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