Section through the pontine region of the human brain, stained by the Weigert method. Note, in the pons (P), the transversely running ponto-cerebellar fibres, the fasciculi of the pyramidal tract (cut transversely), and scattered islands of gray matter − the pontine nuclei.

 Above is seen the lower end of the aqueduct where it joins the upper end of the fourth ventricle. In the roof of the aqueduct is the decussation of the trochlear nerve (IV) and in the floor the medial longitudinal bundle (Md) stands out conspicuously. Laterally to this on either side (Scp) is the superior cerebellar peduncle (brachium conjunctivum). This has its origin in the dentate nucleus of the cerebellum, and at this level it is seen approaching the mid-line and beginning its decussation (Dec). Superficial to the superior cerebellar peduncle, and lying here on the surface, is the lateral fillet (Lf) − an auditory tract passing up on its way to the inferior corpus quadrigeminum and the medial geniculate body. More ventrally placed, and on a deeper plane, is the medial fillet (Mf) conveying impulses of general sensation up to the thalamus.

Original card