The Pharynx PDF

The University of Jordan Faculty Of Medicine The Pharynx DR. AHMED SALMAN Associate professor of anatomy & embryology DR.AHMED SALMAN The Pharynx 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 6th cervical...

The University of Jordan Faculty Of Medicine The Pharynx DR. AHMED SALMAN Associate professor of anatomy & embryology DR.AHMED SALMAN The Pharynx 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 6th cervical vertebra (opposite the lower border of the cricoid cartilage) Diameter : it is widest at its beginning and narrowest at its lower end at the pharyngeo-oesophageal junction . DR.AHMED SALMAN Parts of the Pharynx : It is divided into 3 parts :1. Nasopharynx which communicates with nasal cavities through the choanae 2. Oropharynx which communicates with the oral cavity through the oropharyngeal isthmus 3. Laryngeopharynx which communicates with laryngeal cavity through the inlet of the larynx DR.AHMED SALMAN DR.AHMED SALMAN Structure of the Pharyngeal Wall : From within outwards, the pharyngeal wall is composed of : 1. Mucous membrane : It is the interior of the pharynx. 2. Fibrous layer : called the pharyngeo-basilar fascia. 3. Muscular coat. 4. Buccopharyngeal fascia : Covers the external aspect of the pharynx. I- The Mucous Membrane or Interior of the Pharynx : •The nasopharynx is lined with respiratory epithelium. •The oropharynx and laryngeopharynx are lined with stratified squamous epithelium. DR.AHMED SALMAN Parts of the Pharynx : A. The Nasopharynx : Extent : It extends from the base of the skull down to the level of the soft palate. Communications : • Anteriorly: with the nasal cavities 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. pharyngeal isthmus is a mucosal fold caused by the underlying palatopharyngeal sphincter DR.AHMED SALMAN Special Features : - At the junction of its roof and the posterior wall, the mucosa contains the nasopharyngeal tonsil . - This tonsil is usually enlarged in children and is called adenoids which may obstruct the nasopharynx with difficult nasal breathing. After 6 years of age, it atrophies. Adenoid Face DR.AHMED SALMAN On each lateral wall of the nasopharynx, there are :  Pharyngeal opening of the auditory tube situated 1 cm behind the inferior nasal concha.  Tubal elevation (Torus tubarius): Above and behind pharyngeal opening ,produced by the cartilage of the auditory tube.  Tubal tonsil : collection of lymphoid tissue around the opening  Pharyngeal recess : A fosaa behind tubal elevation related to ICA . • The lower end of the tubal elevation :  Is continuous with the salpingopharyngeal fold, produced by the salpingeopharyngeus muscle.  Torus levatorius (salpingopalatine) : is an elevation that extends from the opening of the auditory tube towards the palate . It overlies the levator veli palatini muscle Auditory tube is also named pharyngotympanic tube DR.AHMED SALMAN 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. DR.AHMED SALMAN DR.AHMED SALMAN B. The Oropharynx : Extent: It extends from the level of the soft palate down to the level of the upper of the epiglottis. Communications: • Above : with nasopharynx via the pharyngeal isthmus. • Anteriorly : with the mouth cavity via the oropharyngeal isthmus. • Below : is continuous with the laryngeopharynx. DR.AHMED SALMAN Special Features : Anteriorly :  Oropharynx faces the posterior 1/3 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 : It is related to C2 and upper part of C3 vertebrae. Laterally :It presents the palatopharyngeal arch and tonsillar sinus which contains the palatine tonsil. DR.AHMED SALMAN Valleculae median glosso-epiglottic fold Two lateral glosso-epiglottic folds DR.AHMED SALMAN The Palatine Tonsil : mass of lymphoid tissue which lies in the tonsillar sinus in the lateral wall of oropharynx between the palatoglossal and palatopharyngeal arches. Description and Relations : 1-Superiorly : the tonsil invades the soft palate 2- Inferiorly : the tonsil invades the dorsum of the tongue. 