Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Fifth stage سنمار.د ENT Lec-1 15/11/2016 The pharynx Anatomy The pharynx is a conical fibromuscular tube forming the upper part of the air and food passages, controlling and diverting air to the respiratory passages and food and fluid to the esophagus using propulsive waves of muscle contraction. It is 12-14 cm long, extending from the base of the skull to the lower border of the cricoid cartilage ( at the level of C6) where it becomes continuous with the oesophagus. The width of pharynx is 3.5cm at its base and this narrows to 1.5 cm at pharyngo-oesophageal junction which is the narrowest part of digestive tract apart from the appendix. Divisions of the pharynx The pharynx communicates anteriorly with the nasal cavity, mouth and pharynx; and is thus divided anatomically into the nasopharynx (postnasal space), the oropharynx and the laryngopharynx (hypopharynx). 1. Nasopharynx: This extends from base of the skull to the hard palate and communicates anteriorly with the nasal cavity through the posterior nares (choanae). At the junction of the roof and posterior wall, there is a small of lymphoid tissue called the nasopharyngeal tonsil (adenoid). In the lateral wall there are openings of the Eustachian tubes, behind these are the eminences called Eustachian cushions and posterior to these are the fossae of Rosenmuller. These are deep depressions that extend laterally below the skull base, they are in close proximity to the lower cranial nerves. These fossae are common sites for nasopharyngeal CA so may present late with cranial nerves palsies if it extends laterally. 1 Summary • • • • • Anteriorly; nasal cavity Posterosuperiorly; basisphenoid …adenoid Posteriorly; extend down to the junction of the hard and soft palate and is formed by pharyngobasilar fascia in front of C1 (atlas) Inferiorly; the superior surface of the soft palate and opens into the oropharynx. Laterally; openings of the Eustachian tubes Eustacian cushions, fossae of Rosenmuller. Eustachian cushion Pharyngeal orifice of Eustachian tube Fossa of Rosenmuller Nasopharynx (sagital section) 2 Nasal septum Nasal turbinates Fossa of Rosenmuller Eustachian cushion Pharyngeal orifice of Eustachian tube Nasopharynx ( Posterior veiw ) 2. Oropharynx: This extends from the level of hard palate to the level of hyoid bone (in front of 2nd&3rd cervical vertebrae) and opens anteriorly into the oral cavity. The palatine tonsils are situated in its lateral wall lying between the anterior and posterior pillars. The dividing line between the oropharynx and mouth is: junction of hard palate and soft palate above, anterior pillar laterally, and junction of anterior 2/3 and posterior 1/3 of the tongue (circumvallate papillae). circumvallate papillae The Tongue The tonsils and adenoid 3 3. Hypopharynx: It extends from the level of hyoid to the upper end of esophagus (in front of 3rd to 6th cervical vertebra) and communicates anteriorly with the larynx and below with the esophagus. It consist of three parts: a) Pyriform fossa: two potential spaces on each side of the pharynx forming a lateral food channel during swallowing. b) Postcricoid area: lies behind the cricoid cartilage. c) Posterior pharyngeal wall. A B C The structure of pharyngeal wall The pharyngeal wall consists of 4 layers from inside to outside: a. Mucous membrane. b. Pharyngobasillar fascia aponeurosis) c. Muscular coat d. Buccopharyngeal fascia (pharyngeal 4 Mucous membrane The nasopharynx is lined by pseudostratified ciliated columnar epithelium with goblet cells (respiratory epithelium), with some minor salivary glands. The oro- and hypopharynx are lined by nonkeratinizing stratified squamous epithelium. REMEMBER; Air Passages = Respiratory Epithelium Food Passages = Squamous Epithelium Pharyngobasillar fascia This is a strong fibrous layer attached superiorly to the base of the skull. It is strengthened posteriorly by strong fibrous band called “median pharyngeal raphe”. This raphe attaches above to the base of the skull, and gives insertion to the constrictor muscles. Muscle layer 1. Circular (outer layer): consists of three constrictor muscles overlapping one another from below upward. a) Superior constrictor. b) Middle constrictor. c) Inferior constrictor; has 2 parts: a) Thyropharyngeus (oblique) arises from thyroid cartilage b) Cricopharyngeus (transverse) arises from the cricoid cartilage and passes backwards forming the upper esophageal sphincter. Killian’s Dehiscence: This is a potential gap between fibers of thyropharyngeus and cricopharyngeus muscles. Normally cricopharyngeus muscle relaxes when food