From this level the fibres of the internal capsule again diverge, as fasciculi whose physiological independence has been well determined, going dorsad and frontad to certain gyri of the cerebral cortex where their fibres join ganglion-cells. Three large fasciculi and corresponding cortical areas are recognized as constituting the pyramidal tract, strictly speaking: (1) A fasciculus which extends frontad to the base of the second frontal gyrus where it coalesces with the precentral, the centre and fasciculus for movements of the facial muscles of the opposite side; (2) a fasciculus which extends to the precentral and postcentral gyri, more especially in their middle part, constituting the centre and fasciculus for movements of the arm and hand; (3) another fasciculus which goes dorso-mesad, almost vertically in the brain, to join the ends of the pre- and postcentral gyri at the top of the hemisphere, and their continuation upon its mesal aspect known as the paracentral lobule, centre and fasciculus for movements of the opposite foot and leg. Besides these three great cortical areas and their connected fasciculi of nerve-fibres, which go to make up the pyramidal tract, we recognize (4) a cortical centre for speech movement of the tongue and lips in the base of the left third frontal gyrus over the fissure of Sylvius (Broca's speech-centre), with a connected white fasciculus which passes into the elbow of the internal {87} capsule, and can be traced (by means of secondary degeneration) into the inner part of the base of the crus and into the pons, but not to the pyramid. Another probable centre (5), for coarse lingual movements and for the various movements of deglutition, is in the folds of the insula, its fasciculus not joining the pyramid. [Illustration: FIG. 9. Longitudinal (sagittal) Section through the Brain, to show the distribution of the fasciculi of the internal capsule. Fasciculi of motor tract in dotted lines, to fronto-parietal convolutions. Fasciculi of sensory tract in full lines, to temporo-parieto-occipital convolutions: _N. C._, nucleus caudatus; _N. L._, nucleus lentiformis; _T.O._, thalamus opticus. 1, level of crus cerebri; 2, level of pons; 3, level of oblongata. (This diagram is to be used in conjunction with Fig. 7.)] The location of two other motor centres—one for the movement of the eyeballs in or near the gyrus angularis, and one for vocal laryngeal movements in the base of the right third frontal gyrus (homologous to the speech-centre in the left hemisphere), is problematical, or at least not well enough established to be recognized in a practical treatise. Recent experimental researches have shown that to electrical excitation at least the fasciculi for the tongue, face, arm, and leg yield the same distinct reaction (isolated muscular contractions) as do their respective centres or cortical areas; perhaps they are more excitable.