Unit
- Location and size: The prostate is a walnut-shaped gland located below the bladder and surrounding the urethra. It typically weighs about 20-30 grams in young men and tends to enlarge with age. Understanding its position is critical for comprehending how BPH causes urinary obstruction.
- Zonal anatomy: The prostate is divided into three zones: peripheral, central, and transition. BPH originates predominantly in the transition zone, which encircles the urethra. Hyperplasia in this zone directly compresses the urethral lumen, leading to voiding symptoms.
- Histological structure: The gland consists of glandular epithelium, smooth muscle, and fibromuscular stroma. The epithelial cells secrete prostatic fluid that nourishes sperm. The smooth muscle fibers, controlled by alpha-adrenergic receptors, contribute to dynamic obstruction when hypertrophied.
- Blood supply and innervation: The prostate receives blood from the inferior vesical and middle rectal arteries. Its nerve supply comes from the pelvic plexus, including sympathetic and parasympathetic fibers. These nerves regulate smooth muscle tone and glandular secretion.
- Lymphatic drainage: Lymph from the prostate drains primarily to the obturator and internal iliac lymph nodes. Knowledge of this drainage is important for understanding potential routes of metastasis in prostate cancer, though BPH is benign.
- Relation to surrounding structures: The prostate sits adjacent to the bladder base, seminal vesicles, and rectum. Its posterior surface is palpable on digital rectal exam (DRE). The prostatic urethra passes through the gland, making it susceptible to compression during hyperplasia.
- Changes with age: Prostate volume increases under the influence of dihydrotestosterone (DHT). While both BPH and prostate cancer become more common with age, BPH is a non-malignant growth that typically begins after age 40. By age 60, more than half of men have histologic BPH.
- Clinical relevance: Anatomic knowledge helps healthcare professionals interpret diagnostic tests like ultrasound and MRI, explain symptoms to patients, and anticipate complications such as acute urinary retention. It forms the foundation for all subsequent module topics.
- Prostatic capsule: The prostate is enclosed by a thin fibromuscular capsule that is continuous with the pelvic fascia. This capsule acts as a barrier to the spread of disease and is surgically important during procedures like transurethral resection. In BPH, the capsule limits outward expansion, forcing hyperplastic tissue to compress the urethra internally.
- Ejaculatory ducts: These paired ducts pass obliquely through the prostate and empty into the prostatic urethra at the seminal colliculus. They carry sperm and seminal vesicle fluid. Their course through the gland means that BPH can interfere with ejaculation, contributing to symptoms such as painful ejaculation or hematospermia in some patients.
- Stromal composition: The fibromuscular stroma of the prostate consists of collagen, elastin, and abundant smooth muscle. This stroma provides structural support and contractile function. In BPH, stromal hyperplasia often exceeds glandular hyperplasia, leading to a firm, nodular enlargement that increases both static and dynamic components of bladder outlet obstruction.
Terminology
- Prostate gland
- A male reproductive gland that produces seminal fluid and surrounds the urethra below the bladder.
- Transition zone
- The region of the prostate where benign prostatic hyperplasia typically originates; it encircles the urethra.
- Dihydrotestosterone (DHT)
- A potent androgen derived from testosterone that drives prostate growth.
Quick Revision
- The prostate is located below the bladder and surrounds the urethra; its enlargement in BPH compresses the urethra.
- BPH arises from the transition zone, affecting urine flow.
- The gland has glandular and smooth muscle components, both of which contribute to obstruction.
- Anatomical knowledge is essential for understanding symptoms, diagnostics, and treatment rationale.
Disclaimer
Educational use only. Not intended for practical surgery, incisions, or other surgical procedures. It does not qualify you to perform physical operations.