The trigeminal (V), facial (VII), glossopharyngeal (IX), vagus (X), and hypoglossal (XII) cranial nerves provide information from the swallowing center back to the muscles that aid in swallowing, with the trigeminal, hypoglossal, and nucleus ambiguus comprising the efferent levels. The vagus nerve also contains preganglionic fibers that can influence the behavior of swallowing.
The brain controls all aspects of swallowing including initiation, coordination of muscle movement, and reflexes. A region of the brain called the medulla oblongata is responsible for controlling these functions. The lower part of the medulla oblongata contains the nuclei of the swallowing center which sends signals via the spinal cord to other parts of the body to initiate swallowing. These nuclei include the inferior salivatory nucleus, the oral motor nucleus, and the dorsal nucleus of the vagus. The upper part of the medulla oblongata contains the nuclei of the respiratory center which regulates breathing. The trigeminal nerve passes through this area so it is also involved in regulating swallowing.
Swallowing is a complex series of movements controlled by several areas of the brain. The cerebellum helps control how quickly and smoothly muscles contract and relax during eating and drinking. The cerebral cortex controls voluntary movement and is responsible for planning and initiating swallowing. The basal ganglia help control involuntary bodily functions such as walking, talking, and swallowing.
The trigeminal (V), facial (VII), glossopharyngeal (IX), vagus (X), accessory (XI), and hypoglossal nerves are the cranial nerves linked with swallowing (XII). The trigeminal nerve is responsible for sensations of taste, pain, and temperature in the face. It also controls the muscles of the tongue. The facial nerve is responsible for moving the muscles of the face. The glossopharyngeal nerve carries sensory information from the throat and neck to the brain. The vagus nerve is responsible for controlling digestion and regulating body processes such as heart rate and blood pressure. The accessory nerve helps control the muscles of the ear. The hypoglossal nerve controls the muscles of the tongue.
Cranial nerve involvement can occur as a symptom or side effect of certain diseases or disorders. For example, people who develop amyotrophic lateral sclerosis (also known as Lou Gehrig's disease) may lose the ability to swallow and require artificial feeding through a tube placed into their stomach. The cause of this disorder is unknown but research suggests that both genetic factors and environmental toxins may play a role.
Swallowing is a complex function that involves many different structures and types of nerves.
Trigeminal Nerves and Muscles Involved in Swallowing (cranial nerve V) Facial expressions (cranial nerve VII) Glossopharyngeal (glossopharyngeal) Vagus Nerve (cranial nerve X) Phrenic Nerve (cranial nerve XI) Diaphragm (muscle)
The muscles of the face that control facial expressions are located in the brain. These nerves and muscles help control how fast the muscles of the throat move when swallowing. The vagus nerve carries sensory information about the position of the esophagus and the level of acidity in your stomach to the brain, where it is interpreted as pain or hunger. The vagus also carries certain reflexes that protect the lungs and heart.
The phrenic nerve carries motor signals from the brain to the diaphragm, the muscle that you use when you breathe. If you have pneumonia or some other illness that affects the breathing system, your doctor may prescribe medicine that restrains this nerve from sending messages to the diaphragm so that you can breathe more easily.
The vagus nerve connects with many other organs including the heart, lungs, and pancreas. It sends information about your body's acid-base balance to the brain, where it is interpreted as pain or hunger. It also carries certain reflexes that protect the lungs and heart.
Swallowing Requires Cranial Nerves and Muscles Swallowing happens in three stages, each of which necessitates the precise synchronization of muscles in the mouth, pharynx (your throat), larynx (your voice box), and esophagus (the tube that carries food from your throat to your stomach). The first stage is oral preparation. The second stage is oral transport. The third and final stage is esophageal expulsion.
The muscles responsible for these movements are controlled by nerves that originate in the brain and travel through canals in the skull to reach their destinations. The four major cranial nerves involved in swallowing are the facial nerve, which travels down from the brain to the face; the trigeminal nerve, which travels up from the brain to the face, jaw, and tongue; the vagus nerve, which travels down from the brain to the chest and abdomen; and the hypoglossal nerve, which travels down from the brain to the base of the skull and controls the muscles of the tongue.
In general, the more extensive the damage to the nervous system, the more serious the resulting dysphagia (difficulty swallowing). Damage to the motor neurons that control the muscles of the face, mouth, neck, or throat can lead to dysphasia if they also affect the nerves that control the breathing muscles.