Title:
URL Source: blob://pdf/3ce96363-d8d2-4c5a-aaa8-fec6fab46511
Markdown Content:
Sympathetic ner vous system Instructor Information
# Contact: Dr/ zienab helmy eldken.
# Dr/ Eman Hamdy Basha
# Department: Medical Physiology.
# Official email:
[email protected]. jo
#
[email protected] Learning Outcomes
Describe sympathetic supply to the head & neck.
Identify Horner syndrome.
Demonstrate sympathetic supply to the thorax.
Explain sympathetic supply to the abdomen.
Describe sympathetic supply to the pelvis.
Clarify Orbelli phenomenon. Autonomic ner vous system
Def: It is part of peripheral nervous system concerned with regulation and control of
involuntary or visceral functions in the body .
Divisions: It is divided into;
Sympathetic nervous system (thoraco-
lumbar division).
Parasympathetic nervous system (cranio-sacral division). Origin:
- LHCs of first and second thoracic segments.
Relay:
- Superior cervical ganglion (SCG).
Function:
Eye:
a. Contraction of dilator pupillae ms
dilatation of pupil (mydriasis).
# Sympathetic to the head and neck b. Contraction of smooth ms in eye lids widening of palpebral fissure.
c. Contraction of Muller s ms (behind eye ball)
exophthalmos.
d. Vasoconstriction (V .C ) of blood vessels of lacrimal glands
and trophic secretion.
Eye Salivary Glands:
Vasoconstriction of salivary gland blood vessels.
Trophic secretions: little, viscous, poor in water and rich in enzymes.
Skin:
V.C of skin blood vessels.
Hair erection due to contraction of piloerector muscle.
Sweat secretion.
Cerebral blood vessels:
Mild vasoconstriction.
# Sympathetic to the head and neck Horner syndrome
Def : It is a group of signs which result from
interruption of sympathetic supply to head and neck.
Causes:
Lesion in T1 and T2 segments.
Lesion in SCG.
Site: Manifestations occur at the same side of the lesion. Signs:
Ptosis dropping of upper eye lids due to
paralysis of superior tarsal ms.
Miosis constriction of pupil due to paralysis of dilator pupillae ms.
Anhydrosis absence of sweat secretion leading to dryness of affected side of the face.
Enophthalmos sinking of eye ball into orbit
due to paralysis of Muller's ms.
Vasodilatation of skin blood vessels, so the skin becomes red and warm.
Horner syndrome Sympathetic supply to thorax
Origin: LHCs of upper 4 or 5 thoracic segments of spinal cord.
Relay: 3 cervical ganglia and upper 4 thoracic ganglia.
Functions:
Heart:
It the heart rate, force of contraction, conductivity and excitability the effectiveness of heart as a pump.
Coronary vessels:
Direct effect vasoconstriction.
Indirect effect vasodilatation(due to accumulation of metabolites). Lungs:
> a.
Inhibition of the smooth ms of the bronchi bronchodilatation.
b. Inhibition of the mucus secretion of air passages.
c. Vasoconstriction of the pulmonary blood vessels.
Sympathetic supply to thorax Sympathetic supply to thorax Sympathetic supply to the abdomen
Origin : LHCs of T6-12 segments of spinal cord (splanchnic nerves).
Relay :
Collateral (prevertebral) ganglia (celiac, superior mesenteric ,and inferior mesenteric).
Functions:
GIT (Stomach, small intestine and proximal part of large intestine): Relaxation of their walls and contraction of their
sphincters inhibition of digestion and delayed evacuation of
their contents. Liver:
- Stimulation of glycogenolysis increases blood glucose.
Gallbladder:
- Relaxation of its wall and contraction of sphincter of Oddi retention of bile.
Spleen:
- Contraction of smooth muscles in splenic capsule pouring of about 250 ml of stored blood into the general circulation.
Sympathetic supply to the abdomen Pancreas:
- It inhibits both endocrine and exocrine pancreatic secretion
Kidneys:
Stimulation of juxtaglomerular cells
increase renin secretion.
Decreases renal blood flow.
Decreases urine output.
GIT vessels : Vasoconstriction(V.C).
Sympathetic supply to the abdomen Sympathetic to Supra renal medulla (SRM)
Origin: LHCs of T10 and 11 segments of spinal cord.
Relay:
- SRM is supplied by sympathetic preganglionic nerve
fibers (with no postganglionic nerve fibers) which relay
directly with the SRM cells (chromaffin cells).
Functions:
Stimulation of sympathetic nerves to SRM releases large
quantities of adrenaline (80%) and noradrenalin (20%) into the circulating blood.
In stress conditions, SRM acts together with sympathetic
nervous system ( sympatho-adrenal system). Sympathetic supply to pelvis
Origin: LHCs of L1 , L2 ,and L3 segments of spinal cord
Relay:
Inferior mesenteric ganglia.
Functions:
Urinary bladder:
Relaxation of its wall and contraction of internal urethral sphincter urine
retention.
Rectum:
Relaxation of its wall and contraction of internal anal sphincter retention
of faces. Sex organs:
Male:
I. Contraction of smooth ms in the walls of seminal vesicle ,epididymis ,vas deferens and ejaculatory duct ejaculation of semen.
II. VC of blood vessels of pelvic viscera including external sex organs.
Female:
VC of blood vessels of external sex organs.
Variable effects on uterus, mainly inhibitory but may be excitatory in late
pregnancy.
Sympathetic supply to pelvis Orbelli phenomenon
Means sympathetic stimulation to skeletal muscles that cause
acceleration of chemical reactions in muscle which leads to:
Better muscle contraction.
Delayed fatigue.
Early recovery after fatigue. Guyton AC, and Hall JE (2021); Text book of medical physiology, 14th ed., W.B. Saunders Company.
Sembulingam, K., & Sembulingam, P. (2022); Essentials of medical physiology
(9th ed.). Jaypee Brothers Medical Publishers.