“… 10,11 The MSA is short, measuring 2 to 4 cm in length, and can be located in the midline or on either side of the body 12,13 . According to some studies, it is agenetic in 2.1% of individuals, in which case the sacral area blood supply is dependent on collateral circulation and is likely very susceptible to ischemic insults 10,11 . When the MSA is present, it originates from the aorta in 90% of cases; third, fourth (most commonly), or fifth lumbar artery in 6% of cases; and common iliac artery in 4% of cases (Figure 2).…”