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One of the many incredible benefits of vagus nerve stimulation (VNS) that some people experience is a boost in their mood. In fact, people with treatment-resistant depression, anxiety, and PTSD have been using medical VNS for years withexcellent results. To better understand why these effects are possible, it's helpful to have a comprehensive understanding of the vagus nerve, and that's what we're going to provide you today as we explore the anatomy of the vagus nerve in detail.
Before we get into the gross anatomy of the vagus nerve, let's begin with an overview of what it is, what it does, and how it does what it does.
The vagus nerve is the longest in the body, originating from the brainstem and extending into the abdomen. It hasten terminal branches, and once you read about them, the function(s) of the vagus nerve becomes a lot more apparent:
The vagus nerve has multiple functions, including regulating heart rate, digestion, breathing, salivation, sweating, swallowing, and speaking. It also plays a vital role in keeping our moods stable and helping us to stay relaxed and calm. Based on all of the branches of the vagus nerve, you can start to see how things like heart rate, speech, and digestion can be connected to it.
Now let's get into the finer details of vagus nerve anatomy.
Specifically, we'll tell you about the following:
The vagus nerve is the longest of the twelve cranial nerves. Its main function is to send information from the brain to the organs in order to regulate them.
The other eleven cranial nerves are the olfactory nerve (I), 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, accessory or spinal accessory nerves, and hypoglossal nerve.
Here's a quick recap of each of these cranial nerves:
Notably, while many of these cranial nerves serve specific functions, the vagus nerve has many functions. As we explore the anatomy of the vagus nerve, it will become clear just how extensive this nerve and its functions genuinely are.
The vagus nerve begins at the jugular fossa, a shallow depression located at the base of the skull. Here, it has two main terminal branches: meningeal and auricular.
The meningeal branch is a branch of the vagus nerve responsible for supplying the dura mater with sensory information. In contrast, the auricular branch provides sensory innervation to various structures in the ear.
The vagus nerve also has four branches that pass through the neck: the pharyngeal branches, superior laryngeal nerves, recurrent laryngeal nerves, and the superior cardiac nerves.
There are also four vagal branches in the thorax: the inferior cardiac nerve, anterior bronchial, posterior bronchial, and the esophageal branches.
The left and right vagus nerve also begin to take different paths at this point.
Finally, the vagus nerve also has all-important branches in the abdomen: the gastric, celiac, and hepatic branches.
The celiac branch supplies vagus nerve fibers to the celiac ganglion, sending them to various abdominal organs, including the pancreas and spleen. For example, vagus nerve fibers supply motor and autonomic innervation to the stomach as well as gastrointestinal smooth muscle. This relates to the gut-brain axis, which is a critical vagus nerve pathway that is involved in its ability to improve mood and symptoms of mental health disorders.
Read more about this gut-brain and vagus nerve connectionhere.
The hepatic branch provides parasympathetic innervation to the liver, gallbladder, and biliary tract to perform their respective functions.
The gastric branches are worth explaining in abit more detail:
"The branches of the right vagus nerve forms the posterior gastric plexus on the posteroinferior surface of thestomach, while the branches of the left vagus nerve forms the anterior gastric plexus on the antero-superior surface of the stomach. Both of the divisions run between the layers oflesser omentum.
The fibers from the anterior gastric extend as far as the pylorus and the upper part of the duodenum, while posterior vagal trunk, in addition to posterior gastric branches, sends fibers to major abdominal autonomic plexus from which vagal fibers are distributed to the territories of celiac, renal and superior mesenteric arteries."
With the gross anatomy of the vagus nerve out of the way, let's look at the vagus nerve in even greater detail, starting with its microscopic anatomy.
As this2015 report explains, the vagus nerve carries five different fiber types: general somatic afferent, general visceral afferent, special visceral afferent, general visceral efferent, and special visceral efferent fibers.
The vagus nerve transmits its fibers to many different parts of the body. Again, as the longest of the cranial nerves, the vagus nerve has a wide distribution throughout the body and is involved in many important physiological functions.
Its main targets are the diaphragm, heart, lungs, gastrointestinal tract, and liver. It also supplies vagal fibers to structures of the neck, such as the larynx and pharynx, for speech production and swallowing. The vagus nerve also supplies autonomic innervation to various organs, such as:
Another interesting vagus nerve function is its role in the cough reflex. Stimulation of vagal afferents, a branch of vagus nerve fibers located within the respiratory tract, triggers a coughing response.
This response is mediated through vagal pathways, which activate various muscles in the larynx and pharynx to create an airflow that can expel foreign particles from the respiratory system. The vagus nerve thus plays an important role in defending our lungs against invasion by bacteria or other hazardous substances.
The vagus nerve also helps regulate respiration by sending signals to nearby muscles responsible for controlling the rate and depth of breathing. This makes it an integral part of the autonomic nervous system's control over cardiovascular and respiratory functions.
There are numerous ongoing vagus nerve studies, with a particular focus on how vagal stimulation can help treat mental health disorders.
A few clinical trials currently underway include:
There are alsoFDA-approved uses for VNS, including treating epilepsy and depression. As research continues to uncover new insights into vagus nerve anatomy, there may soon be even more applications for vagal stimulation as a potential therapeutic option. In the meantime, however, vagal stimulation remains a powerful tool for promoting mental health and wellness.
The vagus nerve is a complex network of nerves that plays a crucial role in our physiology. Its anatomy is responsible for both motor and sensory functions, allowing it to play a key part in numerous bodily activities. It also has implications for mental health, with vagal stimulation used as a treatment for various psychological disorders. As research continues to reveal more about vagus nerve anatomy, we can hope to uncover even more ways this important cranial nerve can be harnessed to promote physical and mental health.
To try VNS for yourself, give the Xen byNeuvana vagus nerve stimulation device a try. It allows you to explore the benefits of vagus nerve stimulation in a non-invasive and comfortable manner.