Introduction

Prostate cancer is the leading cause of cancer-related death in men in the United States. With advancements in technology and research, robotic-assisted laparoscopic prostatectomy has become widely used for precise surgical dissection of anatomical planes. This precision is aided by knowledge gained from cadaver studies and visualization of anatomy through pre- and intraoperative imaging techniques. Our 3D animated video (https://youtu.be/—btx1UsWUk) presents the most updated anatomy of the prostate, its surrounding structures, and neuroanatomy. It is based on literature published from July 2002 to January 2022. Using Autodesk Maya software, we created a detailed 3D animation video to explain the complex anatomy in a clear and accessible manner.

Figure 1. Hood components: detrusor apron, endopelvic fascia.10

Figure 2. Periprostatic anatomy.

Figure 3. Periprostatic anatomy.

Prostate Capsule and Periprostatic Fascia

The prostate is a dense fibromuscular gland located in the true pelvis. It is surrounded by the endopelvic fascia (Figure 1), which consists of a visceral and parietal layer, followed by the prostatic fascia and prostatic capsule.¹ These layers contain intermingling nerves, while vessels lie between the prostatic fascia and capsule (Figures 2 and 3). The capsule covers the prostate laterally and posteriorly, while ventrally it fuses with the lateral borders of the anterior fibromuscular stroma (AFMS). The prostatic capsule extends to the posterolateral prostate, medially enveloping the neurovascular bundle (NVB) and becoming the pararectal fascia covering the rectum. The fusion of the capsule with the levator fascia laterally and the Denonvilliers fascia posteriorly results in denser areas compared to other prostatic regions. This anatomical background has led to the classification of grades of nerve sparing, with athermal and traction-free techniques employed to achieve a balanced oncologic and functional outcome. Preoperative mapping of nerves on imaging plays a vital role in achieving better nerve sparing.^2,3

AFMS

The anterolateral aspect of the prostate contains fibromuscular tissue known as the AFMS. The upper part of the AFMS consists of circular fibers from the detrusor apron, while the lower part comprises striated sphincter fibers. From the base toward the apex at the urethra, the AFMS is intermingled with skeletal muscle fibers from the urogenital diaphragm. The levator ani muscles are present at the mid prostate, and detrusor-like smooth muscle extends from the mid gland to the base of the prostate.

Figure 4. Neural hammock, demonstration of autonomic fibers, and somatic supply.

Figure 5. Parasympathetic nerve supply to the prostate and urethra, pelvic plexus.

Neuroanatomy

The prostate receives its autonomic neural supply from sacral and lumbar roots (Figures 4 and 5). Sympathetic innervation comes from T10-L2, parasympathetic innervation from S2-S4, and somatic supply from the pudendal nerve originating from S2-S4, which further branches to the corporal bodies and penile hilum. These nerve fibers form the pelvic plexus, also known as the inferior hypogastric plexus or the proximal neurovascular plate. The autonomic fibers from the proximal neurovascular plate are distributed into the NVB or predominant NVB and the accessory neural pathway in a spray-like pattern, with 60% of fibers on the posterolateral aspect and 40% on the anterolateral aspect of the prostate.^4-7

Seminal Vesicles and Vas Deferens

The seminal vesicles and vas deferens are extraperitoneal tubular structures located at the base of the prostate. They are surrounded anteriorly by the bladder base and posteriorly by the rectum. The seminal vesicles are surrounded by major portions of nerves posterolaterally and have associations with the pelvic plexus.

The Dorsal Venous Complex

The dorsal venous complex is composed of nerve fibers, dorsal veins, and prostatic arteries from the anterolateral pedicles. It runs as the anterior division of the pelvic NVB, from the prostate-bladder groove, inferiorly on the anterolateral surface of the prostate toward the penile hilum, overlying the urethral striated sphincter anterolaterally. Anteriorly, it is located in a space between the detrusor apron and AFMS. The deep venous complex is a key landmark for achieving optimal functional outcomes postrobot-assisted laparoscopic prostatectomy.

Figure 6. Urethral sphincter complex.

Figure 7. Urethral sphincter complex.

Urethral Sphincter Complex

The urethral sphincter complex consists of the external rhabdosphincter, inner lissosphincter, and the membranous urethra with supporting structures (Figures 6 and 7). The inner lissosphincter is a complete cylinder of circular and longitudinal muscle fibers around the urethra. The prostatic nerve fibers, upon reaching the urethra, lie adjacent to the membranous urethra along the lateral and dorsolateral sides, between the 3 and 9 o’clock positions. From a clinical and surgical standpoint, the internal urethral sphincter plays a major role in continence, and preserving maximal urethral length has a functional role in the early return of continence postradical prostatectomy.⁸

Puboprostatic Ligamentous Complex

The puboprostatic ligamentous complex comprises the puboprostatic ligaments, arcus tendinous, and puboperinealis muscle (Figure 8). The puboperinealis muscle flanks the prostatic urethral junction, acting as a “hammock” supporting the urethra posteriorly and contributing to the quick-stop phenomenon of urination. The puboprostatic ligamentous complex fixes the bladder, prostate, and membranous urethra to the pubic symphysis and plays a crucial role in urogenital competence. It contributes to the formation of the hood, along with the periprostatic fascia and detrusor apron, and has a role in erectile function and continence.⁹

Figure 8. Hood components: dorsal venous complex (DVC), puboprostatic ligaments.¹⁰

Detrusor Apron

The detrusor apron is an extension of detrusor fibers from the bladder to the posterior pubic bone, contributing to the AFMS of the prostate (Figures 1 and 2). Anterior to the prostate, the detrusor apron splits into anterior, middle, and posterior layers. The anterior layer anchors to the posterior surface of the pubic bone, the middle layer joins the fascial sheath of the deep venous complex, and the posterior layer forms the AFMS.

Conclusions

This video provides a deeper understanding and visual insight into the most recent neuroanatomical findings from various studies in the past 2 decades. The prostate has a complex anatomy with close proximity of the NVB.