The main aim of this study is to present, describe and compare the most significant anatomical classifications of the internal iliac artery (IIA) and its branches, their pros and cons, to relate them to clinical practice and note their clinical importance, and to offer a new classification based on number of main vessels origins. Many classifications covering the detailed morphology of the IIA have been developed, focusing on the destination of vessels making it possible to determine the name and type of branching precisely. However, because the allocation criteria are overdetailed and of doubtful accuracy, these classifications have become impractical for clinical practice and advanced statistical calculations. The argument of this research paper is that highly variable vascularized regions should be classified from either an anatomical point of view to determine detailed morphology aspects or a clinical perspective. Presented classification proposes unification of many branching types presented among various classifications, which look identical when determining the origin pattern from the main vessel and differ only in the destination point of the vessel, what brings clarity and increases the statistical usefulness of the collected data. This should translate into better cooperation between scientists and clinicians and thus benefit patients. The paper proposes a new, clinically useful classification based on the model of vessel origins from the main stem. The IIA is the main vascular supply to the pelvic region, so precise knowledge of origin and its branching pattern is essential for all clinicians, especially for general and orthopaedic surgeons, gynecologists, obstetricians and urologists.

The middle rectal artery is a very important anatomical structure in rectal cancer surgery. It is the only vessel that penetrates through the proper rectal fascia into the pelvic cavity, and therefore threatens the integrity of total mesorectal excision. Moreover, it is very closely related to the lateral lymphatic drainage root. The definition of the middle rectal artery is ambiguous, and different frequencies, origins, and trajectories have been reported in various papers. The frequency of the middle rectal artery is reported to range from 12 to 97 %. Traditionally, the middle rectal artery is described as an artery that penetrates the pelvic plexus from the lateral side along with the lateral ligament; the frequency of this lateral type of middle rectal artery ranges from 20 to 30 %. However, the reports that describe higher frequency values also consider another type of middle rectal artery, which penetrates the neuro-vascular bundle from the antero-lateral direction; this antero-lateral type of middle rectal artery tends to be a small vessel, and frequently forms a common trunk with the prostatic artery. With advancements in endoscopic surgery, the knowledge of the precise anatomy of this structure is becoming more crucial for optimal rectal cancer surgery.