Morphology of the middle rectal arteries. A study of 30 cadaveric dissections.

The middle rectal arteries were studied in 30 cadavers of adult and older individuals (29 Caucasians and one Negro) of both sexes (15 males and 15 females). The middle rectal artery was present in 56.7% of the cases, bilaterally (36.7%) or unilaterally (20%), originating from the internal pudendal (40%), inferior gluteal (26.7%), internal iliac (16.8%), and less frequently from other pelvic branches. The average external diameter of the middle rectal artery was found to be 1.7 mm, its average length about 7 cm, and the point of penetration in the rectal wall about 6 cm (average) superior to the anus. The most frequent sites of the rectal wall pierced by the middle rectal arteries were the anterior (50% of the cases) and posterior (45%) quadrants of the rectum, whether isolated or combined (43.3%). These anatomical features justify, when needed and possible, the preservation of the middle rectal artery in surgical interventions on related organs. The term middle rectal arteries in Nomina Anatomica should be changed to inferior rectal arteries and indented under internal pudendal artery; the current term inferior rectal arteries should be changed to anal arteries to follow the already adopted division of the terminal intestine into rectum and anal canal.