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AUTONOMIC CONTROL OF THE PELVIC VISCERA & CONTROL OF MICTURITION. BY DR. O. A. ROBERTS DEPT OF OBGYN, UCH, IBADAN. AUTONOMIC CONTROL OF THE PELVIC VISCERA. AUTONOMIC SYSTEM OF NERVES: Lies- Sidewall of Pelvis lat. to Rectum
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AUTONOMIC CONTROL OF THE PELVIC VISCERA & CONTROL OF MICTURITION BY DR. O. A. ROBERTS DEPT OF OBGYN, UCH, IBADAN.
AUTONOMIC CONTROL OF THE PELVIC VISCERA AUTONOMIC SYSTEM OF NERVES: Lies- Sidewall of Pelvis lat. to Rectum Sympathetic: Fibres From Hypogastric Plexus plus upper sacral ganglia of the Sypathetic Trunk. The plexus is ganglionated (T11&12). Pre-ganglionic Fibres (half) synapse here while post-g. do not Synapse. Parasympathetic fibres only synapse in the Visceral walls. Arising from S 2-4 bodies (Nervi Erigentes) SYMPATHETIC FIBRES = VASOCONSTRICTOR PARASYPATHETIC = MOTOR TO BLADDER, GUT & SECRETOMOTOR TO GUT GLANDS.
AUTONOMIC CONTROL OF THE PELVIC VISCERA • THE SYMPATHETIC FIBRES ARE MOTOR TO SMTH. MUSCLE OF BLADDER & ANAL SPHINCTERS. • COURSE OF PAIN AND SENSORY FIBRES COMPLEX: • MOST TRAVEL WITH SYMP. SYSTEM, ESPECIALLY, FROM GUT & GONADS. THOSE FROM BLADDER & RECTUM ?TRAVEL IN NERVI ERIGENTIS. SAME FOR CERVIX UTERINE FIBRES FOLLOW HYPOGASRIC NN. TO DORSAL NERVE ROOTS OF T11 & 12.
AUTONOMIC CONTROL OF THE PELVIC VISCERA • THE VAGINAL SUPPLY: • Sympathetic ganglia in Lower Lumbar via Hypogastric plexus. • Parasymp. Outflow S2-4 (nervi erigentis). • N.B. Nerve endings undecorated but PACINIAN copuscles found in adventitia. • VULVAL SUPPLY: • Postganglionic Symp. Fibres from Hypogastric plex. Via Pudendal Nn. • Parasympathetic S2-4 as Nervi Erigentis to join the pelvic plexus.
CONTROL OF MICTURITION BLADDER = HOLLOW MUSC. ORGAN BEHIND SYMPHISIS. MADE UP OF SMOOTH MUSCLE SYNCITIUM. DETRUSOR MUSCLE= ↑Achase parasympathetic Nn S2-4 BLADDER DOME, URETHRA, BLADDER NECK = ß & α Adrenergic receptor symp. Outflow T10 - L2. RHABDOSPHINCTER URETHRAE: Striated mm. in the middle of urethra – circularly arranged (External Sphincter or INTRINSIC SPHINCTER MECHANISM). FOR URETHRAL CLOSURE AT REST
CONTROL OF MICTURITION • S2-4 Nn. Roots traveling with Pelvic Splanchnic Nn. Supply smooth muscle of the urethra (longitudinally arranged & continuous with detrusor). • EXTRINSIC SPHINCTER MECHANISM: • Striated periurethral Mm (Levator ani) at junction of middle & lower 1/3of the Urethra. • For additional closure force at times of physical effort BOTH mechanisms Maintain greater I.U.P. than I.V.P. Ξ +VE Closure pressure.
CONTROL OF MICTURITION • Visceral Afferents => thoracolumbar nn & sacral efferents conveying the sensation of Bladder distention. • CNS control of Micturition: Complex, requiring a sacral spinal reflex arc modulated by frontal lobe, thalamus, B.G. & hypothalamus: Bladder stretch receptors => Visc. Afferents => (with Pelvic Splanch. Nn.) => S2-4 Cord =>Controlled by Excitatory & Inhibitory receptor Centres which prevent Detrusor contractions & maintain Urethra sphincter control.
CONTROL OF MICTURITION PHYSIOLOGY: • Storage Phase • I.V.P. = 10cm H2O • Gradual filling to 150-250ml => When 400-600ml of urine => Desire to void, I.V.P. = 25cm H2O. • Beyond this => Irresistible urge to void => release of cortical inhibition & voiding.
CONTROL OF MICTURITION Voiding Phase • Relaxation of Pelvic Floor mm., Intrinsic straited mm. of the Urethra, fall in I.U.P.. Then efferent Parsymp. Detrus or stim. & contration (max 60cm H2O ). Once voiding in progress, I.V. P constant. Detusor mm efficiency ↑ with shortening of the Fibres, hence less force is reqd to maintain Mict. • N. B.Interruption is by contr. of Extrinsic Striated mm. of Pelvic floor.
