The male urethra is a narrow tube, about 7 to 8 inches (20 cm) long, that runs from the bladder to the tip of the penis. It serves a dual purpose: it carries urine out of the body and also serves as the channel through which semen exits during ejaculation. That dual role makes it unique in the male body, functioning as part of both the urinary and reproductive systems.
Where It Runs and How It’s Shaped
The urethra begins at the base of the bladder and travels through the prostate gland, then through the pelvic floor, and finally along the length of the penis to the opening at the tip. It’s not a straight tube. The path bends at the pubic bone, creating a natural curve that matters during medical procedures like catheter insertion. The tube itself is fibromuscular, meaning it’s made of both fibrous tissue and muscle, which allows it to expand slightly when fluid passes through and then return to its resting state.
Different sections of the urethra pass through different structures. The first portion runs through the prostate, where it receives semen from the ejaculatory ducts. This is the segment that connects the urinary tract to the reproductive tract. The remaining portions continue through the pelvic floor muscles and then travel within the spongy tissue of the penis to the external opening.
How It Handles Both Urine and Semen
The male urethra is the only channel that serves two different body systems. During urination, urine flows from the bladder through the full length of the urethra. During ejaculation, semen enters the urethra at the prostate and exits through the same opening. The body prevents these two fluids from mixing through a coordination of muscle contractions and nerve signals. During ejaculation, the bladder neck clamps shut so urine doesn’t enter the urethra, and during urination, the reproductive ducts remain closed.
Two Sphincters Control the Flow
Two ring-shaped muscles, called sphincters, control when urine leaves the body. They work differently, and understanding the distinction helps explain how bladder control works.
The internal sphincter sits right where the urethra exits the bladder. It’s made of smooth muscle, the same type found in your digestive tract, and it operates automatically. You don’t consciously control it. Your nervous system keeps it closed by default and opens it when conditions are right for urination. Sympathetic nerve activity (the “fight or flight” system) keeps it shut. Parasympathetic activity (the “rest and digest” system) causes the bladder to contract and the internal sphincter to relax.
The external sphincter is lower, sitting where the urethra passes through the pelvic floor. It’s made of skeletal muscle, the same type you use to move your arms and legs, and you can control it voluntarily. This is the muscle that lets you hold your urine when your bladder is full and you’re not near a restroom. Urination begins when you voluntarily relax this external sphincter. Both sphincters need to open for urine to flow.
Why Length Matters for Infections
At 20 cm, the male urethra is roughly four times longer than the female urethra. That extra length creates a longer path that bacteria must travel to reach the bladder, which is one reason urinary tract infections are far less common in men than in women. The distance alone doesn’t make men immune to UTIs, but it provides a meaningful physical barrier. When men do develop UTIs, there’s often an underlying cause like an enlarged prostate or a structural problem in the urinary tract that makes the infection more likely.
Common Problems That Affect the Male Urethra
Urethral Stricture
A stricture is a narrowing of the urethra caused by scar tissue. The scarring can develop from an injury, a sexually transmitted infection, or as a side effect of a medical procedure. The most common sign is a weak urine stream. You might find yourself straining to urinate, feeling like your bladder isn’t fully empty, needing to urinate frequently, or experiencing pain during urination. Some people feel a sudden, urgent need to go even right after using the restroom. In severe cases, the narrowing can become so tight that urine can’t pass at all, a situation called acute urinary retention that requires immediate treatment.
Urethritis
Urethritis is inflammation of the urethra, most often caused by bacterial infections including sexually transmitted infections like chlamydia and gonorrhea. Symptoms typically include burning during urination and discharge from the urethral opening. Non-infectious causes, such as irritation from chemicals or physical trauma, can also trigger inflammation.
Prostate-Related Issues
Because the urethra passes directly through the prostate gland, prostate enlargement can squeeze the urethra and restrict urine flow. This is extremely common in older men. The symptoms overlap with stricture: a weak stream, difficulty starting urination, frequent nighttime trips to the bathroom, and a feeling that the bladder hasn’t fully emptied. Prostate inflammation, called prostatitis, can also irritate the portion of the urethra running through the gland and cause painful urination.
The Urethra During Medical Procedures
The male urethra’s length and natural curve make certain procedures, particularly catheter insertion, more involved than in women. The bend at the pubic bone means a catheter must navigate that curve to reach the bladder. Holding the penis upright during insertion helps straighten this bend and allows the catheter to pass more smoothly. The prostate can also create mild resistance as the catheter passes through that segment, especially if the prostate is enlarged. These are routine considerations for any healthcare provider performing the procedure, but they explain why catheterization can feel uncomfortable and why it sometimes takes a moment longer in men.