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Male Urethra

The male urethra is an approximately 18–20 cm muscular conduit that carries urine from the bladder neck to the external meatus and, during ejaculation, semen to the outside. The two functions impose competing demands on its sphincteric, neural, and mucosal biology.[1]

Gray's Anatomy figure of the male urethra laid open on its anterior surface

Gray's Anatomy Fig. 1142 — The male urethra laid open on its anterior (upper) surface, showing the prostatic, membranous, and penile segments.

Segmental Anatomy​

The urethra divides both anatomically (by the structure it traverses) and functionally (into posterior and anterior segments).[1]

SegmentLengthCourseSurgical relevance
ProstaticMean 4.01 cm anterior / 4.86 cm posterior in 33 prostatectomy casts[21]Through the prostate from bladder neck to apex; the ejaculatory ducts open at the verumontanum within this segment[21]Altered by TURP/HoLEP/simple prostatectomy; adjacent to the bladder-neck stenosis site after outlet surgery; proximal reconstruction target in PFUI
Membranous1–2 cmThrough the perineal membrane; a short, relatively narrow and fixed segmentSurrounded by the rhabdosphincter — an important continence structure after prostatectomy; vulnerable in pelvic-fracture urethral injury
Bulbar~5–6 cmWithin the bulb of the corpus spongiosum in the perineumThe most common stricture location; main working segment of anastomotic and augmentation urethroplasty
Penile (pendulous)~10 cmThrough the penile shaft within the corpus spongiosumStricture site after instrumentation/hypospadias repair; substitution urethroplasty territory
Fossa navicularisTerminalDilated segment within the glansMeatal stenosis and distal stricture site; lichen-sclerosus territory

Functionally the urethra is divided at the urogenital diaphragm into:

  • Posterior urethra. Prostatic and membranous segments; supported by the perineal membrane and the rhabdosphincter; drains to pelvic nodes.
  • Anterior urethra. Bulbar, penile and fossa navicularis segments lie within the corpus spongiosum. Current EAU guidance describes drainage of anterior urethral tumors, including bulbar tumors, through superficial and deep inguinal nodes and then pelvic nodes; older anatomy literature groups bulbar tumors with proximal pelvic drainage.[1][23]

This anterior and posterior split governs lymphatic drainage for urethral cancer staging, trauma mechanism (straddle versus pelvic-fracture shears), and reconstruction approach (perineal versus retropubic or trans-pubic access for PFUI).

Within the corpus spongiosum, the urethra does not sit centrally throughout its length: proximally, in the bulb, it lies more eccentric and ventral within the spongiosal tissue.[19]

Mucosal Biology​

The epithelial lining transitions along the length:[1][4]

SegmentEpithelium
Prostatic (proximal)Urothelium, then a small zone of prostatic glandular epithelium
Membranous and bulbarPseudostratified columnar
PenilePseudostratified columnar transitioning distally
Fossa navicularis and meatusSquamous lining varies across the distal urethra; a circumscribed nonkeratinized, glycogen-rich, estrogen-responsive zone lies in the fossa navicularis.[4]

Two operative consequences:

  • A circumscribed glycogen-rich squamous zone in the fossa navicularis showed estrogen-dependent expansion in the specific long-term estrogen-exposure cases described by the original histology study.[4] LS can involve the meatus and distal urethra; reconstruction should avoid LS-affected genital skin when graft or flap augmentation is needed.[14]
  • Minor prostatic glands scattered along the urethra[3] explain the occasional finding of prostatic-type tissue in ectopic locations on reconstructive histology.

The urethra is glandular throughout:

  • Glands of Littré. Mucus-secreting glands along the penile and bulbar urethra. Inflammation around these glands is one proposed route to spongiofibrosis.
  • Cowper's (bulbourethral) glands. Lie in the urogenital diaphragm lateral to the membranous urethra; ducts empty into the proximal bulbar urethra.
  • Lacuna magna. A dorsal pocket in the fossa navicularis; site of occasional irritative symptoms in children.

