What are six cranial nerves that provide the innervation for both swallowing and speech?
1. CN. V The Trigeminal Nerve
2. CN. VII The Facial Nerve
3. CN. IX The Glossopharygeal Nerve
4. CN. X The Vagus Nerve
5. CN. XI The Spinal Accessory Nerve
6. CN. XII The Hypoglossal Nerve
CN. V The Trigeminal Nerve
The efferent portion of the trigeminal nerve innervates the muscles involved in chewing and the muscle which tenses the velum. It helps in raising the larynx and pulling it forward during the pharyngeal swallow.
The trigeminal nerve carries feedback about all kinds of sensation, except taste, from the anterior 2/3 of the tongue.
CN. V also carries sensory information from the face, mouth and mandible.
CN. VII The Facial Nerve
The facial innervates the lip muscles to contract during the oral preparatory and oral transport stages of the swallow to prevent food from dribbling out of the mouth. The facial also innervates the buccinator muscles of the cheeks to prevent the pocketing of food between the teeth and the cheeks.
The facial carries information about taste from the anterior 2/3 of the tongue.
CN. IX The Glossopharygeal Nerve
It innervates the 3 salivary glands in the mouth. The saliva from these glands mixes with the chewed up food to form a bolus. Also, along with the vagus (CN. X), it provides some innervation to the upper pharyngeal constrictor muscles.
It helps to elevate the larynx and pulls it forward during the pharyngeal stage of the swallow. This action also aids in the relaxation and opening of the cricopharyngeus muscle.
The glossopharyngeal nerve mediates all sensation, including taste, from the posterior 1/3 of the tongue.
CN. IX also carries sensation from the velum and the superior portion of the pharynx.
CN. X The Vagus Nerve
The vagus is responsible for raising the velum.
Along with CN. IX it innervates the pharyngeal constrictor muscles.
The vagus along with CN. XI innervates the intrinsic musculature of the larynx and is responsible for vocal fold adduction during the swallow.
The vagus also innervates the cricopharyngeus muscle and controls the muscles involved in the esophageal stage of the swallow as well as those that control respiration. (This is the only cranial nerve that influences structures inferior to the neck.)
The vagus carries sensory information from the velum and posterior and inferior portions of the pharynx.
The vagus also mediates sensation in the larynx.
CN. XI The Spinal Accessory Nerve
CN. XI helps to depress the velum, constrict the pharynx, and tense the velum.
Along with CN.X, it innervates the levator veli palatini (to raise the velum).
(CN. XI is strictly a motor nerve.)
CN. XII The Hypoglossal Nerve
The hypoglossal innervates all extrinsic and intrinsic tongue muscles
(It is strictly a motor nerve.)