Pharynx : Divisions, structures and clinical correlates

Revised ppt

1. PHARYNX DR. SUNDIP CHARMODE ASSOCIATE PROFESSOR DEPAETMENT OF ANATOMY AIIMS RAJKOT

2. OBJECTIVES Structure, boundaries and features of various divisions of pharynx Muscles of pharynx with their attachments, and their action Nerve and blood supply Clinical correlates

3. INTRODUCTION Musculo-membranous tube lined internally by mucus membrane, that links the oral and nasal cavities in the head to the larynx and esophagus in neck. Extends from base of skull to the level of 6 th cervical vertebra, where it becomes continuous with the esophagus

4. DIVISIONS OF PHARYNX Nasopharynx Oropharynx Laryngopharynx

5. MEASUREMENTS Length: 12 – 14 cm Width: Maximum of 3.5 cm at naso -pharynx Minimum at 1.5 cm at pharyngo-esophageal junction

6. SKELETAL FRAMEWORK The superior and anterior margins of the pharyngeal wall are attached to bone and cartilage, and to ligaments . The two sides of the pharyngeal wall are welded together posterior in the midline by a vertically oriented cord-like ligament - Pharyngeal raphe . Extends from pharyngeal tubercle (base of the skull) to level of 6 th cervical vertebra where it blends with connective tissue in the posterior wall of oesophagus.

7. SKELETAL FRAMEWORK There is an irregular C -shaped line of pharyngeal wall attachment on the base of the skull. The open part of the C  faces the nasal cavities.

8. ATTACHMENT OF LATERAL PHARYNGEAL WALL First part Second part Third part

9. RELATIONS OF PHARYNX Above: S upported by the body of sphenoid and basilar part of occipital bone Below: C ontinuous with esophagus opposite C6 vertebra In front: C ontinuous with nasal cavity, oral cavity, and with larynx Behind: Upper six cervical vertebra and intervertebral disc Pre and para-vertebral muscles covered by prevertebral fascia Retro-pharyngeal space and its contents

10. RELATIONS OF PHARYNX On each side: Styloid process and styloid group of muscles Carotid sheath and its contents Lateral lobe of thyroid gland Lateral wall of nasopharynx communicates with tympanic cavity through auditory tube

11. NASOPHARYNX/ EPIPHARYNX

12. INTERIOR OF NASO-PHARYNX Nasopharynx is situated behind the nasal cavity and above soft palate. Boundaries are: Anterior wall Posterior wall Lateral walls Floor Roof

13. BOUNDARIES AND FEATURES Anterior wall: deficient and communicates with nasal cavity through choanae

14. BOUNDARIES AND FEATURES Roof and posterior wall: Forms continuous surface, slopes backward and downward Supported by body of sphenoid , basilar part of occipital bone and anterior arch of atlas

15. FEATURES Roof and Posterior wall Naso-pharyngeal tonsil Pharyngeal bursa (pouch of Luschka) Pharyngeal hypophysis – roof, cell are derived from extension of Rathke’s pouch Lateral wall Presents on each side following features: Pharyngeal opening of auditory tube Tubal elevation, Tubal tonsils, Two mucous folds: Salpingo -pharyngeal fold Salpingo -palatine fold Pharyngeal recess (Fossa of Rosenmuller)

16. BOUNDARIES AND FEATURES Floor: Communicates with oropharynx through Pharyngeal Isthmus In front: Posterior surface and free margin of soft palate Behind: Passavant ridge formed by the palato-pharyngeal sphincter and on each side by palato-pharyngeal arch containing muscle of same name.

17. OROPHARYNX/ MESOPHARYNX

18. INTERIOR OF ORO-PHARYNX Oropharynx is situated behind the oral cavity and supported dorsally by bodies of C2, C3 vertebra and contents of retro-pharyngeal space.

19. BOUNDARIES AND FEATURES In front: communicates with oral cavity through oro -pharyngeal isthmus Below: communicates with laryngo-pharynx at the level of upper border of epiglottis Lateral wall: presents on each side, palatine tonsil lodged in tonsillar fossa

20. ORO-PHARYNGEAL ISTHMUS Boundaries: Above: soft palate Below: dorsal surface of posterior third of tongue Each side: palato-glossal arch with corresponding muscle

21. TONSILLAR FOSSA Boundaries: In front : palato-glossal arch with corresponding muscle Behind: palato-pharyngeal arch with corresponding muscle Apex : soft palate where both arches meet Base: dorsal surface of posterior third of tongue Lateral wall/floor of fossa- superior constrictor and styloglossus covered by pharyngo-basilar fascia.

22. LARYNGO-PHARYNX/ HYPOPHARYNX

23. INTERIOR OF LARYNGO-PHARYNX Laryngo-pharynx extends from upper border of epiglottis to lower border of cricoid cartilage Supported from behind by bodies of C4 to C6 ve rtebra, prevertebral fascia and retropharyngeal space.

