The structures of the urinary system as it relates to the pelvis are the ureters, the bladder, and the urethra. The goal of this chapter is to describe the location, basic function, vascular supply, nerve supply, and support of these structures within the pelvis.
Anatomy of the Pelvic Urinary System Ureter The ureters are paired, thick muscular tubes with a lumen of approximately 3 mm in diameter and are 24 to 30 cm in length. They originate at the renal pelvis and function to propel urine from the kidney to the bladder. In approximately 1% of the population, the ureter is duplicated. Duplications of the ureter are characterized as partial or complete. In partial duplications, the second ureter joins the ﬁrst before reaching the bladder. In complete duplications, both ureters travel side by side to the bladder. In the abdomen, the ureters lie on the medial surface of the psoas major muscle, within the retroperitoneum. The right ureter lies underneath the terminal ileum, cecum, appendix, and ascending colon, and their mesenteries. The ovarian vessels cross the right ureter at its midsection. The left ureter is adherent to the underside of the mesentery of the descending and sigmoid mesocolon, and is crossed by the inferior mesenteric and ovarian vessels. The inferior mesenteric artery is near and looks similar to the left ureter; therefore, care must be taken to distinguish these structures during dissection within this area. The ureters pass into the pelvis near the bifurcation of the common iliac vessels. As they descend into the pelvis, at the level of the ischial spine, they are in close proximity to the suspensory ligament of the ovary and form the posterior limit of the ovarian fossa. This relationship is important to recognize because injury to the ureter can occur during ligation of the infundibulopelvic ligament during oophorectomy. Both ureters travel parallel and medial to the obturator fossa and the internal iliac vessels. In this region of the pelvis, they are lateral to
the sacrospinous ligament and pass through the parametrium of the broad ligament to a location approximately 1.5 cm lateral to the cervix. As the ureters descend to the bladder within the broad ligament, the uterine artery crosses anteriorly (Figure 4-1.1). Within centimeters below the crossing of the ureter by the uterine artery, the inferior vesicular artery can cross the ureter anteriorly or posteriorly. The vaginal artery is posterior and medial to the ureter at this location. Here numerous arteries and veins surround both ureters and this is another common site of ureteral injury during hysterectomy. At the level of the cervix, the ureters traverse the cardinal ligament on its way to the bladder base. They travel medially on the anterior surface of the vagina for 1 to 3 cm before reaching the bladder. The ureters perforate the bladder 5 to 6 cm apart and run obliquely through the detrusor wall for 1.5 cm. The internal ureteral oriﬁces are much closer to each other than to their external penetrations of the bladder wall. As the ureters enter the bladder, they form the trigone, which is a triangular region of the bladder base (Figure 4-1.2). The trigone is made up of a superﬁcial and deep layer that is separate from the detrusor muscle. The superﬁcial layer of the trigone is an extension of the inner muscular layer of the ureter. The ﬁbers from each ureter meet to form a triangular sheet of muscle that extends from the two ureteral oriﬁces and continues distally into the posterior aspect to the proximal urethra. The superior portion of the ureteral muscle of the trigone forms the interureteric ridge. The lateral portions of this muscle are the ureteral bars. Waldeyer’s sheath is a ﬁbromuscular sheet of tissue that originates 2 cm above the bladder and is wrapped around the ureter. This sheath extends longitudinally to the bladder neck and forms the deep portion of the trigone. The trigone sits on the muscles of the detrusor wall and anchors the ureters to the bladder. The distal intravesical portion of the ureter is submucosal and is supported by the detrusor muscle backing. As the bladder ﬁlls, urine compresses the ureter against the muscle backing, creating a ﬂap valve, which prevents reﬂux of urine from the bladder into the ureter. 71
The arterial supply of the ureter arises from branches of various vessels as it descends into the pelvis. The abdominal sources of arterial blood supply to the ureter are the renal artery (30%), the aorta (15.4%), and the gonadal arteries (7.7%). The most signiﬁcant sources of blood to the pelvic ureter are the superior vesicular arteries (12.8%), the inferior vesicular arteries (12.9%), and the internal iliac arteries (8.5%).1 The ureteral veins drain at either end of the ureter and along its length. In the abdominal portion of the ureter, the main veins drain into the renal and gonadal vessels. Additional drainage occurs along other veins in the proximity of the ureter. The pelvic portion of the ureter drains into the plexus of veins within the broad ligament and other adjacent veins. The nervous innervation of the abdominal ureters arises from the renal and aortic plexus. The pelvic ureter receives its nerve supply from the inferior hypogastric and pelvic plexus. These nerves contain cholinergic and adrenergic ﬁbers that regulate ureteral peristalsis. Ureteral peristalsis is not activated by the nervous system, but is thought to modulate its actions.4 Afferent ﬁbers in the lamina propria relay messages of stretch, osmolarity, and pH to the brain. There are few pain receptors in the ureter itself. Most of the pain that we perceive from ureteral obstruction is secondary to distention of the renal capsule, rather than stimula-
Inter ureteric ridge Ureteral bar Deep trigone
Superficial trigone Urethra
Figure 4-1.2. The trigone is a triangular region of the bladder base. It comprises a superﬁcial and deep layer,which is derived from the ureteral musculature and Waldeyer’s sheath, respectively. (Reprinted with the permission of The Cleveland Clinic Foundation.)
