Sechenov School
Home › Human Anatomy › Male Urethra

Male Urethra

Urethra masculina

For medical students2 min readUpdated 2026-10-10

The male urethra is a fibromuscular tube that transports urine from the urinary bladder to the exterior. Unlike the female urethra, the male urethra serves as a shared pathway for both the urinary and reproductive systems, functioning in both urination and ejaculation.

Organ lengthApproximately 20–23 cm on average
FunctionsUrination (micturition) and ejaculation
SphincterExternal urethral sphincter provides voluntary control of micturition

Functions and Characteristics of the Male Urethra

The primary task of the urethra is to expel urine stored in the urinary bladder. However, the male urethra (urethra masculina) has a crucial physiological feature: it is integrated into the male reproductive system (organa genitalia masculina).

Consequently, the organ has a dual role, facilitating both micturition and ejaculation. In contrast, the female urethra (urethra feminina) is significantly shorter and wider, and its physiological role is strictly limited to urinary excretion.

Anatomical Segments

The male urethra is a lengthy tubular structure. In an adult, its total length reaches about 20–23 cm. Topographically, it is divided into several consecutive segments:

  1. Intramural part (pars intramuralis or preprostatic part) — the initial segment.
  2. Prostatic part (pars prostatica) — passes through the prostate gland.
  3. Membranous part (pars membranacea) — the shortest and narrowest segment.
  4. Spongy part (pars spongiosa) — the longest segment, enclosed within the corpus spongiosum of the penis.

Wall Structure and Mucosa

The urethral wall is layered and consists of three main components:

The relief of the mucosa is uneven. Its surface features longitudinal folds, small depressions (urethral lacunae), and dilations, which are functionally important for fluid dynamics during ejaculation and urination.

Sphincter Mechanism

Urinary continence and control over micturition are maintained by specialized muscular structures known as sphincters. Anatomically, surrounding the membranous part (pars membranacea) and the area of the external urethral orifice is the external urethral sphincter (m. sphincter urethrae externus). It consists of skeletal (striated) muscle and is under voluntary control.

Mnemonic

To remember the four parts of the male urethra in order, use the mnemonic: "I Pee Mighty Slowly" (Intramural, Prostatic, Membranous, Spongy).

Frequently asked questions

What anatomical narrowings and dilations are present along the male urethra?

The male urethra features alternating narrowed and dilated segments along its course.

  • Narrowings: The membranous part (pars membranacea) is the narrowest and shortest segment, and the external urethral meatus is the narrowest point overall.
  • Dilations: The prostatic part (pars prostatica), the intrabulbar dilation in the bulbous part (pars bulbosa—the widest segment), and the navicular fossa (fossa navicularis) within the glans penis.
What curvatures does the male urethra form along its course?

The male urethra forms two main curvatures in the flaccid state:

  • Upper (subpubic) curvature: Formed at the transition from the membranous to the spongy part; its concavity faces anteriorly and superiorly.
  • Lower (prepubic) curvature: Formed at the transition from the fixed part to the mobile part of the penis; its concavity faces inferiorly.

Lifting the penis toward the anterior abdominal wall effaces the prepubic curvature, merging them into a single curve with a concavity facing anteriorly and superiorly, which facilitates the passage of rigid catheters.

Which sphincters provide urinary continence and control in males?

Continence is maintained by two primary sphincters:

  • Internal urethral sphincter (m. sphincter urethrae internus / m. sphincter vesicae): Involuntary, composed of smooth muscle, located at the bladder neck and surrounding the initial urethra.
  • External urethral sphincter (m. sphincter urethrae externus): Voluntary, composed of skeletal muscle, located at the level of the membranous urethra.
The ducts of which glands empty into the lumen of the male urethra?

Several accessory gland ducts open into the male urethra:

  • Prostate gland (prostata): Prostatic ducts open into the prostatic urethra on either side of the seminal colliculus (verumontanum).
  • Bulbourethral glands (Cowper's glands, glandulae bulbourethrales): Their ducts open into the proximal bulbous part of the spongy urethra.

Additionally, the ejaculatory ducts (formed by the union of the vas deferens and seminal vesicle ducts) open onto the seminal colliculus in the prostatic urethra.

Which arteries supply blood to the various segments of the male urethra?

Blood supply to the male urethra is derived primarily from branches of the internal pudendal artery (a. pudenda interna).

Which nerves provide innervation to the male urethra?

Innervation is derived from the pelvic plexus (autonomic supply) and the pudendal nerve (somatic supply to the voluntary external urethral sphincter).

How does the male urethra functionally differ from the female urethra?

The male urethra serves a dual function in both the urinary and reproductive systems (urine excretion and ejaculation), whereas the female urethra is shorter, wider, and strictly dedicated to urinary excretion.

What is the average length of the male urethra?

In an adult male, the urethra is approximately 20 to 23 centimeters long.

Where is the external urethral sphincter located?

The external urethral sphincter (m. sphincter urethrae externus) is located around the membranous part of the urethra within the urogenital diaphragm.

What tissue layers form the wall of the urethra?

The urethral wall consists of a mucous membrane (forming folds and lacunae), a muscular layer, and surrounding connective tissue elements.

Go deeper

More topics in Human Anatomy

Salivary GlandsEthmoid BoneAccessory Visual StructuresJoints of the Pectoral GirdleMaxillary ArteryDeep Muscles of the ChestSympathetic and Autonomic Plexuses of the PelvisThymusTestisExternal EarPharynxTelencephalon (Cerebrum): Anatomy and StructureHuman Anatomy →