Bladder innervation
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The document discusses the innervation of the urinary bladder. It describes how the bladder develops from three sources and its anatomy. The bladder has a detrusor muscle layer and two sphincters. Micturition is controlled by higher cortical and brainstem centers that coordinate sympathetic, parasympathetic, and somatic nerve pathways. The sympathetic pathway relaxes the detrusor and contracts the internal sphincter during bladder filling. The parasympathetic pathway contracts the detrusor and relaxes the internal sphincter during voiding. The somatic pathway controls the external urethral sphincter voluntarily. Neurogenic bladder can occur due to nerve damage and is classified based on the lesion level.
Bladder innervation
- 2. DEVELOPMENT OF URINARY BLADDER Developed from 3 sources: • VESICOURETHRAL CANAL ( ENDODERM) - Major parts of urinary bladder & prostatic urethra • PROXIMAL PART OF ALLANTOIS ( ENDODERM) - Apex of urinary bladder • PROXIMAL PORTION OF MESONEPHRIC DUCTS ( MESODERM) - Trigone of urinary bladder
- 3. ANATOMY OF BLADDER • Anterior most element of the pelvic viscera. • Situated in the pelvic cavity when empty, but expands superiorly into the abdominal cavity when full. • At BIRTH – EXTRAPERITONEAL AREA of LOWER ABDOMINAL WALL • 5-6years – DESCENDS INTO TRUE PELVIS
- 4. ANATOMY OF BLADDER TRIGONE- Smooth triangular area between the openings of the ureters and urethra on the inside of the bladder The ureter pierces the bladder wall obliquely, travels 1.5 to 2 cm, and terminates at the urethral orifice. As it passes through the hiatus in the detrusor (intramural ureter), it is compressed and narrows considerably. The intravesical portion of the ureter lies beneath the urothelium and backed by a strong plate of detrusor muscle.
- 5. PARTS OF URINARY BLADDER
- 6. Anatomy of bladder • DETRUSOR MUSCLE Is a layer of the urinary bladder wall made of smooth muscle fibres arranged in spiral, longitudinal and circular bundles. • SPHINCTERS Internal (smooth muscles ) sphincter – bladder neck and proximal urethra External ( striated muscle ) – membranous urethra
- 7. HIGHER CENTRE CONTROL CORTICAL CONTROL AREAS Frontal and cingulate gyri – subcortical nuclei. Inhibition - micturition at the level of pons Excitatory - external urinary sphincter Voluntary control of micturition PONTINE MICTURITON CENTRE Barrington’s nucleus or M – region Coordination of micturition. SPINAL MICTURITON CENTRE T11 – L2 Sympathethic and parasympathethic innervation.
- 8. MICTURATION – BLADDER INNERVATION PARASYMPATHETIC SUPPLY: S2 S3 S4 - Contraction of detrusor muscle - Relaxation of internal sphincter FACILITATES MICTURATION SYMPATHETHIC SUPPLY : L1 L2 L3 -Contraction of external sphincter - Voluntary control WITHOLDS MICTURATION
- 9. NERVE SUPPLY Parasympathetic efferent fibers S2, S3, S4 are - motor to detrusor muscle and inhibitory to the sphincter vesicae. Sympathetic efferent fibers ( T11 to L2 ) - Inhibitory to detrusor and motor to sphincter vesicae. The pudendal nerve ( S2, S3, S4 ) - Supplies sphincter urethrae which is voluntary Sensory nerves Pain sensations by both sympathetic and parasympathetic nerves
