extremities are spread on! Ian- 

 shaped. Its center forms the anterior boundary of the third ventricle between 

 the anterior pillars of the fornix. It passes beneath or through the bead of 

 the caudate nucleus and the posterior two-thirds of the lenticular nucleus where 

 it is spread out in the substance of the temporal lobe. The A.NTERIOB com- 

 missure is a more primitive commissure than the corpus callosum and de- 



