By DR QAZI IMTIAZ RASOOL
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Sympathetic Nervous System
1. Describe the origin and the actions of sympathetic
supply to different body regions: head and neck, thorax,
abdomen, pelvis and body wall.
2. Relate the knowledge to clinical conditions resulting
from sympathetic disorders (Horner’s syndrome).
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A.N.S.
The autonomic nervous system can be divided and
viewed 3 different ways:
1 . Anatomically/Morphological
Sym Para
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2. Chemically/Pharmacolgical
Chol
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Adren
Chemical Division of the A.N.S
The Cholinergic NS derives it’s name from the word
acetylcholine
The Adrenergic NS derives it’s name form the word
adrenalin
Epinephrine is an external form of the body-producing drug
adrenalin.
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3.Functional/physiological
excitatory
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inhibitory
SYMPATHETIC DIVISION
1. THORACO-LUMBAR
2.ADRENERGIC,NON-ADRENERGIC
3.NERVOUS SYSTEM OF TODAY
4.CATABOLIC SYSTEM
5.ERGOTROPIC SYSTEM
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6. “E” division
1. exercise,
2. excitement,
3. emergency,
4. embarrassment
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LIFE
POSSIBLE WITHOUT IT
2. SUBJECT IS SHELTERED AS THEY R LESS RESISTANT
FOR EXTREME OF STRESS
1.
SUBJECT IS
1. WEAK
2. APTHETIC
3. LOWER TEMP,
4. LOW BP
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Sympathetic Pathways
Axons leave the sympathetic trunk in 5 possible ways:
1. spinal nerves
2. Perivascular plexus i.e along blood vessel, e.g. internal
carotid artery.
3. sympathetic nerves straight to the target organ.e.g.e heart.
4. splanchnic nerves
5. Adrenal Medulla Pathway
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Organs of supply
1. Cutaneous blood vessels
2. Deep blood vessels
3. Glands
cardiac muscles
5. pilomotor
6. Smooth muscles
4.
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Physiological Anatomy
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Preganglionic fibers
Cell-bodies
1.
Preganglionic neurons originate in thoracic + lumbar levels of the spinal cord
(T1-L2).
intermediolateral horn
2.
5000 cell bodies
3.
4.
5.
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(lamina VII)
Tracts Desend From Above
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5 types of
sympathetic ganglia
1. Paravertebral
2. Prevertebral/colletral
3. Terminal
4. Intermediate
5. Adrenal gland
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sympathetic ganglion
1. 20000–30000 nerve cell bodies
2. more ganglia than PNS division
3. Multipolar (stellate) Bipolar; Unipolar  very
few
4. Short dendrites may form glomerulus
5. Satellate cells– maintain the neural enviorment
6. R motor ganglia
7. from which neuroblastoma tumours arise
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PARAVERTEBRAL-SYM CHAIN
1. The ganglia vary in size, position, and number, but
there are typically 23 (+- 1)ganglia in each
sympathetic chain…
1. 3 cervical
2. 11 thoracic
3. 4 lumbar
4. 4 sacral
5. 1 coccygeal (ganglion impar)
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Postganglionic Fibers
Spinal nerves
1. Gray rami communicantes: postganglionic neuron
leave sympathetic trunk by entering a short pathway
called a gray rami communicantes & merge with
anterior ramus of a spinal nerve.
2. Each spinal nerve carries a grey rami from its
corresponding ganglias,
3. 8% in spinal nerve r sym;
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superior cervical ganglia
1. Close to base skull, Trans; proc; of C2-3,
Behind carotid sheath
2. Fusion of smaller individual cervical ganglia
3. Largest , Contain Pre, Post, Inter-neurones,
satellate cells.
4. Pathways to head (T1-T4) ascend to S.C.G.
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Superior Cervical Ganglion
1.
1million cells
2.
1: 190
3.
Post gang; enter ventral ramus via grayrami communicantes and then travel to
effectors.
4.
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C1-4, head and neck
Pathways to head
1. Serve skin and blood vessels of the head
2. Stimulate the dilator iris muscles of eye
3. Inhibit nasal and salivary glands
4. Innervate the smooth (tarsal) muscle that lifts the
upper eyelid
5. Sends direct branches as superior Cardiac Nerve to
heart, skin.
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Middle Cervical Ganglion (MCG)
1.
Lies On Vert; C6
Smallest
2.
Pathways To (T1-T6) Ascend To M.C.G.
3.
Post; Thyroid,para
4.
Middle Cardiac Nerve, skin
5.
Gray Rami C5-6
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6.
Inferior Cervical /STELLATE Ganglion
1. Large
2. Between Neck Of Ist Rib and Trans; Proc; Of C7
3. Lies Behind Vertrebral Artery
4. Supplies The Next Two, C7-8
5. Inferior Cardiac Nerve, skin
6. Also Along Subclavian Artery
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1.
5.Adrenal gland
Adrenal=a modified sym: gang:
pyramid-shaped , on top of each kidney
2. Structurally and functionally, they are2 glands:
Adrenal cortex (outside) glandular (epithelial) tissue
Adrenal medulla (inside) is nervous hormonal tissue.
3. Embryologically derived from pheochromoblasts
differentiate into modified neuronal cells
Pheochromocytes (= chromaffin cells; axonless secretory cells
4. Acts as a peripheral amplifier
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Sympathetic Variosities are long
1:25,000 effector cells; cleft ∼50 nm across
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Horner’s Syndrome
in descending pathway b/w T1-T5 Damage to SCG.
1. Miosis – lack of SNS innervation of dilator pupillae
( nothing to counteract PNS sphincter pupillae)
2. Ptosis – drooping of upper eyelid ( inactivity of superior
tarsal muscle (smooth muscle)
3. Anhidrosis – lack of facial sweating
if lesion occurs before branching of sympathetics in the periphery
4. Enophthalmos – sinking of one eye w/in the orbit
(possibly due to inactivity of smooth muscle)
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