Anatomy of pharynx.pptx UNIVERSITY OF UYO

This slide contains descriptive anatomy of the pharynx

1. Anatomy of pharynx By I dyUmoh

2. Introduction The pharynx is a conductive structure located in the midline of the neck . The pharynx is a muscular tube that connects the oral and nasal cavity to the larynx and oesophagus . It begins at the base of the skull It ends at the inferior border of the cricoid cartilage (C6).

3. Introduction The pharynx is the part of the throat, Superiorly behind the mouth and nasal cavity, Inferiorly above the esophagus and trachea (the tubes going down to the stomach and the lung The pharynx carries food and air to the esophagus and larynx respectively. The flap of cartilage called the epiglottis stops food from entering the larynx

4. It is the main structure, in addition to the oral cavity, shared by two organ systems, i.e., the gastrointestinal tract (GIT) the respiratory system . It is funnel-shaped with its upper end being wider and located just below the lower surface of the skull, and its lower end is narrower and located at the level of the sixth cervical vertebra (C6) where the commencement of the esophagus posteriorly and the larynx anteriorly takes place

5. Boundaries of the Pharynx Superior: the posterior part of the body of the sphenoid and the basilar part of the occipital bone Inferior : the upper part of the esophagus, approximately at the level of C6 Anterior: nasal cavity, oral cavity, and larynx Posterior: cervical part of the vertebral column

6. Functions Its muscular-membranous integrity allows it to mediate several vital functions related to either organ system, e.g., Peristalsis and food swallowing, Air conduction Vocalization and voice production Facilitates equalization of middle ear pressure via Eustachian tube Prevents tracheobronchial aspiration and reflux of gastric contents

7. The human pharynx is conventionally divided into three sections : The pharynx is comprised of three parts ( from superior to inferior): Nasopharynx Oropharynx Laryngopharynx It is also important in vocalization

8. Regionally, the pharynx divides into three parts which are from superior to inferior :- the nasal pharynx, located behind the posterior nasal apertures ( choanae ), the oral pharynx, located behind the opening of the oral cavity, the laryngeal pharynx, located behind the inlet (opening) of the larynx . 

9. Nasopharynx First, the nasal pharynx is only related to the respiratory tract as air passes through it from the nasal cavities . Also, within the lateral surface of the back of the nasopharynx, there are two openings, one on either side, which is called the auditory tubes (Eustachian tubes or pharyngotympanic tubes) surrounded by elevations of mucous membrane called tubal elevations. These tubes are connected to the middle ears (tympanic cavities) posteriorly and mainly serve to equalize pressure and facilitate the drainage of the secretions of the middle ears. 

10. Oropharynx Second , the oral pharynx is a continuation of the oral cavity and functions to pass the bolus toward the laryngeal pharynx below. As the bolus passes from the oral cavity, the muscles of the soft palate contract to close the choanae so that food does not enter the nasal cavity. Simultaneously, the epiglottis (single cartilage at the upper part of the larynx) is pushed anteriorly to close the laryngeal inlet preventing food from entering the airways

11. laryngopharynx Lastly , the laryngeal pharynx receives bolus from  the oral pharynx and passes it into the esophagus for digestion. Air passes from the upper two parts of the pharynx (nasal and oral) and enters the laryngeal pharynx toward the inlet of the larynx and from there to trachea down the respiratory tract.

12. Nasopharynx The nasopharynx is found between the base of the skull and the soft palate. It is continuous with the nasal cavity and performs a respiratory function by conditioning inspired air and propagating it into the larynx. This part of the pharynx is lined with respiratory epithelium ; ciliated pseudostratified columnar epithelium with goblet cells. The posterosuperior nasopharynx contains the adenoid tonsils , which enlarge between 3-8 years of age and then regress.

13. Oropharynx The oropharynx is the middle part of the pharynx, located between the soft palate superiorly and the superior border of the epiglottis inferiorly The oropharynx is involved in the voluntary and involuntary phases of swallowing.