Common iliac artery
tion from the ureter. The pain perceived by ureteral and renal capsular distention is likely relayed through the parasympathetic nervous system and can be referred to various sites that share the nerve roots of T11-L2, such as the genitalia, groin, and upper thigh. These are common sites of referred pain during ureteral obstruction.
Figure 4-1.1. As the ureter descends to the bladder within the broad ligament, the uterine artery crosses it anteriorly and the vaginal artery passes underneath it.The inferior vesicular artery can cross the ureter anteriorly or posteriorly. (Reprinted with the permission of The Cleveland Clinic Foundation.)
Bladder The urinary bladder is a hollow muscular organ, which serves as a reservoir for the storage and voluntary expulsion of urine. When ﬁlled to capacity, the bladder is spherical and holds approximately 500 mL of ﬂuid; however, this capacity can vary based on one’s size, sex, or age. The bladder lies in the anterior half of the pelvis and it is bounded anteriorly by the symphysis pubis, laterally by the pelvic sidewalls, and posteriorly by the vagina, cervix, and uterus. The urachus terminates in the umbilicus and anchors the apex of the bladder to the anterior abdominal wall via the median umbilical ligament. Fascia intimately surrounds the bladder surface. The peritoneal lining and cavity cover the superior surface. The transversalis fascia covers the anterolateral surface and the posterior surface is covered by endopelvic fascia. As described by DeLancey,3 the bladder, uterus, vagina, and rectum are attached to the lateral pelvic walls by a
Urologic Anatomic Correlates
network of connective tissue, which is collectively called the endopelvic fascia. This fascia is a continuous unit that is divided into sections that have named parts. The fascia, which attaches the uterus to the lateral pelvis is called the parametria and consists of the broad, cardinal, and uterosacral ligaments. The fasciae that attach the vagina to the pelvis are collectively called the paracolpium. These fasciae contain smooth muscle, blood vessels, lymphatics, and nerves. The paracolpium, cardinal, and uterosacral ligaments are displayed in Figure 4-1.3. The endopelvic fascial support of the vagina is divided into three levels: I, II, and III [Figure 4-1.4; please see Figure 4-2.7, Chapter 4-2 (Genital Anatomic Correlates)]. The most cephalic 3 cm of the vagina is suspended by endopelvic fascia, which extends from the vagina posteriorly and superiorly over the piriformis muscle to the lateral portion of the sacrum. This constitutes level I support, and alteration of this fascia will result in vaginal apex and uterine prolapse. The mid portion of the anterior vagina is attached laterally to the arcus tendineus fasciae of the pelvic sidewall. This layer lies below the bladder body, and contributes support to the bladder and vagina within the pelvis. This portion of the endopelvic fascia is known as the pubocervical fascia. Tears or disruption of the pubocervical fascia via various mechanisms will result in a cystocele. An injury to the central portion of this fascia results in a central cystocele defect. An injury to this fascia between the vagina and the
Rectum Sacrum Uterosacral ligament
Cervix Cardinal ligament Bladder
Tendineus arch Pubocervical fascia
Figure 4-1.3. The bladder, uterus, vagina, and rectum are attached to the lateral pelvic walls by a network of connective tissue, which is collectively called the endopelvic fascia. This fascia is a continuous unit that is divided into sections that have named parts. (Reprinted with the permission of The Cleveland Clinic Foundation.)
