Throat

The pharynx is an unpaired organ located in the head and neck area and is part of the digestive and respiratory systems. It is a hollow funnel-shaped tube suspended from the outer base of the skull. The upper part of the pharynx (pharyngeal vault) is attached to the pharyngeal tubercle of the occipital bone, and the lateral parts are attached to the pyramids of the temporal bones (in front of the external carotid opening) and to the medial plate of the pterygoid process. Below, the pharynx passes into the esophagus at the level of the sixth cervical vertebra. The length of the pharynx in an adult is 12-15 cm. Behind the pharynx are the prevertebral muscles, the prevertebral plate of the cervical fascia and the cervical spine. Between the back wall of the pharynx and the cervical fascia plate is the retropharyngeal (cellular) space (spatium retropharyngeum), filled with loose fibrous connective tissue. The retropharyngeal lymph nodes are located in the retropharyngeal space.

The common and internal carotid arteries, the internal jugular vein, the vagus nerve, the greater horn of the hyoid bone, and the thyroid cartilage plate of the larynx are adjacent to the lateral walls of the pharynx on each side.

On the anterior wall of the pharynx, the openings of the nasal cavity (choanae) open into it, and below - the opening of the oral cavity - the pharynx (fauces). Even lower is the entrance to the larynx. There is a nasal part of the pharynx (pars nasalis pharyngis), or nasopharynx, located behind the choanae. The oral part of the pharynx (pars oralis pharyngis), or oropharynx, is located at the level from the soft palate upward to the entrance to the larynx. The laryngeal part of the pharynx (pars laryngea pharyngis), or laryngopharynx, is located between the entrance to the larynx at the top and the transition of the pharynx into the esophagus at the bottom. The nasal part of the pharynx belongs to the respiratory tract, the oral part - to the respiratory and digestive tracts.

On the inner surface of the pharynx, in the area of its vault where the upper wall passes into the back, there is a cluster of lymphoid tissue - the pharyngeal tonsil (tonstlla pharyngealis - adenoidea). On the lateral walls of the pharynx at the posterior edge of the inferior nasal concha there is a pharyngeal opening of the auditory tube (ostium pharyngeum tubae auditivae). The auditory (Eustachian) tube connects the pharynx with the tympanic cavity, helps equalize the external atmospheric pressure and the pressure in the middle ear cavity (tympanic cavity). Above and behind, the pharyngeal opening of the auditory tube is limited by the tubal ridge (torus tubarius), which continues downwards into a thin tubopharyngeal fold (plica tubopharyngea). Behind the tubal ridge there is a small depression - the pharyngeal pocket (recessus pharyngeus). Near the pharyngeal opening of the auditory tube, on the right and left walls of the pharynx, is located the tubal tonsil (tonsilla tubaria), which is an organ of the immune system.

The upper wall of the pharynx is the vault of the pharynx (fornix pharyngis). In the anterior wall of the pharynx at the top there are two openings - choanae, communicating the nasal cavity with the nasopharynx. Between the soft palate at the top and the root of the tongue below is the pharynx, which is limited on the sides by the palatoglossal arches in front and the palatopharyngeal arches behind. In the anterior wall of the laryngeal part of the pharynx there is an opening leading into the larynx - the inlet to the larynx (aditus laryngis). This opening is limited in front by the epiglottis, on the sides - by the aryepiglottic folds, below - by the arytenoid cartilages of the larynx. Between the inner surface of the thyroid cartilage and the aryepiglottic fold on each side there is a depression - a piriform pocket (recessus piriformis).

The wall of the pharynx is formed by the mucous membrane, compacted submucosa, muscular membrane and adventitia.

The mucous membrane of the nasopharynx is lined with pseudostratified ciliated epithelium. In the area of the oropharynx and laryngopharynx, the mucous membrane is covered with stratified squamous epithelium located on its own plate with a high content of elastic fibers. The submucosa of the nasopharynx and oropharynx is compacted, represented by a fibrous plate called the pharyngeal-basilar fascia (fascia pharyngobasilaris). At the level of the laryngopharynx, the submucosa consists of loose fibrous connective tissue and contains numerous mucous glands.

The muscular membrane of the pharynx is represented by five striated muscles. Among them, there are three pharyngeal constrictors and longitudinal muscles - pharyngeal elevators.

The superior constrictor of the pharynx (m. constrictor pharyngis superior) originates on the medial plate of the pterygoid process of the sphenoid bone, as well as on the pterygomandibular suture (raphe pterygomandibulare) - a fibrous plate stretched between the pterygoid hook of the sphenoid bone and the lower jaw. The muscle fibers of the superior constrictor go downward and backward, where they join the fibers of this muscle on the opposite side along the midline on the back of the pharynx.