3-Medial surface : presents 10 - 15 orifices leading to deep recesses called the tonsillar crypts. DR.AHMED SALMAN palatoglossal Arch palatopharyngeal arch DR.AHMED SALMAN palatoglossal Arch palatopharyngeal arch DR.AHMED SALMAN 4- Its lateral surface : is related to :  Tonsillar hemicapsule : it is an extension from the pharyngeo basilar fascia .  Paratonsillar vein : descends from the soft palate lateral to the tonsillar hemicapsule.  The superior pharyngeal constrictor (pierced by the tonsillar A.) and styloglossus muscle.  Facial A. and its ascending palatine branch are external to the superior constrictor. DR.AHMED SALMAN Arterial Blood Supply: The tonsil is mainly supplied by 1. Ascending palatine branch of the facial artery 2. Tonsillar branch of the facial artery 3. Ascending pharyngeal branch of the external carotid 4. Dorsal lingual branch of the lingual artery 5. Lesser palatine branch of the descending palatine artery Venous Drainage : 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. DR.AHMED SALMAN Lymph Drainage : Is mainly to the jugulo-digastric lymph nodes. Nerve supply of Palatine tonsil Glossopharyngeal N. and lesser palatine nerves of the pterygopalatine ganglion (maxillary N.) Clinical Anatomy : - Tonsillitis causes referred pain in the ear. - Paratonsillar vein may cause hemorrhage during tonsillectomy. DR.AHMED SALMAN DR.AHMED SALMAN Waldeyer' Ring of Lymphoid tissue : Definition: This ring of mucosa-associated lymphoid tissue surrounds the openings into the digestive and respiratory tracts. Components: Anteroinferiorly : lingual tonsil. Laterally : palatine and tubal tonsils. Posterosuperiorly : nasopharyngeal tonsil. Special Features : They have no afferent lymph vessels. Their efferent lymphatics drain to the upper deep cervical lymph nodes. DR.AHMED SALMAN C . Laryngopharynx Extent: It extends from the upper of the epiglottis to lower border of cricoid cartilage (C6 vertebra) Communications: Anteroinferiorly : With larynx via laryngeal inlet Inferiorly : Continuous with oesophagus DR.AHMED SALMAN 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 It is common site of foreign body location DR.AHMED SALMAN DR.AHMED SALMAN DR.AHMED SALMAN II- The Pharynqeobasilar 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 : is attached to 1. The basilar part of the occipital bone 2. Petrous temporal bone (medial to the carotid canal and auditory tube) 3. Posterior border of the medial pterygoid plate 4. Pterygomandibular raphe. DR.AHMED SALMAN • 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. DR.AHMED SALMAN III- The Muscular Coat of the Pharynx : The muscle coat of the pharynx consists of : Outer layer formed of 3 constrictors (superior, middle, inferior). Inner layer formed of 3 longitudinal muscles (stylopharyngeus, salpingopharyngeus and palatopharyngeus). The 3 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. DR.AHMED SALMAN A. The Three Constrictors : (1) The Superior 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. The fibers curve posterosuperiorly to the median pharyngeal raphe. The most superior fibers insert directly into the pharyngeal tubercle. DR.AHMED SALMAN (2) The Middle Constrictor: It arises from the greater and lesser horns of the hyoid bone and the lower part of the stylohyoid ligament. The fibers fan out to be inserted posteriorly into the pharyngeal raphe. (3) The Inferior Constrictor: It has 2 functional parts (thyropharyngeus and cricopharyngeus) Thyropharyngeus part :arises from the oblique line of the thyroid cartilage. Its fibers curve posterosuperiorly to be inserted into the pharyngeal raphe. Cricopharyngeus part : arises from the side of the cricoid cartilage and from the tendinous band which covers the cricothyroid muscle. Its fibers run horizontally to become continuous with those of the opposite side to form a continuous muscle sling around the lower end of the pharynx. DR.AHMED SALMAN The Superior Constrictor Middle Constrictor DR.AHMED SALMAN Thyropharyngeus part : Cricopharyngeus part DR.AHMED SALMAN DR.AHMED SALMAN Functions of the Pharyngeal Constrictors : -The superior and middle constrictors and the thyropharyngeus part of the inferior constrictor have a propulsive action during swallowing. -The cricopharyngeus acts as a sphincter at the lower end of 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. DR.AHMED SALMAN DR.AHMED SALMAN DR.AHMED SALMAN Gaps between pharyngeal constrictor The overlapping of the pharyngeal constrictor muscles leaves four gaps in the musculature for structures to enter or leave the pharynx 1. 