What Is the Prostate?
The prostate is a small gland that is part of the male reproductive system. Its main job is to produce seminal fluid, which nourishes and transports sperm.
Where Is It Located?
Imagine the bladder, the organ that stores urine, like a balloon. The prostate sits just below the bladder, like a small donut wrapped around the first part of the urethra, the tube that carries urine and semen out through the penis. Because of this position, when the prostate becomes enlarged, it can squeeze the urethra and make urination difficult.
What Does It Looks Like?
The prostate is about the size of a walnut in young men and tends to grow slowly with age. It is shaped like an upside-down pyramid, with the wide part, or base, attached to the bladder and the pointed end, or apex, facing downward toward the urogenital diaphragm.
How Does the Prostate Work with Nearby Structures?
The prostate does not work alone; it functions together with nearby structures in the reproductive system to produce, store, and transport semen.
- Vas deferens, also called vasa deferens, are tubes that carry sperm from the testicles to the seminal vesicles. During ejaculation, sperm travels through these tubes to mix with seminal fluid.
- Seminal vesicles are glands located behind the bladder that produce most of the fluid found in semen. This fluid provides nutrients and energy for sperm.
- The prostatic urethra is the part of the urethra that runs through the prostate and carries both urine and semen out of the body.
Understanding the Base and Apex of the Prostate
To better understand the prostate’s shape, it helps to know what is meant by the base and apex.
- The base is the upper portion of the prostate, attached to the bladder. It surrounds the urethra as it exits the bladder.
- The apex is the lower, narrow end of the prostate, located just above the urogenital diaphragm. The urethra passes through here as it leaves the gland.
Lobes of the Prostate
The prostate is divided into five lobes, each with a specific location and clinical importance.
- The anterior lobe (isthmus) is located in front of the urethra; it contains mostly muscle tissue and is rarely affected by disease.
- The posterior lobe lies behind the urethra and below the ejaculatory ducts; this is the most common site for prostate cancer and is the area felt during a digital rectal exam.
- The median lobe sits between the urethra and ejaculatory ducts; it can enlarge with age and cause urinary obstruction, often due to benign prostatic hyperplasia.
- The lateral lobes, right and left, are found on each side of the urethra; they are often involved in benign enlargement that can make urination difficult.
Understanding the lobes helps identify where disease develops. Cancer most often begins in the posterior lobe, while benign enlargement typically affects the median and lateral lobes.
Zones of the Prostate
Doctors and pathologists also describe the prostate by zones, since certain diseases develop more often in specific areas.
- The peripheral zone forms the outer back portion and is where most prostate cancers begin.
- The central zone surrounds the ejaculatory ducts.
- The transition zone is located around the urethra and often enlarges with age, causing urinary symptoms.
- The anterior fibromuscular zone forms the front wall and consists mostly of muscle and connective tissue.
Key Neighbors to the Prostate
- The bladder sits directly above the prostate.
- The rectum lies just behind the prostate, which is why it can be felt during a rectal exam.
Please watch the following video to better visualize what we have learned: