Bladder & urothelial tract
General
Anatomy
Author: Alcides Chaux, M.D.
Last author update: 1 June 2011
Last staff update: 8 September 2023
Copyright: 2003-2024, PathologyOutlines.com, Inc.
PubMed Search: Bladder [title] normal anatomy
Table of Contents
Definition / general | Embryology | Parts of bladder | Relationship to other structures | Blood supply | Lymphatic drainage | Nerve supply | Ureters | Diagrams / tables | Gross description | Microscopic (histologic) descriptionCite this page: Chaux A. Anatomy. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bladderanatomy.html. Accessed December 28th, 2024.
Definition / general
- Hollow organ that serves as a reservoir for urine
- Adult bladder can hold up to 400 - 500 ml of urine without a change in intraluminal pressure
- In addition, can initiate and sustain a contraction until empty
- Distended adult bladder may reach level of umbilicus
- ICD-O-3 coding
Embryology
- Bladder develops during first 12 weeks of gestation
- Bladder and trigone development are regulated by complex epithelial-mesenchymal signaling events (Curr Opin Urol 2009;19:427)
- Urorectal septum divides cloaca into dorsal rectum and ventral urogenital sinus
- Urogenital sinus is further divided into 3 parts: cranial vesical part (forms most of bladder, except trigone), middle pelvic part (forms urethra in bladder neck, prostatic urethra in males and entire urethra in female) and caudal phallic part (primordium of penis or clitoris)
- Trigone develops from dilation, fusion and incorporation of caudal mesonephric ducts into urogenital sinus, forming a triangular area that is site of future ureters
- Mesonephric ducts are gradually absorbed and replaced by endodermal epithelium of urogenital sinus
- Posterior walls, dome and part of lateral walls arise from mesenchyme surrounding urogenital sinus
- Anterior wall and part of lateral walls develop with closure of infraumbilical portion of abdominal wall
- Note: neither urachus or allantois are involved in formation of bladder
Parts of bladder
- Apex / dome: most anterosuperior point; is covered by peritoneum; site of insertion of median umbilical ligament (obliterated urachus) which anchors the bladder to the abdominal wall
- Base: posterior surface, is also covered by peritoneum
- Neck: most distal portion of bladder
- Trigone: area between ureteral and urethral orifices, continuous with bladder neck
Relationship to other structures
- Located in part within the abdomen in children, enters pelvis major at age 6, found entirely within pelvis minor ("true" or obstetric pelvis) after puberty
- Adult bladder rests on rectum and seminal vesicles (males) or cervix and vagina (females); thus, cystectomy for tumor may be combined with removal of prostate and seminal vesicles (males) or hysterectomy and partial vaginectomy (females)
- Ureters enter the bladder posteroinferiorly and obliquely, travel 1.5 - 2 cm through the bladder wall (intravesical portion) and open at the ureteral orifices
- Bladder neck is formed by interlacing and converging fiber of detrusor muscle forming 3 well defined layers; occasionally contains prostatic ducts (males)
- Anteroinferiorly and laterally, there is abundant fat and loose connective tissue (space of Retzius)
- Bladder is relatively free within pelvis (which permits its expansion as it distends) but neck is secured by puboprostatic ligaments (male) and pubovesical ligaments (female)
Blood supply
- Superior, middle and inferior vesical arteries, derived from the anterior trunk of the internal iliac artery
- In addition, minor branches are derived from obturator and inferior gluteal arteries and, in women, uterine and vaginal arteries
- Venous drainage by a rich vesical venous plexus, which empties into internal iliac veins
Lymphatic drainage
- Vesical, internal and external iliac nodes; bladder neck drains to sacral or common iliac nodes
Nerve supply
- Sympathetic from T11-L2 nerves, plays no role in micturition
- Parasympathetic from S2-4, travel to bladder via pelvic nerve and inferior hypogastric plexus, cause contraction of muscularis propria fibers, which puts traction on bladder neck, which opens internal sphincter; important in micturition
Ureters
- 30 cm long, 5 mm in diameter
- Areas of ureteral narrowing are at ureteropelvic junction, crossing of external / common iliac artery and where ureters enter bladder; these are common sites of obstruction and stone impaction
- Ureters enter bladder in oblique manner
- Bladder muscle contraction mechanically closes off ureteral orifice
- Defects cause reflux
Diagrams / tables
Images hosted on other servers:
Development of bladder
Position of bladder in female pelvis
Interior
Position of bladder in male pelvis
Gross description
- Hollow viscus resembling inverted pyramid when empty, sphere when distended
- Internal (mucosal) surface is flat when distended but show abundant folds in an empty bladder
Microscopic (histologic) description
- Allantois: rudimentary structure lined by endoderm that is connected to urachus
- Urachus: formed during descent of abdominal wall, connects umbilicus to apex (dome) of bladder, torn apart as embryo elongates but remnants persist in anterior abdominal wall and may persist in bladder wall (see patent urachus)
