CAMRT Radiography Practice Exam

What are the components of the Circle of Willis?

1. Carotid arteries, vertebral arteries, basilar artery

2. Superior sagittal sinus, inferior sagittal sinus, transverse sinus

3. Hippocampus, thalamus, hypothalamus

4. Arachnoid granulations, mediastinum, cerebellum

The correct answer is: Carotid arteries, vertebral arteries, basilar artery

The Circle of Willis is a vital arterial structure at the base of the brain that provides collateral circulation to ensure adequate blood flow to various brain regions. The correct answer identifies the primary arteries involved in forming this circular anastomosis. The carotid arteries, specifically the internal carotid arteries, contribute to the anterior circulation of the brain by supplying key structures such as the cerebrum. The vertebral arteries, which arise from the subclavian arteries, merge to form the basilar artery, contributing to the posterior circulation of the brain. This arrangement allows blood to flow in such a way that if one part of the circulation is compromised, alternative pathways through the Circle of Willis can maintain cerebral perfusion. In contrast, the other choices mention structures that do not pertain to the arterial network of the Circle of Willis. The superior sagittal sinus, inferior sagittal sinus, and transverse sinus are venous sinuses responsible for draining blood from the brain, not arterial supply. Similarly, the hippocampus, thalamus, and hypothalamus are brain structures rather than vascular components. Lastly, arachnoid granulations are involved in the absorption of cerebrospinal fluid, while the mediastinum and cerebellum are not related to the