THE MEDULLA OBLONGATA. 



703 



fibres. The fibres of the olivary peduncle connect the olivary nucleus with the 

 cerebral hemisphere of the same side. The nucleus is also connected to the anterior 

 horn of the same side of the cord ; and with the opposite cerebellar hemisphere 

 through the internal arcuate fibres. Removal of one cerebellar hemisphere is 

 followed by atrophy of the opposite olivary nucleus. 



Accessory Olivary Nuclei. Two small isolated masses of gray matter are to be 

 found, one on the mesial and the other on the dorsal aspect of the corpus denta- 

 tum. These are the mesial and lateral accessory olivary nuclei. They are con- 

 nected with the restifonn body by some of the internal arcuate fibres. The fibres 

 of the hypoglossal nerve, as they traverse the bulb, pass between the mesial 

 accessory nucleus and the chief olivary nucleus. 



The Raphe. The raphe' is situated in the middle line of the medulla, above the 

 decussation of the pyramids. It consists of nerve-fibres intermingled with nerve- 

 cells. The fibres have different directions, which can only be seen in suitable 

 microscopic sections, thus : 1. Some are antero-posterior ; these in front are con- 

 tinuous with the superficial arciform fibres. 2. Some are longitudinal ; these are 

 derived from the arciform fibres, which on entering the raphe' change their direction 

 and become longitudinal. 3. Some are oblique ; these are continuous with the 

 deep arciform fibres which pass from the raphe'. 



The nerve-cells of the raphe are nmltipolar ; some are connected with the 

 antero-posterior fibres, others with the superficial arcuate fibres. 



Fig. 373. Side view of the brain of man, showing the localization of various functions. (After Ferrier.) 



I. Centre for movements of opposite leg and foot. 2, 3, 4. Centres for complex movements of the arms and legs, 

 as in swimming. 5. Extension forward of the arm and hand. 6. Supination of the hand and flexion of the 

 forearm. 7, 8. Elevators and depressors of the angle of the mouth. 9, 10. Movements of the lips and tongue. 



II. Retraction of the angle of the mouth. 12. Movements of the eyes. 13, 13'. Vision. 14. Hearing, a, b, c, d. 

 Movements of the wrists and lingers. 



Weight of the Encephalon. The average weight of the brain in the adult male 

 is 49 J oz., or a little more than 3 Ibs. avoirdupois ; that of the female 44 oz. ; the 

 average difference between the two being from 5 to 6 oz. The prevailing weight 

 of the brain in the male ranges between 46 oz. and 53 oz., and in the female 

 between 41 oz. and 47 oz. In the male the maximum weight out of 278 cases was 

 65 oz., and the minimum weight 34 oz. The maximum weight of the adult female 



