Autonomic Nervous System
Ms. DS Pillay Room 2P24
OVERVIEW OF THE NERVOUS SYSTEM
NERVOUS SYSTEM
CNS PNS
BRAIN SPINAL CORD
SOMATIC ANS
SYMPATHEIC PARASYMPATHEIC
(intra-mural) Long pre-ganglionic fibre Short pre-ganglionic neuron Long post-ganglionic fibre
Short post-ganglionic fibre
LOCATION OF GANGLIA IN THE ANS
PARASYMPATHETIC
CRANIOSACRAL OUTFLOW In the CNS Parasympathetic Cranial Nerves III -Oculomotor N VII – Facial N IX – Glossopharyngeal N X – Vagus N Spinal Cord = S2,3,4 cord segments
In the PNS Postganglionic neurons in intramural ganglia within visceral wall
Therefore.... PNS = “Craniosacral Outflow”
PARASYMPATHETIC • Pre-ganglionic fibres from - cranial nerves III,VII,IX & X - Sacral segment S2-S4 • Parasympathetic ganglia - Ciliary - Pterygopalatine - Submandibular - Otic • Fibres from sacral segment form pelvic splanchnic nerves which enters inferior hypogastric plexus
CN Nucleus Preganglionic nerve
Ganglion Post ganglionic
nerve
Target organ
3 Edinger-Westphal
Oculomotor Ciliary •Short ciliary •Sphincter pupillae •Ciliary muscles
7 Superior Salivatory
Chorda tympani Sub-mandibular
•Lingual Salivary glands: •Submandibular •Sub-lingual •Lingual •Labial •Buccal
Greater petrosal Pterygo-palatine
•Maxillary •Lacrimal •Nasal •Palatine •Pharyngeal glands
9 Inferior salivatory nucleus
Tympanic branch. Lesser petrosal nerve
Otic ganglion •Auriculotemporal nerve,
•Parotid gland
10 Dorsal vagal nucleus
Vagus Minute ganglia in individual organs.
individual
•Thoracic and abdominal viscera
SACRAL PARASYMPATHETIC OUTFLOW • Origin
Anterior primary rami of the S2, 3
and 4
• Course
Pelvic splanchnic nerves
Hypogastric plexus
• Ganglia
In walls of individual viscera
• Post ganglionic nerves
Individual
Target
Distal transverse colon
Descending colon
Sigmoid colon
Pelvic viscera
External genital organs
SYMPATHETIC NS
The PATHWAY OF THE NEURONS
• Pre-ganglionic fibres & Post-
ganglionic fibres
• Para-vertebral ganglia- 3 cervical
(superior, middle & inferior),usually
11 thoracic,
4 lumbar & 4 sacral.
In the PNS Pair of Sympathetic Chains with ganglia on it, (postganglionic neurons) distributed to ALL VISCERA distributed to SKIN ** distributed to Head and Neck
In the CNS Hypothalamus =“HQ” Spinal Cord = T1 to L2 segments (pre-ganglionic neurons)
HYPOTHALAMUS
PARTS OF THE SYMPATHETIC TRUNK Cervical part Receive preganglionic fibres T1- T5 Lies on the pre-vertebral muscles behind the carotid sheath. Three interconnected ganglia respectively known as superior, middle and inferior cervical sympathetic ganglia Post ganglionic fibres distributed with neighboring arteries to head, neck and upper limb Thoracic Receives preganglionic fibres T1- T5 Lies on the necks of the ribs in the upper part of the thorax and the sides of the vertebra in the lower part. Behind pleura Distributed to thoracic visceral
PARTS OF THE SYMPATHETIC TRUNK Abdominal T6- T12 Lies on the anterolateral surface of the lumbar vertebrae Right trunk lies behind the inferior vena cava Crosses sacral promontory to become continuous with the pelvic trunk. Distributed to abdominal viscera. The Pelvic Pelvic splanchnic L1-L2 Downwards on the pelvic surface of the sacrum, The two trunks usually unite in front of the coccyx and end in a small-unpaired ganglion (ganglion impar).
Autonomic ganglia and plexus
Thorax
Cardiac and pulmonary
Abdomen
Celiac, superior mesenteric, inferior mesenteric
Pelvic
Hypogastric
Sympathetic Parasympathetic Origin thoracolumbar Cranio-sacral
Ganglia Para-vertebral Peripheral (near target)
Neuro transmitters at target Adrenaline/ nor-adrenaline Acetyl-choline
Distribution Wide spread Localised
Predominant effect Fight and flight response calm body maintenance