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


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Introduction

The laryngopharynx, likewise referred to together the hypopharynx, is the most caudal section of the pharynx and is a critical connection suggest through i m sorry food, water, and air pass. Special, it describes the point at which the pharynx divides anteriorly right into the larynx and posteriorly into the esophagus. The action of swallowing, or deglutination, is a complex multistep process performed through several vital structures in the oral cavity, pharynx, and also larynx. Swallowing ensures ideal transport of food and also water posteriorly into the esophagus at the level the the laryngopharynx. Back the laryngopharynx’s major physiologic function is together a cavity with which air, water, and food happen from the dental cavity come their particular destinations, it also contains structures that play crucial role in speech. 

The laryngopharynx is a clinically important anatomical location because of the high proportion of pharyngeal cancers that originate there. The pyriform sinus is the most constant site of laryngopharyngeal cancer, through squamous cabinet carcinoma accounting for 95% that cases. The laryngopharynx is likewise clinically relevant because of a disorder pertained to the retrograde circulation of cradle stomach contents to the laryngopharynx, well-known as laryngopharyngeal reflux (LPR). 


Structure and also Function

STRUCTURE:

The pharynx is located posteriorly to the nasal and oral cavities and functions together a cavity with which food and air happen to the esophagus and also larynx, respectively. The pharynx is consisted of of three separate regions: the nasopharynx, oropharynx, and also laryngopharynx.

Nasopharynx:

The nasopharynx is the many rostral part of the pharynx and also refers come the an ar between the base of the cranium and also the soft palate. It has the opening of the Eustachian tubes that attach the pharynx come the middle ear. It additionally includes the adenoids and also tubal tonsils, which are lymphoid tissues the play critical role in the immune system.

Oropharynx:

The oropharynx is posterior come the oral cavity, between the soft palate and also the pharyngoepiglottic fold. Important structures in ~ the oropharynx include the soft palate, tonsils, basic of the tongue, and pharyngeal bands, which space nodules that lymphoid tissue. The laryngopharynx is the final pharyngeal cavity and is located inferiorly to the oropharynx.<1>

Laryngopharynx (Hypopharynx):

The laryngopharynx;s place is inferior to the epiglottis and also is bordered through the pharyngoepiglottic wrinkles superiorly and also the upper esophageal sphincter inferiorly. It describes the part of the pharynx where the cavity diverges anteriorly right into the larynx and also posteriorly right into the esophagus. It has three main structures: the posterior pharyngeal wall, pyriform sinuses, and the post-cricoid area. The pyriform sinuses, which play an important role in speech, space two pear-shaped recesses located on either side of the laryngeal orifice. Medially to the pyriform sinuses lie the aryepiglottic folds. Thyroid cartilage lies lateral come the laryngopharynx.<1>

The pharyngeal cavity is lined by mucosa and is surrounded by bones muscle. The pharyngeal wall is comprised of three distinct layers of tissue. The within layer that comes in direct contact with the pharyngeal cavity is composed of stratified squamous epithelium. Next, there is the fascial layer, created of the pharyngo-basilar fascia. Back the fascial layer is special superiorly, it progressively decreases in thickness as it travel inferiorly, at some point disappearing by the moment it get the upper esophageal sphincter. The upper esophageal sphincter additionally referred to as the inferior pharyngeal sphincter, is comprised of muscle that role in avoiding the entry of air into the esophagus and reflux of gastric contents into the larynx and pharynx. The is consisted of mostly the cricopharyngeus muscle, together with thyropharyngeus muscle and cervical esophagus. Superficial to the fascial layer, there is an outer muscular layer, i m sorry is composed of constrictors and elevators responsible because that propelling food from the dental cavity come the esophagus.<2>

FUNCTION:

Structures located adjacent to the laryngopharynx play an important role in ensuring appropriate transit the food and liquids from the oral cavity come the stomach. Normal swallowing physiology is an important in preventing aspiration that food and also liquids right into the lungs, which could lead to complications such together pneumonia, acute respiratory distress syndrome, and acute respiratory failure. The action of swallowing entails three stages: oral, pharyngeal, and esophageal. Throughout the pharyngeal stage, the soft palate elevates and comes into call with the posterior and also lateral walls of the pharynx, thereby closing turn off the nasopharynx and also preventing regurgitation that food or liquids right into the nasal cavity. The contraction of the pharyngeal constrictors propels the bolus downwards in the direction of the esophagus. Food beginning the laryngopharynx is selectively pushed posteriorly in the direction of the esophagus by several different mechanisms the are an important to ensuring adequate airway protection. Contraction of the thyrohyoid and suprahyoid muscles reason the hyoid bone and also larynx come elevate and move anteriorly. The epiglottis slopes backward, in order to sealing turn off the larynx. The vocal wrinkle close to seal-off the glottis. The arytenoids tilt forward. Finally, the upper esophageal sphincter relaxes, enabling entry of food and also liquids right into the esophagus.<3>


