BLADDER INNERVATION

NOORMIN HAIDA ADENAND

• Normal voiding is a spinal reflex• Modulated by - CNS (Brain, brain stem & spinal cord) - PNS (ANS & somatic nervous system)• Micturation control center is located in the frontal

lobe

• Signal transmitted by brain is routed through brainstem & spinal cord prior to reaching the bladder.

• Mechanical process of urination is coordinated by pons in Pons Micturation Center

- coordinates - urethral sphincter relaxation - detrusor muscle contraction - facilitates urination

• Bladder full stretch receptors of detrussor muscle

pons brain

pons

inhibit bladder fr contracting

• Spinal cord act as important intermediary between pons & sacral cord

• Sacral cord has specialized area known as sacral reflex center

- responsible for bladder contraction - is the primitive voiding center

• In infants, higher center of voiding control (the brain) is not mature enough to command the bladder

- when urine fills the infant bladder

excitatory signal

sacral cord

detrusor to contract

involuntary detrusor contraction with coordinated voiding

• ANS - regulates action of internal organs under involuntary control - divided into sympathetic parasympathetic • Sympathetic - bladder to increase its capacity without detrusor resting pressure - + internal urinary sphincter to remain tightly closed - urinary accomodation occurs - - micturation reflex

• Parasympathetic - + detrusor muscle to contract• Pudendal nerve - originates from nucleus of Onuf - regulates voluntary actions of

external sphincter diaphragm - its activation causes contraction of the above muscles

Synergistic Dysfunction• Abnormal neuronal supply to the bladder

increased contraction of the detrusor

• However, as there is coordinated relaxation of the internal & external urethral sphincters

voiding of urine

• These bladders are generally safe with low association intravesicular pressures

have a release valve through the sphincter

• Unlikely to cause renal damage

Dysynergistic Dysfunction

• Detrusor and urethral sphincter contraction is uncoordinated which results in

- high vesicular - detrusor hypertrophy - vesicoureteric reflux - renal damage• Unsafe bladders• Need to be treated early to minimize the damage

caused to the kidneys

Atonic Dysfunction

• Lack of detrusor and often sphincter activity• These systems are at low pressure &

generally safe• The bladder is commonly capacious• Constant dribbling incontinence• Do not cause upper tract damage

• The 3 above types are difficult to distinguish in the young as they can all result in children who wet.

• Can only be assessed by detailed urodynamic studies