Autonomic Nervous System Chad Byworth Reference: Material from lecture Autonomic Nervous System, Dr R Tunstall

which have these effects... What is the ANS? The autonomic nervous system allows for the self-regulation of the body viscera, it is split into the... Sympathetic Nervous System Parasympathetic Nervous System which have these effects... Raises heart rate Increases force of contraction Constricts most blood vessels Slows GI transit Constricts sphincters Bronchodilates Increase sweating Dilates pupil (mydriasis) Secretion of seminal fluid/movement of sperm Slows heart rate (no effect on force) Relaxes blood vessels Speeds up GI transit Relaxes sphincters Increases salivation Bronchoconstricts Constricts pupil (miosis) Erection

ANS fibres are classified as pre- and post-ganglionic Preganglionic Target Peripheral ganglion Brainstem nucleus / Cell body in lateral horn What is this portion of the spinal cord? Lateral horn Autonomic (only seen T1-L2 & S2-4)

Sympathetic Nervous System Sympathetic supply arises from the... Sympathetic Chain How are sympathetics to the head supplied? Sympathetics to the head arise from the chain continuing to the base of the skull. Sympathetic nerves exit the CNS at... T1 - L2 What would damage at this level result in? Damage at the level of the L1 vertebral body and below should not affect the sympathetic supply. However parasympathetic outflow to the pelvis will be disrupted.

Sympathetic Nervous System Sympathetics to the head come from the sympathetic chain continuing up to the base of the skull. There are 3 ganglia in the neck, from here the supply continues alongside arteries and cranial nerves. Run to pterygo-palatine ganglion from which they are distributed with CN V Plexus around ICA CN VII Sup. Cervical Ganglia Forms deep petrosal nerve which joins parasympathetic greater petrosal nerve

Patient Case What signs can you see on this patient? What else might you expect to see? Miosis (pupillary constriction) Partial ptosis Anhydrosis (lack of sweating) Vasodilation What is this condition called? What has happened? Horner’s Syndrome Loss of sympathetic supply to one side of the head What could cause this? Pancoast Tumour Iatrogenic Base of Skull Tumour Trauma Lymphadenopathy

Parasympathetic Nervous System Parasympathetic supply arises from... CN III CN VII CN IX CN X 4 cranial nerves Pelvic splanchnic nerves From S2-4 Spinal nerves 3 spinal nerves

Parasympathetic Nervous System Parasympathetic post-ganglionic fibres emerge from... Cranial nerves III, VII, IX & X ...and travel with... Cranial nerve V Loss of parasympathetics to the head can lead to loss of the... Pupillary light reflex, this is because there is unopposed sympathetic action leading to full dilation of the affected pupil.

Neurotransmitters α or β What are the 2 principal neurotransmitters in the peripheral nervous system? Acetylcholine and Noradrenaline Complete with each neurotransmitter and receptor CNS ACh Somatic efferent Nicotinic ACh NA Sympathetic α or β Nicotinic ACh ACh Parasympathetic Nicotinic Muscarinic

Spinal nerve Virginia Lam

What are they? Part of peripheral nervous system Communication between periphery and CNS Peripheral nervous system: Spinal and cranial nerve, autonomic nervous system and somatic sensory and motor nerve

Where are they? from? Arise through numerous rootlets from dorsal and ventral surface of spinal cord The dorsal and ventral root of spinal nerve will combine and form dorsal root ganglion, and extend to be spinal nerve Where do they emerge from in the vertebral column? Intervertebral foramen Dorsal root carries sensory fibre Ventral carries motor Emerge through intervertebral foramen McGraw-Hill Companies

How they are named? A little tricky! Or may be not 31 pairs of spinal nerve 8 pair of cervical 12 thoracic 5 lumbar 5 sacral 1 coccyx Cervical spinal nerves exit …… corresponding vertebrae What happen in thoracic and the following? After T1 level, all spinal nerve exit below the corresponding vertebrae

How spinal nerves distribute? Dorsal and ventral rami Plexus

Ramus Branch off after dorsal root ganglion Both are mixed (somatic motor & sensory, visceral sensory and autonomic) Innervation: Dorsal ramus: deep muscle and skin of the back Ventral ramus: muscle and structure of upper and lower limbs, and skin of anteriolateral of the trunk

Plexuses Plexuses = network of axon Principle plexus: Cervical Brachial Lumbar sacral coccygeal

Why bother? Lumbar puncture Anaesthesia Pathology Epidural Spinal Caudal Pathology IV Disc prolapse Cervical/lumbar spondylosis (osteroarthritis) Trauma to nerve or plexuses Herpes zoster (dermatonal distribution in thorax)

For IV disc prolapse, the damage will be one level below