Oral Cavity, Soft Palate, Pharynx, and Larynx; Development of the Face and Palate

Transcription

1 Oral Cavity, Soft Palate, Pharynx, and Larynx; Development of the Face and Palate Think on this. The ability to eat and drink safely and efficiently is fundamental to our quality of life. The wide variety of food and liquid enjoyed each day requires precise management because of the shared function of the upper aerodigestive system. We seldom think about the freedom and joys experienced through such activities until they are lost or diminished.

2 Oral Cavity Oral cavity consists of: Vestibule space between teeth/gums and lips/cheeks Oral cavity proper space between dental arches Boundaries: Roof hard and soft palate Floor mylohyoid and geniohyoid Laterally cheeks Anteriorly lips Posteriorly palatoglossal folds Junction between oral cavity and oropharynx is the oropharyngeal (faucial) isthmus (PG folds, soft palate, sulcus terminalis). Contents Teeth Tongue Sublingual/submandibular glands and ducts Nerves, vessels, lymphatics

3 Parotid Duct Opening, Ventral Surface of Tongue, and Floor of Mouth Mucous membrane is of ventral surface of tongue and floor of mouth is thin facilitates rapid absorption of drugs, e.g., nitroglycerin Deep lingual artery and vein Lingual nerve Frenulum of tongue Sublingual caruncle opening of the submandibular (Wharton s) duct; narrowest part of duct system common site of stone (sialolith) impaction; unilateral pain/swelling at mealtime Sublingual fold and duct openings

4 Parts of the Tongue and Papillae The tongue consists of 2 parts (separated by the sulcus terminalis): (1) oral or horizontal part = anterior 2/3s of tongue; mucosa of dorsum is thick and contains papillae and taste buds (2) pharyngeal or vertical part = posterior 1/3; mucosa is thin, lacks papillae, and overlies lymphoid tissue=lingual tonsil). The pharyngeal part of the tongue actually represents the anterior wall of the oropharynx. Papillae Filiform papillae are numerous and give a velvety texture to the dorsum of the tongue. They contain no taste buds. Fungiform papillae (appear as bright red dots) are also numerous; circumvallate papillae ( donut looking ) appear in a single row in front of the terminal sulcus. Both fungiform and vallate papillae contain taste buds.

5 Roof of Oral Cavity Hard and Soft Palate Maxilla Primary palate Incisive foramen Hard palate consists of two parts: a) Palatine processes of the maxilla contains sockets for teeth b) Horizontal plate of the palatine bone c) Separates oral cavity from nasal cavities d) Is continuous posteriorly with the soft palate Secondary palate Greater palatine foramen Lesser palatine foramen An intact hard palate is important in infants as it is used to create suction for drawing milk into the infant s mouth. Palatal defects make suckling difficult. Horizontal plate of the palatine bone

6 Roof of Oral Cavity Nerve and Blood Supply Mucosal glands Nasopalatine n., Sphenopalatine a. Branches of maxillary nerve and artery that descend on the nasal septum before emerging through the incisive foramen. Supply area behind the incisor teeth. Greater palatine n.& a. Branches of maxillary nerve and descending palatine artery that descend within the greater palatine canal to emerge through the greater palatine foramen. Supply principal portion of hard palate. Lesser palatine n.& a. Supply soft palate. The mucoperiosteum of the palate is tightly bound to the hard palate and contains numerous mucous glands. Anteriorly, the mucosa contains several transverse palatine folds.

7 Muscular Floor of the Oral Cavity Mylohyoid muscles: O. Mylohyoid line I. Median raphe and body of hyoid N. Nerve to mylohyoid Geniohyoid muscles: O. Inferior mental spine I. Body of hyoid N. C1 branches from CN XII Genio (G.) Mento (L.) = Chin Both muscles are suprahyoid muscles. When the jaw is closed by elevator muscles, the suprahyoids contract to elevate the floor of the mouth and tongue during swallowing.

