1. The document discusses the neurologic control of the urinary system, including the pathways involved in storage and voiding of urine and the effects of lesions along these pathways. 2. It describes how lesions in different areas can result in conditions like urinary frequency, retention, or obstructed voiding and discusses the clinical presentations of different neurogenic bladder disorders. 3. The pathways discussed include the cerebral, cord, urethral, and detrusor reflex loops which coordinate the bladder and sphincter during the storage and voiding phases of micturition.

2.  Central nervous system disorders are
frequent causes of urologic symptoms and
voiding dysfunction
 Appropriate recognition and timely
management relevant to neurological
conditions are important to avoid potentially
irreversible adverse outcomes.

3. Physiologic functions:
 Low pressure storage of adequate volumes of
urine
 periodic, voluntary expulsion of urine from the
bladder in a coordinated manner.
 coordinated activity mediated by the autonomic
and somatic nervous systems
 Disruption of neurotransmission at any level of the
neuraxis may result in significant alterations in urinary
function.

4.  hollow organ
 3 layers
 Compliance-dependent on the native
viscoelastic properties of the bladder wall.
 Low bladder compliance results in high urinary
storage pressure, which if unrecognized and
untreated, leads to upper urinary tract
deterioration and renal failure

5.  S2-4 segments of the spinal cord
 provides excitatory motor input to
the bladder.
 Cholinergic preganglionic neurons
within the intermediolateral
sacral cord send axons to
ganglionic cells within the pelvic
plexus and the bladder wall.
 Postganglionic neurons within the
bladder wall and pelvic plexus
release acetylcholine, which
activates cholinergic receptors on
the detrusor smooth muscle cells
and initiates bladder contraction

6.  originate in theT11-L2 spinal
segments,
 travel in the sympathetic chain
ganglia to the prevertebral ganglia in
the superior hypogastric and pelvic
plexuses
 innervate the bladder via short
adrenergic neurons.
 The bladder contains varying
expression of α- and β-adrenergic
receptors, and sympathetic
stimulation promotes storage of
urine

7.  Activation of β-adrenergic receptors within
the wall of the bladder provides inhibition
and relaxation of the detrusor muscle..

8.  bladder outlet
 α-Adrenergic receptors
predominate
 excitatory input to- results in
increased bladder outlet
closure force.
 internal urethral sphincter or
smooth muscle sphincter, has
a role in the maintenance of
continence and efficient
voiding

9.  Afferent (sensory) transmission of lower urinary
tract stimuli travels via the pelvic, hypogastric,
and pudendal nerves to the dorsal root ganglia
of the lumbosacral spinal cord.
 The pelvic nerve afferents monitor the volume
and the amplitude of bladder contraction viaAδ
and C fibers
 C fibres are also implicated in the transmission
of urgency and pain.

10.  The most proximal segment of the urethra in
consists primarily of smooth muscle, which is not
under voluntary control.
 Innervation of the proximal urethra is similar to that
of the bladder neck.
 At the level of the pelvic floor there is a sheet of
striated muscle extrinsic to the urethra, as well a
discrete layer of striated muscle within the wall of
the urethra.

11.  The extrinsic muscle consists of primarily fast-twitch
muscle fibers and is under voluntary control.
 The intrinsic muscle tissue, also called the intrinsic
sphincter or the rhabdosphincter, consists primary of
slow-twitch fibers and provides passive urinary
continence.
 Innervation of external sphincter and pelvic floor
musculature is primarily somatic from branches of the
pudendal nerve S3 and S4 segments .

12.  The anteromedial portion of the frontal lobes and
cingulate gyrus are involved in the voluntary initiation of
micturition and inhibition of reflex voiding activity.
 In general, cortical input is inhibitory on micturition
reflexes.
 remove the cortical inhibition, which results in increased
excitatory input to the brainstem, facilitation of the
micturition reflex
 urinary frequency and urgency.

13.  reflex can be localized to the
pontomesencephalic reticular formation.
 The pontine micturition center (PMC) or
Barrington’s nucleus, functions as a switch to
regulate bladder capacity and coordinate
bladder and external sphincter activity.
 stimulation of the PMC induces the sacral
parasympathetic neurons to fire, which results
in bladder contraction and reflex voiding

14.  Descending spinal efferent pathways from the
PMC to the sacral cord motor centers are
located in the reticulospinal tracts.
 The pons receives direct ascending input from
the bladder wall afferents, which travel through
the dorsal root ganglia and the posterior
columns of the spinal cord.

15.  Parasympathetic preganglionic neurons.
 Sympathetic preganglionic neurons.
 Somatic centers innervating the external sphincter
and pelvic floor musculature are localized atOnuf’s
nucleus within the anterior horn of the sacral cord at
the spinal cord level S2-4.
 Descending input toOnuf’s nucleus is derived from
the lateral corticospinal tract

16.  Efferent somatic stimulation of the external
sphincter begins atS Onuf’s nucleus and
travels thro the pudendal nerves ,innervates
the sphincter and the pelvic floor.

17.  The central sensorimotor pathways concerned with
micturition and sphincter control can therefore be
summarized as follows
1. The cerebral loop -initiates and inhibits switching between
filling and voiding states
2.Corticospinal pathways - with the voluntary control of the
sphincters and pelvic floor.
3.The cord loop - coordinates detrusor and sphincter
contraction and relaxation.
3
.

18. 4.The urethral reflex loop –maintains the
sphincter tone when the detrusor is inactive.
5.The detrusor reflex loop -causes sphincter
relaxation when the detrusor is active.

20.  lesions above the level of the sacral bladder center and
below the level of the PMC.
 occurs in conditions causing quadriplegia or paraplegia
MS.
 Loss of the normal inhibition from higher centers results
in detrusor contraction
 urinary frequency, urgency
 The bladder capacity is reduced but residual urine may
be increased

21.  Simultaneous contraction of the sphincter and
the detrusor during voiding
 results in obstructed voiding, interrupted urinary
stream, incomplete emptying, and high
intravesical pressures because the sphincter
fails to relax correctly
 Upper urinary tract dilatation and kidney
damage may develop subsequently.

22.  seen with complete lesions below theT12 segment that involve
the conus medullaris and cauda equina.
 occurs with sacral myelomeningocele and tumors of the conus
medullaris–cauda equina region.
 initial shock phase of spinal cord injury.
 The bladder is paralyzed, and there is no awareness of the state
of fullness.
 there is urinary retention because the tone of the detrusor
muscle is abolished and the bladder distends as urine
accumulates.

23.  Motor paralytic bladder
lesions involving the efferent motor fibers to the
detrusor
painful urinary retention
 Sensory paralytic bladder
tabes dorsalis, syringomyelia, or diabetes mellitus.
caused by the impairment of the afferent pathways