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Muscles of the pharynx

Muscle	Start	Attachment	Function	Innervation
Pharyngeal constrictors
Superior pharyngeal constrictor	Medial plate of the pterygoid process of the sphenoid bone, pterygomandibular suture, mandible, root of the tongue	On the back surface of the pharynx it fuses with a similar muscle on the other side	Reduce the lumen of the pharynx	Branches of the pharyngeal plexus
Middle constrictor of the pharynx	Greater and lesser horns of the hyoid bone	Same
Inferior pharyngeal constrictor	Lateral surfaces of the thyroid and cricoid cartilages	» »
Throat lifters
Stylopharyngeus muscle	Styloid process of the temporal bone	Lateral wall of the pharynx	Raises the throat upwards	Branch of the glossopharyngeal nerve
Tube-pharyngeal muscle	The lower surface of the cartilage of the auditory tube near the pharyngeal opening	Same	Raises the pharynx upward and laterally	Branches of the pharyngeal plexus

The middle constrictor of the pharynx (m.constrictor pharyngis medius) originates on the greater and lesser horns of the hyoid bone. The muscle fibers fan out downwards and upwards, fusing with the fibers of the opposite side on the back wall of the pharynx (along the midline). The upper edge of the middle constrictor overlaps the lower part of the superior constrictor of the pharynx.

The inferior constrictor of the pharynx (m.constrictor pharyngis inferior) begins on the lateral surface of the thyroid cartilage plate and on the cricoid cartilage of the larynx.

The muscle bundles fan out downwards, horizontally and upwards, covering the lower part of the middle constrictor and merging with similar bundles on the opposite side along the posterior midline. The lower muscle bundles pass to the posterior wall of the esophagus.

As a result of the fusion of the right and left muscle bundles of the pharyngeal constrictors, the pharyngeal suture (raphe pharyngis) is formed along the midline from behind. The pharyngeal constrictors narrow its lumen.

The longitudinal muscles of the pharynx include two muscles:

The stylopharyngeus muscle (m.stylopharyngeus) begins on the styloid process of the temporal bone, goes down and medially, penetrates the thickness of the lateral wall of the pharynx at the level between the upper and middle constrictors. When contracting, it raises the pharynx and with it the larynx.

The salpingopharyngeal muscle (m.salpingopharyngeus) begins on the lower surface of the cartilage of the auditory tube, near its pharyngeal opening. Muscle bundles are directed downwards, connect with the palatopharyngeal muscle and are woven into the lateral wall of the pharynx. The palatopharyngeal muscle (m.palatopharyngeus) begins on the palatine aponeurosis.

The tubopharyngeal and palatopharyngeal muscles participate in the act of swallowing. In this case, the tubopharyngeal muscle pulls the wall of the auditory tube downwards, widens its pharyngeal opening, which facilitates the flow of air into the tympanic cavity and equalizes the pressure in it, corresponding to atmospheric pressure.

The act of swallowing

The food bolus touches the palate, the root of the tongue and the back wall of the pharynx, irritating the receptors. The nerve impulse goes through the glossopharyngeal nerves to the swallowing center of the medulla oblongata. The neurons of the center generate impulses directed through the trigeminal, glossopharyngeal, vagus and hypoglossal nerves to the muscles of the oral cavity, tongue, pharynx, esophagus and larynx. The combined contraction of these muscles causes the act of swallowing. A distinction is made between a voluntary phase lasting 0.7-1.0 s and an involuntary phase (4-6 s). The act of swallowing is a continuous alternation of the following phases:

1. the muscles of the soft palate contract, the soft palate rises and is pressed against the vault and back wall of the pharynx, separating the nasopharynx from the rest of the pharynx;
2. when the muscular diaphragm of the mouth contracts, the larynx rises and moves forward, the epiglottis closes the entrance to the larynx;
3. when the styloglossus and hyoglossus muscles contract, the root of the tongue moves back, and the food bolus is pushed through the pharynx into the oropharynx;
4. due to the contraction of the palatoglossal muscles, part of the food bolus that has entered the oral part of the pharynx is separated (cut off) from the food that is still in the oral cavity;
5. when a food bolus enters the pharynx, the longitudinal muscles lift the pharynx, pulling it onto the food bolus;
6. A sequential contraction of the pharyngeal constrictors from top to bottom pushes the food bolus from the pharynx into the esophagus.