What is the normal diameter of the vertebral artery?

What is the normal diameter of the vertebral artery?

• A. 3-4 mm
• B. 2-3 mm
• C. 4-5 mm
• D. 1-2 mm

Answer: (B)

Vertebral arteries are small-caliber vessels, and in adults their normal diameter sits in the low millimeter range, about two to three millimeters. This baseline matters because it helps identify abnormalities: if the artery is noticeably smaller than this (hypoplasia) or if it narrows further due to stenosis, it can impact posterior circulation. The vertebral arteries are typically smaller than the carotids, reflecting their role and flow, and the 2–3 mm range is the standard reference point most exams expect for a normal diameter.

Vertebral arteries are small-caliber vessels, and in adults their normal diameter sits in the low millimeter range, about two to three millimeters. This baseline matters because it helps identify abnormalities: if the artery is noticeably smaller than this (hypoplasia) or if it narrows further due to stenosis, it can impact posterior circulation. The vertebral arteries are typically smaller than the carotids, reflecting their role and flow, and the 2–3 mm range is the standard reference point most exams expect for a normal diameter.