Embryology

The pharynx and oral cavity have from the branchial apparatus start in the fourth and also fifth mainly of development. The embryonic pharynx establishes into the branchial apparatus, which is composed of 5 pairs of pouches, arches, and also clefts. These structures eventually construct into almost every one of the frameworks within the head and also neck. The pouches are located medially and also eventually form into endoderm. The clefts are located laterally and also develop into ectoderm. The arcs are located in in between the pouches and also clefts and develop into the mesoderm, which eventually forms the cartilage, muscles, and nerves that the head and also neck. The fourth and sixth arcs develop into the cartilaginous frameworks that comprise the larynx, which includes the arytenoids, cricoid, cuneiform, and thyroid cartilage. The fourth arch develops into most of the pharyngeal constrictors, the cricothyroid muscle, and the levator veli palatini muscle. The 4th arch likewise develops right into the superior 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, inferior thyroid artery, and also superior thyroid artery. The ascending pharyngeal artery branches medially off of the exterior carotid artery (ECA) and also courses in between the ECA and also internal carotid artery together it ascends in the direction of the pharynx. The premium thyroid artery originates native the ECA in ~ the level the the carotid bifurcation. The inferior thyroid artery creates from the thyrocervical trunk and also eventually anastomoses with the exceptional thyroid artery. 

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


Nerves

The Vagus nerve and its branches supply the pharyngeal constrictors. The cell nucleus of cranial nerve X (CN X) is in the medulla in the brainstem. It exits the skull via the jugular foramen before synapsing in ~ the pharyngeal plexus.<5> The pharyngeal plexus, i beg your pardon lies together with the center constrictor, is formed mostly from cranial nerves IX and also X, v some innervation through the maxillary circulation of the trigeminal nerve (CN V2). The plexus has both sensory and motor neurons. Sensory innervation that the laryngopharynx begins in pharyngeal branches of the vagus nerve, which eventually synapse at the pharyngeal plexus.<6> Arnold\"s nerve, a branch the the vagus nerve, likewise has sensory branches the supply the outside auditory canal. Therefore, patients v laryngeal cancer have the right to have ad otalgia.


Muscles

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

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

The details constrictor muscle that is in the vicinity that the laryngopharynx is the inferior constrictor, which is composed of 2 muscles: the thyropharyngeus and cricopharyngeus. The thyropharyngeus muscle is premium to the cricopharyngeus and lies laterally and posteriorly to the laryngopharynx. Relaxation that the cricopharyngeus and also thyropharyngeus permit pharyngeal contents to get in the esophagus.<5>


Surgical Considerations

Laryngopharyngectomy:

Laryngopharyngectomy, finish removal that the larynx and also hypopharynx, is typically reserved together salvage therapy complying with chemoradiation or for patients with progressed cancers of the hypopharynx or larynx. The main treatment because that patients through laryngopharyngeal cancer is radical radiotherapy and/or chemotherapy, as these are organ-preserving treatment modalities.<8><9> If the laryngopharyngectomy is for the treatment of laryngopharyngeal cancer, it is also recommended to dissect the bilateral level II-IV neck lymph nodes. Neck dissection serves two important purposes: (1) identify the extent of nodal involvement and (2) to accessibility vessels provided in totally free flap reconstruction.<10>

Surgical Fundoplication in Laryngopharyngeal Reflux:

Nissen fundoplication is a surgery classically provided in the therapy of gastroesophageal reflux condition (GERD) by which the upper component of the stomach, known as the fundus, is wrapped approximately the esophagus to reinforce the lower esophageal sphincter. Part studies have demonstrated success in dealing with laryngopharyngeal reflux (LPR) with fundoplication in a subset of select patients.<11> Treatment the LPR involves a mix of dietary and also lifestyle changes, and proton pump inhibitors (PPI). Back 50-70% of patients enhance with PPIs, numerous patients still experience from laryngeal irritation regardless of high sheep PPI treatment.<12><13> Researchers hypothesize the patients who fail to boost on PPI treatment may advantage from fundoplication under the premise the reinforcement of the reduced esophageal sphincter (LES) might prevent low volume reflux of acid or nonacid gastric content.<14> However, a prospective regulated trial demonstrated restricted improvement in laryngeal symptoms one year complying with fundoplication surgical procedure for LPR.<15>


Clinical Significance

Cancer:

Studies have displayed that 72% to 87% the pharyngeal cancers arise in the laryngopharynx, frequently referred to as hypopharyngeal cancer in the literature.<16><17> The pyriform sinus has the highest possible proportion of this cancers (78.3%), complied with by the posterior pharyngeal wall (14%), and then the post-cricoid area (8%).<16> Cancers of the hypopharynx account because that 6% of every cancer of the head and neck, more than 95% that which space squamous cabinet carcinoma.<18> various other hypopharyngeal cancers include spindle cabinet carcinoma, salivary gland carcinoma, and basaloid squamous carcinoma.<19>