bolus is pushed by the pharynx towards the esophagus. If this does not happen, mucosa will bulge outward forming a pharyngeal pouch. pharyngeal pouch 5 2. Longitudinal ( internal ): These muscles elevate the larynx and shorten the pharynx during swallowing; a) Stylopharyngeus b) Salpingopharyngeus c) Palatopharyngeus Buccopharyngeal fascia This fascia is loosely attached posteriorly to the prevertebral fascia and laterally it is connected to the styloid process and the carotid sheath. Nerve supply of the pharynx The pharyngeal plexus is formed in the buccopharyngeal fascia and consists of: 1. Pharyngeal branch of IX cranial n. 2. Pharyngeal branch of X cranial n. 3. Sympathetic fibers from superior cervical ganglion. All muscles of the pharynx are supplied by pharyngeal branch of the vagus except stylopharyngeus which is supplied by pharyngeal branch of IX. Waldeyer’s ring: It is a collection of lymphoid tissue in the nasopharynx and oropharynx at the entrance to the airodigestive tract. It is composed of: 1. Nasopharyngeal tonsil (adenoid): lies in the midline between the roof and posterior wall of the nasopharynx. Its free surface shows about 5 vertical fissures. 2. Tubal tonsils: lie behind the opening of the Eustachian tubes. 3. Palatine tonsils. 4. Lingual tonsils: embedded in the posterior 1/3 of the tongue. 5. Lateral pharyngeal bands: behind the posterior tonsillar pillars, become prominent in patients with post nasal discharge. 6. Lymphoid nodules scattered on the posterior pharyngeal wall. 6 Hypertrophy of the lymphoid tissue of Waldeyer’s ring occurs in the earlier years of childhood, probably in response to URTI. Maximum hypertrophy occurs between 4-10 years, thereafter some regression in size is to be expected, and in old age it atrophies. Waldeyer’s ring is characterized by: 1. 2. 3. 4. Sub-epithelial lymphoid tissue. Lack of definite capsule. They have efferent lymph vessels, but NO afferent vessels. They function as one unit; when a member of it is removed the other parts undergo compensatory hypertrophy. 5. The exact function is unknown but it is thought that it has a protective function by: a) Formation of lymphocytes. b) Secretion of antibodies mainly IgA. c) Localization of infection entering the body by initial contact with the incoming organism. 7 Palatine tonsils Two masses of lymphoid tissue situated on each side of oropharynx. Each tonsil is situated between palatoglossus muscle anteriorly, and palatopharyngeus posteriorly. Its medial surface is pitted by a number of crypts. Laterally the tonsil is enclosed by a dense fibrous capsule separating the tonsil from the superior constrictor (tonsillar bed). This capsule provides a convenient plane for dissection of the tonsil during tonsillectomy. Blood supply of the tonsil From the External Carotid Artery & its branches 1- Tonsillar artery (from facial artery) 2- Ascending palatine artery (from facial artery) 3- Ascending pharyngeal artery (from external carotid) 4- Descending palatine artery ( from maxillary artery. 5- Dorsalis lingulae artery (from lingual artery) 8 Blood suply of the tonsil Venous drainage To the paratonsillar vein which drains to the pharyngeal plexus. The plexus drain to the internal jugular veins. Retropharyngeal space ( Space of Gillette) It is a potential space that lies between the pre vertebral fascia posteriorly and the buccopharyngeal fascia anteriorly. It extend from the base of the skull to the superior mediastenum. It contains retropharyngeal lymph nodes of Rouviere: few lymph nodes that disappear spontaneously during the 3rd or 4th year of life. 9 Parapharyngeal Space It is a potential space that lies lateral to the pharynx and connects posteriorly with the retropharyngeal space. It extends from the base of the skull to the hyoid bone (i.e. it is lateral to the nasopharynx and oropharynx ). It is bounded medially by the superior constrictor muscle and laterally by the medial ptrygoid muscle, mandible and deep lobe of parotid gland. Its posterior wall is the prevertebral muscle and fascia. It contains: 1) Deep cervical lymph nodes. 2) Last 4 cranial nerve and cervical sympathetic trunk. 3) Great vessels of the neck; common carotid artery and internal jugular vein. Parotid gland Prevertebral fascia Buccopharyngeal fascia Parapharyngeal space Retropharyngeal space Functions of the pharynx 1) 2) 3) 4) Food and air inlet. Play an important role in speech through vocal resonance and articulation. The immunologic function of Waldeyer's ring. Deglutition; which is divided into three stage; Oral stage ( voluntary ) Pharyngeal stage ( involuntary ) Eosophageal stage ( involuntary ) 10