24. BOUNDARIES AND FEATURES In front: Upper part: Presents laryngeal inlet , through which it communicates with laryngeal cavity through oro -pharyngeal isthmus Lower part: formed by posterior surface of arytenoids and lamina of cricoid cartilages , covered by mucous membrane

25. LARYNGEAL INLET Above and in front : upper margin of epiglottis Below and behind: inter-arytenoid fold of mucous membrane On each side: aryepiglottic fold

26. BOUNDARIES AND FEATURES Lateral wall: On each side of laryngeal inlet, presents piriform fossa – mucous membrane covered depression Boundaries of Piriform fossa Medially: A ryepiglottic fold Laterally: mucous membrane covering the medial surface of lamina of thyroid cartilage and thyrohyoid membrane Above : It is separated from epiglottic vallecula by the pharyngo-epiglottic fold (lateral glosso -epiglottic fold)

27. IMPORTANCE OF PIRIFORM FOSSA Deeper in ruminating animals and act as lateral food channels to convey the bolus of food Acts as catch point for foreign body Injury to internal laryngeal nerve which enter through the thyro-hyoid membrane - absent cough reflex- aspiration.

28. WALDEYER’S RING They are composed of rings of lymphoid tissue which encircles the cephalic part of air and food passages, provide defensive mechanism: Lingual tonsils -ventrally Palatine tonsils - laterally Tubal tonsils - laterally Naso-pharyngeal tonsils - dorsally

29. STRUCTURE OF PHARYNX Wall of pharynx presents following coats from outside inside: Areolar coat/Bucco-pharyngeal fascia Muscular Submucosa Mucosa

30. AREOLAR TISSUE LAYER Known as B ucco-pharyngeal fascia Not well defined , attached above to base of skull Represents epimysium of pharyngeal muscles Covers outer surface of constrictor muscles of pharynx as a loose membrane . It extends forwards over buccinator .

31. MUSCLES OF PHARYNX The muscles of the pharynx are organized into two groups based on the orientation of muscle fibres . The constrictor muscles have fibres oriented in a circular direction relative to the pharyngeal wall and The longitudinal muscles have fibres oriented vertically.

32. MUSCLES OF PHARYNX Outer circular layer: 3 paired muscles Superior constrictor Middle constrictor Inferior constrictor – Thyro-pharyngeus, Crico-pharyngeus Inner longitudinal layer: 3 paired muscles Stylopharyngeus Palato-pharyngeus Salpingo-pharyngeus

33. ACTIONS OF CONSTRICTOR MUSCLES All the constrictors contract reflexly during deglutition and induce a wave of peristalsis which passes in caudal direction. Thyro-pharyngeus acts propulsive in nature Crico-pharyngeus acts as a sphincter, normally kept closed except during deglutition. When the Thyro-pharyngeus contracts, the Crico-pharyngeus relaxes and vice versa.

34. ACTIONS OF LONGITUDINAL MUSCLES They elevate the larynx and shorten the pharynx during swallowing and at the same time, the palato-pharyngeus sphincter closes the pharyngeal isthmus.

35. STRUCTURES PASSING BETWEEN CONSTRICTORS Gap Structures passing Through the sinus of Morgagni (the interval between the base of skull and superior constrictor) Auditory tube, Levator veli palitini , Ascending palatine artery, palatine branch of ascending pharyngeal artery Between superior and middle constrictor Stylopharyngeus, glossopharyngeal nerve Between middle and inferior constrictor Internal laryngeal nerve, superior laryngeal vessels Below the inferior constrictor Recurrent laryngeal nerve, inferior laryngeal vessels

36. SUBMUCOSA This is thickened in the upper part to form the pharyngo-basilar fascia which closes the sinus of Morgagni and is attached to base of skull. MUCOUS MEMBRANE Naso-pharynx - ciliated columnar epithelium Oro- pharyx and Larygo -pharynx : non-keratinized stratified squamous epithelium

37. NERVE SUPPLY - MOTOR Motor: All pharyngeal muscles are supplied by cranial part of accessory nerve via the pharyngeal plexus except stylopharyngeus Inferior constrictor is supplied additionally by recurrent laryngeal nerve and external laryngeal nerve

38. NERVE SUPPLY - SENSORY Nasopharynx- by pharyngeal branch of pterygopalatine ganglion, conveying fibers of the Maxillary nerve Oro-pharynx- G lossopharyngeal nerve Laryngo-pharynx- I nternal laryngeal nerve

39. PHARYNGEAL PLEXUS Formed by Pharyngeal branch of vagus carrying fibers from cranial part of accessory nerve Pharyngeal branch of glossopharyngeal nerve A branch from superior cervical ganglion of sympathetic trunk Sometime, a branch from external laryngeal nerve

40. PHARYNGEAL PLEXUS The plexus lies on B ucco-pharyngeal fascia which covers middle constrictor. Vagal fibers – motor Glossopharyngeal fibers – sensory Sympathetic fibers - vasomotor

41. ARTERIAL SUPPLY Ascending pharyngeal artery Ascending palatine and tonsillar branches of facial artery Greater palatine, pharyngeal and pterygoid branches of maxillary artery Dorsal lingual branches of lingual artery

42. VENOUS DRAINAGE The veins accompany the arterie s, form plexus which joins the pterygoid venous plexus which finally drain into Internal jugular vein

43. CLINICAL CORRELATION Dysphagia – difficulty in swallowing Odynophagia – painful deglutition Pharyngeal diverticulum – in neuromuscular incoordination, when both parts contract simultaneously, intra-pharyngeal pressure rises, mucus membrane bulges through dehiscence forming diverticulum .

44. CLINICAL CORRELATION Zenker’s diverticulum- outpouching in posterior pharyngeal wall through Killan’s triangle – point of least resistance, located superior to cricopharyngeal and inferior to thyro-pharyngeus parts of inferior constrictor. May present with dysphagia, rarely pain.

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