A report on Vagus nerve and Parasympathetic nervous system

Plan of the upper portions of the glossopharyngeal, vagus, and accessory nerves.
Autonomic nervous system innervation, showing the parasympathetic (craniosacral) systems in blue.
H&E stained fibers of the vagus nerve (bottom right) innervate the sinoatrial node tissue (middle left)
Inferior view of the human brain, with the cranial nerves labeled.
Section of the neck at about the level of the sixth cervical vertebra
Transverse section of thorax, showing relations of pulmonary artery
The arch of the aorta, and its branches
Dura mater and its processes exposed by removing part of the right half of the skull, and the brain
The tracheobronchial lymph glands
Section of the medulla oblongata at about the middle of the olive
Hind- and mid-brains; postero-lateral view
Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ
The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses
The celiac ganglia with the sympathetic plexuses of the abdominal viscera radiating from the ganglia
The position and relation of the esophagus in the cervical region and in the posterior mediastinum, seen from behind
The thyroid gland and its relations
The thymus of a full-term fetus, exposed in situ
Deep dissection of vagus nerve
Vagus nerve – dissection

The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract.

- Vagus nerve

Specific nerves include several cranial nerves, specifically the oculomotor nerve, facial nerve, glossopharyngeal nerve, and vagus nerve.

- Parasympathetic nervous system
Plan of the upper portions of the glossopharyngeal, vagus, and accessory nerves.

11 related topics with Alpha

Overall

Heart

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Muscular organ in most animals.

Muscular organ in most animals.

Human heart during an autopsy
Computer-generated animation of a beating human heart
The human heart is in the middle of the thorax, with its apex pointing to the left.
Heart being dissected showing right and left ventricles, from above
Frontal section showing papillary muscles attached to the tricuspid valve on the right and to the mitral valve on the left via chordae tendineae.
Layers of the heart wall, including visceral and parietal pericardium
The swirling pattern of myocardium helps the heart pump effectively
Arterial supply to the heart (red), with other areas labelled (blue).
Autonomic innervation of the heart
Development of the human heart during the first eight weeks (top) and the formation of the heart chambers (bottom). In this figure, the blue and red colors represent blood inflow and outflow (not venous and arterial blood). Initially, all venous blood flows from the tail/atria to the ventricles/head, a very different pattern from that of an adult.
Blood flow through the valves
The cardiac cycle as correlated to the ECG
The x-axis reflects time with a recording of the heart sounds. The y-axis represents pressure.
Transmission of a cardiac action potential through the heart's conduction system
Conduction system of the heart
The prepotential is due to a slow influx of sodium ions until the threshold is reached followed by a rapid depolarization and repolarization. The prepotential accounts for the membrane reaching threshold and initiates the spontaneous depolarization and contraction of the cell; there is no resting potential.
3D echocardiogram showing the mitral valve (right), tricuspid and mitral valves (top left) and aortic valve (top right). The closure of the heart valves causes the heart sounds.
Cardiac cycle shown against ECG
Heart and its blood vessels, by Leonardo da Vinci, 15th century
Animated heart
Elize Ryd making a heart sign at a concert in 2018
The tube-like heart (green) of the mosquito Anopheles gambiae extends horizontally across the body, interlinked with the diamond-shaped wing muscles (also green) and surrounded by pericardial cells (red). Blue depicts cell nuclei.
Basic arthropod body structure – heart shown in red
The human heart viewed from the front
The human heart viewed from behind
The coronary circulation
The human heart viewed from the front and from behind
Frontal section of the human heart
An anatomical specimen of the heart
Heart illustration with circulatory system
Animated Heart 3d Model Rendered in Computer

The heart receives nerve signals from the vagus nerve and from nerves arising from the sympathetic trunk.

The vagus nerve of the parasympathetic nervous system acts to decrease the heart rate, and nerves from the sympathetic trunk act to increase the heart rate.

Autonomic nervous system innervation.

Autonomic nervous system

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Division of the peripheral nervous system that supplies smooth muscle and glands, and thus influences the function of internal organs.

Division of the peripheral nervous system that supplies smooth muscle and glands, and thus influences the function of internal organs.

Autonomic nervous system innervation.
Autonomic nervous system, showing splanchnic nerves in middle, and the vagus nerve as "X" in blue. The heart and organs below in list to right are regarded as viscera.
Function of the autonomic nervous system
A flow diagram showing the process of stimulation of adrenal medulla that makes it release adrenaline, that further acts on adrenoreceptors, indirectly mediating or mimicking sympathetic activity.

The autonomic nervous system has three branches: the sympathetic nervous system, the parasympathetic nervous system and the enteric nervous system.

The parasympathetic division has craniosacral “outflow”, meaning that the neurons begin at the cranial nerves (specifically the oculomotor nerve, facial nerve, glossopharyngeal nerve and vagus nerve) and sacral (S2-S4) spinal cord.

The human heart

Heart rate

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Speed of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm).

Speed of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm).