- 12. TYPE OF NERVE NERVE FIBRES ACTION COMMENTS SYMPATHETIC HYPOGASTRIC NERVE (L1,L2L3) INFERIOR MESENTRIC GANGLION MOTOR TO INTERNAL URETHRAL SPHICTER, INHIBITORY TO DETRUSOR NO SIGNIFICANT ROLE IN MICTURITION; ALONG WITH IUS PREVENT REFLUX OF SEMEN INTO THE BLADDER DURING EJACULATION PARASYMPATHETIC PELVIC NERVES (S2,S3,S4) MOTOR TO DETRUSOR INHIBITORY TO INTERNAL URETHRAL SPHINCTER STRECH RECEPTORS PRESENT ON THE WALL OF THE URINARY BLADDER SENSORY FIBRES IN THE PELVIC NERVES INTERMEDIOLATERAL COLUMN OF SPINAL CORD PARASYMPATHETIC NERVES MUSCARINIC RECEPTORS EMPTYING OF URINARY BLADDER SOMATIC PUDENDAL NERVES (S1, S3, S4) VOLUNTARY CONTROL OF EXTERNAL URETHRAL SPHICTER THIS MAINTAINS THE TONIC CONTRACTIONS OF THE SKELETAL MUSCLE FIBRES OF THE EXTERNAL SPHICTER, SO THAT THIS SPHICTER IS CONTRACTED ALWAYS. DURING MICTURITION, THIS NERVE IS INHIBITED, CAUSING RELAXATION OF THE EXTERNAL SPHINCTER AND VOIDING OF URINE SENSORY HYPOGASTRIC, PELVIC AND PUDENDAL NERVES CORTICAL SENSATION
- 13. NERVE ON DETRUSOR MUSCLE ON INTERNAL SPHINCTER ON EXTERNAL SPHINCTER FUNCTION Sympathetic nerve Relaxation Constriction Not supplied Filling of urinary bladder Parasympathetic nerve Constriction Relaxation Not supplied Emptying of urinary bladder Somatic nerve Not supplied Not supplied Constriction Voluntary control of micturition
- 14. Bladder filling stage Supraspinal centre inhibits PMC. Increased thoracolumbar sympathetic outflow Decreased sacral parasympathetic outflow to lower urinary tract. Increased activity of the pudendal nerve. Detrusor smooth muscle relaxation, bladder neck smooth muscle contraction, external urinary sphincter contraction.
- 15. Bladder emptying stage • Supra spinal centres’ inhibitory outflow to PMC suppressed. • Decreased thoracic sympathetic outflow. • Increased sacral parasympathetic outflow. • Supresed pudendal nerve • Detrusor smooth muscle contraction, bladder neck smooth muscle relaxation, external urinary sphincter relaxation.
- 17. NEUROGENIC BLADDER • Defined as the one whose function has been modified due to interference with its nerve supply .
- 18. Epidemiology • Usually affects 1. 40-90% multiple sclerosis 2. 37 – 72% Parkinsonism 3. 15% stroke 4. 70 – 84 % spinal cord injury 5. 61 % spina bifida 6. Other causes- autonomic neuropathy, pelvic surgery sequelae, cauda equina syndrome
- 19. aims • Preservation of renal function. • Regular adequate emptying • Prevention and control of infection and incontinence • Minimize residual urine • Judious and proper management –prevents renal damage .
- 20. NEUROGENIC BLADDER classification & level of lesion • Uninhibited bladder- lesions above the PMC • Upper motor neuron bladder – lesions between PMC & Sacral spinal cord • Mixed type A bladder – sacral cord lesions that damage detrrusor nucles but spares pudendal nucleus • Mixed type B bladder – sacral lesions sparing detrusor nucleus but damage pudendal nucleus • Lower MotorNeuron bladder – sacral nerve root injuries
- 21. • Uninhibited bladder :urinary frequency , urgency, incontinence. • UMN bladder dysfunction: high bladder contractions – VUR – renal damage • Mixed Type A bladder: hypertonic external urinary sphincter , urinary retention • Mixed type B bladder: flaccid external urinary sphincter , urinary incontinence • LMN Lesions – detrusor areflexia
- 22. Autonomous bladder • Lesion : sacral segment of the spinal nerve • Seen in: 1. Congenital : spina bifida, meningomyelocoele 2. Trauma 3. Infective : arachnoiditis, radiculitis 4. Neoplasms of the cord • Affected individual may not be able to sense when the bladder is full • Symptoms : difficulty in passing urine, urinary incontinence • Bladder gradually over distends till the urine dribbles out
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