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StatPearls . Treasure Island (FL): StatPearls Publishing; 2021 Jan-.


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Introduction

The laryngopharynx, likewise referred to as the hypopharynx, is the many caudal section of the pharynx and is a critical connection suggest through i beg your pardon food, water, and also air pass. Specifically, it describes the point at i beg your pardon the pharynx divides anteriorly into the larynx and also posteriorly right into the esophagus. The action of swallowing, or deglutination, is a complicated multistep procedure performed by several important structures in the oral cavity, pharynx, and also larynx. Swallowing ensures appropriate transport of food and also water posteriorly into the esophagus at the level that the laryngopharynx. Return the laryngopharynx’s primary physiologic role is as a cavity with which air, water, and food pass from the dental cavity come their respective destinations, it likewise contains structures that play vital role in speech. 

The laryngopharynx is a clinically vital anatomical location due to the fact that of the high proportion of pharyngeal cancers the originate there. The pyriform sinus is the most frequent site of laryngopharyngeal cancer, through squamous cabinet carcinoma accountancy for 95% of cases. The laryngopharynx is also clinically relevant because of a disorder concerned the retrograde flow of cradle stomach contents to the laryngopharynx, recognized as laryngopharyngeal reflux (LPR). 


Structure and also Function

STRUCTURE:

The pharynx is situated posteriorly to the nasal and oral cavities and functions as a cavity v which food and also air happen to the esophagus and also larynx, respectively. The pharynx is comprised of three different regions: the nasopharynx, oropharynx, and laryngopharynx.

Nasopharynx:

The nasopharynx is the many rostral section of the pharynx and refers to the an ar between the basic of the cranium and also the soft palate. It consists of the opened of the Eustachian tubes that attach the pharynx come the center ear. It likewise includes the adenoids and tubal tonsils, which space lymphoid tissues the play an essential role in the immune system.

Oropharynx:

The oropharynx is posterior come the oral cavity, between the soft palate and also the pharyngoepiglottic fold. Necessary structures within the oropharynx encompass the soft palate, tonsils, basic of the tongue, and also pharyngeal bands, which space nodules of lymphoid tissue. The laryngopharynx is the last pharyngeal cavity and also is situated inferiorly come the oropharynx.<1>

Laryngopharynx (Hypopharynx):

The laryngopharynx;s place is inferior to the epiglottis and also is bordered by the pharyngoepiglottic fold superiorly and the top esophageal sphincter inferiorly. It describes the part of the pharynx wherein the cavity quarter anteriorly right into the larynx and also posteriorly right into the esophagus. It has three key structures: the posterior pharyngeal wall, pyriform sinuses, and also the post-cricoid area. The pyriform sinuses, i m sorry play vital role in speech, space two pear-shaped recesses situated on either next of the laryngeal orifice. Medially to the pyriform sinuses lied the aryepiglottic folds. Thyroid cartilage lies lateral come the laryngopharynx.<1>

The pharyngeal cavity is inside wall by mucosa and also is surrounding by skeleton muscle. The pharyngeal wall surface is comprised of three unique layers that tissue. The within layer the comes in direct call with the pharyngeal cavity is created of stratified squamous epithelium. Next, over there is the fascial layer, created of the pharyngo-basilar fascia. Back the fascial great is thick superiorly, it gradually decreases in thickness together it travels inferiorly, eventually disappearing by the time it will the upper esophageal sphincter. The upper esophageal sphincter additionally referred to as the worse pharyngeal sphincter, is consisted of of muscle that role in staying clear of the entry of air right into the esophagus and reflux of gastric components into the larynx and pharynx. It is made up mostly the cricopharyngeus muscle, together with thyropharyngeus muscle and cervical esophagus. Superficial come the fascial layer, over there is an outer muscular layer, which is created of constrictors and elevators responsible because that propelling food from the dental cavity to the esophagus.<2>

FUNCTION:

