Pharynx Anatomy Summary PDF

ynx Ph hi Def: It is a musculo-membranous tube which lies behind the nose, mouth and larynx. extent It extends from the base of the skull down to the sixth cervical vertebra (opposite to the lower border of the cricoid cartilage) Diameter it is widest at its beginning and narrowest at its lower e...

ynx Ph hi Def: It is a musculo-membranous tube which lies behind the nose, mouth and larynx. extent It extends from the base of the skull down to the sixth cervical vertebra (opposite to the lower border of the cricoid cartilage) Diameter it is widest at its beginning and narrowest at its lower end at the pharyngeo-esophageal junction . Structure of the pharyngeal wall From within outwards, the pharyngeal wall is composed of : Fibrous layer -Mucous membrane : It is the interior of the pharynx. -Fibrous layer : called the pharyngeobasilar fascia. -Muscular coat. -Buccopharyngeal fascia : Covers the external aspect of the pharynx. Mucous membrane Muscular coat N Lumen of the pharynx Buccopharyngeal fascia Mucous membrane Pharynx is divided into three parts: communicates with nasal cavities through the choanae Lining: respiratory epithilium communicates with the oral cavity through the oropharyngeal isthmus. Lining: stratified squamous epithelium communicates with laryngeal cavity through the inlet of the larynx. Lining: stratified squamous epithilium Oropharynx Nasopharynx Extent It extends from the base It extends from the level of the It extends from the upper of the of the skull down to the soft palate down to the level of epiglottis to lower border of cricoid cartilage (C 6 vertebra) level of the soft palate. the upper of the epiglottis. Anteriorly: with the nasal cavities Communications via the posterior nasal apertures (choanae). Inferiorly : with the oropharynx through the pharyngeal isthmus. Laterally : with the tympanic cavity (on each side) via the auditory tube.(middle ear). Sensory nerve supply Laryngopharynx Above : with nasopharynx via the pharyngeal isthmus. Anteriorly : with the mouth cavity via the oropharyngeal isthmus. Below : is continuous with the laryngeopharynx. is supplied by pharyngeal branch from the pterygo-palatine ganglion (maxillary N.). glossopharyngeal nerve & Special features At the junction of the roof and posterior wall * Nasopharyngeal tonsils → is located at the junction of its roof and the posterior wall. This tonsil is usually enlarged in children and is called adenoids which may obstruct the nasopharynx with difficult nasal breathing. After six years of age, it atrophies. Anteroinferiorly : With larynx via laryngeal inlet. Inferiorly : Continuous with oesophagus. glossopharyngeal nerve is a mucosal fold caused by the underlying palatopharyngeal sphincter NASOPHARYNX ( More details ) On each lateral wall of the nasopharynx There are: -Pharyngeal opening of the auditory tube → situated cm behind the inferior nasal concha. S The lower end of the tubal elevation Is continuous with the salpingopharyngeal fold, produced by the salpingeopharyngeus muscle. -Tubal elevation (Torus tubarius) → Above and behind pharyngeal opening ,produced by Torus levatorius (salpingopalatine): the cartilage of the auditory tube. is an elevation that extends from the opening of the auditory tube -Tubal tonsil → collection of lymphoid towards the palate . It overlies the tissue around the opening levator veli palatini muscle. -Pharyngeal recess → A fossa behind tubal elevation related to Internal carotid artery . *Auditory tube is also named pharyngotympanic tube Lateral wall of the nasopharynx Pharyngobasillar fascia + posterior or median pharyngeal ligament/raphe Pharyngeal tonsil cm behind the posterior end of inferior turbinate Opening of auditory tube Bounded above (tubal opening) and behind by tubal elevation (torus tubaris) Tubal elevation Pharyngeal recess Salpingopharyngeal fold * Vertical fold of mucous Salpingopalatine membrane that is raised fold by salpingopharyngeus Above & behind the tubal elevation is a recess called fossa Extends from anterosuperior angle of tubal elevation to the soft palate. of Rossenmuller→ lies above the upper edge of the superior constrictor muscle & common site for origin of carcinoma. muscle. * running downwards from the posterior margin of tubal elevation, gradually fading on the side wall of the pharynx. Functional Considerations Nasopharynx should be kept permanently opened