Pharynx

Anatomy of Pharynx

1. Pharynx

2. The pharynx is a musculofascial half-cylinder that links the oral and nasal cavities in the head to the larynx and esophagus in the neck. The pharyngeal cavity is a common pathway for air and food.

3. The pharynx is attached above to the base of the skull and is continuous below, approximately at the level of vertebra CVI , with the top of the esophagus. The walls of the pharynx are attached anteriorly to the margins of the nasal cavities , oral cavity, and larynx. Based on these anterior relationships the pharynx is subdivided into three regions, the nasopharynx, oropharynx, and laryngopharynx:

4. The posterior apertures ( choanae ) of the nasal cavities open into the nasopharynx . The posterior opening of the oral cavity ( oropharyngeal isthmus ) opens into the oropharynx. The superior aperture of the larynx (laryngeal inlet) opens into the laryngopharynx.

5. In addition to these openings, the pharyngeal cavity is related anteriorly to the posterior one-third of the tongue and to the posterior aspect of the larynx. The pharyngotympanic tubes open into the lateral walls of the nasopharynx. Lingual, pharyngeal, and palatine tonsils are on the deep surface of the pharyngeal walls. The pharynx is separated from the posteriorly positioned vertebral column by a thin retropharyngeal space containing loose connective tissue.

6. Although the soft palate is generally considered as part of the roof of the oral cavity, it is also related to the pharynx. The soft palate is attached to the posterior margin of the hard palate and is a type of "flutter valve" that can : swing up (elevate) to close the pharyngeal isthmus, and seal off the nasopharynx from the oropharynx , swing down (depress) to close the oropharyngeal isthmus and seal off the oral cavity from the oropharynx .

7. Skeletal Framework

8. pharyngeal raphe The two sides of the pharyngeal wall are welded together posteriorly in the midline by a vertically oriented cord-like ligament (the pharyngeal raphe) . This connective tissue structure descends from the pharyngeal tubercle on the base of the skull to the level of cervical vertebra CVI where the raphe blends with connective tissue in the posterior wall of the esophagus.

9. Superior Attachment

10. Superior Attachment 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. Each arm of the C begins at the posterior margin of the medial plate of the pterygoid process of the sphenoid bone, just inferior to the cartilaginous part of the pharyngotympanic tube. The line crosses inferior to the pharyngotympanic tube and then passes onto the petrous part of the temporal bone where it is just medial to the roughening for the attachment of one of the muscles ( levator veli palatini ) of the soft palate. From here , the line swings medially onto the occipital bone and joins the line from the other side at a prominent elevation of bone in the midline (the pharyngeal tubercle) .

11. Anterior Attachments First part On each side, the anterior line of attachment of the lateral pharyngeal wall begins superiorly on the posterior edge of the medial pterygoid plate of the sphenoid bone just inferior to where the pharyngotympanic tube lies against this plate . It continues inferiorly along the edge of the medial plate of the pterygoid process and onto the pterygoid hamulus . From this point, the line descends along the pterygomandibular raphe to the mandible where this part of the line terminates .

12. Anterior Attachments The pterygomandibular raphe is a linear cord-like connective tissue ligament that spans the distance between the tip of the pterygoid hamulus and a triangular roughening immediately posterior to the third molar on the mandible. It joins a muscle of the lateral pharyngeal wall (superior constrictor) with a muscle of the lateral wall of the oral cavity ( buccinator ) .

13. Anterior Attachments Second part The second part of the line of attachment of the lateral pharyngeal wall is related to the hyoid bone. It begins on the lower aspect of the stylohyoid ligament, which connects the tip of the styloid process of the temporal bone to the lesser horn of the hyoid bone. The line continues onto the lesser horn and then turns and runs posteriorly along the entire upper surface of the greater horn of the hyoid where it terminates.

14. Anterior Attachments Third part The most inferior and third part of the line of attachment of the lateral pharyngeal wall begins superiorly on the superior tubercle of the thyroid cartilage, and descends along the oblique line to the inferior tubercle. From the inferior tubercle, the line of attachment continues over the cricothyroid muscle along a tendinous thickening of fascia to the cricoid cartilage where it terminates .

15. Pharyngeal wall

16. Muscles T he muscles of the pharynx are organized into two groups based on the orientation of muscle fibers. T he constrictor muscles have fibers oriented in a circular direction relative to the pharyngeal wall, whereas the longitudinal muscles have fibers oriented vertically.

