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A rare variety of origin of obturator artery- a case report
Manimay Bandopadhyay, Sharmistha Biswas
Department of Anatomy, Calcutta National Medical College, Kolkata-700014,
West Bengal, India
Correspondence address: Dr.Manimay Bandopadhyay,
c/o Dr. M .L .Banerjee. 168, Nilgunj road, Belghoria, Kolkata
Pin - 700056, West Bengal, India
Phone no. 033-24842692, 919433379645
E-mail address. manimaybandopadhyay@yahoo.co.in, drsharmisthabiswas @ rediffmail.com

Running title: Abnormal origin of obturator artery- a case report

ABSTRACT
A rare variety of origin of obturator artery was found while doing dissection on a 54 year old Indian male. The artery originated from the posterior division of the internal iliac artery. The rest of its course as well as other branches of the internal iliac artery were normal. Knowledge of such a variation in the origin of obturator artery is important while doing various gynecological, surgical and orthopedic operations. Obturator artery develops due to uneven growth of the anastomosis between developing internal and external iliac artery. Obturator artery is last to develop amongst the branches of internal iliac. This is likely to be the cause of such a variation.
KEYWORDS
Obturator artery, internal iliac artery, external iliac artery

INTRODUCTION
Internal iliac artery divides into two divisions from which various branches arise within the pelvis. One of them is obturator artery, which usually arises from the anterior division. It traverses along the lateral pelvic wall, being crossed by ureter medially. In male and female vas deferens and ovary lie in its medial relation respectively. Within the pelvis it gives iliac, vesical and pubic branches. It divides into an anterior and posterior branch at obturator foramen and enters inferior extremity (1). Posterior branch of it gives an acetabular branch which enters the hip joint. The artery is important in various gynecological and orthopedic operations. Though origin of the artery is variable but very rarely it arises from the posterior division of internal iliac artery.
CASE REPORT
During routine dissection for undergraduate teaching, of intact formaldehyde preserved cadaver of a 54-year-old Indian male, a rare variation of origin of obturator artery had been revealed. The artery started from the posterior trunk of internal iliac artery. The rest of its course was normal. It was crossed by ureter as well as the vas deferens. This anomaly was present on the left side only, right side being normal. Other branches of the internal iliac artery were normal. This variety of origin of obturator artery was found following dissection of 60 cadavers over a period of 6 years, the incidence rate being 1.66%.
DISCUSSION
Pick et al (1942) had dissected 640 cadavers to study the variation of origin of obturator artery. He found that maximally (27%) it started from inferior epigastric artery and in only 03% from posterior division of internal iliac artery (2). Braithwaite J L, 1952, after dissecting 169 cadavers found not a single obturator artery originating from posterior division, though in 41% (highest) it was originating from the anterior division of internal iliac (3). Various workers had reported other variations of origin of the obturator artery, but we did not come across any reported case similar to ours. Knowledge of variation in the origin of the obturator artery is important while doing pelvic and groin surgeries requiring appropriate ligation and such aberrant origins may be a significant source for persistent bleeding in the setting of acute trauma. Itokazu had emphasized importance of obturator artery, 1997 for successful rotational acetabular osteotomy (ROA) because of its supply of the acetabulum (4).
Developmental explanation
The right and left dorsal aortae fuse caudal to the tenth dorsal intersegmental artery during fourth week of foetal life to form the descending aorta. The stem of the umbilical artery, the specialized ventral segmental branch, on each side degenerates and a new stem forms by way of an anastomosis with the fifth lumbar dorsal intersegmental artery. This new stem persists as the common iliac artery and gives off branches that become the external and internal iliac arteries(5). Definitive obturatory artery forms as a result of uneven growth of anastomosis of external and internal iliac arteries which is connected with peculiarities of regional organogenesis (6). The obturator artery arises comparatively late to supply the medial thigh. And thus it may be the cause of such wide variation in its origin.

REFERENCES
1. Standring SM. Gray’s Anatomy, In:True pelvis, pelvic floor and perinium, 39th Edn; Elsevier Churchill Livingstone. 2005, pp 1360-62.
2. Pick J. W., Anson B. J., Ashley F.L. The origin of obturator artery- a
study of 640 body halves. Am J Anat.1942; 70: 317-344.
3. Braithwaite J L.Variations in origin of parietal branches of internal iliac
artery. J Anat. 1952; 86: 423-430
4. Itokazu M, Takahashi K, Matsunaga T, Hayakawa D,
Emura S, Isono H, Shoumura S. A study of arterial supply of the human
acetabulum using a corrosion casting method. Clin. Anat.1997; 10:77-81
5. Standring SM. Gray’s Anatomy, In:Development of cardiovascular and lymphatic
system, 39th Edn; Elsevier Churchill Livingstone. 2005, pp 1044.
6. Petrenko VM. Development of the obturator artery in human prenatal
ontogenesis. Morfologia .2000; 118(4): 51-3.



Legends
Plate: 1 showing the view of the left side of the pelvis. Obturator artery (blue arrow) arising from posterior division of the internal iliac artery (red arrow) is accompanying the obturator nerve (yellow arrow).
Plate: 2 same views where the structures are coloured for better delineation. It shows that the artery is crossed by ureter and the vas deferens (Green). Red and yellow arrow showing anterior and posterior division of internal iliac artery respectively.
Photographs
Plate: 1 Plate: 2

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