The pharynx (plural: pharynges) is the part of the
throat behind the
mouth and
nasal cavity
The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nasal ...
, and above the
oesophagus
The esophagus ( American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to ...
and
trachea
The trachea, also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air- breathing animals with lungs. The trachea extends from t ...
(the tubes going down to the
stomach and the
lungs). It is found in vertebrates and invertebrates, though its structure varies across species. The pharynx carries food and air to the esophagus and
larynx respectively. The flap of cartilage called the
epiglottis
The epiglottis is a leaf-shaped flap in the throat that prevents food and water from entering the trachea and the lungs. It stays open during breathing, allowing air into the larynx. During swallowing, it closes to prevent aspiration of food in ...
stops food from entering the larynx.
In humans, the pharynx is part of the
digestive system and the
conducting zone of the
respiratory system
The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies g ...
. (The conducting zone—which also includes the
nostrils of the
nose
A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passe ...
, the
larynx,
trachea
The trachea, also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air- breathing animals with lungs. The trachea extends from t ...
,
bronchi, and
bronchioles—filters, warms and moistens air and conducts it into the
lungs). The human pharynx is conventionally divided into three sections: the nasopharynx, oropharynx, and laryngopharynx. It is also important in
vocalization.
In humans, two sets of
pharyngeal muscles form the pharynx and determine the shape of its
lumen. They are arranged as an inner layer of longitudinal muscles and an outer circular layer.
Structure
Nasopharynx
The upper portion of the pharynx, the nasopharynx, extends from the base of the
skull to the upper surface of the
soft palate. It includes the space between the
internal nares and the soft palate and lies above the oral cavity. The
adenoids, also known as the pharyngeal tonsils, are
lymphoid tissue structures located in the posterior wall of the nasopharynx.
Waldeyer's tonsillar ring is an annular arrangement of lymphoid tissue in both the nasopharynx and oropharynx. The nasopharynx is lined by
respiratory epithelium that is pseudostratified, columnar, and ciliated.
Polyps or
mucus
Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It ...
can obstruct the nasopharynx, as can congestion due to an upper respiratory infection. The
auditory tube, which connects the middle ear to the pharynx, opens into the nasopharynx at the pharyngeal opening of the auditory tube. The opening and closing of the auditory tubes serves to equalize the barometric pressure in the middle ear with that of the ambient atmosphere.
The anterior aspect of the nasopharynx communicates through the
choanae with the nasal cavities. On its lateral wall is the
pharyngeal opening of the auditory tube, somewhat triangular in shape and bounded behind by a firm prominence, the
torus tubarius or cushion, caused by the medial end of the cartilage of the tube that elevates the
mucous membrane.
Two folds arise from the cartilaginous opening:
* the salpingopharyngeal fold, a vertical fold of mucous membrane extending from the inferior part of the torus and containing the
salpingopharyngeus muscle
* the salpingopalatine fold, a smaller fold, in front of the salpingopharyngeal fold, extending from the superior part of the torus to the palate and containing the
levator veli palatini
The levator veli palatini () is the elevator muscle of the soft palate in the human body. It is supplied via the pharyngeal plexus. During swallowing, it contracts, elevating the soft palate to help prevent food from entering the nasopharynx. ...
muscle. It also contains some muscle fibres called ''salpingopalatine muscle''
The
tensor veli palatini is lateral to the levator and does not contribute to the fold, since the origin is deep to the cartilaginous opening.
Oropharynx
The oropharynx lies behind the oral cavity, extending from the
uvula
The palatine uvula, usually referred to as simply the uvula, is a conic projection from the back edge of the middle of the soft palate, composed of connective tissue containing a number of racemose glands, and some muscular fibers. It also conta ...
to the level of the
hyoid bone. It opens anteriorly, through the
isthmus faucium, into the mouth, while in its lateral wall, between the
palatoglossal arch and the
palatopharyngeal arch, is the
palatine tonsil. The anterior wall consists of the base of the tongue and the
epiglottic vallecula
The epiglottic valleculae are paired spaces between the root of the tongue and anterior surface of the epiglottis. Each vallecula is bordered medially by the median glossoepiglottic fold and laterally by the lateral glossoepiglottic fold.
The vall ...
