ORIGIN COURSE AND TERMINATION OF CORTICOSPINAL FIBERS IN ARMADILLO (DASYPUS NOVEMCINCTUS MEXICANUS)

Details of the corticospinal tract of the armadillo, a representative of order Edentata, are described for the first time in this study. Corticospinal fibers arise both rostral and caudal to the supraorbital sulcus. In the spinal cord they travel within the dorsal part of the ventral funiculus and within the lateral funiculus. Most of the fibers crossed at the pyramidal decussation. A few fascicles cross more caudally within the cord and a very few terminate on their side of origin. Corticospinal fibers were traced to T6, but most ended between the 4th and 8th cervical segments. Most of the fibers from the pre-supraorbital cortex terminated in the lateral zone of lamina VI (Rexed 1952), within the ventral and lateral portions of lamina V and within the dorsal, lateral area of lamina VII. This same cortical area projected the most fascicles to laminae VII and VIII. Cortices caudal to the supraorbital sulcus distributed fibers profusely to the medial portions of laminae V and VI, but gave lesser contributions to other areas of those same laminae and to laminae VII and VIII. Corticospinal fibers did not end within lamina IX. The probable functional significance of the above projections in the armadillo is discussed. © 1969.