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 2. A gap between the superior and middle pharyngeal constrictors Stylopharyngeus, glossopharyngeal nerve, and stylohyoid ligament 3. A gap between the middle and inferior pharyngeal constrictors Internal laryngeal nerve and superior laryngeal artery and vein. 4. Inferior to the inferior pharyngeal constrictor Recurrent laryngeal nerve and inferior laryngeal artery DR.AHMED SALMAN DR.AHMED SALMAN B. The Three Longitudinal Muscles : ALL have different origins, but alt are inserted into the posterior border of the thyroid cartilage. (1) The stylopharyngeus muscle : Arises from the styloid process and is inserted into the posterior border of the thyroid cartilage. (2) The salpingopharyngeus muscle :  Arises from the inferior border of the pharyngeal end of the cartilage of the auditory tube.  It descends in the salpingopharyngeal fold to join the palatopharyngeus muscle.  Both are inserted into the posterior border of the thyroid cartilage. DR.AHMED SALMAN (3) The palatopharyngeus muscle : Arises from the upper surface of the palatine aponeurosis. It descends in the palatopharyngeal fold to be inserted into the posterior border of the thyroid cartilage. Actions : These 3 muscles elevate the larynx and pharynx upwards (in the second stage of swallowing) to close the laryngeal inlet. IV- The Buccopharynqeal Fascia : It is a this thin layer of fascia covers the external surface of the constrictors and passes forwards to cover the buccinator DR.AHMED SALMAN Stylopharyngeus muscle Salpingopharyngeus DR.AHMED SALMAN Palatopharyngeus DR.AHMED SALMAN Mechanism of Deglutition (swallowing) is the complex process that transfers a food bolus from the mouth through the pharynx and esophagus into the stomach. Solid food is masticated (chewed) and mixed with saliva to form a soft bolus (mass) that is easier to swallow. DR.AHMED SALMAN Stages of Deglutition : • Stage 1: voluntary; the bolus is compressed against the palate and pushed from the mouth into the oropharynx, mainly by movements of the muscles of the tongue and soft palate . • Stage 2: involuntary and rapid; the soft palate is elevated, sealing off the nasopharynx from the oropharynx and laryngopharynx . The pharynx widens and shortens to receive the bolus of food as the suprahyoid muscles and longitudinal pharyngeal muscles contract, elevating the larynx. • Stage 3: involuntary; sequential contraction of all three pharyngeal constrictor muscles creates a peristaltic ridge that forces the food bolus inferiorly into the esophagus DR.AHMED SALMAN Arterial Blood Supply of the Pharynx : 1. Ascending pharyngeal A. of ECA. 2. Ascending palatine and tonsillar arteries of the facial A. 3. Greater palatine and pharyngeal arteries of the maxillary A. 4. Dorsal lingual branches from the lingual A 5. Pharyngeal branches from the inferior thyroid artery DR.AHMED SALMAN 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. DR.AHMED SALMAN Nerve Supply of the Pharynx : Pharyngeal plexus is formed by 1. Pharyngeal branch of the vagus nerve 2. Branches from the external laryngeal nerve from the superior laryngeal branch of the vagus 3. Pharyngeal branches of the glossopharyngeal nerve DR.AHMED SALMAN 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 N. -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 N. through the pharyngeal plexus with additional sensory branches as follows : • Nasopharynx : is supplied by pharyngeal branch from the pterygo-palatine ganglion (maxillary N.). Oropharynx and laryngopharynx: glossopharyngeal nerve DR.AHMED SALMAN DR.AHMED SALMAN DR.AHMED SALMAN