Structures located nearby to the laryngopharynx play an important role in ensuring suitable transit that food and liquids native the dental cavity to the stomach. Common swallowing physiology is an essential in preventing aspiration that food and also liquids into the lungs, which can lead to symptom such as pneumonia, acute respiratory tract distress syndrome, and also acute respiratory tract failure. The act of swallowing entails three stages: oral, pharyngeal, and esophageal. Throughout the pharyngeal stage, the soft palate elevates and also comes into contact with the posterior and also lateral walls of the pharynx, thereby closing turn off the nasopharynx and preventing regurgitation the food or liquids into the sleep cavity. The contraction of the pharyngeal constrictors propels the bolus downwards towards the esophagus. Food beginning the laryngopharynx is selectively driven posteriorly towards the stomach by several various mechanisms that are vital to ensuring adequate airway protection. Contraction of the thyrohyoid and also suprahyoid muscles cause the hyoid bone and also larynx to elevate and move anteriorly. The epiglottis slopes backward, in order to sealing turn off the larynx. The vocal crease close come seal-off the glottis. The arytenoids tilt forward. Finally, the upper esophageal sphincter relaxes, enabling entry the food and liquids into the esophagus.<3>


Embryology

The pharynx and oral cavity derive from the branchial apparatus start in the fourth and fifth mainly of development. The embryonic pharynx creates into the branchial apparatus, i m sorry is written of five pairs that pouches, arches, and clefts. These frameworks eventually construct into almost every one of the structures within the head and neck. The pouches are located medially and eventually kind into endoderm. The clefts are located laterally and also develop right into ectoderm. The arcs are situated in between the pouches and clefts and also develop into the mesoderm, which eventually forms the cartilage, muscles, and nerves that the head and neck. The fourth and sixth arcs develop right into the cartilaginous frameworks that consist of the larynx, which includes the arytenoids, cricoid, cuneiform, and also thyroid cartilage. The fourth arch develops into most of the pharyngeal constrictors, the cricothyroid muscle, and also the levator veli palatini muscle. The fourth arch also develops right into the premium laryngeal branch the the Vagus nerve (CN 10).<4>


Blood Supply and also Lymphatics

The blood it is provided to the laryngopharynx is via the ascending pharyngeal artery, worse thyroid artery, and superior thyroid artery. The ascending pharyngeal artery branches medially off of the external carotid artery (ECA) and courses in between the ECA and internal carotid artery together it ascends in the direction of the pharynx. The superior thyroid artery originates indigenous the ECA in ~ the level of the carotid bifurcation. The inferior thyroid artery establishes from the thyrocervical trunk and also eventually anastomoses through the exceptional thyroid artery. 

The venous drainage the the pharynx is via the venous plexus that drains straight into the interior jugular veins.<5>


Nerves

The Vagus nerve and its branches supply the pharyngeal constrictors. The nucleus of cranial nerve X (CN X) is in the medulla in the brainstem. It exits the skull via the jugular foramen prior to synapsing at the pharyngeal plexus.<5> The pharyngeal plexus, i m sorry lies along with the center constrictor, is created mostly native cranial nerves IX and also X, v some innervation by the maxillary circulation of the trigeminal nerve (CN V2). The plexus consists of both sensory and motor neurons. Sensory innervation of the laryngopharynx begins in pharyngeal branches the the vagus nerve, which eventually synapse in ~ the pharyngeal plexus.<6> Arnold\"s nerve, a branch the the vagus nerve, also has sensory branches that supply the outside auditory canal. Therefore, patients with laryngeal cancer deserve to have advert otalgia.


Muscles

Pharyngeal constrictors surround the pharynx posteriorly and also laterally, conference midline at the posterior raphe. The pharyngeal constrictors are consisted of of three circularly oriented muscles, the superior, medial, and inferior constrictors, that duty to propel food and also water native the oropharynx with the laryngopharynx, and also on to the esophagus. Back oriented circularly around the pharynx, constrictors room arranged longitudinally, i beg your pardon aids in maintaining the airway in ~ the pharynx. 

