Studies in the Osteopathic Sciences Volume 2 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1911 edition. Excerpt: ... CHAPTER V THE NUTRITION OF THE NERVOUS SYSTEM Neurons are nourished by the lymph which bathes them, and the lymph is derived from the blood circulating through the vessels. The central nervous system and the sensory and sympathetic ganglia are alike in the lack of lymphatic vessels. In every case, in mammals, the nerve cell lies surrounded by a pericellular lymph space, and it is thus bathed on every side by the nutrient lymph. The whole extent of the neuron, to the ultimate extremity of its finest dendrite, is so placed as to enable it to perform to the best possible advantage those functions of absorption of foodstuffs and elimination of wastes upon which the normal conditions of metabolism depend. The lymph is drained from the nervous system by perivascular lymph channels. Both veins and arteries are surrounded by these lymph channels, but no lymphatic vessels are found elsewhere. Thus arose the older idea that the brain contained no lymph. The arterial supply of the cord is very plentiful. The two posterior spinal arteries and the anterior spinal artery extend through the length of the cord, and receive with each nerve root branches from the cervical, lumbar or intercostal arteries. The anastomosis of these arteries is complex and efficient. It is not conceivable that any vertebral lesion short of actual crushing could bring about a diminution of the arterial supply to the cord through direct pressure. The effects upon the spinal circulation indirectly produced through vasomotor impulses may be discussed at a later time. From these longitudinal arteries and their anastomotic branches arise the arteries which enter the cord. These smaller arteries are of two classes, centripetal and centrifugal. Both sets are composed of terminal...