Sphincter Complex​

Male continence is maintained by two sphincters with complementary temporal profiles:[8][9][12]

SphincterMuscle typeLocationRole
Lissosphincter (internal, smooth)Autonomic smooth muscle; myogenic tone via L-type Ca²⁺ channelsBladder neck through the membranous urethra toward the perineal membrane; thinner distally[8]Tonic closure at rest; bladder-neck contraction during ejaculation helps prevent retrograde flow
Rhabdosphincter (external, striated)Striated muscle supplied from Onuf's nucleus (S2–S4) via the pudendal nerveMembranous urethra, with fibers extending over the prostate apexTonic closure during storage and reflex recruitment during cough/Valsalva; major residual continence structure after radical prostatectomy

Two anatomic facts drive operative decisions:

  • An anterolateral omega configuration with a posterior fibrous raphe has been described.[8] Serial sections of three adult males and two fetuses also identified a circular membranous rhabdosphincter with posteroinferior wings.[28] Lateral dissection at the prostate apex can threaten sphincter fibers and local innervation.
  • The rhabdosphincter contains both slow- and fast-twitch fibers, which is consistent with sustained tonic closure pressure and a phasic response.

Continence after radical prostatectomy. Continence after radical prostatectomy depends on preserved membranous urethral length, intact rhabdosphincter innervation, and preserved pelvic support (pubourethral ligaments, puboperinealis).[25] Longer membranous urethral length on preoperative MRI is associated with a higher likelihood of continence at 12 months.[25] Apical nerve sparing and puboprostatic-ligament preservation may improve early continence recovery, although randomized evidence for these techniques is low certainty.[26]

Innervation​

The male urethra receives autonomic, somatic and sensory input through pelvic-plexus and pudendal pathways.[7][10][11][12] The two routes described below refer specifically to pelvic-plexus branches reaching the urethra and corpora cavernosa.[6]

Somatic​

  • The pudendal nerve (S2–S4), via Onuf's nucleus, supplies the rhabdosphincter and pelvic-floor muscles. In an older anatomic and physiologic study of three male cadavers and five patients with neurogenic dysfunction, S3 stimulation accounted for nearly 70% of the measured external-sphincter closure-pressure response.[11]
  • Clinical corollary: sacral-root and pudendal injuries can impair sphincter function.

Autonomic​

  • The sympathetic supply (T10–L2) runs via the hypogastric nerve and pelvic plexus. α₁-adrenergic tone contracts the bladder neck and proximal urethra during storage and ejaculation.[9][10]
  • The parasympathetic supply (S2–S4) runs via the pelvic nerve. It modulates urethral smooth muscle with cholinergic and nitrergic fibers; nitric oxide is the dominant inhibitory transmitter and is responsible for urethral relaxation at the onset of voiding.

Dual origin of urethral and cavernosal nerves​

The nerves to the urethra and corpora cavernosa arise from the pelvic plexus and reach the urethra through two anatomically distinct pathways:[6]

  1. Dorsal route. Along the ejaculatory ducts and seminal vesicles to the prostate base and proximal urethra.
  2. Lateral route. Along the inferior vesical artery, forming the neurovascular bundle (NVB) at the posterolateral aspect of the prostate.

Both routes must be respected during nerve-sparing prostatectomy, pelvic-fracture urethral repair, and rectourethral fistula repair; preserving only the lateral NVB does not preserve all cavernosal input.

Sensory​

Sensory afferents travel with the pudendal (somatic) and pelvic (visceral) nerves. Mechano- and chemosensitive feedback from the urethra contributes to state-dependent lower-urinary-tract reflexes: in the rat, urethral flow at low bladder volume reinforces sphincteric guarding, and at high volume it augments voiding.[13]

Vascular Supply​

Lateral cross-section of the penis showing the corpus spongiosum containing the urethra

Lateral cross-section of the penis demonstrating the urethra within the corpus spongiosum, flanked by the paired corpora cavernosa.

Urethral blood supply is segmental and bidirectional, with clinically important redundancy. This redundancy is why the urethra can be mobilized for reconstruction, and why each reconstructive technique specifies which feeders must be preserved.

