Spinal Cord

 Spinal cord is the posterior extension of medulla oblongata. It is enclosed in a neutral canal of vertebral column. In adult human being it is 42-45 cm long and 2 cm thick. It is soft, whitish, slightly flattened, cylindrical tube with a narrow cavity called central canal. Posterior end tapers to form conus medullaris and further into a thread like structure called filum terminale, which is merely the posterior extension of pia meter. Spinal cord shows cervical swelling and lumbar swelling. The spinal cord acts as a pathway for conduction of nerve impulses between the brain and different parts of the body. It also controls spinal reflexes and minimizes the load of the brain. T.S. of spinal card shows inner, 'H' Shaped grey matter surrounding the central canal. It contains cytons or cell bodies of neurons. Two dorsolateral horns and two ventrolateral horns give 'H'-shaped appearance. Dorsal horns extend in dorsal roots while ventral horns extend in ventral roots of spinal nerves. The white matter surrounds the grey matter; which divides in three columns or funiculi on either side. These are dorsal funiculi, lateral funiculi and ventral funiculi. They have the bundles of nerve fibres forming ascending and descending tracts. Ascending tracts are sensory and conduct sensory impulses to the  brain and are present in dorsal funiculi. The descending tracts are motor tracts and carry motor organs like muscles and glands. These are located in ventral and lateral funiculi.