Posterolateral surface of prostate

The posterolateral surface of the prostate refers to the anatomical region located at the junction of the posterior and lateral aspects of the prostate gland. It is not a formally named discrete surface in classical anatomical descriptions the prostate is traditionally described as having an apex, a base, and anterior, posterior, and inferior-lateral surfaces but the posterolateral aspect is a critically important anatomical landmark in both surgical and radiological contexts.

Anatomical Features

The posterolateral surface corresponds to the area where the peripheral zone - the largest glandular zone, comprising approximately 70% of the prostate's glandular tissue - extends from the base to the apex along the posterior and lateral aspects of the gland. The peripheral zone ducts exit posterolaterally from the urethral wall on both sides, with branches curving anteriorly and posteriorly. On T2-weighted MRI, this region is typically visible as a sharply demarcated rim representing the fibrous pseudocapsule of the prostate.

Key Structures at the posterolateral surface

• Neurovascular bundles (NVBs): Loose connective and adipose tissue containing the periprostatic venous plexus intermixed with arteries, nerves, and lymphatics is located at the posterolateral aspects of the prostate. These structures, collectively termed the neurovascular bundles, contain autonomic nerve fibers (parasympathetic from S2S4 and sympathetic from T11L2) critical for erectile function. The NVBs are situated between the fascial layers covering the prostate in this region.

• Fascial layers: The prostatic fascia surrounds the medial aspect, while the endopelvic fascia partially engulfs the prostate laterally. Posteriorly, Denonvilliers' fascia separates the prostate and seminal vesicles from the rectum. At the posterolateral margin, the prostatic fascia merges with the endopelvic fascia.

• Nerve distribution: The majority of periprostatic nerves are concentrated at the posterolateral and posterior surfaces. In cadaveric studies, approximately 6268% of counted nerves were located in the posterolateral and posterior sectors across the base, mid-region, and apex of the prostate. Autonomic fibers are distributed in a spray-like pattern into the neurovascular bundle, the proximal plate, and accessory pathways.

Clinical Significance

The posterolateral surface is the most surgically relevant region during radical prostatectomy, as it is the site where nerve-sparing dissection is performed to preserve erectile function and urinary continence. The choice of dissection plane at this surface complete nerve-sparing, partial nerve-sparing, or non-nerve-sparing directly impacts both oncologic and functional outcomes. Approximately 70% of prostate cancers arise from the peripheral zone, which predominates at the posterolateral surface, making this region the most common site of extracapsular extension and positive surgical margins.