A study of 25 fresh cadaveric urethras (ages 6 months to 73 years) measured mean urethral extensibility of 66.2 ± 7.2% under traction, similar across the penile, bulbar and membranous segments; extensibility decreased with age.[18] The authors proposed an ex-vivo anatomical traction limit near 75% of maximal constant-traction length, corresponding to a gap-to-normal-urethra ratio of about 1:4.[18]

SegmentDominant supplyClinical note
Prostatic / bladder neckInferior vesical artery, prostatic branchesDisrupted by bladder-neck contracture after TURP or radiation
MembranousPerineal and inferior vesical contributionsWatershed at the urogenital diaphragm
BulbarBulbar artery (branch of internal pudendal) + retrograde flow from dorsal and urethral arteriesNon-transecting repair preserves spongiosal continuity and bulbar arterial flow; conventional transecting EPA divides spongiosum and urethral arteries and may compromise perfusion. Preserving antegrade flow may be especially relevant after hypospadias repair or prior urethroplasty, or when future AUS implantation is possible.[22]
PenileUrethral artery (branch of internal pudendal) — paired longitudinal vessels within the corpus spongiosumCavernosal dissection in penile urethroplasty must preserve these
Glans / fossa navicularisDorsal artery anastomosisPreserved by dorsal onlay and dorsal-inlay techniques

Venous drainage parallels the arteries; the deep dorsal vein of the penis drains the penile and glandular urethra into the prostatic (Santorini's) plexus and thence the internal iliac system.

Physiology — Storage, Voiding, and Ejaculation​

Storage​

  • Tonic lissosphincter tone holds the bladder neck closed.
  • Rhabdosphincter tone contributes to urethral closure during storage; pressure varies by person, measurement method and age, so this page does not use a fixed >100 cmH₂O normal cutoff.
  • On cough or Valsalva, reflex recruitment of fast-twitch rhabdosphincter fibers increases closure pressure faster than intra-abdominal pressure rises. This is the functional basis of stress continence.

Voiding​

In ultrasound observations of one male and one female volunteer, the anterior and lateral urethral muscle unit thinned as the lumen opened at voiding onset, before visible bladder contraction.[5] Coordinated voiding also involves:

  • Somatic (pudendal) tone drops first.
  • Parasympathetic nitrergic output relaxes urethral smooth muscle and opens the lumen.
  • Sympathetic α-tone is simultaneously withdrawn.
  • In the two volunteers studied, visible bladder contraction followed urethral opening.[5]

Detrusor–sphincter dyssynergia specifically describes involuntary striated-sphincter contraction concurrent with detrusor contraction, usually in a neurological voiding disorder (see The Bladder).[24]

Ejaculation​

  • Sympathetic activity closes the bladder neck and contracts the seminal tract during emission. Outlet surgery can impair bladder-neck closure; reduced or absent antegrade ejaculation with α-blockers does not necessarily represent retrograde ejaculation.[20]
  • During ejection, pudendal-driven contractions of the bulbospongiosus and ischiocavernous muscles expel semen.[20]

