Anatomy clinical correlates: Male pelvis and perineum

The pelvis lies between the abdomen and the lower limbs, forming the lower part of the trunk. It supports and contains organs of the gastrointestinal system, the urinary system, and the reproductive system.

Furthermore, the structure and contents of the pelvis differs between biological male and biological female individuals. For biological males, there are many clinical conditions that can affect the pelvis and the perineum, and we mean more than just the ones that will make you famous on Youtube or get you on America’s Funniest Home Videos.

The pelvis is formed by the ilium, ischium, pubis, and sacrum, forming a ring of bones called the pelvic ring. Pelvic bones, like any other bone in the body, are susceptible to injury and subsequent fracture. Fractures of the pelvis usually occur following severe trauma, and this can happen through a variety of mechanisms.

Fractures can occur in isolation, but since the pelvis is shaped like a bony ring, they tend to occur in two or more areas simultaneously, which means they’re unstable fractures. Think of trying to break a pretzel at only one point!

Direct trauma, for example a car crash, may fracture susceptible areas such as the pubic rami, the acetabulum, the sacroiliac joints, and the ala of the ilium. Other mechanisms of injury include falling directly on one of the lower limbs, which can force the head of the femur into the pelvic cavity through the acetabulum. These different injuries can damage pelvic structures such as vessels, nerves, and viscera, resulting in a variety of clinical manifestations.

One classic example is called an open book fracture, where there is pelvic ring disruption due to anterior widening typically at the pubic symphysis. Fracture of the medial portion of the pubic rami can lead to injury of the urinary bladder and urethra, as well as sensory damage to the anterior and medial thigh and motor weakness to the muscles supplied by the femoral nerve.