17. Constrictor muscles The narrowest part of the pharyngeal cavity.

18. Constrictor muscles The constrictor muscles overlap each other in a fashion resembling the walls of three flower pots stacked one on the other . Collectively, the muscles constrict or narrow the pharyngeal cavity. When the constrictor muscles contract sequentially from top to bottom, as in swallowing, they move a bolus of food through the pharynx and into the esophagus.

19. Constrictor muscles

20. Constrictor muscles A special band of muscle (the palatopharyngeal sphincter ) originates from the anterolateral surface of the soft palate and circles the inner aspect of the pharyngeal wall , blending with the inner aspect of the superior constrictor. When the superior constrictor constricts during swallowing, it forms a prominent ridge on the deep aspect of the pharyngeal wall that catches the margin of the elevated soft palate, which then seals closed the pharyngeal isthmus between the nasopharynx and oropharynx.

21. Longitudinal muscles

22. The palatopharyngeus forms an important fold in the overlying mucosa (the palatopharyngeal arch) . This arch is visible through the oral cavity and is a landmark for finding the palatine tonsil, which is immediately anterior to it on the oropharyngeal wall. In addition to elevating the pharynx, the palatopharyngeus participates in closing the oropharyngeal isthmus by depressing the palate and moving the palatopharyngeal fold toward the midline.

23. Fascia

24. The pharyngeal fascia is separated into two layers , which sandwich the pharyngeal muscles between them : A thin layer ( buccopharyngeal fascia) coats the outside of the muscular part of the wall and is a component of the pretracheal layer of cervical fascia A much thicker layer ( pharyngobasilar fascia) lines the inner surface.

25. Gaps in the pharyngeal wall and structures passing t h rough them Above the margin o f the superior constrictor, the pharyngeal wall is deficient in muscle and completed by pharyngeal fascia. The levator veli palatini passes through the pharyngeal fascia inferior to the pharyngotympanic tube and enters the soft palate. The tendon of the tensor veli palatini turns medially around the pterygoid hamulus and passes through the origin of the buccinator muscle to enter the soft palate.

26. One of the largest and most important apertures in the pharyngeal wall is between the superior and middle constrictor muscles of the pharynx and the posterior border of the mylohyoid muscle, which forms the floor of the mouth. This triangular-shaped gap ( oropharyngeal triangle ) not only enables the stylopharyngeus to slip into the pharyngeal wall, but also allows muscles, nerves, and vessels to pass between regions lateral to the pharyngeal wall and the oral cavity, particularly to the tongue.

27. The gap between the middle and inferior constrictor muscles allows the internal laryngeal vessels and nerve access to the aperture in the thyrohyoid membrane to enter the larynx. The recurrent laryngeal nerves and accompanying inferior laryngeal vessels enter the larynx posterior to the inferior horn of the thyroid cartilage deep to the inferior margin of the inferior constrictor muscle.

28. Nasopharynx

29. The nasopharynx is behind the posterior apertures ( choanae ) of the nasal cavities and above the level of the soft palate. Its ceiling is formed by the sloping base of the skull and consists of the posterior part of the body of the sphenoid bone and the basal part of the occipital bone. The position of the pharyngeal isthmus is marked on the pharyngeal wall by a mucosal fold caused by the underlying palatopharyngeal sphincter, which is part of the superior constrictor muscle.

30. There is a large collection of lymphoid tissue (the pharyngeal tonsil ) in the mucosa covering the roof of the nasopharynx . Enlargement of this tonsil, known then as adenoids , can occlude the nasopharynx so that breathing is only possible through the oral cavity.

31. The most prominent features on each lateral wall of the nasopharynx are : the pharyngeal opening of the pharyngotympanic tube , mucosal elevations and folds covering the end of the pharyngotympanic tube and the adjacent muscles.

32. The opening of the pharyngotympanic tube is posterior to and slightly above the level of the hard palate, and lateral to the top of the soft palate. Because the pharyngotympanic tube projects into the nasopharynx from a posterolateral direction, its posterior rim forms a n elevation or bulge on the pharyngeal wall. Posterior to this tubal elevation (torus tubarius ) is a deeprecess (pharyngeal recess)

33. Mucosal folds related t o the pharyngotympanic tube include: the small vertical salpingopharyngeal fold, which descends from the tubal elevation and overlies the salpingopharyngeus muscle , and a broad fold or elevation (torus levatorius ) that appears to emerge from just under the opening of the pharyngotympanic tube, continues medially onto the upper surface of the soft palate, and overlies the levator veli palatini muscle.

