io86 



HUMAN ANATOMY. 



composed of from ten to twelve leaflets, a second and smaller set, known as the paraflocculus 

 or accessory flocculus, lies behind and lateral to the main group, often completely buried beneath 

 the overhanging margin of the biventral lobule. In the embryo and in many mammals, the 

 paraflocculus is of considerable size and then shares the relatively much greater development 

 of the flocculus than seen in the adult human brain. The connection between the flocculus 

 and the nodule is established by the lateral part of the inferior medullary velum, which 

 constitutes the peduncle of white matter for the floccular folia. In this manner the nodule 

 and the two flocculi, with the intermediate part of the medullary velum, constitute the 

 lobus noduli. 



Lobus Uvulae. — The uvula, the next part of the inferior worm, is laterally compressed 

 between the deeper parts of the two tonsils. It varies in form and often appears as a narrow 

 ridge-like structure, triangular on section, of which the median crest alone is seen when the 

 tonsils are in place. The uvula is limited in front by the postnodular fissure, and behind by 

 the prepyramidal, which laterally, as the post-tonsillar fissure, curves outward along the postero- 

 lateral border of the tonsil. The free median surface of the uvula is usually cleft into two or 

 three major subdivisions, which in turn are scored by shallower incisions, so that from six to ten 

 leaflets are present. Some two dozen additional folia mark the hidden lateral surfaces, the 

 entire number being thus usually raised to thirty or more. 



The tonsil or amygdala (tonsilla), the segment of the hemisphere associated with the uvula, 

 is a pyramidal mass lying between the worm and the biventral lobule and forming the central 

 zone of the general quadrant embracing the lower surface of the entire hemisphere. The free 

 convex inferior surface of the tonsil is irregularly triangular in outline and bounded by a rela- 

 tively straight median margin (along the sulcus valleculce), an outwardly arched postero-lateral 



Fig. 940. 



Lobulus centra'is 

 Superior cerebellar peduncle 



Middle cerebellar peduncle 



Inferior 

 medullary velum 



Great 

 horizontal fissure 



Postero-inferior 



lobule 



Biventral lobule 



.Ala lobuli centralis 



Superior medullary velum 

 Fourth ventricle 



Nodule 



Accessory flocculus 



I'locculus 



Uvula 



Pyramid 



Tonsil 

 Inferior aspect of cerebellum, after removal of pons and medulla. 



border (along the curved posttonsillar fissure) and a notched anterior edge. This, the chief 

 surface, is marked by a straight furrow that extends from the indentation on the anterior border 

 backward and inward and marks a line along which the curved folia, from nine to fourteen in 

 number, abut. Of the other surfaces bearing folia— the median, posterior and lateral — that 

 directed towards the uvula (median) alone is entirely unattached, the others, with the superior, 

 receiving the stalk of white matter. The deeper part of the tonsil is subdivided, so that on 

 removing the larger and more superficial portion of the amygdala a buried and accessory 

 segment of its mass often remains. Beneath (really above) the tonsil, a narrow tongue, 

 marked with short transverse folia, stretches from the posterior part of the uvula across the roof 

 of the space occupied by the tonsil to the upper and lateral part of the amygdala. This tract, 

 known as the furrowed band (alae uvulae) connects the worm with the hemisphere and thus 

 joins the uvula and the two tonsils into the lobus uvulae. The posterior border of the 

 furrowed band is free, whilst its anterior one is continuous with the inferior medullary velum. 

 After removal of the tonsil by cutting through its supero-lateral stalk, a deep recess is left, 

 which is bounded medially by the uvula and laterally by the biventral lobule and roofed 

 in by the furrowed band and the inferior velum. To this space the older anatomists gave the 

 name, "bird's nest" [nidus a-Jis). 



Lobus Pyramidis. — The pyramid (pyramis) the segment of the inferior worm lying behind 

 the uvula and in front of the tuber, is partly covered by the tonsils. Posterior to the latter 



