Practical anatomy : a manual of dissections / by Christopher Heath.

  • Heath, Christopher, 1835-1905.
Date:
1885
Catalogue details

Licence: Public Domain Mark

Credit: Practical anatomy : a manual of dissections / by Christopher Heath. Source: Wellcome Collection.

    619/682 (page 527)
    The Cerebellum. The Cerebellum (Fig. 258, 28), or small brain, lies beneath the posterior lobes of the cerebrum, and in the skull is separated from them by the tentorium cerebelli. It is of a darker colour than the cerebrum, and its surface is divided into laminse instead of convolu- tions, and these are separated by shallow sulci. The cerebellum is divisible into two lateral halves united by a commissure, and the horizontal fissure divides the organ into an upper and a lower part. The upper surface is flat except in the median line, where there is a slight ridge forming the commissure, and called the superior vermi- form process. The upper part of each hemisphere is divided into an anterior and a posterior lobe by an indistinct fissure. The anterior lobe is, the larger, and of a square shape, reaching as far back as the posterior extremity of the vermiform process. The posterior lobe is the small portion behind the level of the ver- miform process, and reaches to the horizontal fissure. The central lobe consists of a few folia close to the anterior border, and is partly concealed by the anterior lobe. The cerebellum is connected to the cerebrum and spinal cord by three peduncles or crura, of which the superior one can now be seen. The Superior Peduncle (Fig. 266, 3) {processus a cerebello ad testes) is a broad, flattened white band, which is connected below with the inferior vermiform process, and passes forwards to the corpora quadrigemina, the two peduncles of opposite sides converging at the posterior border of the testes. The two processes are prolonged beneath the corpora quadrigemina to the optic thalami, their fibres decussating in their passage. The Valve of Vieussens (Fig. 265, 13) {Velum medullare anterius) is the thin layer of white nervous matter stretched between the two superior peduncles of the cerebellum, and connected with the anterior extremity of the inferior vermiform process. It is narrow in front, but broader behind, where it has a little grey matter connected with it, and is often torn through, in which case the cavity of the fourth ventricle is exposed. The fourth pair of nerves arises from the middle line of the valve close behind the corpora quadrigemina (Fig. 268,15). [The preparation is to be turned over for the examination of the remaining peduncles and of the under surface of the cerebellum.] The Middle Peduncle (Fig. 266, 4) {processus a cerebello ad pon- tern) has been already seen at the base of the brain. It is the largest