Generality
The pharynx is the muscle-membranous duct, located at the bottom of the mouth, which connects the oral and nasal cavities with the larynx and esophagus.
Anatomical component of the throat, the pharynx is part of both the digestive tract, as food transits there, and the respiratory system, as it is also a place for crossing the air.
Between the base of the skull, superiorly, and the VI cervical vertebra, below, the pharynx can be divided into 3 superimposed portions, whose names, starting from the upper, are: nasopharynx (or nasopharynx), oropharynx and hypopharynx (or laryngopharynx).
The pharynx has a fundamental role in the digestive process and in the respiratory process; it also contributes to phonation, maintaining the right pressure inside the middle ear and defending the body from bacteria and viruses.
The pharynx is the protagonist of various medical conditions, including pharyngitis, throat cancer and enlargement of the adenoids.
What is Pharynx?
The pharynx is the muscle-membranous duct, located at the bottom of the mouth, which connects the oral and nasal cavities with the larynx and the esophagus .
The pharynx is one of the anatomical components of the throat and, since both food and air pass through it, it is an integral part of both the digestive system and the respiratory system .
In anatomy, the term "throat" includes the pharynx, the larynx and the proximal (or initial) parts of the esophagus and trachea .
Anatomy
Approximately 13 centimeters long, the pharynx is a funnel- shaped anatomical passage (or cone ), seat of muscles and covered, superficially, with a layer of mucosa .
The muscles and mucosa present at the level of the pharynx are the reason why the latter is defined with the expression "muscle-membranous duct".
Observed inside the human body, the anatomical tract constituting the pharynx begins at the base of the skull and ends at the level of the VI cervical vertebra and of the point where the cricoid cartilage takes place.
On the basis of an anatomical convention, which serves to facilitate its description, the pharynx can be divided into 3 overlapping sections, whose names are, starting from the top: rhinopharynx (or nasopharynx ), oropharynx and hypopharynx (or laryngopharynx ).
Location of the Pharynx
The pharynx resides in the throat, behind the oral cavity, below the nasal cavity and above the initial portions of the larynx (organ of the respiratory system) and esophagus (organ of the digestive system).
Subdivisions of the Pharynx
RINOFARINGE OR NASOFARINGE
The nasopharynx is the upper subdivision of the pharynx; it begins at the level of the base of the skull, where it borders on the nasal cavities, and ends at the level of the upper surface of the soft palate, where it adjoins the oropharynx and the oral cavity.
As a demonstration that it is an integral part of the respiratory system, the pharynx has a characteristic respiratory epithelium, therefore a pseudostratified, columnar and ciliated epithelium.
The nasopharynx hosts the so-called adenoid tonsils (or pharyngeal tonsils or, more simply, adenoids); these lymph gland organs are active and grow between 3 and 8 years of life, then regress, losing their functions (as they are no longer necessary).
Furthermore, the nasopharynx accommodates the oral openings of the Eustachian tube (or trumpet of Eustachium ), that is the ducts that connect the middle ear to the pharynx.
Did you know that ...
The nasopharynx communicates with the nasal cavities through ducts known as choana .
oropharynx
The oropharynx represents the intermediate subdivision of the pharynx, limited by the soft palate, superiorly, and by the epiglottis, inferiorly.
Including between nasopharynx and hypopharynx, the oropharynx opens anteriorly on the oral cavity; the connecting tract between the oropharynx and the oral cavity is called the jaw isthmus .
In anatomy, the expression "isthmus of the jaws" indicates the region of oropharynx located posterior to the oral cavity and bounded by the soft palate, superiorly, by the palatoglossian arches, laterally, and by the tongue, inferiorly.
The oropharynx includes several anatomical structures, including:
- The 1/3 posterior of the tongue ;
- Lingual tonsils (tonsils located at the base of the tongue);
- Palatine tonsils (tonsils located in the tonsillar fossa);
- The upper constrictor muscle (which, as will be seen later, is a pharynx muscle).
At the level of the oropharynx, the pharynx becomes a passage organ not only for the air, but also for the food (after all, it is exactly behind the oral cavity).
HYPOFARINGE OR LARINGOFARINGE
The hypopharynx is the lower part as well as the last, starting from the top, of the pharynx.