Elevator muscles, which encompass the palatopharyngeus, stylopharyngeus, and salpingopharyngeus, assist in swallowing by pulling the larynx increase behind the base of the tongue, thereby protecting the airway. Elevation that the laryngopharynx also functions in shortening the pharynx during swallowing to boost the passage of food and also liquids.<7>

The particular constrictor muscle the is in the vicinity the the laryngopharynx is the worse constrictor, i m sorry is composed of two muscles: the thyropharyngeus and also cricopharyngeus. The thyropharyngeus muscle is exceptional to the cricopharyngeus and also lies laterally and posteriorly to the laryngopharynx. Relaxation the the cricopharyngeus and also thyropharyngeus enable pharyngeal contents to get in the esophagus.<5>


Surgical Considerations

Laryngopharyngectomy:

Laryngopharyngectomy, complete removal the the larynx and also hypopharynx, is generally reserved together salvage therapy following chemoradiation or for patients with progressed cancers the the hypopharynx or larynx. The main treatment for patients with laryngopharyngeal cancer is radical radiotherapy and/or chemotherapy, together these room organ-preserving treatment modalities.<8><9> If the laryngopharyngectomy is because that the therapy of laryngopharyngeal cancer, that is additionally recommended come dissect the bilateral level II-IV neck lymph nodes. Neck dissection offer two necessary purposes: (1) recognize the level of nodal involvement and (2) to accessibility vessels supplied in free flap reconstruction.<10>

Surgical Fundoplication in Laryngopharyngeal Reflux:

Nissen fundoplication is a surgical treatment classically provided in the therapy of gastroesophageal reflux disease (GERD) through which the upper part of the stomach, known as the fundus, is wrapped approximately the stomach to reinforce the lower esophageal sphincter. Some studies have demonstrated success in dealing with laryngopharyngeal reflux (LPR) v fundoplication in a subset of pick patients.<11> Treatment that LPR involves a combination of dietary and lifestyle changes, and proton pump inhibitors (PPI). Although 50-70% the patients boost with PPIs, countless patients still endure from laryngeal irritation in spite of high dose PPI treatment.<12><13> Researchers hypothesize that patients that fail to boost on PPI therapy may benefit from fundoplication under the premise that reinforcement the the lower esophageal sphincter (LES) might prevent short volume reflux of acid or nonacid gastric content.<14> However, a prospective regulated trial demonstrated limited improvement in laryngeal symptom one year following fundoplication surgery for LPR.<15>


Clinical Significance

Cancer:

Studies have presented that 72% to 87% that pharyngeal cancers to happen in the laryngopharynx, frequently referred to as hypopharyngeal cancer in the literature.<16><17> The pyriform sinus has actually the highest proportion of these cancers (78.3%), adhered to by the posterior pharyngeal wall surface (14%), and also then the post-cricoid area (8%).<16> Cancers of the hypopharynx account because that 6% of all cancer that the head and neck, more 보다 95% of which space squamous cabinet carcinoma.<18> various other hypopharyngeal cancers incorporate spindle cell carcinoma, salient gland carcinoma, and also basaloid squamous carcinoma.<19>

Hypopharyngeal cancers space dangerous since of your late presentation and also predilection for metastasizing, with much more than 85% the cancers have actually spread past the laryngopharynx at the moment of diagnosis. The most common site the metastasis (65%) is to local lymph nodes. Cancer of the hypopharynx is a devastating diagnosis, with a 5-year survival rate as low as 29%.<19> The main risk factors are alcohol consumption and smoking, although other environmental exposures such as asbestos, at home air pollution, and coal dust additionally have web links to hypopharyngeal cancer.<20><21><22>

Hypopharyngeal cancer can existing with dysphagia, a significant neck mass, voice impairment, hoarseness, and/or referred otalgia. Therapy is a complex multidisciplinary decision that involves collaboration among medical oncologists, radiation oncologists, and head and neck surgeons. The is a highly controversial topic due to the fact that there is no uniform consensus for the best technique to treatment.<23> Treatment choices include radiation, chemotherapy, surgery, or a combination thereof, with surgical treatment being the preferred therapeutic option.<24> The score of treatment is to obtain local tumor manage while simultaneously maintaining the function of the many important structures located surrounding to the laryngopharynx, which is connected in speech, swallowing, and respiration. In situations of advanced disease, laryngectomy or laryngopharyngectomy might necessary.