tendineus arc will result in a paravaginal cystocele defect. The posterior wall of the vagina is attached to the superior fascia of the levator ani muscles and forms the rectovaginal fascia. Injury to this portion of the endopelvic fascia will result in a rectocele. The anterior and posterior endopelvic fascia of the mid vaginal wall constitutes level II support. The region of the vagina that extends 2 to 3 cm above the hymenal ring is fused to the urethra, medial surface of the levator ani muscles, and the perineal body. At this level, there is no intervening connective tissue of the endopelvic fascia that separates the vagina from the urethra. This portion of the vagina and endopelvic fascia constitutes level III support. The levator muscles provide additional support to pelvic organs by closing the vagina and forming a shelf, which supports these organs. Strain on the pelvic organ fascial supports through gravity and Valsalva, are limited by the levator ani muscle. Alteration to the integrity or function of the pelvic ﬂoor muscle and fascial supports results in pelvic organ prolapse. On a microscopic basis, the bladder wall comprises an inner transitional cell lining, a middle muscular layer, and an outer adventitial layer. The inner transitional cell lining is covered by a glycosaminoglycan layer, which is thought to be a protective barrier from urinary irritants. The transitional cell epithelium comprises six layers of cells that rest on a basement membrane. Deep to the basement membrane is a thick ﬁbroelastic connective tissue called the lamina propria. The lamina propria contains many blood vessels and loosely arranged smooth muscle ﬁbers. The middle muscular layer consists of three large interlacing bundles of smooth muscle: an inner longitudinal, middle circular, and an outer longitudinal muscular layer. The outer adventitial layer consists of fat and connective tissue. The gross evaluation of the bladder interior is done by cystoscopy, which is a common clinical tool for evaluation of intravesical pathology. On placement of the cystoscope into the urethra, the urethral mucosa is compressed and the urethra is closed. The cystoscope can be easily placed through the closed urethra. The trigone, which has been previously described, is the ﬁrst structure seen on placement of the cystoscope into the bladder. The trigone is triangular in shape as a result of the internal urethral opening being equidistant to the ureteral oriﬁces, forming an equilateral triangle. It is common to observe a ﬂuffy white coating on the trigone surface of women, which is known as squamous metaplasia. The ureteral oriﬁces lie approximately 3 cm apart and usually appear as small slits; however, there can be many variations to their appearance. The ureteral bars and the interureteric ridge are often used to locate the ureteral oriﬁces; therefore, knowing the relationship of these structures is critical. The mucosa of the bladder is wrinkled or folded when the bladder is empty, and smooth when the bladder is full. This occurs because the mucosa is loosely bound to the underlying musculature on most of the detrusor surface, except for the trigone, which always appears smooth. On the surface of the bladder mucosa are numerous superﬁcial blood vessels. An
Figure 4-1.4. The three levels of pelvic support of the vagina and uterus showing the continuity of supportive structure throughout the entire length of the genital tract. (Reprinted with the permission of The Cleveland Clinic Foundation.)
air bubble is often introduced during cystoscopy and can be seen in the dome of the bladder. This bubble is used to identify the dome and allows for orientation during cystoscopy. The impression of the uterus on the anterior surface of the bladder can be appreciated in its partially ﬁlled state. The arterial supply of the bladder arises from the superior and inferior vesical arteries, which are branches of the internal iliac vessels. The superior vesicular artery is usually a single artery, but may have 2 to 3 branches that supply the dome and posterior portions of the bladder. The venous drainage of the bladder originates from the dorsal vein of the clitoris as it bifurcates to empty into the laterally placed vaginal plexuses. This plexus of veins connects with the ovarian, uterine, and rectal plexuses to drain into the internal iliac veins.
Urethra The urethra is a ﬁbromuscular conduit, which serves to allow evacuation of urine from the bladder and provides urinary continence. The female urethra is 3 to 4 cm in length and is approximately 5 mm in diameter. The external oriﬁce lies above the vaginal introitus and 2.5 cm below the glands clitoris. In the pelvis, the urethra lies anterior to the vagina and beneath the pubic bone. Transitional cells line the proximal two-thirds of the urethra. These cells change to a nonkeratinized stratiﬁed squamous epithelium in the distal one-third of the urethra. Urethral glands are distributed throughout its length and empty into the lumen. Obstruction and infection of these glands are thought to give rise to urethral diverticula. A group of these glands, known as Skene’s glands, coalesce distally and
Figure 4-1.5. A transverse section through the mid portion of the female urethra.The female urethra is composed of an infolding epithelium, a ﬁbromuscular envelope of spongy tissue,a middle smooth muscle,and an outer skeletal muscle layer. (Reprinted with the permission of The Cleveland Clinic Foundation.)