The human heart
Autonomic Innervation of the Heart – Cardioaccelerator and cardioinhibitory areas are components of the paired cardiac centers located in the medulla oblongata of the brain. They innervate the heart via sympathetic cardiac nerves that increase cardiac activity and vagus (parasympathetic) nerves that slow cardiac activity.
Effects of Parasympathetic and Sympathetic Stimulation on Normal Sinus Rhythm – The wave of depolarization in a normal sinus rhythm shows a stable resting HR. Following parasympathetic stimulation, HR slows. Following sympathetic stimulation, HR increases.
Heart rate (HR) (top trace) and tidal volume (Vt) (lung volume, second trace) plotted on the same chart, showing how heart rate increases with inspiration and decreases with expiration.
The various formulae provide slightly different numbers for the maximum heart rates by age.
Fox and Haskell formula; widely used.
At 21 days after conception, the human heart begins beating at 70 to 80 beats per minute and accelerates linearly for the first month of beating.
Wrist heart rate monitor
Heart rate monitor with a wrist receiver
ECG-RRinterval
In obstetrics, heart rate can be measured by ultrasonography, such as in this embryo (at bottom left in the sac) of 6 weeks with a heart rate of approximately 90 per minute.
Pulsatile retinal blood flow in the optic nerve head region revealed by laser Doppler imaging

While heart rhythm is regulated entirely by the sinoatrial node under normal conditions, heart rate is regulated by sympathetic and parasympathetic input to the sinoatrial node.

The accelerans nerve provides sympathetic input to the heart by releasing norepinephrine onto the cells of the sinoatrial node (SA node), and the vagus nerve provides parasympathetic input to the heart by releasing acetylcholine onto sinoatrial node cells.

Diagram of the human lungs with the respiratory tract visible, and different colours for each lobe

Lung

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The lungs are the primary organs of the respiratory system in humans and most animals, some fish and some snails.

The lungs are the primary organs of the respiratory system in humans and most animals, some fish and some snails.

Diagram of the human lungs with the respiratory tract visible, and different colours for each lobe
Cross-sectional detail of the lung
Thick elastic fibres from the visceral pleura (outer lining) of lung
TEM image of collagen fibres in a cross sectional slice of mammalian lung tissue.
A lobule of the lung enclosed in septa and supplied by a terminal bronchiole that branches into the respiratory bronchioles. Each respiratory bronchiole supplies the alveoli held in each acinus accompanied by a pulmonary artery branch.
Alveoli and their capillary networks.
3D Medical illustration showing different terminating ends of bronchioles.
The lungs as main part of respiratory tract
3D rendering of a high-resolution CT scan of the thorax. The anterior thoracic wall, the airways and the pulmonary vessels anterior to the root of the lung have been digitally removed in order to visualize the different levels of the pulmonary circulation.
Lungs during development, showing the early branching of the primitive bronchial buds
The effect of the respiratory muscles in expanding the rib cage.
Tissue death of the lung due to a pulmonary embolism
3D still image of constricted airways as in bronchial asthma.
Lung tissue affected by emphysema using H&E stain.
On inhalation, air travels to air sacs near the back of a bird. The air then passes through the lungs to air sacs near the front of the bird, from where the air is exhaled.
The cross-current respiratory gas exchanger in the lungs of birds. Air is forced from the air sacs unidirectionally (from left to right in the diagram) through the parabronchi. The pulmonary capillaries surround the parabronchi in the manner shown (blood flowing from below the parabronchus to above it in the diagram). Blood or air with a high oxygen content is shown in red; oxygen-poor air or blood is shown in various shades of purple-blue.
The axolotl (Ambystoma mexicanum) retains its larval form with gills into adulthood
Book lungs of spider (shown in pink)
thumb|Chest CT (axial lung window)
thumb|Chest CT (coronal lung window)

Input from the parasympathetic nervous system occurs via the vagus nerve.

Left View of the human brain from below, showing origins of cranial nerves. Right Juxtaposed skull base with foramina in which many nerves exit the skull.

Cranial nerves

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Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs.

Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs.

Left View of the human brain from below, showing origins of cranial nerves. Right Juxtaposed skull base with foramina in which many nerves exit the skull.
The oculomotor (III), troclear (IV) and abducens (VI) nerves supply the muscle of the eye. Damage will affect the movement of the eye in various ways, shown here.
The facial nerve (VII) supplies the muscles of facial expression. Damage to the nerve causes a lack of muscle tone on the affected side, as can be seen on the right side of the face here.
A damaged glossopharyngeal nerve (IX) may cause the uvula to deviate to the affected side.
The cranial nerves in the horse.
Ventral view of a sheep's brain. The exits of the various cranial nerves are marked with red.

The nerves are: the olfactory nerve (I), the optic nerve (II), oculomotor nerve (III), trochlear nerve (IV), trigeminal nerve (V), abducens nerve (VI), facial nerve (VII), vestibulocochlear nerve (VIII), glossopharyngeal nerve (IX), vagus nerve (X), accessory nerve (XI), and the hypoglossal nerve (XII).