; the lateral wall is made up of the tonsil, tonsillar fossa, and tonsillar (faucial) pillars; the superior wall consists of the inferior surface of the soft palate and the uvula. Because both food and air pass through the pharynx, a flap of connective tissue called the
epiglottis
The epiglottis is a leaf-shaped flap in the throat that prevents food and water from entering the trachea and the lungs. It stays open during breathing, allowing air into the larynx. During swallowing, it closes to prevent aspiration of food in ...
closes over the
glottis when food is swallowed to prevent
aspiration. The oropharynx is lined by non-keratinized squamous stratified epithelium.
The ''HACEK'' organisms (''
Haemophilus,
Actinobacillus actinomycetemcomitans,
Cardiobacterium hominis,
Eikenella corrodens,
Kingella'') are part of the normal oropharyngeal flora, which grow slowly, prefer a carbon dioxide-enriched atmosphere, and share an enhanced capacity to produce
endocardial infections, especially in young children.
''
Fusobacterium
''Fusobacterium'' is a genus of anaerobic, Gram-negative, non-sporeforming bacteria belonging to Gracilicutes. Individual cells are slender, rod-shaped bacilli with pointed ends.
Strains of ''Fusobacterium'' cause several human diseases, includin ...
'' is a pathogen.
Laryngopharynx
The laryngopharynx, (
Latin
Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
: ''pars laryngea pharyngis''), also known as hypopharynx, is the
caudal part of the pharynx; it is the part of the throat that connects to the esophagus. It lies inferior to the epiglottis and extends to the location where this common pathway diverges into the respiratory (
laryngeal) and digestive (
esophageal) pathways. At that point, the laryngopharynx is continuous with the esophagus posteriorly. The esophagus conducts food and fluids to the stomach; air enters the larynx anteriorly. During swallowing, food has the "right of way", and air passage temporarily stops. Corresponding roughly to the area located between the 4th and 6th
cervical vertebrae, the superior boundary of the laryngopharynx is at the level of the
hyoid bone. The laryngopharynx includes three major sites: the
pyriform sinus
On either side of the laryngeal orifice in humans is a recess, termed the pyriform sinus (also piriform recess, piriform sinus, piriform fossa, or smuggler's fossa), which is bounded medially by the aryepiglottic fold, laterally by the thyroid car ...
, postcricoid area, and the posterior pharyngeal wall. Like the oropharynx above it, the laryngopharynx serves as a passageway for food and air and is lined with a
stratified squamous epithelium. It is innervated by the
pharyngeal plexus.
The vascular supply to the laryngopharynx includes the
superior thyroid artery
The superior thyroid artery arises from the external carotid artery just below the level of the greater cornu of the hyoid bone and ends in the thyroid gland.
Structure
From its origin under the anterior border of the sternocleidomastoid the su ...
, the
lingual artery
The lingual artery arises from the external carotid artery between the superior thyroid artery and facial artery. It can be located easily in the tongue.
Structure
The lingual artery first branches off from the external carotid artery. It runs ...
and the
ascending pharyngeal artery. The primary neural supply is from both the
vagus and
glossopharyngeal
The glossopharyngeal nerve (), also known as the ninth cranial nerve, cranial nerve IX, or simply CN IX, is a cranial nerve that exits the brainstem from the sides of the upper medulla, just anterior (closer to the nose) to the vagus nerve. B ...
nerves. The vagus nerve provides an
auricular branch also termed "Arnold's nerve" which also supplies the external auditory canal, thus laryngopharyngeal cancer can result in referred
ear pain
Ear pain, also known as earache or otalgia, is pain in the ear. Primary ear pain is pain that originates from the ear. Secondary ear pain is a type of referred pain, meaning that the source of the pain differs from the location where the pain is ...
. This nerve is also responsible for the
ear-cough reflex in which stimulation of the ear canal results in a person coughing.
Function
The pharynx moves food from the mouth to the esophagus. It also moves air from the
nasal
Nasal is an adjective referring to the nose, part of human or animal anatomy. It may also be shorthand for the following uses in combination:
* With reference to the human nose:
** Nasal administration, a method of pharmaceutical drug delivery
* ...
and
oral
The word oral may refer to:
Relating to the mouth
* Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid
** Oral administration of medicines
** Oral examination (also known as an oral exam or or ...
cavities to the
larynx. It is also used in human speech, as
pharyngeal consonants are articulated here, and it acts as a
resonating chamber during phonation.