empty through two small ducts on either side of the external urethral meatus. Histologically, the female urethra is composed of an infolding epithelium, a ﬁbromuscular envelope of spongy tissue, a middle smooth muscle, and an outer skeletal muscle layer (Figure 4-1.5). The urethral mucosa is thrown into folds, allowing for a mucosal to mucosal coaptation. This forms a seal similar to a washer on a sink and is one of several mechanisms of continence. Under the mucosa is the lamina propria, which contains a rich vascular spongy tissue. This layer, when congested, constricts the mucosal lining enhancing mucosal coaptation. The smooth muscle of the urethra consists of longitudinal ﬁbers, which emanate from the internal longitudinal ﬁbers of the bladder. The outer semicircular smooth muscle ﬁbers arise from the outer longitudinal layer of the bladder. Both sets of smooth muscle start at the bladder neck and extend to the distal urethra, where they end in a ﬁbrous ring. The outer semicircular smooth muscle is more prominent in the mid urethra, where the smooth muscle ﬁbers mix with the striated ﬁbers of the external urethral sphincter. Both smooth muscle layers become sparse in the distal urethra. Constriction of these muscles extenuates the mucosal to mucosal coaptation. Collagen forms a major component, and elastin a minor component of the urethral smooth muscle layers. Collagen is thought to be a contributor to passive closure of the urethra, whereas elastic ﬁbers are thought to prevent overdistention of the urethra. DeLancey4 has described the relationship of the paraurethral structures in the female. The location of these
structures were described as a percentile of total urethral length, with the zero percentile deﬁned as the internal urethral meatus and the 100th percentile as the external urethral meatus. The rationale for this scheme is that urethral length can vary, and there is no exact and reproducible length where these structures exist along the urethra from person to person. Instead, the periurethral muscles tend to lie in regions of the urethra as a percentile of its total length. The internal urethral meatus is the zero percentile. At the level of the bladder neck, the urethra passes through the wall of the bladder. The end of the bladder wall constitutes the 15th percentile of the urethra. At this level, the striated urethral sphincter muscle surrounds the urethra and extends from the 18th to the 64th percentile. At the 54th percentile, the urogenital diaphragm, the compressor urethrae and the urethrovaginal sphincter are encountered and extend to the 76th percentile (Figure 4-1.6). These periurethral muscles are continuous with the striated sphincter. The urethral compressor originates from the ischial tuberosity and extends over the urethra to the opposite tuberosity. The transverse vaginal muscle is a thin sheet, which is characterized as part of the compressor that lies below the urethra, ﬁlling the space between the urethra and the urethrovaginal sphincter. The urethrovaginal sphincter is ﬂat and merges on the ventral side of the urethra with the urethral compressor, and extends along the sides of the urethra and vagina to enclose them in a circular manner. The pubococcygeus muscle is the most medial portion of the levator musculature and runs from the pubis to the coccyx. It is positioned on the lateral sidewall of the vagina and urethra. When this muscle contracts, it provides some urethral compression; however, it is not considered a true sphincter muscle. The point of maximal urethral pressure at rest in the supine position correlates to this area of muscle described. The maximum
Figure 4-1.6. Periurethral muscles. (Reprinted with the permission of The Cleveland Clinic Foundation.)
voluntary increase in urethral pressure also correlates to this area. From the 79th to the 100th percentile of the urethra, the bulbocavernosus and ischiocavernosus muscles lie adjacent to, but do not connect to, the urethra. These muscles do not contribute to continence. The remaining urethra is composed of ﬁbrous tissue and does not have a signiﬁcant muscular component. This tissue is derived from the subcutaneous tissue and suspensory ligament of the clitoris. Between the 20th and 60th percentile of the urethra, the pubourethral ligament and the vaginolevator run anteriorly from the urethra and vaginal wall, respectively, to attach to the pelvic wall. The pubourethral ligament connects the urethra to the pubis and the vaginolevator connects the vagina to the pubococcygeus portion of the levator ani muscle. Fibrous tissue and muscle make up these structures. It has been implied that the support and compression of the urethra on a hammock of vaginal tissue causes compression of the urethra with Valsalva. This is thought to be one of many contributors to continence. The urethral arterial blood supply arises from the inferior vesical arteries at the bladder neck, as well as the vaginal branches of the internal iliac vessels. The urethra’s venous drainage originates from the inferior, middle, and superior vesicular veins, as well as the clitoral plexus.
The Lower Urinary Tract The lower urinary tract (LUT) is a group of interrelated structures that are responsible for the storage and expulsion of urine. The components of the LUT consist of the bladder and the outlet. The outlet is deﬁned as the urethra and urethral sphincters.
