Morphological comparison of the pudendal canal and its neurovascular elements in human and domestic mammals

Abstract

The structural organization of the pelvis and perineum is complex and poorly understood, especially in non‐primate mammals. A relevant feature of these regions is the pudendal canal, which is the passage for the pudendal vessels and nerve at the caudal surface of the pelvic diaphragm (coccygeous and levator ani muscles). These elements are responsible for the blood supply and innervation of the perineum and involve extensive consideration in numerous clinical interventions. The pudendal canal is well described in humans, but not in other species. Therefore, with the aim of studying and comparing the pudendal canal and its neurovascular elements we dissected the pelvic diaphragm and traced the pudendal vessels and nerve in dogs (n=20), goats (n=10), pigs (n=10), horse (n=5), cats (n=3), and humans (n=20). We found that, unlike humans, the pudendal canal in domestic animals is a narrow passage that results from the extensive union of the pelvic diaphragm to the pelvic wall. In large animals, the pelvic diaphragm was a simple muscular layer with a prominent insertion in the external anal sphincter. In small animals, the diaphragm is formed by a group of muscular bundles with greater insertion at the caudal vertebrae. The presence of nerves were variable according to the specific conformation of the sacral plexus. However, the branching pattern of the pudendal vessels and nerve were similar. A notable feature in domestic animals was the presence of the caudal rectal nerve inside the pudendal canal, which is not a feature normally found in humans.