The cranial nerves are composed of twelve pairs of nerves that emanate from the nervous tissue of the brain. In order to reach their targets they must ultimately exit/enter the cranium through openings in the skull. Hence, their name is derived from their association with the cranium.
Multiple etiologies can produce symptoms. This review will broadly examine the normal functions, clinical examination, and various pathologies of cranial nerves IX and X. Keywords: Glossopharyngeal, Vagus, cranial nerve disorders, dysphonia, dysphagia
Defects may occur anywhere from the brainstem to the peripheral nerve and can result in significant impairment in speech, swallowing, and breathing. Multiple etiologies can produce symptoms. This review will broadly examine the normal functions, clinical examination, and various pathologies of cranial nerves IX and X.
The nuclei of cranial nerves IX and X receive bilateral input from the cortex, and unilateral lesions are often asymptomatic. Bilateral lesions of the corticobulbar tracts result in pseudobulbar palsy. Symptoms include slow, dysarthric speech and variable dysphagia, while pharyngeal and palatal reflexes remain intact.
The trigeminal nerveThe trigeminal nerve (V) is the largest cranial nerve, and it has both a sensory and a motor division. The motor division of the trigeminal nerve, which has its own nucleus located in the pons, innervates the “muscles of mastication” and also the tensor muscle of the tympanic membranes of the ear.
The trigeminal nerve is the largest cranial nerve and has both motor and sensory functions. Its motor functions help a person to chew and clench the teeth.
Trigeminal neuralgia is caused by irritation of the trigeminal nerve, which starts at the ear and branches out to the forehead, cheeks, and lower jaw. Pain from this disorder is usually limited to one side of the face and can be triggered by actions such as eating or brushing teeth.
Trigeminal NerveMotor and sensory nerve-Trigeminal Nerve-Carries sensory information from most of the head, neck, sinuses, and face. Also carries sensory information for ear and tympanic membrane. Provides motor supply to the muscles of masticulation (chewing), and to some of the muscles on the floor of the mouth.
Cranial nerve VIII brings sound and information about one's position and movement in space into the brain. The auditory and vestibular systems subserve several functions basic to clinical medicine and to psychiatry.
The facial nerve is the 7th cranial nerve and carries nerve fibers that control facial movement and expression. The facial nerve also carries nerves that are involved in taste to the anterior 2/3 of the tongue and producing tears (lacrimal gland).
A trigeminal nerve injury may affect a small area, like part of your gum, or a large area, like one side of your face. The injury can cause problems with chewing and speaking. The extent depends on where the nerve damage occurs. You may have ongoing numbness or facial pain in the area that the nerve serves.
Sixth nerve palsy occurs when the sixth cranial nerve is damaged or doesn't work right. This causes problems with eye movement. The affected eye may not be able to move away from the midline normally. Sometimes, only the sixth cranial nerve has problems.
Activation of CN VII causes the entire left side of the face to move. Bell's Palsy, or a true left CN VII paralysis causes paralysis of the entire left side of the face. This includes loss of the ability to wrinkle the left forehead on the affected side.
The optic nerve is the second cranial nerve (CN II) responsible for transmitting visual information. The optic nerve contains only afferent (sensory) fibers, and like all cranial nerves is paired.
It innervates the muscles of mastication: medial pterygoid, lateral pterygoid, masseter and temporalis. The mandibular nerve also supplies other 1st pharyngeal arch derivatives: anterior belly of digastric, mylohyoid, tensor veli palatini and tensor tympani.
Muscles of masticationMasseter.Temporalis.Lateral pterygoid.Medial pterygoid.
The vagus nerve contains visceral efferent and afferent fibers and innervates the head, neck, thorax, and abdomen.3The efferent motor fibers of the vagus nerve supply all striated muscles of the larynx and pharyx, except the stylopharyngeus (supplied by IX) and the tensor veli palatini (supplied by V3).
The vagus nerve receives sensory input from the larynx, pharynx, external auditory canal, lateral aspect of the tympanic membrane, and the meninges of the posterior fossa.6Subglottic sensation is mediated by the recurrent laryngeal nerve, whereas the internal branch of the superior laryngeal nerve mediates sensation from the supraglottis. Glottic sensation likely involves both nerves. The vagus nerve also receives general visceral afferent information from the trachea, bronchi, lungs, heart, aortic arch, esophagus, and abdominal viscera.3The vagus nerve also supplies parasympathetic innervation to smooth muscle and glands of the pharynx, larynx, and thoracic and abdominal viscera.
The glossopharyngeal (IX) and vagus (X) nerves mediate the complex interplay between the many functions of the upper aerodigestive tract. Swallowing, breathing , and communicating all rely on delicate interactions between the sensory inputs and motor outputs of many of the cranial nerves. These processes are individually crucial to a patient’s basic vital functions; that each must work in perfect concert in a narrow anatomical space speaks to the important roles of cranial nerves IX and X.
The glossopharyngeal and vagus nerves mediate the complex interplay between the many functions of the upper aerodigestive tract. Defects may occur anywhere from the brainstem to the peripheral nerve and can result in significant impairment in speech, swallowing, and breathing. Multiple etiologies can produce symptoms.
Patients with deficits in the glossopharyngeal or vagus nerves may present with dysphagia, dysphonia, dyspnea, or a combination of these symptoms. Many symptoms are subtle and overlap with other disease processes, sometimes making diagnoses elusive.
Patients with dysfunction of the vagus nerve may present with dysphagia, hoarseness, or dyspnea, while patients with an isolated glossopharyngeal lesion may remain asymptomatic because of redundancy in the motor output of the nerve. Often, the two nerves are affected in concert given their anatomic proximity.
Asking the patient to recite passages that are highly difficult to articulate, such as “lips teeth tip of the tongue”, can differentiate between dysphonic and dysarthric problems. Examination of the oral cavity, including anatomical features and movement patterns of the lips, palate, and tongue will also guide diagnosis for patients presenting with dysarthria.10
The abducent nerve enervates a muscle, which moves the eyeball. The facial nerve enervates the muscles of the face (facial expression). The vestibulocochlear nerve is responsible for the sense of hearing and balance (body position sense). The glossopharyngeal nerve enervates muscles involved in swallowing and taste.
The trochlear nerve controls an extraocular muscle. The trigeminal nerve is responsible for sensory enervation of the face and motor enervation to muscles of mastication (chewing). The abducent nerve enervates a muscle, which moves the eyeball. The facial nerve enervates the muscles of the face (facial expression).
The vagus nerve enervates the gut ( gastrointestinal tract ), heart and larynx. The accessory nerve enervates the sternocleidomastoid muscles and the trapezius muscles. The hypoglossal nerve enervates the muscles of the tongue.
The olfactory nerve carries impulses for the sense of smell. The optic nerve carries impulses for the sense of sight. The occulomotor nerve is responsible for motor enervation of upper eyelid muscle, extraocular muscle and pupillary muscle. The trochlear nerve controls an extraocular muscle.
The following are the list of cranial nerves, their functions, and tumor examples: The olfactory nerve carries impulses for the sense of smell.
D. Patient calls their primary-care provider (PCP) instead of 911 at sign of stroke.
D. Polypharmacy is a major contributor to confusion in older adults.
Which statement about confusion is true?#N#A. Confusion is a disease process .#N#B. Confusion is always temporary.#N#C. Age is a reliable predictor of confusion.#N#D. Polypharmacy is a major contributor to confusion in older adults.