Clinical significance
Inflammation
Inflammation of the pharynx, or
pharyngitis
Pharyngitis is inflammation of the back of the throat, known as the pharynx. It typically results in a sore throat and fever. Other symptoms may include a runny nose, cough, headache, difficulty swallowing, swollen lymph nodes, and a hoa ...
, is the painful inflammation of the throat.
Pharyngeal cancer
Pharyngeal cancer
Head and neck cancer develops from tissues in the lip and oral cavity (mouth), larynx (throat), salivary glands, nose, sinuses or the skin of the face. The most common types of head and neck cancers occur in the lip, mouth, and larynx. Symptoms ...
is a cancer that originates in the neck and/or throat.
Waldeyer's tonsillar ring
Waldeyer's tonsillar ring is an anatomical term collectively describing the annular arrangement of lymphoid tissue in the pharynx. Waldeyer's ring circumscribes the naso- and oropharynx, with some of its tonsillar tissue located above and some below the soft palate (and to the back of the oral cavity). It is believed that Waldeyer's ring prevents the invasion of microorganisms from going into the air and food passages and this helps in the defense mechanism of the respiratory and alimentary systems.
Etymology
The word ''pharynx'' () is derived from the
Greek φάρυγξ ''phárynx'', meaning "throat". Its plural form is ''pharynges'' or ''pharynxes'' , and its adjective form is ''
pharyngeal'' (
or ).
Other vertebrates
All vertebrates have a pharynx, used in both feeding and respiration. The pharynx arises during development in all vertebrates through a series of six or more outpocketings on the lateral sides of the head. These outpocketings are
pharyngeal arches, and they give rise to a number of different structures in the skeletal, muscular, and circulatory systems. The structure of the pharynx varies across the vertebrates. It differs in dogs, horses, and ruminants. In dogs, a single duct connects the nasopharynx to the nasal cavity. The tonsils are a compact mass that points away from the lumen of the pharynx. In the horse, the auditory tube opens into the guttural pouch and the tonsils are diffuse and raised slightly. Horses are unable to breathe through the mouth as the free apex of the rostral epiglottis lies dorsal to the soft palate in a normal horse. In
ruminants the tonsils are a compact mass that points towards the lumen of the pharynx.
Pharyngeal arches
Pharyngeal arches are characteristic features of vertebrates whose origin can be traced back through
chordates
A chordate () is an animal of the phylum Chordata (). All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These five ...
to basal
deuterostomes who also share endodermal outpocketings of the pharyngeal apparatus. Similar patterns of gene expression can be detected in the developing pharynx of
amphioxi
The lancelets ( or ), also known as amphioxi (singular: amphioxus ), consist of some 30 to 35 species of "fish-like" benthic filter feeding chordates in the order Amphioxiformes. They are the modern representatives of the subphylum Cephalochorda ...
and
hemichordates. However, the vertebrate pharynx is unique in that it gives rise to
endoskeletal
An endoskeleton (From Greek ἔνδον, éndon = "within", "inner" + σκελετός, skeletos = "skeleton") is an internal support structure of an animal, composed of mineralized tissue.
Overview
An endoskeleton is a skeleton that is on the i ...
support through the contribution of
neural crest cells.
Pharyngeal jaws
Pharyngeal jaws are a "second set" of
jaws contained within the pharynx of many species of fish, distinct from the primary (oral) jaws. Pharyngeal jaws have been studied in
moray eels where their specific action is noted. When the moray bites
prey, it first bites normally with its oral jaws, capturing the prey. Immediately thereafter, the pharyngeal jaws are brought forward and bite down on the prey to grip it; they then retract, pulling the prey down the eel's esophagus, allowing it to be swallowed.
Invertebrates
Invertebrates also have a pharynx. Invertebrates with a pharynx include the
tardigrade
Tardigrades (), known colloquially as water bears or moss piglets, are a phylum of eight-legged segmented micro-animals. They were first described by the German zoologist Johann August Ephraim Goeze in 1773, who called them Kleiner Wasserb� ...
s,
annelids and
arthropod
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...
s, and the
priapulids (which have an eversible pharynx).
The "pharynx" of the
nematode worm is a muscular food pump in the head, triangular in cross-section, that grinds food and transports it directly to the intestines. A one-way valve connects the pharynx to the excretory canal.