Clinical Correlations for the Reconstructive Urologist​

  • Stricture geography. The bulbar urethra is a common stricture location. Spongiofibrosis can accompany inflammation or injury. Length, location, tissue quality, prior treatment and patient goals also matter when considering non-transecting repair, excision-and-primary-anastomosis (EPA), or substitution urethroplasty.[14]
  • Pelvic-fracture urethral injury (PFUI). Anterior pelvic-fracture displacement is associated with urethral injury.[15] A single-center, 119-man retrospective study reported an approximately 10% increase in urethral injury risk per millimeter of pubic-symphysis diastasis or inferomedial pubic-bone displacement.[15] PFUI often disrupts the posterior urethra near the membranous segment.[2][16] For complete disruption, diversion followed by deferred urethroplasty after at least three months is standard; selected stable patients with short gaps may have earlier repair, and early endoscopic realignment is an option when feasible.[16]
  • Post-prostatectomy incontinence. Sphincteric injury, support changes and bladder dysfunction can all contribute. The AUA/GURS/SUFU guideline recommends that clinicians discuss artificial urinary sphincter (AUS) with patients who have mild to severe SUI after prostate treatment and male slings for mild to moderate SUI . Slings should not be routinely implanted in severe SUI , and radiation has been correlated with decreased sling efficacy and faster failure.[17] For stress incontinence after primary, adjuvant or salvage radiotherapy in patients seeking surgery, the guideline recommends offering AUS over a sling or adjustable balloon .[17]
  • Post-TUR bladder-neck stenosis. Fibrotic narrowing at the bladder neck may follow surgery for benign prostatic obstruction. For nonobliterative stenosis, the EAU recommends TUR or hot-knife incision first line ; intralesional steroid has only retrospective support in recurrent cases. Complete obliteration should not receive endoluminal treatment . Refractory stenosis may require Y-V or T-plasty . Counsel about new or worse incontinence after endoluminal treatment and new incontinence after reconstruction .[27]
  • Lymphatic drainage informs cancer workup. EAU guidance groups the bulbar urethra with anterior drainage through inguinal and then pelvic nodes, while the membranous and prostatic urethra drain to pelvic nodes. Older anatomy literature groups bulbar tumors with proximal pelvic drainage. Assess both inguinal and pelvic basins when staging a bulbar tumor.[1][23]
  • Retrograde ejaculation. Semen flows into the bladder during climax, usually because the bladder neck fails to close. Distinguish retrograde flow from absent antegrade ejaculation when counseling about sexual function and fertility. Counsel about fertility before prostate or bladder-neck surgery. These operations can alter ejaculation, while orgasm may remain intact.[20]
  • Nerve-sparing in PFUI and rectourethral fistula repair. Cadaveric anatomy describes dorsal and lateral routes relevant to erectile function. Preserve identifiable nerves when feasible.
  • Lichen sclerosus and the distal urethra. LS may involve the glans, meatus and fossa navicularis and extend proximally. When LS-related penile urethral stricture requires augmentation, current guidance advises against affected genital skin and favors oral-mucosa graft strategies in suitable patients; the EAU guideline states "do not use genital skin in augmentation penile urethroplasty in males with lichen sclerosus" .[14]

Videos​

Male urethra — anatomy
Segmental and sphincteric anatomy overview

References​

1. Carroll PR, Dixon CM. "Surgical Anatomy of the Male and Female Urethra." Urol Clin North Am. 1992;19(2):339–346. doi:10.1016/s0094-0143(21)00397-9

2. Johnsen N, Wessells H, Archer-Arroyo K, et al. "Best Practices Guidelines — Management of Genitourinary Injuries." American College of Surgeons. 2025.

3. Cohen RJ, Garrett K, Golding JL, Thomas RB, McNeal JE. "Epithelial Differentiation of the Lower Urinary Tract With Recognition of the Minor Prostatic Glands." Hum Pathol. 2002;33(9):905–909. doi:10.1053/hupa.2002.127440

4. Holstein AF, Davidoff MS, Breucker H, Countouris N, Orlandini G. "Different Epithelia in the Distal Human Male Urethra." Cell Tissue Res. 1991;264(1):23–32. doi:10.1007/BF00305719

5. Watanabe H, Takahashi S, Ukimura O. "Urethra Actively Opens From the Very Beginning of Micturition: A New Concept of Urethral Function." Int J Urol. 2014;21(2):208–211. doi:10.1111/iju.12212

6. Röthlisberger R, Aurore V, Boemke S, et al. "The Anatomy of the Male Inferior Hypogastric Plexus: What Should We Know for Nerve Sparing Surgery." Clin Anat. 2018;31(6):788–796. doi:10.1002/ca.23079

7. Akita K, Sakamoto H, Sato T. "Origins and Courses of the Nervous Branches to the Male Urethral Sphincter." Surg Radiol Anat. 2003;25(5–6):387–392. doi:10.1007/s00276-003-0151-9

8. Koraitim MM. "The Male Urethral Sphincter Complex Revisited: An Anatomical Concept and Its Physiological Correlate." J Urol. 2008;179(5):1683–1689. doi:10.1016/j.juro.2008.01.010

9. Sergeant GP, Hollywood MA, Thornbury KD. "Spontaneous Activity in Urethral Smooth Muscle." Adv Exp Med Biol. 2019;1124:149–167. doi:10.1007/978-981-13-5895-1_6

10. Wecht JM, Krassioukov AV, Alexander M, et al. "International Standards to Document Autonomic Function Following SCI (ISAFSCI): Second Edition." Top Spinal Cord Inj Rehabil. 2021;27(2):23–49. doi:10.46292/sci2702-23

