Anatomical studies of the collateral blood supply to the brain and upper extremity.

Abstract

between the occipital artery and vertebral arteries are constant. The presence of these connections has also been proved in angiographical examinations. 2z,~~ Cooper 9 demonstrated the connection between the superior and inferior thyroid arteries; he also demonstrated the presence of contrast medium in the vertebral artery distal to the site of the carotid or vertebral ligation. Ljubomudrow 3~ showed that possible channels of collateral circulation are the arterial branches (and their connections) of the inferior and superior thyroid, ascending and transversing cervical, superior intercostal, and posterior auricular arteries. In 1956, Whisnant and coworkers ~ performed similar investigations on 12 dogs, ligating the carotid and vertebral arteries. As a rule the dogs survived the operations, and some showed little sign of damage to the central nervous system. In nine other dogs, the authors tried to limit the flow of blood to the brain by ligating both vertebral arteries at the level of the transverse process of the sixth vertebra, both the common external and internal arteries, and also the pharyngeal ascending artery and the occipital arteries. Coma was observed in only three dogs, while in others the symptoms were hardly noticeable. Postmortem examinations showed no important damage in the cerebral tissue in seven of the nine animals. Injection of contrast medium into the arterial system demonstrated the role of the internal thoracic artery and of the costo-cervical trunk as possible channels of collateral blood sup