. Cunningham's Text-book of anatomy. Anatomy. 664 THE NERVOUS SYSTEM. White medullary' substance Motor, cortex Sensory cortex doubled lines which are less dense than those of the sensory cortex ; this area forms the crest of the gyrus centralis posterior, and then gives place to another slightly modified type of cortex which forms the anterior wall of the sulcus postcentralis. Thus the sensory cortex has two fringing bands analogous to those already noticed alongside the visual and acoustic areas. The motor and sensory areas cross on to the medial aspect of the hemisphere, into a region known
. Cunningham's Text-book of anatomy. Anatomy. 664 THE NERVOUS SYSTEM. White medullary' substance Motor, cortex Sensory cortex doubled lines which are less dense than those of the sensory cortex ; this area forms the crest of the gyrus centralis posterior, and then gives place to another slightly modified type of cortex which forms the anterior wall of the sulcus postcentralis. Thus the sensory cortex has two fringing bands analogous to those already noticed alongside the visual and acoustic areas. The motor and sensory areas cross on to the medial aspect of the hemisphere, into a region known as the lobulus paracentralis. Gyrus centralis ante^OT^f^yras centralis posterior In this region a fuiTOW (sulcus paracentral) is sometimes found along the line of demarca- tion of the medial parts of the motor and sensory areas (Fig. 589). That portion of the parietal region which intervenes between the gyrus centralis pos- terior and the occipital region is usually subdivided into two distinct parts (lobulus parietalis superior and lobulus parietalis in- ferior) by a horizontal furrow, called the sulcus interparietalis proprius. The term sulcus interparietalis is usually applied in a purely arbitrary and artificial manner to a complex of four genetically distinct and in- dependent furrows (Fig. 593, p1^2, p3, and^?4), the sulcus postcentralis inferior (p1), the sulcus postcentralis superior (p2), the sulcus inter- parietalis proprius (ramus horizontalis) (ps), and the sulcus paroccipitalis (ramus occipitalis) Q?4), which ends in the sulcus occipitalis transversus. These four furrows develop quite independently one of the other, the postcentral sulci as the posterior boundary of the sensory territory, the paroccipital sulcus as the supero-lateral boundary of the visual territory, and the more variable horizontal ramus (the sulcus interparietalis, in the strict sense of the term) as a demarcation w |H 1 - BLj Boundary line between motor and sensory cortex Fig. 592.—Section acr
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
