nervous system med 6573 visceral nervous system urinary bladder control / referred pain

Nervous SystemMed 6573

Visceral Nervous SystemUrinary Bladder Control / Referred

Pain

Urinary Bladder

Lower Motor Neurons

Sensory innervation (Visceral sensation)

Fullness and micturition sensation (urination imminent or physiological responses) - dependent upon mechanoreceptors in bladder wall

Urinary Bladder Control

Visceral afferent fibers (S2, S3, S4 and T12 - L2)

Pain sensations

Visceral afferents for pain travel with hypogastric nerves (sympathetic) to T12 and L2 and pelvic splanchnic nerves (parasympathetic nerves) (S2, S3, S4)

Spinothalamic tract transmits afferents input to higher centers

Transmit impulses with pelvic splanchnic nerves (S2, S3, S4) to spinal cord

Spinothalamic tract and dorsal column - medial lemniscal pathway transmit impulses to higher centers (thalamus and cerebral cortex).

LMN Innervation

Plate 414

Pelvic splanchnic nerves (S2-S4)

Inferior hypogastric plexus

Superior hypogastric plexus (T11-L1)

Sympathetic

Parasympathetic


Visceral afferent fibers (S2, S3, S4 and T12 - L2)Pain sensations



Lumbar splanchnics

Hypogastric nerves

LMN Innervation

Plate 414



Hypogastric nerves

Sympathetic

Parasympathetic

Vesical plexus


Visceral afferent fibers (S2, S3, S4 and T12 - L2)Pain sensations



LMN Innervation



Hypogastric nerves

Sympathetic

Parasympathetic

Vesical plexus


Visceral afferent fibers (S2, S3, S4 and T12 - L2)

Fullness and micturition sensation (urination imminent or physiological responses)

Transmit impulses with pelvic splanchnic nerves (S2, S3, S4) to spinal cord

Spinothalamic tract and dorsal column - medial lemniscal pathway transmit impulses to higher centers (thalamus and cerebral cortex).

Dependent upon mechanoreceptors in bladder wall

Plate 414

LMN Innervation

Motor innervation

Somatic motor - alpha motor neurons supplying the pudendal nerve (S2, S3, S4) cause contraction of the external urethral sphincter (skeletal muscle of UG diaphragm)


Visceral efferent fibers (S2, S3, S4 and T12 - L2)

Parasympathetics - pelvic splanchnics (S2, S3, S4) stimulate detrusor muscle (smooth muscle of urinary bladder) to contractSympathetics - inferior hypogastric / vesical plexi (T10 or 11 - L2) produce relaxation of the detrusor muscle (-receptors) and contraction of the internal urethral sphincter (-receptors)

LMN Innervation



Hypogastric nerves

Sympathetic

Parasympathetic

Vesical plexus

Visceral efferent fibers (S2, S3, S4 and T12 - L2)

Plate 414

Pudendal nerve

Motor innervation

Parasympathetics - pelvic splanchnics (S2, S3, S4) stimulate detrusor muscle (smooth muscle of urinary bladder) to contractSympathetics - inferior hypogastric / vesical plexi (T10 or 11 - L2) produce relaxation of the detrusor muscle (-receptors) and contraction of the internal urethral sphincter (-receptors)Somatic motor - alpha

motor neurons supplying the pudendal nerve (S2, S3, S4) cause contraction of the external urethral sphincter (skeletal muscle of UG diaphragm)

LMN Innervation

Urinary Bladder ControlMotor innervation

LMN Innervation

Urinary Bladder ControlMotor innervation

T11 - L1

S2 - S4

S2 - S4

Inferior hypogastric plexus (vesical plexus)

LMN Innervation

Upper Motor Neurons

Supratentorial level - regulates the pontine micturition centerCortical centerLocated on the medial surface of the superior frontal gyrusServes as center for voluntary control and initiation and cessation of micturition

Hypothalamus - serves to regulate autonomic control of the urinary bladder

Centers for micturition (urination) control

Urinary Bladder ControlUMN Innervation

Posterior fossaPontine micturition centerControls sympathetic, parasympathetic and somatic output

through spinopontospinal pathways

Centers for micturition (urination) control


Sacral spinal cord (S 2,3,4) (site of lower motor neurons)

UMN Innervation

Initiation of Urination (Micturition)


Superior frontal gyrus (medial surface)Initiates and terminates the process of urination (voluntary control center)Influences the hypothalamus, pontine center and sacral spinal cord

Hypothalamus

Insula

UMN Innervation

Initiation of Urination (Micturition)


Pontine centersStimulates parasympathetics to contract bladderInhibits sympathetics and relaxes the internal urethral sphincterInhibits the somatic nucleus, resulting in relaxation of the external urethral sphincter

Final Result: Urination occurs

UMN Innervation

Clinical Lesions Altering Urinary Bladder Control

Clinical Lesions Altering Urinary Bladder Control

Non-reflex neurogenic bladder (Flaccid bladder or Lower motor neuron neurogenic bladder)Bilateral damage of the sacral spinal cord or spinal nerve roots

(cauda equina)Characterized by incontinence and urinary retention

Lesions

Reflex neurogenic bladder (Upper motor neuron neurogenic bladder) - two possible types due to lesions involving upper motor neurons (lesions involve CNS)

Involves connections between the pontine micturition center and the frontal lobe

Patient is incontinent, but empties fully

Emptying of the bladder is normal because reflex control by the pontine micturition center is intact

Uninhibited reflex bladder

Clinical Lesions Altering Urinary Bladder Control Lesions

Results from spinal cord lesions above the sacral levels

Patient is incontinent and bladder does not empty fully

Emptying of the bladder is incomplete because the spinal reflex pathways that trigger the pontine micturition centers are interrupted

Automatic (spastic) reflex bladder

Reflex neurogenic bladder (Upper motor neuron neurogenic bladder) - two possible types due to lesions involving upper motor neurons (lesions involve CNS)

Clinical Lesions Altering Urinary Bladder Control Lesions

Visceral / Referred Pain

Visceral pain

Results from excessive stretch, violent or spasmodic contractions, or decreased blood supply (ischemia)

Perceived in the region of the organ itself


Visceral pain

Visceral pain pathways (GVA) - visceral sensory pain neurons travel with sympathetic nerve fibers to the visceral afferent nucleus found at spinal cord levels, except for some pain fibers in the inferior hypogastric plexus that travel with the pelvic splanchnic nerves to visceral afferent nucleus found at spinal cord levels S2 - S4

The visceral afferent nucleus sends nerve fibers along with the spinothalamic and spinoreticular tracts to the reticular formation, hypothalamus, and ventral posterior nucleus of the thalamus


Referred pain

Pain from visceral organs is referred to a cutaneous or somatic region because the two loci are part of the same segmental level and connections at the cortical level overlap


Referred pain

Pain from visceral organs is referred to a cutaneous or somatic region because the two loci are part of the same segmental level and connections at the cortical level overlap

T1-T5

T7-T8

C3-C5

T7-T9

T9-T10Appendix - T10

T11-T12

T12-L1


Visceral / Referred PainPlate 327

Visceral pain pathways (GVA) - visceral sensory pain neurons travel with sympathetic nerve fibers to the visceral afferent nucleus found at spinal cord levels, except for some pain fibers in the inferior hypogastric plexus that travel with the pelvic splanchnic nerves to visceral afferent nucleus found at spinal cord levels S2 - S4.

Nervous SystemMed 6573

EndVisceral Nervous System

Urinary Bladder Control / Referred Pain

Practice Quiz on Web Vista

nervous system med 6573 visceral nervous system urinary bladder control / referred pain

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