11. Juenemann KP, Lue TF, Schmidt RA, Tanagho EA. "Clinical Significance of Sacral and Pudendal Nerve Anatomy." J Urol. 1988;139(1):74–80. doi:10.1016/s0022-5347(17)42297-x

12. Yashiro K, Thor KB, Burgard EC. "Properties of Urethral Rhabdosphincter Motoneurons and Their Regulation by Noradrenaline." J Physiol. 2010;588(Pt 24):4951–4967. doi:10.1113/jphysiol.2010.197319

13. Danziger ZC, Grill WM. "Sensory Feedback From the Urethra Evokes State-Dependent Lower Urinary Tract Reflexes in Rat." J Physiol. 2017;595(16):5687–5698. doi:10.1113/JP274191

14. European Association of Urology. EAU Guidelines on Urethral Strictures: Disease Management in Males, §6.3.1.e. Current online edition accessed 2026-09-20.

15. Basta AM, Blackmore CC, Wessells H. Predicting urethral injury from pelvic fracture patterns in male patients with blunt trauma. J Urol. 2007;177:571–575. doi:10.1016/j.juro.2006.09.040

16. European Association of Urology. EAU Guidelines on Urological Trauma, §4.4.3 (posterior male urethral injury; limited update March 2026).

17. American Urological Association/Genitourinary Reconstructive Surgeons/Society of Urodynamics, Female Pelvic Medicine & Urogenital Reconstruction. "Incontinence After Prostate Treatment: AUA/GURS/SUFU Guideline." 2019; amended 2024. Statements 17, 20 and 21.

18. Da Silva EA, Sampaio FJ. "Urethral Extensibility Applied to Reconstructive Surgery." J Urol. 2002;167(5):2042–2045. doi:10.1097/00005392-200205000-00022

19. Humphrey PA. Male Urethra and External Genitalia Anatomy. In: Brandes SB, Morey AF, eds. Advanced Male Urethral and Genital Reconstructive Surgery. 2nd ed. Humana Press; 2014:17–23. doi:10.1007/978-1-4614-7708-2_2

20. Shindel AW, Althof SE, Carrier S, et al. Disorders of Ejaculation: An AUA/SMSNA Guideline. J Urol. 2022;207(3):504-512. doi:10.1097/JU.0000000000002392 (2020 guideline).

21. Chen H, Zhang CA, Gill HS. "Anatomical study of the prostatic urethra using vinyl polysiloxane casts." Prostate. 2020;80(3):241–246. doi:10.1002/pros.23937

22. Bugeja S, Andrich DE, Mundy AR. "Non-transecting bulbar urethroplasty." Transl Androl Urol. 2015;4(1):41–50. doi:10.3978/j.issn.2223-4683.2015.01.07

23. European Association of Urology. "EAU Guidelines on Primary Urethral Carcinoma: Diagnostic Evaluation and Staging." EAU Guidelines. 2026;§5.5–5.7. Guideline. ISBN 978-94-92671-32-5.

24. Abrams P, Blaivas JG, Stanton SL, Andersen JT. "The standardisation of terminology of lower urinary tract function." Neurourol Urodyn. 1988;7:403–426. International Continence Society full text. doi:10.1002/nau.1930070502

25. Negrean C, Alam A, Hickling D, et al. "Preoperative Magnetic Resonance Imaging Membranous Urethral Length as a Predictor of Urinary Continence After Radical Prostatectomy: A Systematic Review and Meta-analysis." Eur Urol Focus. 2025;11(4):648–661. doi:10.1016/j.euf.2025.02.002

26. Ippoliti S, Colalillo G, Egbury G, et al. "Continence-Sparing Techniques in Radical Prostatectomy: A Systematic Review of Randomized Controlled Trials." J Endourol. 2023;37(10):1088–1104. doi:10.1089/end.2023.0188

27. European Association of Urology. "EAU Guidelines on Urethral Strictures: Disease Management in Males," §6.3.5.a (posterior urethral stenosis). 2026. Guideline.

28. Wu Y, Dabhoiwala NF, Hagoort J, et al. "Architecture of structures in the urogenital triangle of young adult males; comparison with females." J Anat. 2018;233(4):447–459. doi:10.1111/joa.12864