Urinary Bladder

Q: What anatomical structures form the apices of the vesical trigone (trigonum vesicae)?

The apices of the vesical trigone (trigonum vesicae) are formed by the internal urethral orifice and the two ureteric orifices. Anterior apex — corresponds to the internal urethral orifice (ostium urethrae internum).Posterior apices (base of the trigone) — formed by the orifices of both ureters, which are connected by the interureteric fold (plica interureterica). The mucosa in this area is tightly fused to the muscle and lacks folds.

Q: What organs border the urinary bladder (syntopy) in males and females?

The syntopy of the urinary bladder differs by sex. SurfaceIn MalesIn FemalesAnteriorPubic symphysisPubic symphysisPosteriorRectal ampulla, ampullae of ductus deferens, seminal vesicles, and terminal parts of uretersUterus; in the subperitoneal space, the vaginaInferiorInitial part of the urethra and prostate glandUrogenital diaphragmSuperiorLoops of small, sigmoid, and cecal intestineIntestinal loops rest against the apexLateral—Levator ani muscle Anterior surface is separated from the pubic symphysis by the retropubic space.

Vesica urinaria

For medical students2 min readUpdated 2026-10-10

The urinary bladder (vesica urinaria) is an unpaired hollow muscular organ that serves as a urine reservoir in the human body. From the perspective of topographical anatomy, it is located strictly within the lesser pelvis, which serves as a critical landmark when studying adjacent structures.

LocationLesser pelvis (neither the peritoneal cavity nor the retroperitoneal space)

Main MuscleDetrusor muscle (m. detrusor vesicae), responsible for expelling urine

Special RegionVesical trigone, where the mucosa lacks folds

Blood SupplySupplied by branches of the internal iliac artery

Topography and Main Parts

When studying the vesica urinaria, the first thing to memorize is its localization. Anatomy test questions often try to confuse students by offering options such as the peritoneal cavity, retroperitoneal space, or greater pelvis. Remember once and for all: the organ lies in the lesser pelvis.

Anatomically, the organ is typically divided into four distinct parts. Each has its own Latin name, which must be memorized thoroughly for exams:

Apex — apex vesicae. The anterosuperior narrowed part of the organ.
Body — corpus vesicae. The largest, middle part that forms the main volume.
Fundus — fundus vesicae. The expanded posteroinferior part of the organ.
Neck — cervix vesicae. The narrowed inferior part that directly transitions into the urethra.

Note that the fundus (fundus) is anatomically directed posteriorly and inferiorly, which often causes confusion when examining specimens.

Wall Structure

The wall of this hollow organ has a classic layered structure, yet possesses several unique features. The layers from inside out are as follows:

Mucosa (tunica mucosa). In most regions, it forms prominent folds when the organ is empty.
Submucosa (tela submucosa). Ensures the mobility of the mucosa and the formation of folds.
Muscular layer (tunica muscularis). A powerful layer specifically named the detrusor muscle (m. detrusor vesicae). Contraction of this muscle executes the primary function of the organ.
Outer coat. Depending on the degree of filling and the specific wall segment, it is represented either by a serous coat (peritoneum) or an adventitial coat (connective tissue).

An important element of the muscular apparatus is the internal urethral sphincter (m. sphincter urethrae internus). This structure is located directly in the region of the neck (cervix vesicae) and plays a critical role in continence.

Vesical Trigone

When studying the internal relief of the organ on macro-specimens, attention is always drawn to a special area located on the fundus (fundus vesicae). This area is called the vesical trigone (trigonum vesicae).

Its main distinguishing feature is that the mucosa in this region is completely smooth and devoid of folds. This is because the submucosa is entirely absent in the trigone area, causing the mucosa to be tightly fused with the underlying muscular layer.

Blood Supply and Innervation

Understanding the neurovascular supply of the organ is essential for clinical practice. Arterial blood supply is derived from the iliac vessels, specifically via branches of the internal iliac artery (a. iliaca interna).

Neural regulation governing the complex work of the muscular coat (detrusor) and sphincter is provided by branches originating from the specialized vesical plexus (plexus vesicalis).

