Descending motor tract responsible for rapid skilled movements.

Ans. is 'b' i.e., Rubrospinal tract o Pyramidal (corticospinal) tract and extrapyramidal tracts concerned with the muscles of the trunk and proximal portion of limbs (Le., the muscle mainly concerned with the postural control) occupy anterior white column of spinal cord and terminate in the medial ventral horn on the medial group of intemeurons. These tracts are collectively called medial pathways. Medial pathways include ventral (anterior) corticospinal tract, vestibulospinal tracts, reticulospinal tract and rubrospinal tract.o On the other hand, descending tracts concerned with distal muscles of the limb (i.e., those muscles which mediate fine skilled movements(A1 13)) occupy lateral white column and are called lateral pathways. Lateral pathways include lateral corticospinal tract and rubrospinal tracts.