14. Oropharynx It contains the following structures: Posterior one-third of the tongue. Lingual tonsils – lymphoid tissue at the base of the tongue. Palatine tonsils – lymphoid tissue located in the tonsillar fossa (between the palatoglossal and palatopharyngeal arches of the oral cavity). Superior constrictor muscle Waldeyer’s ring is the ring of lymphoid tissue in the naso - and oropharynx formed by the paired palatine tonsils, the adenoid tonsils and lingual tonsil .

15. Waldeyer's tonsillar ring Waldeyer's tonsillar ring is an anatomical term collectively describing the annular arrangement of lymphoid tissue in the pharynx. Waldeyer's ring circumscribes the naso - and oropharynx, with some of its tonsillar tissue located above and some below the soft palate (and to the back of the oral cavity ). It is believed that Waldeyer's ring prevents the invasion of microorganisms from going into the air and food passages and this helps in the defense mechanism of the respiratory and alimentary systems .

16. Laryngopharynx The most distal part of the pharynx, L aryngopharynx is located between the superior border of the epiglottis and inferior border of the cricoid cartilage (C6). It is continuous inferiorly with the  oesophagus . It is found posterior to the larynx and communicates with it via the laryngeal inlet, lateral to which one can find the piriform fossae . The laryngopharynx contains the middle and inferior pharyngeal constrictors .

17. Muscles There are two main groups of pharyngeal muscles ;  longitudinal pharyngeal circular pharyngeal The muscles of the pharynx are mostly innervated by the vagus nerve the only exception being the  stylopharyngeus (glossopharyngeal nerve ).

18. Muscles Pharyngeal constrictors: Superior Pharyngeal middle pharyngeal inferior Pharyngeal ; Longitudinal muscles: Palatopharyngeus , salpingopharyngeus . Stylopharyngeus

19. Muscles Circular muscles The circular muscles contract sequentially from superior to inferior to constrict the pharyngeal lumen and thus propel the bolus of food inferiorly into the oesophagus They are arranged like stacked glasses, which form an incomplete muscular circle around the pharynx . There are three circular pharyngeal constrictor muscles – superior pharyngeal constrictor middle pharyngeal constrictor inferior pharyngeal constrictor

20. Lateral view of the deep structures of the pharynx. Visible are the circular muscles of the pharynx, and the stylopharyngeus .

21. Circular Pharyngeal Constrictors Superior pharyngeal constrictor   the uppermost pharyngeal constrictor. It is located in the oropharynx. Originates from the pterygomandibular ligament, alveolar process of mandible, medial pterygoid plate and pterygoid hamulus of the sphenoid bone. Inserts posteriorly onto the pharyngeal tubercle of the occiput and the pharyngeal raphe.

22. Middle pharyngeal constrictor located in the laryngopharynx. Originates from the stylohyoid ligament and the horns of the hyoid bone . Inserts posteriorly into the pharyngeal raphe. Inferior pharyngeal constrictor  located in the laryngopharynx . It has two components: Thyropharyngeal fibres originate from the thyroid cartilage Cricopharyngeal fibres originate from the cricoid cartilage All fibres insert posteriorly onto the pharyngeal raphe

23. Longitudinal Pharyngeal muscles The longitudinal muscles They act to shorten and widen the pharynx, and elevate the larynx during swallowing. The longitudinal muscles are: the stylopharyngeus , palatopharyngeus and salpingopharyngeus

24. Longitudinal Pharyngeal muscles Stylopharyngeus   – originates from the styloid process of the temporal bone and inserts onto the pharyngeal wall. Unlike the other pharyngeal muscles, it is innervated by the glossopharyngeal nerve (CN IX). Palatopharyngeus – originates from the hard palate of the oral cavity and inserts onto the pharyngeal wall. Innervated by the vagus nerve (CN X). Salpingopharyngeus – originates from the Eustachian tube and inserts onto the pharyngeal wall. Innervated by the vagus nerve (CN X). In addition to contributing to swallowing, it also opens the Eustachian tube to equalise the pressure in the middle ear.

