Reference > Anatomy of the Human Body > Page 575
Henry Gray (1825–1861).  Anatomy of the Human Body.  1918.

The Ganglionic System.—All the vessels of this system are given off from the arterial circle of Willis, or from the vessels close to it. They form six principal groups: (I) the antero-medial group, derived from the anterior cerebrals and anterior communicating; (II) the postero-medial group, from the posterior cerebrals and posterior communicating; (III and IV) the right and left antero-lateral groups, from the middle cerebrals; and (V and VI) the right and left postero-lateral groups, from the posterior cerebrals, after they have wound around the cerebral peduncles. The vessels of this system are larger than those of the cortical system, and are what Cohnheim designated terminal arteries—that is to say, vessels which from their origin to their termination neither supply nor receive any anastomotic branch, so that, through any one of the vessels only a limited area of the thalamus or corpus striatum can be injected, and the injection cannot be driven beyond the area of the part supplied by the particular vessel which is the subject of the experiment.

The Cortical Arterial System.—The vessels forming this system are the terminal branches of the anterior, middle, and posterior cerebral arteries. They divide and ramify in the substance of the pia mater, and give off branches which penetrate the brain cortex, perpendicularly. These branches are divisible into two classes, long and short. The long, or medullary arteries, pass through the gray substance and penetrate the subjacent white substance to the depth of 3 or 4 cm., without intercommunicating otherwise than by very fine capillaries, and thus constitute so many independent small systems. The short vessels are confined to the cortex, where they form with the long vessels a compact net-work in the middle zone of the gray substance, the outer and inner zones being sparingly supplied with blood. The vessels of the cortical arterial system are not so strictly “terminal” as those of the ganglionic system, but they approach this type very closely, so that injection of one area from the vessel of another area, though possible, is frequently very difficult, and is only effected through vessels of small caliber. As a result of this, obstruction of one of the main branches, or its divisions, may have the effect of producing softening in a limited area of the cortex.
4. The Arteries of the Upper Extremity. a. The Subclavian Artery
  The artery which supplies the upper extremity continues as a single trunk from its commencement down to the elbow; but different portions of it have received different names, according to the regions through which they pass. That part of the vessel which extends from its origin to the outer border of the first rib is termed the subclavian; beyond this point to the lower border of the axilla it is named the axillary; and from the lower margin of the axillary space to the bend of the elbow it is termed brachial; here the trunk ends by dividing into two branches the radial and ulnar.

The Subclavian Artery (A. Subclavia) (Fig. 520).—On the right side the subclavian artery arises from the innominate artery behind the right sternoclavicular articulation; on the left side it springs from the arch of the aorta. The two vessels, therefore, in the first part of their course, differ in length, direction, and relation with neighboring structures.
  In order to facilitate the description, each subclavian artery is divided into three parts. The first portion extends from the origin of the vessel to the medial border of the Scalenus anterior; the second lies behind this muscle; and the third extends from the lateral margin of the muscle to the outer border of the first rib, where it becomes the axillary artery. The first portions of the two vessels require separate descriptions; the second and third parts of the two arteries are practically alike.


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