Hypopharyngeal cancers room dangerous due to the fact that of their late presentation and predilection because that metastasizing, with more than 85% of cancers have spread beyond the laryngopharynx at the time of diagnosis. The most usual site that metastasis (65%) is to regional lymph nodes. Cancer of the hypopharynx is a devastating diagnosis, through a 5-year survival rate as low together 29%.<19> The key risk factors are alcohol consumption and smoking, although other ecological exposures such together asbestos, at home air pollution, and also coal dust also have web links to hypopharyngeal cancer.<20><21><22>

Hypopharyngeal cancer can existing with dysphagia, a prominent neck mass, voice impairment, hoarseness, and/or advert otalgia. Therapy is a complicated multidisciplinary decision that involves collaboration among medical oncologists, radiation oncologists, and also head and neck surgeons. The is a extremely controversial topic because there is no uniform consensus for the best strategy to treatment.<23> Treatment choices include radiation, chemotherapy, surgery, or a combination thereof, with surgery being the wanted therapeutic option.<24> The goal of treatment is to achieve local tumor manage while simultaneously preserving the function of the many important structures located adjacent to the laryngopharynx, i beg your pardon is connected in speech, swallowing, and respiration. In situations of progressed disease, laryngectomy or laryngopharyngectomy might necessary.

Laryngopharyngeal reflux:

Laryngopharyngeal reflux (LPR) is a extremely controversial topic because of a disagreement among otolaryngologists and also gastroenterologists concerning its pathophysiology. Otolaryngologists think that LPR is due to retrograde flow of cradle stomach components to the laryngopharynx, resulting in mucosal injury and irritation.<25> The pathophysiology that GERD is similar in the it is as result of the reflux of gastric components into the esophagus. Interestingly, LPR hardly ever presents v heartburn (20%) or regurgitation, also though the acid and other corrosive stomach contents must traverse the esophagus to with the larynx. Gastroenterologists argue that low comorbidity of GERD amongst patients v LPR signifies that an alternate etiology have to exist.

LPR is one of the most usual presentations in otolaryngology clinics, with some research studies demonstrating as plenty of as 10% the visits because of symptoms second to LPR.<26> LPR presents with symptoms of cough, hoarseness, neck clearing, and also globus sensation.<25> It is a difficult diagnosis to make because of nonspecific symptoms the mimic numerous other problems that affect the larynx, including allergies, vocal abuse, smoking, infections, and also alcohol abuse.<27><28> More than fifty percent of patients presenting with hoarseness have some kind of the reflux-associated disease.<29><30> Complications of LPR encompass subglottic stenosis, contact ulcers, granulomas, and lower airway disease, among others.<31> Diagnosis is often made based upon a cautious history.<25> Since LPR is associated with top aerodigestive street cancer, a full laryngopharyngeal check is essential if LPR is suspected.<32><33>

Documenting an answer to treatment can be a challenge since there are few objective physical exam findings to determine the level of disease. Belafsky et al. Emerged the Reflux Symptom Index, an LPR grading system designed to assist clinicians recognize the relative impact of treatment in their LPR patients.<34> Another an approach for assessing the severity the symptoms and also progression of the disease is through acoustic voice analysis, which actions frequency, intensity, signal-to-noise ratio, and also perturbation in patient presenting with hoarseness.<29> Regardless, clinicians must regularly rely on subjective symptoms acquired in background as well as clinical judgment to assess an answer to treatment.

The an initial diagnostic test suggested is laryngoscopy, which commonly shows nonspecific indicators of laryngeal irritation the leads to redness, thickening, and edema confined come the posterior larynx.<28> Diagnosis can be shown using three various approaches: endoscopic observation of damaged laryngopharyngeal tissue, pH security studies, or symptomatic response to empiric medical and also behavioral therapy.<25>

Treatment the LPR is a mix of behavior change and clinical treatment. Patient are often initially prescribed acid-suppressing medication, such as PPIs, to aid in both treatment and diagnosis that LPR.<35> Other medical therapies encompass H2 receptor antagonists, mucosal cytoprotectants, and also prokinetic agents. Behavior modification includes the avoidance the alcohol, smoking cigarettes cessation, and also weight loss. Patient should additionally be instructed to avoid dietary cause such together chocolate, carbonated beverages, citrus fruits, fats, red wines, caffeine, spicy tomato products, and meals prior to bedtime.

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<36> If way of life changes and also medical treatment fail in managing symptoms, patients with far-ranging reflux as result of lower esophageal sphincter incompetence deserve to opt because that surgical intervention. Although part otolaryngologists advocate for fundoplication, over there is limited evidence demonstrating that efficacy in addressing symptoms the LPR.<15>