to allow free breathing. This is achieved by : • The well-developed pharyngeobasilar fascia. • Its wall is mostly uncovered by the pharyngeal constrictors. Special features OROPHARYNX Anteriorly -Oropharynx faces the posterior third of the tongue. -The back of the tongue is connected to the front of the epiglottis by the median glosso-epiglottic fold and the two lateral glosso-epiglottic folds. -Between these three folds, there are two depressed areas called the valleculae. Posteriorly Laterally It is related to C and upper part of C vertebrae. It presents the palatopharyngeal arch and tonsillar sinus which contains the palatine tonsil. Palatine tonsils Definition Description & relations mass of lymphoid tissue which lies in the tonsillar sinus in the lateral wall of oropharynx between the palatoglossal and palatopharyngeal arches. Inferiorly Superiorly Medial surface Lateral surface Is related to: presents the tonsil the tonsil -Tonsillar hemicapsule : it is an extension from the pharyngeo basilar fascia . orifices leading to invades the invades the -Paratonsillar vein : descends from the soft deep recesses soft palate dorsum of the palate lateral to the tonsillar hemicapsule. called the tonsillar -The superior pharyngeal constrictor tongue. (pierced by the tonsillar A.) and crypts. styloglossus muscle. -Facial A. and its ascending palatine branch are external to the superior constrictor. Arterial blood supply Venous Drainage Lymph drainage Nerve supply of palatine tonsil Clinical anatomy ~ ascending palatine branch of facial artery. ~ lesser palatine branch of descending palatine artery. ~ dorsal lingual branch of lingual artery. ~ tonsillar branch of facial artery ~ ascending pharyngeal branch of external carotid artery. by tonsillar plexus of veins which join the Para tonsillar vein. The Para tonsillar vein pierces the superior pharyngeal constrictor muscle to join pharyngeal venous plexus. Is mainly to the jugulo-digastric lymph nodes. Glossopharyngeal Nerve Lesser palatine nerves of the pterygopalatine ganglion (maxillary Nerve) - Tonsillitis causes referred pain in the ear. - Paratonsillar vein may cause hemorrhage during tonsillectomy. Waldeyer's Ring of Lymphoid tissue This ring of mucosa-associated lymphoid tissue surrounds the openings into the digestive and respiratory tracts. Components: Laterally Posterosuperiorly Anteroinferiorly nasopharyngeal tonsil. palatine and tubal tonsils. lingual tonsil. Special features They have no afferent lymph vessels. Their efferent lymphatics drain to the upper deep cervical lymph nodes. LARYNGOPHARYNX The piriform fossa Is a small recess on either side of laryngeal inlet Boundaries Medially: Aryepiglottic fold Laterally: Thyroid cartilage and thyrohyoid membrane. -Beneath the mucous membrane of the fossa the branches of the internal laryngeal N. are passing. -common site of foreign body location. The pharyngeobasilar fascia It is a thick fibrous layer which lies between the mucosa and muscular coat of the upper part of the pharynx. *It is thick in the nasopharynx where the muscle fibers are absent. Attachments Above The basilar part of the occipital bone Petrous temporal bone (medial to the carotid canal and auditory tube) Posterior border of the medial pterygoid plate Pterygomandibular raphe. Below at level of soft palate, it diminishes in thickness forms the tonsillar hemi capsule at oropharynx. Posteriorly it is strengthened by the pharyngeal raphe. Function It provides a rigid wall for the nasopharynx, keeping it permanently opened. The muscular coat of the pharynx consists of: Outer layer: formed of three constrictors The three constrictors have the following features : • They form curved sheets of muscles in the posterolateral walls of the pharynx. • They overlap each other from below upwards. • They are mostly absent in the side wall of the nasopharynx. • They have different origins, but all are inserted posteriorly into the pharyngeal raphe which descends from the pharyngeal tubercle on the skull base down to the esophagus. • They are all inserted in the pharyngeal raphe Origin Superior constrictor Middle constrictor Inferior constrictor It arises from : • Pterygoid hamulus and its adjoining part of the medial pterygoid plate. • Pterygomandibular raphe (it gives origin also to buccinator muscle). • Posterior end of the mylohyoid line of the mandible. It arises from the greater and lesser