25. Posterior view of the pharynx. The pharynx has been split down the midline and opened, to show the longitudinal muscles

26. Innervation Motor and sensory innervation of the majority of the pharynx (except nasopharynx) is achieved by the  pharyngeal plexus. The pharyngeal plexus, which overlies the middle pharyngeal constrictor, is formed by: Pharyngeal branches from the glossopharyngeal nerve (CN IX). Pharyngeal branch of the  vagus nerve (CN X. Branches from the external laryngeal nerve. Sympathetic fibres from the superior cervical ganglion.

27. Innervation Sensory The pharynx receives sensory innervation from the glossopharyngeal nerve . In addition: The anterior and superior aspect of the nasopharynx is innervated by the maxillary nerve (CN V2) The inferior aspect of the laryngopharynx (surrounding the beginning of the larynx) is innervated by the internal branch of the vagus nerve.

28. Innervation Motor All the muscles of the pharynx are innervated by the vagus nerve (CN X), except for the stylopharyngeus , which is innervated by the glossopharyngeal nerve (CN IX).

29. Blood Supply and Venous Drainage Vasculature Arterial supply to the pharynx is via branches of the external carotid artery: Ascending pharyngeal artery Branches of the facial artery Branches of the lingual and maxillary arteries . Venous drainage is achieved by the pharyngeal venous plexus , which drains into the internal jugular vein.

30. Blood Supply and Venous Drainage The arterial supply is derived from branches of the external carotid artery , the ascending palatine and tonsillar branches of the facial artery , the maxillary artery, and the dorsa l lingual branches of the lingual artery . The pharyngeal veins drain into the internal jugular vein

31. Vasculature of the pharynx. Right arterial supply via the ECA and left venous plexus shown.

32. Lymphatic Drainage The lymphatic drainage of the pharynx is direct drainage, which means that lymph passes directly toward the deep cervical lymph nodes (DCLNs ). The deep cervical lymph nodes are the groups of lymph nodes located along the course of the internal jaguar vein or indirect drainage toward the deep cervical lymph nodes via the retropharyngeal lymph nodes (located behind the pharynx) or paratracheal lymph nodes (alongside the course of the trachea ). There is a ring of lymphoid tissue that is formed by four lymph groups, referred to as the Waldeyer ring . This ring protects the entrance of the GIT and the respiratory tract . It is formed superiorly by the pharyngeal tonsils, also known as adenoids, in the roof of the nasal pharynx . The palatine tonsils and tubal tonsils (around the auditory tubes) form the lateral wall of the ring . Inferiorly, the ring forms by the lingual tonsils on the posterior surface of the tongue

33. Surgical Considerations Performing surgical operations in the pharynx require delicate technique considering what this structure represents and also to the overlap of the neurovascular bundles and muscles overlying it. A practitioner should be familiar with the structural components of the pharynx as the anatomical knowledge is fundamental in all traumatic and surgical cases, airway evaluation has to be considered, accordingly . Breathing issues, difficulty swallowing (dysphagia), and malignancy resection all represent important surgical implications . Assessment of breathing and swallowing is considered crucial, especially in postoperative patients .

34. Feeding tubes (an alternative way of food passage instead of passing through the mouth) are also of surgical importance. Also, preserving the stylopharyngeus muscle in lateral pharyngoplasty for the treatment of patients with obstructive sleep apnea is indeed necessary. As part of airway management ,  the pharynx can be bypassed using endotracheal intubation . Furthermore, devices represent a means of control . If the ways mentioned above seem not possible, cricothyroidotomy can be a life-saving procedure . Airway obstruction due to tonsil enlargement and neck trauma outside the airway is of surgical importance especially when the latter causes elevated pressure leading to airway compromise which can be life-threatening and requires an immediate intervention such as thyroidectomy .

