Seminal colliculus

The seminal colliculus (Verumontanum) is a small, elevated, rounded eminence located on the posterior wall of the prostatic urethra. It serves as a critical anatomical landmark in the male genitourinary tract.

Key anatomical features:

• It is situated at the midpoint of the prostatic urethra, where the urethra angulates anteriorly at approximately 35°, dividing the prostatic urethra into proximal and distal segments.

• The ejaculatory ducts open on either side of the seminal colliculus, delivering seminal fluid and sperm into the prostatic urethra during ejaculation. The apex of the colliculus and the bilateral ejaculatory duct openings form a shape resembling an isosceles triangle.

• The prostatic utricle, a small blind-ending pouch (a vestigial remnant of the Müllerian duct), opens at the summit of the seminal colliculus between the ejaculatory duct orifices.

• At the level of the seminal colliculus, the ejaculatory ducts and prostatic utricle are surrounded predominantly by longitudinal smooth-muscle fibers, which form a distinctive longitudinal muscular column in the posterior urethral wall that may play a role in ejaculation.

Relationship to prostatic zones (McNeal's zonal anatomy):

The seminal colliculus is the reference point from which the glandular zones of the prostate are defined. The peripheral zone ducts radiate laterally from the urethra distal to the verumontanum, the central zone ducts arise near the ejaculatory duct orifices and fan out toward the base, and the transition zone ducts arise from the posterolateral urethral wall proximal to the verumontanum.

Clinical significance:

The seminal colliculus is an essential landmark during transurethral procedures. During transurethral resection of the prostate (TURP), the distance from the verumontanum to the prostatic apex (mean ~1.2 cm) provides a safety margin to avoid injury to the external urethral sphincter. It is also a key reference point during transurethral seminal vesiculoscopy, where the ejaculatory duct openings on the colliculus must be identified for instrument passage.