157 venous drainage vertebral arteries

The posterior cerebral artery supplies the occipital lobe and portions of the medial and inferior temporal lobe. The arterial supply of the spinal cord is derived from the vertebral arteries and the radicular arteries. The brain is supplied by the internal carotid arteries (the anterior circulation) and the vertebral arteries, which join at the pon tomedullary junction to form the basilar artery (collectively termed the posterior circulation). The brainstem is supplied by the posterior system. The medulla receives blood from branches of the vertebral arteries as well as from the spinal arteries and the posterior inferior cerebellar artery (PICA). The pons is supplied by paramedian and short circumferential branches of the basilar artery. Two major long circumferential branches are the anterior inferior cerebellar artery (AICA) and the superior cerebellar artery. The midbrain receives its arterial supply primarily from the posterior cerebral artery as well as from the basilar artery. The venous drainage of the spinal cord drains directly to the systemic circulation. By contrast, veins draining the cerebral hemispheres and brain stem drain into the dural sinuses. Cerebrospinal fluid also drains into the dural sinuses through unidirectional valves termed arachnoid villi. 

Technically, selective angiography has to be performed according to a rigorous protocol. To assess as precisely as possible the anatomic components of the AVM, it is important to inject selectively the internal and external carotid arteries and vertebral arteries. Analysis of the arterial feeders, nidus, and venous drainage is obtained by performing multiple projections (anteroposterior, lateral, and oblique). Three-dimensional angiography may be helpful. 

The principal arteries that should be studied include the ipsilateral vertebral artery, the internal carotid artery, the distal external carotid, the posterior auricular, the occipital arteries and bilateral ascending pharyngeal arteries. It is important to visualize the venous drainage pattern and recognize the presence of a venous thrombosis. 

---