1. Nervous System Med 6573 Visceral Nervous System Urinary Bladder Control / Referred Pain

2. Urinary Bladder

3. Lower Motor Neurons

4. 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

5. Plate 414 Pelvic splanchnic nerves (S2-S4) Inferior hypogastric plexus Superior hypogastric plexus (T11-L1) Sympathetic Parasympathetic Sensory innervation (Visceral sensation) 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 Lumbar splanchnics Hypogastric nerves LMN Innervation

6. Plate 414 Pelvic splanchnic nerves (S2-S4) Inferior hypogastric plexus Hypogastric nerves Sympathetic Parasympathetic Vesical plexus Sensory innervation (Visceral sensation) 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 LMN Innervation

7. Pelvic splanchnic nerves (S2-S4) Inferior hypogastric plexus Hypogastric nerves Sympathetic Parasympathetic Vesical plexus Sensory innervation (Visceral sensation) 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

8. 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) Urinary Bladder Control Visceral efferent fibers (S2, S3, S4 and T12 - L2) Parasympathetics - pelvic splanchnics (S2, S3, S4) stimulate detrusor muscle (smooth muscle of urinary bladder) to contract Sympathetics - 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

9. Pelvic splanchnic nerves (S2-S4) Inferior hypogastric plexus 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 contract Sympathetics - 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

10. Urinary Bladder Control Motor innervation LMN Innervation

11. Urinary Bladder Control Motor innervation T11 - L1 S2 - S4 Inferior hypogastric plexus (vesical plexus) LMN Innervation

12. Upper Motor Neurons

13. Supratentorial level - regulates the pontine micturition center Cortical center Located on the medial surface of the superior frontal gyrus Serves 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 Control UMN Innervation

14. Posterior fossa Pontine micturition center Controls sympathetic, parasympathetic and somatic output through spinopontospinal pathways Centers for micturition (urination) control Urinary Bladder Control Sacral spinal cord (S 2,3,4) (site of lower motor neurons) UMN Innervation

15. Initiation of Urination (Micturition) Urinary Bladder Control 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

16. Initiation of Urination (Micturition) Urinary Bladder Control Pontine centers Stimulates parasympathetics to contract bladder Inhibits sympathetics and relaxes the internal urethral sphincter Inhibits the somatic nucleus, resulting in relaxation of the external urethral sphincter Final Result: Urination occurs UMN Innervation

17. Clinical Lesions Altering Urinary Bladder Control

18. 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

19. 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

20. 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

21. Visceral / Referred Pain

22. Visceral pain Results from excessive stretch, violent or spasmodic contractions, or decreased blood supply (ischemia) Perceived in the region of the organ itself Visceral / Referred Pain

23. 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 Visceral / Referred Pain

24. 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 Visceral / Referred Pain

25. 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-T10 Appendix - T10 T11-T12 T12-L1 Visceral / Referred Pain

26. Plate 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.

27. Visceral / Referred Pain Plate 328 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.

28. Visceral / Referred Pain Plate 345 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.

29. Nervous System Med 6573 End Visceral Nervous System Urinary Bladder Control / Referred Pain

30. Practice Quiz on Web Vista