Lower Urinary Tract Function As described by Wein,5 the LUT has two phases of function, the ﬁlling/storage phase, and the emptying phase. In the ﬁlling/storage phase, the bladder is able to accommodate increasing volumes of urine at low intravesical pressures with appropriate sensation. This occurs in the absence of involuntary bladder contractions. The bladder outlet is closed and remains closed throughout this process. In the emptying phase, there is a lowering of resistance at the level of the smooth and striated sphincters. The bladder smooth muscle then contracts with an adequate magnitude, in the absence of anatomic obstruction, to evacuate urine. The bladder and outlet have reciprocal actions under normal circumstances, which are regulated by the nervous system. When the bladder is contracting, the outlet is relaxed, and when the bladder is relaxed, the outlet is contracting. This scheme describes the general process of urinary storage and micturition. Any alteration in the function of the LUT will affect one of these basic actions.
Nervous System Innervation of the Lower Urinary Tract Three sets of peripheral nerves have a signiﬁcant role in LUT function. These nerves include the sacral parasympathetics, the thoracolumbar sympathetics, and the sacral somatic nerves.
Autonomic Innervation The parasympathetic nervous system’s general role in LUT function is to facilitate emptying. The parasympathetic efferent ﬁbers originate in the intermediolateral region of the gray matter within the sacral cord (S2-4) and emerge as preganglionic ﬁbers from the ventral root. The pelvic nerve conveys these ﬁbers to the LUT. Acetylcholine is the primary neurotransmitter at the ganglia and the effector sites. The receptors of this system are muscarinic and nicotinic. There are ﬁve subtypes of known muscarinic receptors (M1–M5) and they are located on all autonomic effector cells. In the human bladder there is a predominance of M2 receptors. The M3 receptors are primarily responsible for bladder contractions. There are no known muscarinic receptors speciﬁc for the bladder. The muscarinic receptors are the targets of anticholinergics for the treatment of the overactive detrusor. The nicotinic receptors are located on autonomic ganglia and the motor end plates of skeletal muscle. Atropine competitively inhibits these muscarinic sites. High doses of nicotine inhibit nicotinic sites. The sympathetic nervous system’s general role in LUT function is to facilitate storage of urine. The efferent ﬁbers of this system originate in the intermediolateral region of the gray matter within the thoracolumbar spinal cord (T10L2). These nerves traverse the paravertebral ganglia and join the hypogastric plexus anterior to the aorta. This plexus divides into the right and left hypogastric nerves. These merge with the pelvic nerve to form a pelvic plexus or inferior hypogastric plexus. The primary neurotransmitters of the sympathetic nervous system are acetylcholine and norepinephrine. Acetylcholine is released at the ganglion and norepinephrine (adrenergic) at the effector sites. There are two primary types of receptors (alpha and beta) in the sympathetic nervous system and they are characterized on the basis of differential effects elicited by catecholamines. The alpha receptors are stimulated by norepinephrine and methoxamine, but not isoproterenol. When stimulated, alpha receptors elicit smooth muscle contraction. Two subtypes of alpha receptors exist, A1 and A2. These receptors are located throughout the bladder, but are predominantly in the bladder base and neck. Stimulation of alpha receptors increases outlet resistance (i.e. phenylpropanolamine). Alpha receptors are not as prominent in the female urethra and bladder neck as they are in the male. Beta receptors are stimulated the most by
Urologic Anatomic Correlates
isoproterenol, less by epinephrine, and least by norepinephrine. When stimulated, beta receptors elicit an inhibitory effect on detrusor muscle contraction. Two subtypes of beta receptors exist, B1 and B2. Beta 1 receptors are located in the cardiovascular system. The beta 2 receptors are located throughout the bladder, but to a greater extent are within the bladder body. Beta receptor stimulation in the LUT inhibits bladder contraction and causes receptive relaxation of the detrusor to allow for increasing bladder volumes, without increasing intravesical pressure (detrusor compliance).
Somatic Innervation The somatic nervous system originates in efferent ﬁbers of S2–S4, which form the pudendal nerve. The pudendal nerve in turn innervates the striated sphincter and the pelvic ﬂoor. The motor ganglia are located in the anterior horn of the spinal cord and the primary neurotransmitter is acetylcholine. The receptors of the somatic system are nicotinic and their activity is blocked by curare.