Mnemonic

To remember the wall layers from inside to outside, use the sequence: Mucosa, Submucosa, Muscular, Serous/adventitial.

Frequently asked questions

Which specific arteries supply blood to the urinary bladder?

The blood supply to the urinary bladder is provided by branches of the internal iliac artery (a. iliaca interna). The primary source specified in materials is:

Inferior vesical artery (a. vesicalis inferior) — supplies the bladder fundus and ureters.

Other specific arteries nourishing the body and apex of the organ are not detailed in these sources.

What anatomical structures form the apices of the vesical trigone (trigonum vesicae)?

The apices of the vesical trigone (trigonum vesicae) are formed by the internal urethral orifice and the two ureteric orifices.

Anterior apex — corresponds to the internal urethral orifice (ostium urethrae internum).
Posterior apices (base of the trigone) — formed by the orifices of both ureters, which are connected by the interureteric fold (plica interureterica).

The mucosa in this area is tightly fused to the muscle and lacks folds.

How does the relationship of the urinary bladder to the peritoneum change depending on its degree of filling?

The relationship of the urinary bladder to the peritoneum depends on its filling state. When full, the urinary bladder assumes a mesoperitoneal position and is covered by peritoneum on three sides. Sources also indicate that the superior surface of the urinary bladder is covered by peritoneum.

What are the sources of sympathetic and parasympathetic innervation of the urinary bladder?

Innervation of the urinary bladder is provided by the sympathetic and parasympathetic divisions of the autonomic nervous system.

Sympathetic innervation — preganglionic neurons lie in spinal cord segments L1–L2. Postganglionic fibers originate from the celiac, renal, inferior mesenteric, and hypogastric plexuses.
Parasympathetic innervation — centers are located in sacral segments S2–S4 (or S3–S5). Impulses travel via pelvic splanchnic nerves (nn. splanchnici pelvini), synapsing in the hypogastric (vesical) plexus.

Branches of the vesical plexus (plexus vesicalis) form intramural networks within the organ wall.

What organs border the urinary bladder (syntopy) in males and females?

The syntopy of the urinary bladder differs by sex.

Surface	In Males	In Females
Anterior	Pubic symphysis	Pubic symphysis
Posterior	Rectal ampulla, ampullae of ductus deferens, seminal vesicles, and terminal parts of ureters	Uterus; in the subperitoneal space, the vagina
Inferior	Initial part of the urethra and prostate gland	Urogenital diaphragm
Superior	Loops of small, sigmoid, and cecal intestine	Intestinal loops rest against the apex
Lateral	—	Levator ani muscle

Anterior surface is separated from the pubic symphysis by the retropubic space.

To which lymph nodes does lymph drainage from the urinary bladder occur?

Lymphatic vessels of the urinary bladder originating from the muscle layer and fascia drain to:

Sacral lymph nodes;
External iliac lymph nodes;
Internal iliac lymph nodes.

Lymphatic vessels of the urinary bladder anastomose with vessels of the prostate, seminal glands, and urethra. Direct connections of bladder vessels with uterine and vaginal vessels at the base of the broad ligament of the uterus are also noted.

In which body cavity is the urinary bladder located?

The organ is located exclusively within the lesser pelvis.

Where is the vesical trigone (trigonum vesicae) located and what is its special feature?

It is located on the fundus of the bladder (fundus vesicae). Its main feature is that the mucosa in this zone is completely devoid of folds.

What is the main muscle of the urinary bladder called?

It is called the detrusor, or m. detrusor vesicae, which forms the muscular coat of the organ.

Where is the internal urethral sphincter located?

The internal sphincter (m. sphincter urethrae internus) is located in the region of the bladder neck (cervix vesicae).

Go deeper

Detailed structure of the muscular coat (detrusor) and the orientation of muscle fibers.
Topographic relations of the serous coat (peritoneum) to the urinary bladder during filling and emptying.
Formation and branches of the vesical plexus (plexus vesicalis).
Anatomical boundaries and angles of the vesical trigone (trigonum vesicae).