Additional ganglia for nerves with parasympathetic function exist, and include the ciliary ganglion of the oculomotor nerve (III), the pterygopalatine ganglion of the maxillary nerve (V2), the submandibular ganglion of the lingual nerve, a branch of the facial nerve (VII), and the otic ganglion of the glossopharyngeal nerve (IX).

Course of the left recurrent laryngeal nerve

Recurrent laryngeal nerve

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Course of the left recurrent laryngeal nerve
Passing under the subclavian artery, the right recurrent laryngeal nerve has a much shorter course than the left which passes under the aortic arch and ligamentum arteriosum.
Recurrent laryngeal nerve visible during resection of a goitre

The recurrent laryngeal nerve (RLN) is a branch of the vagus nerve (cranial nerve X) that supplies all the intrinsic muscles of the larynx, with the exception of the cricothyroid muscles.

Parasympathetic fibers to segments of the trachea and esophagus in the neck originate in the dorsal nucleus of the vagus nerve.

The digestive tract, with the esophagus marked in red

Esophagus

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Organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the stomach.

Organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the stomach.

The digestive tract, with the esophagus marked in red
The esophagus is constricted in three places.
A mass seen during an endoscopy and an ultrasound of the mass conducted during the endoscopy session.

Its smooth muscle is innervated by involuntary nerves (sympathetic nerves via the sympathetic trunk and parasympathetic nerves via the vagus nerve) and in addition voluntary nerves (lower motor neurons) which are carried in the vagus nerve to innervate its striated muscle.

Sinoatrial node shown at 1. The rest of the conduction system of the heart is shown in blue.

Sinoatrial node

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Group of cells known as pacemaker cells, located in the wall of the right atrium of the heart.

Group of cells known as pacemaker cells, located in the wall of the right atrium of the heart.

Sinoatrial node shown at 1. The rest of the conduction system of the heart is shown in blue.
Figure 2: Low magnification stained image of the SA node (center-right on image) and its surrounding tissue. The SA node surrounds the sinoatrial nodal artery, seen as the open lumen. Cardiac muscle cells of the right atrium can be seen to the left of the node, and fat tissue to the right.
Figure 3: Sinoatrial node action potential waveform, outlining major ion currents involved (downward deflection indicates ions moving into the cell, upwards deflection indicates ions flowing out of the cell).
Schematic representation of the atrioventricular bundle

This is a result of the activity of two sets of nerves, one acting to slow down action potential production (these are parasympathetic nerves) and the other acting to speed up action potential production (sympathetic nerves).

The parasympathetic nerves supplying the SA node (in particular the Vagus nerves) originate in the brain.

Acetylcholine

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Organic chemical that functions in the brain and body of many types of animals (including humans) as a neurotransmitter.

Organic chemical that functions in the brain and body of many types of animals (including humans) as a neurotransmitter.

Acetylcholine pathway.
Acetylcholine processing in a synapse. After release acetylcholine is broken down by the enzyme acetylcholinesterase.
Muscles contract when they receive signals from motor neurons. The neuromuscular junction is the site of the signal exchange. The steps of this process in vertebrates occur as follows: (1) The action potential reaches the axon terminal. (2) Calcium ions flow into the axon terminal. (3) Acetylcholine is released into the synaptic cleft. (4) Acetylcholine binds to postsynaptic receptors. (5) This binding causes ion channels to open and allows sodium ions to flow into the muscle cell. (6) The flow of sodium ions across the membrane into the muscle cell generates an action potential which induces muscle contraction. Labels: A: Motor neuron axon B: Axon terminal C: Synaptic cleft D: Muscle cell E: Part of a Myofibril
Components and connections of the parasympathetic nervous system.
Micrograph of the nucleus basalis (of Meynert), which produces acetylcholine in the CNS. LFB-HE stain.

Acetylcholine is also a neurotransmitter in the autonomic nervous system, both as an internal transmitter for the sympathetic nervous system and as the final product released by the parasympathetic nervous system.

The concept of neurotransmitters was unknown until 1921, when Otto Loewi noted that the vagus nerve secreted a substance that inhibited the heart muscle whilst working as a professor in the University of Graz.

Nuclei of origin of cranial motor nerves schematically represented; lateral view. ("X" visible at bottom center.)

Dorsal nucleus of vagus nerve

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Nuclei of origin of cranial motor nerves schematically represented; lateral view. ("X" visible at bottom center.)
Section of the medulla oblongata at about the middle of the olive.
The cranial nerve nuclei schematically represented; dorsal view. Motor nuclei in red; sensory in blue.
Dorsal motor nucleus of Vagus with Lewy body pathology

The dorsal nucleus of vagus nerve (or posterior nucleus of vagus nerve or dorsal vagal nucleus or nucleus dorsalis nervi vagi or nucleus posterior nervi vagi) is a cranial nerve nucleus for the vagus nerve in the medulla that lies ventral to the floor of the fourth ventricle.

It mostly serves parasympathetic vagal functions in the gastrointestinal tract, lungs, and other thoracic and abdominal vagal innervations.