Sensory Innervation Sensory innervation of the bladder is via the pelvic and hypogastric nerves. Sensory input from the urethra is through the pudendal nerve. The tachykinins are the primary neurotransmitters and include substance P, and neurokinin A and B. These neurotransmitters relay their messages through A delta and C ﬁbers. A delta ﬁbers are ﬁnely myelinated, located in smooth muscle, and sense bladder fullness. The C ﬁbers are unmyelinated, located in the mucosa and muscle, and sense nociception and overdistention of the detrusor. Up-regulation of these ﬁbers is thought to be one of the possible etiologies of bladder pain. Other neurotransmitters of the nervous system that are thought to have a key role in LUT function are listed below. Detrusor contractions Prostaglandins Detrusor relaxation Adenosine 5¢-triphosphate Opioids Urethral relaxation Nitric oxide Opioids Urethral contraction Serotonin Epinephrine Supporters of micturition Gamma-aminobutyric acid (inhibitory) Enkephalins (inhibitory) Glutamate (facilitative) Dopamine (facilitative)
Nervous System Regulation of Lower Urinary Tract Function The LUT is a dynamic and complex system. It is not a system that stores urine in a passive manner. For example, the bladder has the ability to accept increasing volumes of urine without increasing intravesical pressure (accommodation). Another example of the LUT’s dynamic ability is the guarding reﬂex, which is an increase in urethral pressure with a cough or sneeze, a protective measure against incontinence. This complex relationship between the various components of the LUT is regulated by the central nervous system.
Storage Phase of Lower Urinary Tract Function During ﬁlling, the normal bladder has a minimal change in intravesical pressure until capacity is reached. At low volumes, the elastic and viscoelastic properties are primarily responsible for compliance. Elasticity allows the constituents of the bladder wall to stretch without a signiﬁcant increase in bladder wall tension. The viscoelasticity of the bladder causes stretch to induce an increase in tension, followed by a decay when ﬁlling stops. In the animal model, it has been shown that at a certain level of bladder distention, spinal sympathetic reﬂexes facilitory to bladder storage, are evoked. This allows smooth muscle relaxation of the bladder by beta receptor stimulation (accommodation). Spinal sympathetic reﬂexes inhibit parasympathetic activity at the level of the parasympathetic ganglia during ﬁlling. Clinically, detrusor compliance may be altered by any processes that can damage the elastic tissues (chronic cystitis, radiation, ischemia, etc.) or neurologic abnormalities, which affect smooth muscle modulation (peripheral nerve injury). During ﬁlling, the normal outlet displays an increase in urethral pressure. This is primarily the result of striated sphincter muscle activity and to a lesser extent smooth muscle sphincter activity. Pudendal motor neurons are activated by bladder afferent input, which activates striated sphincter muscle activity.
Voiding Phase of Lower Urinary Tract Function The cerebral cortex has facilitative and inhibitory centers of micturition, which relay signals via the pons to the bladder. The primary inﬂuence of the cortical system on the micturition reﬂex is inhibitory. Therefore, under normal circumstances, voiding is a reﬂex function under voluntary control. Sensory input from bladder wall distention is the primary stimulus for micturition. This stimulus is interpreted by the cerebral cortex, and in the appropriate social setting, there is a voluntary decrease in somatic
neural discharge to the striated sphincter. There is subsequently a decrease in spinal sympathetic reﬂex activity and an increase in the parasympathetic neural outﬂow from the sacral cord, via the pelvic nerve. This results in a bladder contraction and funneling of the outlet. The pons is responsible for coordination of the micturition reﬂex by orchestrating the interaction of the bladder and outlet. Uncoordinated voiding activity would occur if not inﬂuenced by the pons, which regulates the sacral reﬂex arc, via ascending and descending spinal pathways.
References 1. 2. 3. 4. 5.
McCormak LU, Anson BJ. The arterial supply of the ureter. Q Bull Northwest Univ Med School 1950;24:1. Shulman CC. Innervation of the ureter. Anat Cin 1981;3:127. DeLancey J. Anatomic aspects of vaginal eversion after hysterectomy. Am J Obstet Gynecol 1992;166:1717–1728. DeLancey J. Correlative study of paraurethral anatomy. Am J Obstet Gynecol 1986;68:91–97. Wein AJ. Neuromuscular dysfunction of the lower urinary tract and its treatment. In: Campbell MF, Walsh PC, Retik AB, eds. Campbell’s Urology. 7th ed. Philadelphia: WB Saunders; 1998:953–1006.
Urologic Anatomic Correlates
4-1 Urologic Anatomic Correlates Jonathan Jay
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