Anatomy of the Bladder
References: (Benninghoff, 1993).
Gross Anatomy of the Bladder
Surface Anatomy of the Bladder
The bladder has a volume capacity of 400–500 ml and is of ovoid shape. The bladder can be divided in the corpus with two lateral walls, dorsal wall and ventral wall. At the apex, the dorsal and ventral wall meets and the urachus starts and runs to the umbilicus. The bladder neck surrounds the bladder trigone (see below).
Adjacent organs of the urinary bladder
The bladder lies preperitoneally behind the symphysis, the peritoneum covers parts of the ventral and dorsal wall. The space anterior to the bladder and behind the abdominal wall is called retropubic space (space of retzius). The space enables varius filling conditions of the urinary bladder. The bladder is adjacent to the small intestine and sigmoid colon (dorsal, towards the abdomen). The iliac vessels are lateral to the bladder. The bladder neck in men contacts prostate [fig. anatomy of the male pelvis]. In women, the bladder trigone and bladder neck are kranial to the vagina, the uterus is located posterior to the bladder [fig. anatomy of the female pelvis].
fig. Anatomy of the male pelvis, median sagittal section. Figure modified from Gray's Anatomy, Lea and Febinger 1918, Philadelphia, USA.
|fig. Anatomy of the female pelvis, median sagittal section. Figure modified from Gray's Anatomy, Lea and Febinger 1918, Philadelphia, USA.
Peritoneum and anatomy of the inner surface of the abdominal wall
The peritoneum covers the rectum and the dorsal wall of the bladder, forming a peritoneal pouch in the pelvis: rectovesical pouch in men (exacavatio rectovesicalis), and recto-uterine pouch in women (excavatio vesico-uterina). The urinary bladder and adjacent structures determine the inner surface of the lower abdominal wall [fig. anatomy of the inner surface of the abdominal wall]:
||fig. Anatomy of the inner surface of the abdominal wall: Figure modified from Gray's Anatomy, Lea and Febinger 1918, Philadelphia, USA.
Interior of the Bladder
The interior of the bladder are the trigone of the bladder (trigonum vesicae), side walls of the bladder, rear and front wall [fig. interior of the bladder].
fig. Internal anatomy of the urinary bladder: frontal section of the bladder and a view of the front wall, the bladder trigone and posterior wall of the bladder. Figure modified from Gray's Anatomy, Lea and Febinger 1918 Philadelphia, USA.
Trigone of the bladder
The internal urethral orifice (Ostium urethrae internum) and both orifices of the ureters (ostium ureteris right and left) limit the trigone of the bladder. The plica interureterica is a mucosa fold between the orifices of the ureters and helps to identify the orifices during transurethral ureteral catheterisation. The wall of the bladder trigone consists of three layers:
Ureter and the superficial bladder trigone:
the ureter enters obliquely through the bladder wall. The inner smooth muscle layer of the ureter forms with the inner smooth muscle layer of the contralateral ureter the superficial trigone. The superficial trigone extends into the prostatic urethra to the seminal colliculus in men and to the external urethral orifice in women. Thus, the superficial bladder trigone a tubular structure above the orifices of the ureter, and a flat structure below the orifices.
Waldeyer Sheath and the deep trigone bladder:
a separate external smooth muscle layer (Waldeyer's Sheat) accompanies the distal ureter to the bladder. After passing through the bladder wall the Waldeyer's Sheath forms with fibers of the detrusor muscle the deep trigone of the bladder. Like above, these muscle fibers range from two orifices of the ureter to the bladder neck.
Detrusor muscle of the bladder:
the inner longitudinal layer extends into the urethra in women until the ostium urethrae externum, and in male until the caudal end of the prostate. The middle circularly arranged layer and the outer longitudinal layer extend to the bladder neck. In women, they surround the urethra and support the external urinary sphincter. The detrusor muscle is innervated by parasympathetic nerve fibers (S2–4).
the contraction of the trigone pulls the orifices of the ureters caudal to the bladder neck. This results in a strong increase of the uretero-vesical resistance. The dysfunction of the trigone (transection, lumbar sympathectomy) may lead to vesicoureteral reflux. Second, the contraction of the trigone reduces the resistance of the bladder neck, thus facilitating the urination. Third, the rise of vesical pressure during bladder filling and voiding also compresses the ureters due to the oblique passage through the bladder wall and serves as an important element for the valve function.
Sphincter of the Urinary Bladder
The sphincter of the urinary bladder consists of smooth muscle (internal sphincter muscle) and striated muscle (external sphincter muscle).
Internal sphincter muscle:
The smooth muscle of the bladder trigone surrounds longitudinally as well as circularly the bladder neck (see above).
External sphincter muscle:
the striated external sphincter muscle has a horseshoe-shaped aspect. In women, he surrounds the middle and proximal urethra. In men, the muscle surrounds the entire length of the membranous urethra. In both cases, the striated sphincter has a close contact with the pelvic floor, however, can be distinguish clearly from the pelvic floor muscles.
Anatomy of the female urethra
Please refer to Section: Anatomy of the female urethra.
Vascular supply of the Bladder
Branches of the internal iliac artery: A. iliolumbalis (1), A. sacralis mediana (2), A. rectalis media of the contralateral side (3), A. iliaca externa (4), A. epigastrica inferior (5), A. obturatoria (6), A. vesicalis superior (7), A. vesicalis inferior (8), A. rectalis media (9), A. pudenda interna (10), A. glutealis inferior (11), A. glutealis superior (12), A. umbilicalis und Lig. umbilicale (13). Fig. from Gray’s Anatomy, Lea and Febinger 1918, Philadelphia, USA.
Arteries of the bladder
Superior vesical artery:
from the non-obliterated portion of umbilical artery
Inferior vesical artery:
directly from the internal iliac artery.
from uterine artery in women, obturator artery, internal pudendal artery.
Veins of the bladder:
the blood from the bladder drain into the vesical venous plexus. The internal iliac vein receives the blood of the vesical venous plexus.
Innervation of the bladder
Somatic nervous system:
The pudendal nerve from the sacral plexus controls the striated external sphincter muscle. Afferent nerve fibers of the pudendal nerve measure the urinary bladder filling (via the stretch of the urothelium) and the contraction of the detrusor muscle (via the wall tension).
Autonomic nervous system:
Parasympathetic preganglionic neurons are located in the sacral cord (S2 to S4) and run via the ventral roots to the parasympathetic ganglia next to the pelvic organs. In the case of the bladder, the ganglions are located in the detrusor muscle and in the vescical venous plexus.
The preganglionic sympathetic nerve fibers come from the thoracolumbal cord (TH1 to L2) and are switched to postganglionic fibers in the ganglia of the sympathetic trunk. The postganglionic fibers run via the hypogastric nerve into the pelvis.
The innervation of the detrusor muscle is mainly parasympathetic. While the sympathetic innervation of the detrusor muscle is of secondary importance, the bladder neck is innervated by the sympathicus to close the bladder neck during ejaculation. The parasympathetic, the sympathetic and the somatic nervous system have afferent nerve fibers, which pass through the dorsal root to the spinal cord.
Index: 1–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Benninghoff 1993 BENNINGHOFF, A.:
- Makroskopische Anatomie, Embryologie und Histologie des
München; Wien; Baltimore : Urban und Schwarzenberg, 1993