Laryngopharyngeal reflux:

Laryngopharyngeal reflux (LPR) is a highly controversial topic because of a disagreement among otolaryngologists and also gastroenterologists about its pathophysiology. Otolaryngologists think that LPR is because of retrograde flow of digestive stomach components to the laryngopharynx, causing mucosal injury and also irritation.<25> The pathophysiology of GERD is comparable in that it is as result of the reflux of gastric materials into the esophagus. Interestingly, LPR hardly ever presents through heartburn (20%) or regurgitation, also though the acid and also other corrosive stomach components must traverse the esophagus to with the larynx. Gastroenterologists argue the low comorbidity the GERD amongst patients with LPR signifies the an alternating etiology need to exist.

LPR is one of the most common presentations in otolaryngology clinics, with some research studies demonstrating as plenty of as 10% of visits because of symptoms an additional to LPR.<26> LPR presents through symptoms that cough, hoarseness, neck clearing, and globus sensation.<25> It is a an overwhelming diagnosis come make due to nonspecific symptoms the mimic plenty of other conditions that affect the larynx, including allergies, vocal abuse, smoking, infections, and also alcohol abuse.<27><28> More than half of patient presenting with hoarseness have some type of the reflux-associated disease.<29><30> Complications of LPR include subglottic stenosis, call ulcers, granulomas, and also lower airway disease, among others.<31> Diagnosis is frequently made based on a careful history.<25> Since LPR is connected with upper aerodigestive tract cancer, a full laryngopharyngeal check is necessary if LPR is suspected.<32><33>

Documenting response to treatment deserve to be a challenge since there are few objective physical test findings to determine the level of disease. Belafsky et al. Developed the Reflux Symptom Index, an LPR grading system designed to assist clinicians identify the relative effect of therapy in your LPR patients.<34> Another method for examining the severity the symptoms and also progression the the an illness is with acoustic voice analysis, which measures frequency, intensity, signal-to-noise ratio, and also perturbation in patients presenting v hoarseness.<29> Regardless, clinicians must often rely on subjective symptoms acquired in background as well as clinical judgment to assess response to treatment.

The an initial diagnostic test indicated is laryngoscopy, which typically shows nonspecific indications of laryngeal irritation that leads to redness, thickening, and edema confined to the posterior larynx.<28> Diagnosis have the right to be confirmed using three various approaches: endoscopic observation of damaged laryngopharyngeal tissue, pH security studies, or symptomatic an answer to empiric medical and behavioral therapy.<25>

Treatment that LPR is a combination of behavior alteration and medical treatment. Patient are often initially prescribed acid-suppressing medication, such as PPIs, to help in both treatment and diagnosis that LPR.<35> Other medical therapies incorporate H2 receptor antagonists, mucosal cytoprotectants, and prokinetic agents. Behavior alteration includes the avoidance the alcohol, smoking cigarettes cessation, and weight loss. Patients should likewise be instructed to prevent dietary triggers such together chocolate, carbonated beverages, citrus fruits, fats, red wines, caffeine, spicy tomato products, and also meals before bedtime.

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<36> If way of living changes and also medical treatment fail in regulating symptoms, patient with far-reaching reflux as result of lower esophageal sphincter incompetence can opt for surgical intervention. Although part otolaryngologists advocate for fundoplication, there is limited evidence demonstrating the efficacy in addressing symptoms of LPR.<15>