Lecture Notes in Human Anatomy - Hryhorieva O.A., Svitlytskyi A.O. 2020

The Study of Viscera (Splanchnologia)
Anatomy of the Nervous System
Autonomic Nervous System

Lecture outline:

1. Centers of regulation of autonomic Functions

2. Structural Features of the ANS

3. Parasympathetic division

4. Sympathetic division

The part of The Nervous system that innervates The Heart, Blood and Lymphatic vessels, viscera, and other Organs containing smooth Muscle Cells and Glandular Epithelium

is a complex of central and peripheral neural structures that regulate the functional level of Homeostasis required for an adequate response of all body systems.

Functions:

✵ coordinates The activity of all Internal Organs

✵ regulates metabolic and trophic processes in all organs and Tissues

✵ maintains the constancy of the body's internal environment

Centers of regulation of autonomic functions

Hypothalamus; limbic system; Cerebellum;

reticular formation;

Structural Features of the ANS:

✵ the efferent pathway consists of 2 Neurons

✵ a simple autonomic reflex arc is represented by 3 neurons

✵ The Cell body of the second neuron of the reflex arc (the first efferent neuron) is located in the autonomic nuclei of the CNS

✵ the cell body of the third neuron of the reflex arc (the second efferent neuron) is located outside the CNS

Central division:

✵ (I) parasympathetic nuclei of Cranial Nerves III, VII, IX, and X are located in the Brainstem

✵ (II) autonomic (sympathetic) Nucleus forms the lateral intermediate Column from CVII to LII

✵ (III) sacral parasympathetic nuclei are located in the grey matter of 3 sacral segments of the Spinal Cord from SII to SIV

Peripheral division:

✵ (I) autonomic nerves and branches

✵ (II) Autonomic plexuses

✵ (III) ganglia of autonomic plexuses

✵ (IV) Sympathetic trunk

✵ (V) terminal ganglia

sympathetic trunk

White communicating rami approach, while 1) connecting branches, 2) postganglionic nerves to internal organs, and ganglia of autonomic plexuses that have passed in transit through the sympathetic trunk ganglia lead away

White rami are present only in C_VIII–L_II Spinal Nerves and connect exclusively to the thoracic and upper lumbar ganglia. Gray rami emerge along the entire length

Interganglionic Branches of the sympathetic trunk

✵ Connect the sympathetic trunk ganglia

✵ Convey fibers to the sympathetic trunk ganglia at levels above C₈ and below L₂

Contain predominantly preganglionic sympathetic fibers

✵ 3 ganglia connected by interganglionic fibers. Preganglionic fibers approach via the interganglionic branch of the thoracic region

✵ Superior cervical ganglion — the largest ganglion (2×0.5 cm). Branches given off: gray rami to I–IV spinal nerves, internal carotid nerve, external carotid nerves (forming the common carotid plexus), jugular nerve (as part of cranial nerves IX, X, XII), laryngopharyngeal and superior cervical cardiac nerves.

✵ Middle cervical ganglion — inconstant (0.5 cm). Branches given off: gray rami to V–VII spinal nerves, middle cervical cardiac nerve, contributes to The formation of the common carotid plexus

✵ Cervicothoracic (stellate) ganglion — formed by the fusion of the inferior cervical ganglion with the first thoracic ganglion. Irregular in shape (0.8 cm). Branches given off: gray rami to VI–VII spinal nerves, subclavian plexus nerve, vertebral nerve, inferior cervical cardiac nerve.

✵ Consists of 10–12 ganglia (3–5 mm in diameter). White communicating rami approach from all thoracic spinal nerves. Branches given off: gray communicating rami (to adjacent spinal nerves), thoracic cardiac nerves (from 2–5 ganglia), fine sympathetic branches forming the pulmonary (right and left), esophageal, and thoracic aortic plexuses, greater splanchnic nerve (5th–9th ganglia), lesser splanchnic nerve (10th–11th ganglia — terminating in the celiac plexus), lowest splanchnic nerve (12th ganglion — terminating in the renal plexus)

✵ 3–5 ganglia and their connecting interganglionic branches. Spindle-shaped (~6 mm). White communicating rami approach the two upper lumbar ganglia. The remaining ganglia lack white communicating rami. Branches given off: gray rami (to lumbar spinal nerves), lumbar splanchnic nerves (to the abdominal and visceral plexuses)

✵ Sacral region:

✵ 4 sacral ganglia (spindle-shaped, ~5 mm). Connected by interganglionic branches. The right and left trunks terminate in the ganglion impar. Branches given off: gray rami (to sacral spinal nerves), sacral splanchnic nerves (to the superior and inferior hypogastric plexuses)

✵ From the celiac ganglia: diaphragmatic plexus, unpaired plexus of the celiac trunk (splenic, gastric, hepatic, pancreatic), plexuses of parenchymatous organs (subserous, intermuscular, submucosal), suprarenal plexus (20th century)

✵ From the aortorenal ganglia: renal, ureteric, testicular/ovarian plexuses

✵ From the superior mesenteric ganglion: superior mesenteric plexus

✵ Inferior mesenteric ganglion — branches are given off to form the corresponding plexus, reaching the colon (subserous, intermuscular, and submucosal plexuses) and rectum (upper part)

✵ Superior hypogastric plexus — located below the aortic bifurcation. Approaches from the lower lumbar and upper sacral ganglia of the sympathetic trunk. Divides into the right and left inferior hypogastric plexuses

✵ Inferior hypogastric plexus — sacral splanchnic nerves (from the sacral ganglia) approach it, forming the middle and inferior rectal, prostatic, and Ductus deferens plexuses, as well as the uterovaginal plexus. Transit: preganglionic parasympathetic fibers from S_II–S_IV (pelvic splanchnic nerves) sympathetic trunk.