File:Alitta virens pharynx (lateral).jpg, Everted pharynx of '' Alitta virens'' (also known as ''Nereis virens''), lateral view
File:Prorhynchus fontinalis pharynx.jpg, Pharynx of the flatworm ''Prorhynchus fontinalis
''Prorhynchus'' is a genus of flatworms belonging to the family Prorhynchidae.
Species:
* '' Prorhynchus alpinus''
* '' Prorhynchus fontinalis''
* '' Prorhynchus hastatus''
References
{{Taxonbar, from=Q4993239
Platyhelminthes ...
''
File:Peerj-297-fig-5 Platydemus manokwari.png, Pharynx of the flatworm ''Platydemus manokwari
''Platydemus manokwari'', also known as the New Guinea flatworm, is a species of large predatory land flatworm.
Native to New Guinea, it has been accidentally introduced to the soil of many countries, including the United States. It was als ...
'' visible as the worm feeds on a snail.
File:C elegans anatomy.png, Longitudinal section through the roundworm '' Caenorhabditis elegans'' showing the position of the pharynx in the animal body.
File:Lamprey Larva x sect pharynx labelled.png, Microscopic cross section through the pharynx of a larva from an unknown lamprey species.
Additional images
Image:Illu nose nasal cavities.jpg, Nose and nasal
Image:Gray907.png, Coronal section
The coronal plane (also known as the frontal plane) is an anatomical plane that divides the body into dorsal and ventral sections. It is perpendicular to the sagittal and transverse planes.
Details
The coronal plane is an example of a longit ...
of right ear, showing auditory tube and levator veli palatini
The levator veli palatini () is the elevator muscle of the soft palate in the human body. It is supplied via the pharyngeal plexus. During swallowing, it contracts, elevating the soft palate to help prevent food from entering the nasopharynx. ...
muscle
Image:Gray955.png, The entrance to the larynx, viewed from behind
File:Slide1kuku.JPG, Deep dissection of human larynx, pharynx and tongue seen from behind
File:Gray994.png, The nasopharynx, oropharynx, and laryngopharynx or larynx can be seen clearly in this sagittal
The sagittal plane (; also known as the longitudinal plane) is an anatomical plane that divides the body into right and left sections. It is perpendicular to the transverse and coronal planes. The plane may be in the center of the body and divi ...
section of the head and neck.
See also
*
Cricopharyngeal ligament
The cricopharyngeal ligament extends from the cricoid
The cricoid cartilage , or simply cricoid (from the Greek ''krikoeides'' meaning "ring-shaped") or cricoid ring, is the only complete ring of cartilage around the trachea. It forms the back p ...
*
Nasopharyngeal carcinoma
Nasopharyngeal carcinoma (NPC), or nasopharynx cancer, is the most common cancer originating in the nasopharynx, most commonly in the postero-lateral nasopharynx or pharyngeal recess ( fossa of Rosenmüller), accounting for 50% of cases. NPC occurs ...
*
Pharyngeal aspiration
*
Pharyngeal consonant
*
Pharyngeal (disambiguation)
*''
Saccopharynx
''Saccopharynx'' is a genus of deep-sea eels with large mouths, distensible stomachs and long, scaleless bodies. Commonly, these fish are called gulpers or gulper eels. It is the only genus in the family Saccopharyngidae, and is part of the deriv ...
'', a genus of deep-sea eel-like fishes with large mouths, distensible stomachs and long scaleless bodies
*
Salpinx in anatomy
*
Tonsil
*
Tornwaldt cyst
A Tornwaldt cyst also spelt as Thornwaldt or Thornwald cyst is a benign cyst located in the upper posterior nasopharynx. It can be seen on computed tomography (CT) or magnetic resonance imaging
Magnetic resonance imaging (MRI) is a medical ...
References
General
Pharynx Stedman's Online Medical Dictionary at Lippincott Williams and Wilkins
* ''Human Anatomy and Physiology'' Elaine N. Marieb and Katja Hoehn, Seventh Edition.
* ''TNM Classification of Malignant Tumours'' Sobin LH & Wittekind Ch (eds)Sixth edition UICC 2002
External links
*
*
*
{{Portal bar, Anatomy
Digestive system
Human head and neck
Human throat
Human voice
Animal anatomy