34. Oropharynx

35. The oropharynx is posterior to the oral cavity, inferior to the level of the soft palate, and superior to the upper margin of the epiglottis. The palatoglossal folds (arches ) , one on each side, that cover the palatoglossal muscles , mark the boundary between the oral cavity and the oropharynx . The arched opening between the two folds is the oropharyngeal isthmus. Just posterior and medial to these folds are another pair of folds (arches) , the palatopharyngeal folds , one on each side, that overlie the palatopharyngeus muscles .

36. The anterior wall of the oropharynx inferior to the oropharyngeal isthmus is formed by the upper part of the posterior one-third or pharyngeal part of the tongue. Large collections of lymphoid tissue (the lingual tonsils) are in the mucosa covering this part of the tongue.

37. A pair of mucosal pouches ( valleculae ) , one on each side of the midline , between the base of the tongue and epiglottis, are depressions formed between a midline mucosal fold and two lateral folds that connect the tongue to the epiglottis.

38. Laryngopharynx

39. The laryngopharynx extends from the superior margin of the epiglottis to the top of the esophagus at the level of vertebra CVI

40. The laryngeal inlet opens into the anterior wall o f the laryngopharynx . Inferior to the laryngeal inlet, the anterior wall consists of the posterior aspect of the larynx.

41. There is another pair of mucosal recesses ( piriform fossae ) between the central part of the larynx and the more lateral lamina of the thyroid cartilage. The piriform fossae form channels that direct solids and liquids from the oral cavity around the raised laryngeal inlet and into the esophagus .

42. Vessels

43. Arteries Numerous vessels supply the pharyngeal wall {Fig. 8 . 2 0 2 ) . Arteries that supply upper parts o f the pharynx include: the ascending pharyngeal artery, the ascending palatine and tonsillar branches of the facial artery, and numerous branches of the maxillary and the lingual arteries . All these vessels are from the external carotid artery. Arteries that supply the lower parts of the pharynx include pharyngeal branches from the inferior thyroid artery , which originates from the thyrocervical trunk of the subclavian artery .

44. Veins Veins of the pharynx form a plexus , which drains superiorly into the pterygoid plexus in the infratemporal fossa, and inferiorly into the facial and internal jugular veins

45. Lymphatics Lymphatic vessels from the pharynx drain into the deep cervical nodes and include retropharyngeal ( between the nasopharynx and vertebral column), paratracheal , and infrahyoid nodes . The palatine tonsils drain through the pharyngeal wall into the jugulodigastric nodes in the region where the facial vein drains into the internal jugular vein (and inferior to the posterior belly of the digastric muscle).

46. Nerves Motor and most sensory innervation (except for the nasal region ) of the pharynx is mainly through branches of the vagus [X] and glossopharyngeal [IX] nerves, which form a plexus in the outer fascia of the pharyngeal wall.

47. The pharyngeal plexus i s formed by : the pharyngeal branch of the vagus nerve [X] , branches from the external laryngeal nerve from the superior laryngeal branch of the vagus nerve [X ] , and pharyngeal branches of the glossopharyngeal nerve [IX] .

48. The pharyngeal branch of the vagus nerve [ X] originates from the upper part of its inferior ganglion above the origin of the superior laryngeal nerve and is the major motor nerve of the pharynx . All muscles of the pharynx are innervated by the vagus nerve [X] mainly through the pharyngeal plexus, except for the stylopharyngeus , which is innervated directly by a branch of the glossopharyngeal nerve [IX]

49. Each subdivision o f the pharynx has a different sensory innervation : The nasopharynx is innervated by a pharyngeal branch of the maxillary nerve [V2] that originates in the pterygopalatine fossa and passes through the palatovaginal canal in the sphenoid bone to reach the roof of the pharynx . The oropharynx is innervated by the glossopharyngeal nerve [IX] via the pharyngeal plexus . The laryngopharynx is innervated by the vagus nerve [X ] via the internal branch of the superior laryngeal artery .

50. Thanks for Attention