Pharynx Anatomy PDF

ANATOMY OF THE PHARYNX PHARNYX - Wide muscular tube approx. 12cm long situated behind nose, mouth and larynx - Superiorly extends till base of skull & inferiorly continues with oesophagus at level of C6 vertebra - Anterior to upper 6 cervical vertebrae STRUCTURE (Walls from within – outward)...

ANATOMY OF THE PHARYNX PHARNYX - Wide muscular tube approx. 12cm long situated behind nose, mouth and larynx - Superiorly extends till base of skull & inferiorly continues with oesophagus at level of C6 vertebra - Anterior to upper 6 cervical vertebrae STRUCTURE (Walls from within – outward) 1. Mucosa 2. Submucosa 3. Pharyngobasilar fascia (thin sheet of conntissue forms pharyngeal raphe on posterior aspect) 4. Muscular coat containing I. Inner longitudinal layer: Stylopharyngeus, salpingopharyngeus, palatopharyngeus II. Outer circular layer: 3 pharyngeal constrictors 5. Buccopharyngeal fascia MUSCLES OF PHARYNX - Superior, middle and inferior constrictor muscles - Palatopharyngeous - Salpingopharyngeus - Stylopharyngeus Constrictor muscles are at the outer part of the pharynx (involuntary contraction from superior to inferior end) Palatopharyngeus, Stylopharyngeus and Salpingopharyngeus are at the inner part of the pharynx (elevate he larynx and shorten pharynx during swallowing and speaking) NERVE SUPPLY TO MUSCLES Stylopharyngeus – glossopharyngeal nerve All other muscles – pharyngeal branch of vagus nerve via pharyngeal plexus of nerves (inferior constrictor supplied by external and recurrent laryngeal nerves) WALDEYER’S RING - palatine, tubal, lingual and pharyngeal tonsils Incomplete circular band of lymphoid tissue around the superior part of the pharynx 1. Anteroinferior part of the ring - lingual tonsil 2. Lateral parts of the ring - palatine and tubal tonsils 3. Posterior and superior parts of the ring - pharyngeal tonsil Acts as a first line of defense against microbes that enters the body via the nasal and oral routes STRUCTURE ASSOCIATED LAB/ LECTURE PHOTO PARTS NASOPHARYNX - Situated behind nose and above the lower border of the soft palate - Lined by ciliated columnar epithelium (respiratory function) - Walls are rigid and noncollapsable (air passage is kept patent) - Comm w/ nasal cavity thru posterior nasal apertures (choanae) - Extends until lower border of soft palate - Comm w/oropharynx thru pharyngeal isthmus - Supplied by branches of maxillary nerves (pharyngeal branch from pterygopalatine ganglion [V nerve]). The rest of the pharynx is supplied by IX and X nerves. - Roof, floor, posterior wall and 2 later walls as boundaries - BOUNDARIES - Anteriorly Communicates w/ posterior nasal aperture - Roof Posterior part of body of Sphenoid bone and basilar part of occipital bone (basiocciput) and anterior arch of atlas. Pharyngeal tonsil. Pathologically enlarged pharyngeal tonsil = adenoids may make nasal breathing impossible - Floor/ Inferiorly communicates w/ Mobile and formed by soft palate Pharyngeal isthmus (comm/ w oropharynx) - Posterior wall Anterior arch of Atlas (1st cervical vertebra) - Lateral Wall I) Opening of Eustachian/ Auditory tube (connects nasopharynx to middle ear cavity). Lies half inch behind the inferior nasal concha II) Tubal Elevation (cartilage of auditory tube also contains tubal tonsil) bounds the tubal opening III) Salpingopharyngeal fold from posterior end/ margin of tubal elevation and gradually fading in the side wall of the pharynx (as a result of theunderlying salpingopharyngeal muscle) IV) Pharyngeal Recess/ Fossa of Rosenmuller (groove situated behind tubal elevation andalpingopharyngeal fold). A catheter missing the tubal opening may pass to the recess, perforate the lateral wall of nasopharynx and may enter the ICA. V) Salpingopalantine fold (mucosal fold extending from anterior end of tubal elevation to the soft palate) VI) Levator palati/ levator veli palatini muscle raises a fold of mucous mem below the opening of auditory tube. (triangular elevation below opening) OROPHARYNX - Middle part of pharynx behind oral cavity - Lower boarder of soft palate to upper border of epiglottis - Above comm w/ nasopharynx thru pharyngeal isthmus - Anteriorly comm w/ oral cavity thru oropharyngeal isthmus - Below comm w/ laryngopharynx at upper border of epiglottis - In front of 2nd and 3rd cervical vertebrae (Behind it is supported by the axis and C3 vertebra) - Supplied by glossopharyngeal nerve Lateral Wall of Oropharynx - Palatoglossal fold or arch (prod by palatoglossus muscle) - Palatopharyngeal fold or arch (prod by palatopharyngeus muscle) - Palatine tonsil located between the arches (tonsillar fossa) - The wall of the oropharynx is formed by all three constrictors. Palatine Tonsil - Lies in tonsillar fossa in lateral walls of the oropharynx - Fossa bounded anteriorly by the palatoglossal fold and posteriorly by the palatopharyngeal fold - The folds meet at the apex formed by the soft palate - Base of fossa is formed by the dorsal surface of the posterior one third of the tongue LARYNGOPHARYNX - Behind larynx infront of lower part C3, and the 4th, 5th cervical vertebrae. - From upper border of epiglottis to C6 (lower border of cricoid cartilage) - Continues inferiorly as oesophagus - Supplied by branches of vagus nerve ANTERIOR WALL PRESENTS: - Inlet of larynx in upper part and posterior surfaces of cricoid and arytenoid cartilages of larynx in the lower part - Pharyngeal wall in this region is formed by the overlapping of three constrictors - Piriform fossa (small depression on either side of the larynx) PIRIFORM FOSSA - Lateral boundary formed by the thyrohyoid membrane and lamina of thyroid cartilage/ thyrohyoid membrane - Medial boundary formed by aryepiglottic fold (separates it from the inlet of larynx) - Internal laryngeal nerve and superior laryngeal vessels – deep to the mucous membrane NB: food particles may get impacted in the fossa. If not removed carefully, internal laryngeal nerve may be injured. - Causes loss of sensations (anaesthesia) in supra- glottic part of larynx leading to loss of cough reflex – which may cause aspiration pneumonia and death NERVE SUPPLY OF PHARYNX - Supplied by pharyngeal plexus of nerves form by pharyngeal branches of glossopharyngeal, vagus and superior cervical sympathetic ganglion - Pharyngeal plexuses are located on the middle constrictor ARTERIAL SUPPLY - Ascending pharyngeal artery of external carotid artery - Ascending palatine and tonsillar arteries of facial artery - Palatine, pharyngeal branches of maxillary artery VENOUS DRAINAGE - Veins of pharynx terminate at internal jugular vein and facial vein LYMPHATIC DRAINAGE - Retropharyngeal and deep cervical lymph nodes