Prostatic Urethra

Structure/Morphology

The prostatic urethra is the widest and longest portion of the urethra, at 3–4 cm long (Standring, 2016). The urethral crest is a raised ridge that lies between two prostatic sinuses within the prostatic urethra. Prostatic ducts open into the prostatic sinuses. The seminal colliculus is a rounded eminence of the urethral crest with a slit that opens into the prostatic utricle (vestigial remnant of the embryonic uterovaginal canal). The ejaculatory ducts open into the prostatic utricle.

Anatomical Relations

The prostatic urethra passes through the central region of the prostate and continues inferiorly as the membranous urethra.

Function

The prostatic urethra provides passage for urine to travel through the prostate. In addition, it contains the opening of the ejaculatory ducts (sperm and seminal fluid) and several prostatic ducts.

Arterial Supply

The prostatic urethra is supplied by prostatic branches of the inferior vesical and middle rectal arteries.

Venous Drainage

The venous plexus surrounding the urethra drains into the vesical plexus surrounding the bladder. The vesical plexus then drains into the internal pudendal veins.

Innervation

The prostatic urethra has both somatic and autonomic innervation. The somatic innervation is supplied by the second to fourth sacral nerves. The pelvic splanchnic nerve supplies parasympathetic innervation to the prostatic urethra. The inferior hypogastric plexus is extended inferiorly as the prostatic plexus, which supplies mixed sympathetic, parasympathetic, and visceral afferent fibers to the intramural part of the urethra.

Lymphatic Drainage

Lymphatic drainage of the intramural part of urethra drains into the internal and external iliac nodes.

List of Clinical Correlates

—Prostate cancer

—Benign prostatic hyperplasia

—Kidney stones

—Hypospadias

—Urethritis

—Catheterization

References

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41 edn.: Elsevier Limited.