The competence of the hypopharynx begins at the level of the upper border of the epiglottis, right where the oropharynx ends its path, and ends at the lower edge of the cricoid cartilage, exactly where the path of the esophagus begins.
Being below the epiglottis, the hypopharynx represents the tract of pharynx crossed exclusively by food (whose destiny is to take the esophagus).
Composed of stratified squamous epithelium, the hypopharynx houses the middle and lower constrictor muscles of the pharynx.
Finally, according to the most common anatomical descriptions, on the laryngopharynx it is possible to identify 3 distinct areas, called: pyriform sinus, post-cricoid area and posterior pharyngeal wall (or posterior pharyngeal wall ).
Pharynx muscles
The pharynx comprises two groups of muscles, called a circular group and a longitudinal group, of 3 elements each. From this it follows that in the anatomical tract corresponding to the pharynx 6 muscles, 3 of the circular group (or circular muscles of the pharynx ) and 3 of the longitudinal group (or longitudinal muscles of the pharynx ) take place.
CIRCULAR MUSCLES OF THE FARINGE
Characterized by a round shape, the 3 circular muscles of the pharynx are known by the names of: upper constrictor muscle, middle constrictor muscle and lower constrictor muscle .
The task of these muscles is to promote, through a coordinated contraction, the addressing of the food towards the esophagus.
- Upper constrictor muscle: located in the oropharynx, it is the constrictor muscle placed higher (hence the term "upper");
- Average constrictor muscle: based in the hypopharynx, it is the constrictor muscle placed between the upper and lower constrictor (hence the term "medium");
- Lower constrictor muscle: also located in the hypopharynx, it is the lower constrictor muscle (hence the term "lower");
LONGITUDINAL MUSCLES OF THE FARINGE
The longitudinal muscles of the pharynx are known by the names of: stilopharyngeal muscle, palatofarigeo muscle and salpingopharyngeal muscle .
These muscles have more than one function; they serve, in fact, to: widen or narrow the pharynx; elevate the larynx during swallowing; finally, open the Eustachian tube, when it is necessary to balance the pressure inside the middle ear.
- Streopharyngeal muscle: its course goes from the styloid process of the temporal bone to the pharynx;
- Palatopharyngeal muscle: born in the hard palate and ends in the pharynx;
- Salpingopharyngeal muscle: originates in the Eustachian tube and ends in the pharynx.
Innervation of the Pharynx
The innervation of the pharynx is mainly due to the pharyngeal plexus and, only to a small extent, to the maxillary nerve .
More specifically, the pharyngeal plexus provides, with the glossopharyngeal nerve ( IX cranial nerve ), to the sensory innervation of the oropharynx and to the innervation of the stilopharyngeal muscle only and, with the vagus nerve ( X cranial nerve ), to the sensory innervation of the hypopharynx and to the innervation of the remaining muscles of the pharynx; the maxillary nerve (branch of the trigeminal nerve or V cranial nerve ), on the other hand, deals with the sensitive innervation of the nasopharynx only.
The pharyngeal plexus is the particular formation of nerves, which includes the pharyngeal branches of the glossopharyngeal nerve, the pharyngeal branches of the vagus nerve and the sympathetic fibers of the superior cervical ganglion.
Sensory innervation of the pharynx | Motor innervation of the pharynx | ||
| Partition | Nerve involved | Muscles | Nerve involved |
nasopharynx | Maxillary nerve | Circular muscles (upper constrictor, average constrictor and lower constrictor) | Vague nerve |
| oropharynx | Glossopharyngeal nerve | Palatopharyngeal and salpingopharyngeal longitudinal muscles | Vague nerve |
| hypopharynx | Vague nerve | Styropharyngeal longitudinal muscle | Glossopharyngeal nerve |
Blood Circulation in the Pharynx
The inflow of oxygenated blood to the pharynx belongs to branches and sub-branches of the external carotid artery ; more specifically, the pharynx receives oxygen and nourishment from:
- The ascending pharyngeal artery (direct branch of the external carotid artery);
- The ascending palatine artery (branch of the facial artery, which in turn is a branch of the external carotid artery);
- The descending palatine artery (branch of the maxillary artery, which in turn is a branch of the external carotid artery).