horns of the hyoid bone and the lower part of the stylohyoid ligament. It has two functional parts: Thyropharyngeus part :arises from the oblique line of the thyroid cartilage. Cricopharyngeus part : arises from the side of the cricoid cartilage and from the tendinous band which covers the cricothyroid muscle. Insertion Function The fibers curve posterosuperiorly to the median pharyngeal raphe. The most superior fibers insert directly into the pharyngeal tubercle. propulsive action during swallowing. The fibers fan out to be inserted posteriorly into the pharyngeal raphe. propulsive action during swallowing. Thyropharyngeus part : Thyropharyngeus part: fibers curve propulsive posterosuperiorly to be action during inserted into the swallowing. pharyngeal raphe. Cricopharyngeus part : Cricopharyngeus part: fibers run horizontally to acts as a become continuous with sphincter at the those of the opposite lower end of the side to form a continuous muscle sling pharynx. around the lower end of Cricopharyngeus the pharynx. -It is in a continuous state of contraction to prevent suction of air into the oesophagus. -It relaxes only at the end of the second stage of swallowing to allow passage of food into the oesophagus. -If it fails to relax, the pharyngeal mucous membrane herniates posterolaterally between the thyropharyngeus and cricopharyngeus (through the dehiscence of Killian) producing a pharyngeal pouch. Gaps between pharyngeal constrictors: The overlapping of the pharyngeal constrictor muscles leaves four gaps in the musculature for structures to enter or leave the pharynx • Superior to the superior pharyngeal constrictor The levator veli palatini, pharyngotympanic tube, and ascending palatine artery pass through a gap between the superior pharyngeal constrictor and the cranium • A gap between the superior and middle pharyngeal constrictors Stylopharyngeus, glossopharyngeal nerve, and stylohyoid ligament • gap between the middle and inferior pharyngeal constrictors Internal laryngeal nerve and superior laryngeal artery and vein. • Inferior to the inferior pharyngeal constrictor Recurrent laryngeal nerve and inferior laryngeal artery Inner layer: formed of three longitudinal muscles ALL have different origins, but alt are inserted into the posterior border of the thyroid cartilage. Origin Insertion Arises from the styloid Stylopharyngeus process and is inserted into the posterior border of the thyroid cartilage. -Arises from the inferior Salpingopharyngeus border of the pharyngeal end of the cartilage of the auditory tube. -It descends in the salpingopharyngeal fold to join the palatopharyngeus muscle. Arises from the upper Palatopharyngeus surface of the palatine aponeurosis ( soft palate) ,and descends in the palatopharyngeal fold Posterior border of thyroid cartilage Action elevate the larynx and pharynx upwards (in the second stage of swallowing) to close the laryngeal inlet. Figure The buccopharyngeal fascia It is a this thin layer of fascia covers the external surface of the constrictors and passes forwards to cover the buccinator Arterial blood supply of the pharynx . Ascending pharyngeal A. of ECA. . Ascending palatine and tonsillar arteries of the facial A. . Greater palatine and pharyngeal arteries of the maxillary A. . Dorsal lingual branches from the lingual A . Pharyngeal branches from the inferior thyroid artery Venous drainage -Veins of the pharynx collect into the pharyngeal venous plexus external to the superior constrictor. - This venous plexus is drained superiorly into the pterygoid venous plexus and inferiorly into the IJV. Lymph drainage Into the retropharyngeal lymph nodes, then to the deep cervical lymph nodes. Nerve supply Pharyngeal plexus Formed by: Pharyngeal branch of the vagus nerve. Branches from the external laryngeal nerve from the superior laryngeal branch of the vagus Pharyngeal branches of the glossopharyngeal nerve Motor nerve supply: -All the constrictors and longitudinal muscles of the pharynx are supplied by the vagus N. through the pharyngeal plexus EXCEPT stylopharyngeus, supplied by the glossopharyngeal Nerve. -The cricopharyngeus part of the inferior constrictor has additional nerve supply from the recurrent and external laryngeal nerves. Sensory nerve supply Mainly by the pharyngeal branch of the glossopharyngeal Nerve through the pharyngeal plexus with additional sensory branches as in the table in page two.