35. Clinical Significance Pharyngitis The inflammation of the pharynx is also known as "sore throat." It can be brought about by several causative agents with the viruses being the commonest. Generally, the characteristic presentation is discomfort, pain, irritation, and dysphagia. The pain is treated using non-steroidal anti-inflammatory drugs (NSAIDs) for both adults and children. Aspirin is also also an option for adults. However, when the disease results from S treptococcus pyogenes , the etiologic diagnosis and specific treatment plan are needed . Dysphagia As noted earlier, it is the inability to swallow properly due to muscle weakness, nerve damage, or certain diseases. It can lead to many complications, such as food or saliva aspiration, malnutrition, etc. Its prevalence is high in which approximately 50% of elderly patients and 50% of those with neurological dysfunctions have this condition .

36. Adenoiditis It is the inflammation of the adenoid lymph tissues that are present in the upper part of the nasal pharynx as has been explained earlier. It is present secondarily to an infection. Those usually affected present with cold-like symptoms, rhinorrhea, nasal obstruction, and breathing problems . Sleep Apnea The muscles of the pharynx can become hypotonic in certain occasions like during sleep. In such a case, they become too weak to prevent the collapse of the airways resulting in difficulty breathing. Several factors can be associated with sleep apnea, and those include obesity, generalized hypotonia , and large tongue ( macroglossia ).

37. Zanier Diverticulum In the laryngeal pharynx between the inferior constrictor and cricopharyngeus muscles is a small triangular gap called the Killian dehiscence. In the case of weakness or hypotonia , the pharyngeal mucosa and submucosa could get herniated and bulged between these two parts ; this can lead to different problems as food accumulates in this herniation. Since such a diverticulum is confined to the mucosa and submucosa with no trace to the muscular layer, it is described as a false diverticulum

38. Zanier Diverticulum(Pharyngeal Diverticulum (Pouch)

39. Pharyngeal Diverticulum (Pouch) Pharyngeal Diverticulum (Pouch) The inferior pharyngeal constrictor is split into two parts; the thyropharyngeus and the cricopharyngeus . This area between the two is a weak area in the mucosa. Normally during swallowing , the thyropharyngeus contracts as the cricopharyngeus relaxes, allowing the bolus of food to be propelled into the oesophagus and preventing the intrapharyngeal pressure from rising. If this coordinated relaxation of the cricopharyngeus does not occur , the intrapharyngeal pressure tends to rise and pharyngeal mucosa forms a midline diverticulum in the area between the thyropharyngeus and cricopharyngeus . It is possible for food to accumulate here, leading to dysphagia .

40. Summary The pharynx is a musculomembranous cavity that connects the oral and nasal cavities to the larynx and esophagus. It is divided into the nasopharynx (extending approx. from the base of the skull to the soft palate ), the oropharynx (extending approx. from the uvula to the level of the hyoid bone), and the laryngopharynx (extending approx. from C4 to C6).

41. The pharynx plays a role in deglutition, vocalization, and air conduction. The arterial supply is derived from branches of the external carotid artery , the ascending palatine and tonsillar branches of the facial artery , the maxillary artery, and the dorsa l lingual branches of the lingual artery . The pharyngeal veins drain into the internal jugular vein

42. The lymphatics drain directly into the deep cervical nodes , either directly or through the retropharyngeal or paratracheal nodes .

43. Motor and sensory innervation are mainly via branches of the vagus and glossopharyngeal nerves . The pharyngeal mucosa is lined by both stratified squamous epithelium and ciliated pseudostratified epithelium with goblet cells

44. diseases Diseases that may affect the pharynx include infections pharyngitis , tonsillitis , diphtheria , infectious mononucleosis , sleep apnea , dysphagia , and pharyngeal cancer