Instead, the dense network of superficial venous vessels, which forms the so-called pharyngeal venous plexus, fulfills drainage from the pharynx of blood.
Boundaries and Anatomical Relationships of the Pharynx
In summary, the pharynx borders on:
- The nasal cavity and the base of the skull, above;
- The soft palate, the oral cavity and the tongue, anteriorly;
- The larynx and the esophagus, below;
- The vertebral tract between the I cervical vertebra and the VI cervical vertebra, posteriorly.
Function
The pharynx plays a decisive role in digestive function and respiratory function ; in addition, it contributes to:
- The production of sounds and words ( phonation ),
- The maintenance of the right pressure at the level of the eardrum, thanks to the connection guaranteed by the Eustachian tube e
- Protect the human body from having aggressive pathogens, thanks to the lymph glandular tissues of the tonsils present in the site.
Please note
The immune function performed by the tonsils of the pharynx (ie the last of the functions listed above) is small, when compared with other more specific organs, and is subject to a progressive regression.
Digestive functions of the Pharynx
The pharynx helps the digestive process, through the contraction of its muscles; contracting, in fact, the muscles of the pharynx cause the food to take a very precise direction, the only useful and not dangerous: the way of the esophagus.
It is important to point out that, when they come into action, the pharynx muscles close the larynx, so that the food cannot reach the airway and prevent breathing.
Pharynx Respiratory Functions
When the human being is not eating, his pharynx is, again thanks to his muscles, in a state whereby the air passes through it, until he enters the larynx and then the trachea.
The fact that the pharynx possesses, for a stretch, a respiratory epithelium is very important for the purpose of cleaning the inhaled air.
diseases
The pharynx is at the center of various medical conditions; among these, they certainly deserve a mention: pharyngitis, throat cancer and enlargement of the adenoids.
Pharyngitis
Known as sore throat and pharyngodynia, pharyngitis is inflammation of the pharynx.
Pharyngitis is a condition that recognizes numerous causes, including, for example, viral or bacterial infections of the upper airways, mold allergy, dust, pollen or animal hair and gastroesophageal reflux.
Pharyngitis is responsible for discomfort or real pain in the pharynx, especially when the patient swallows.
Pharyngitis therapy depends on the triggering causes .
In general, inflammation of the pharynx is a condition of slight clinical relevance, the resolution of which occurs within a few days and in a completely spontaneous manner.
Throat cancer
With the expression "throat tumor", doctors indicate a generally malignant neoplasm, which originated from the uncontrolled proliferation of one of the cells belonging to the pharynx, larynx or palatine tonsils.
At present, the precise causes of throat cancer are unknown; it is, however, a fact that factors such as cigarette smoking and alcohol abuse increase the risk of forming the neoplasm in question.
Throat cancer is responsible for not very specific symptoms, such as pain in the throat, cough, hoarseness, difficulty swallowing etc., which however have the peculiarity of being persistent (and this feature must represent an alarm bell).
Throat cancer therapy depends on the stage of progression of the tumor, at the time of diagnosis; for early-stage tumors, in fact, the treatment usually consists of radiotherapy and / or chemotherapy ; for tumors at more advanced stages, instead, it involves the use of surgery, in order to remove the tumor.
Enlarged Adenoids
More known with the slang expression " enlarged adenoids ", the enlargement of the adenoids is, as can be guessed, the abnormal enlargement of the adenoid tonsils, present at the level of the pharynx.
Generally, adenoid enlargement episodes are due to viral or bacterial infections, which affect the upper airways and cause inflammation of the aforementioned tonsils.
With their swelling, the adenoid tonsils are responsible for several symptoms, including throat pain, difficulty swallowing without discomfort, halitosis, swollen lymph nodes on the neck, snoring, etc.
The treatment of adenoid enlargement is conservative, for sporadic cases, while it is surgical, for chronic cases (in which the adenoid tonsils are permanently enlarged).
Did you know that ...
The enlargement of the adenoids can clog the Eustachian tube, affecting the regulation of the pressure inside the middle ear.
Remember that this is possible, because the adenoid tonsils and the Eustachian tubes all reside on the subdivision of the pharynx known as nasopharynx.