8 Extrinsic and Intrinsic Musculature of the Tongue Tongue: Thick and muscular Mobile Involved with taste, breakdown of foodstuffs to a consistency safe to swallow Speech

9 Nerve Supply of the Tongue: Sensory, Motor, Taste Including circumvallate papillae

10 Hypoglossal Nerve (CN XII) Lesion A 22-year-old man is brought to the emergency department because of a suprahyoid stab wound that extends from one side of the neck to the other. His tongue deviates to the right when protruded; there is no loss of sensory modality on the tongue. The injury most likely involves which of the following nerves? A. Left hypoglossal B. Right hypoglossal C. Right glossopharyngeal D. Right lingual E. Left vagus

11 Osteology of the Mandible Edentulous Mandible

12 Submandibular and Sublingual Salivary Glands Note the classic spiral relationship of the lingual nerve to the submandibular duct. Sublingual gland Submandibular (Wharton s) duct Lingual n. Submandibular ganglion Mylohyoid m. Submandibular gland Geniohyoid m. Submandibular duct is narrowest at the sublingual caruncle, commonly the point of stone (sialolith) impaction.

13 Parasympathetic nerve supply to submandibular and sublingual glands

14 Blood Supply to Tongue Lingual artery: Passes deep to hyoglossus Dorsal lingual a. to posterior region of tongue Deep lingula a. enters ventral surface of tongue Sublingual a. supplies floor of mouth and sublingual gland

15 Lymphatic Drainage of Lips and Tongue

16 Soft Palate Soft Palate Fibromuscular; contains mucous glands Mobile Attached to hard palate via a connective tissue palatine aponeurosis Contains 5 prs of skeletal muscle (motor innervation: CN X, except TVP [CN V3]) Depressed during chewing to keep foodstuffs in the oral cavity and maintain an open airway Elevated during swallowing to seal off nasopharynx from the oropharynx a b Torus tubarius Inferior concha c LVP Torus levatorius a = incisive canal b = palatine process of maxilla c = horizontal plate of palatine LVP = levator veli palatini Palatoglossal fold = Opening of auditory tube Palatine tonsil Palatopharyngeal fold

17 Muscles of the Soft Palate Muscle Origin Insertion Innervation Action Tensor veli palatini Levator veli palatini Musculus uvulae Scaphoid fossa (medial pterygoid plate), fibrous part of auditory tube Cartilage of auditory tube, petrous portion of temporal bone Posterior nasal spine of hard palate Palatine aponeurosis Superior surface of palatine aponeurosis Connective tissue of uvula Mandibular nerve (CN V3) Vagus nerve (CN X, via pharyngeal plexus) Vagus nerve (CN X, via pharyngeal plexus) Palatoglossus Palatine aponeurosis Side of tongue Vagus nerve (CN X, via pharyngeal plexus) Palatopharyngeus Palatine aponeurosis Pharyngeal wall Vagus nerve (CN X, via pharyngeal plexus) Tenses soft palate and opens auditory tube (during swallowing, yawning) Elevates soft palate Shortens and raises uvula Pulls soft palate onto tongue Pulls pharyngeal wall superiorly (elevates), anteriorly, and medially during swallowing

18 Bony Landmarks * M P P * Hamulus MPP = Medial pterygoid plate * = Scaphoid fossa Opening of bony portion of auditory tube Pharyngeal tubercle Cartilaginous portion of auditory tube

19 Soft Palate Muscles of the Soft Palate Tensor veli palatini Levator veli palatini Palatopharyngeus Musculus uvulae Palatoglossus

20 Lateral Pharyngeal Wall mucosa removed Muscles of the Soft Palate Tensor veli palatini Levator veli palatini Musculus uvulae Palatoglossus Palatopharyngeus

21 Soft Palate posterior view

22 Pharynx Posterior pharyngeal wall covered by buccopharyngeal fascia Cranial end of the foregut Dual function respiratory/digestive Funnel-shaped from posterior view Related to skull base and cervical spine Lateral walls have gaps Anterior wall missing 3 Parts: Nasopharynx, oropharynx, laryngopharynx 3 Parts: Nasopharynx from tip of soft palate to base of skull Oropharynx from tip of soft palate to tip of epiglottis Laryngopharynx from tip of epiglottis to lower border of cricoid cartilage

23 Features of the Lateral Pharyngeal Wall Nasopharynx Torus tubarius; Salpingopharyngeal fold Torus levatorius Pharyngeal recess Pharyngeal tonsil (midline) Adenoids Salpingopharyngeal fold Oropharynx Palatoglossal fold/anterior tonsillar pillar Palatopharyngeal fold/posterior tonsillar pillar Palatine tonsil Laryngopharynx/Hypopharynx Piriform recess or fossa Aryepiglottic fold Sensory innervation of the pharynx

24 Oropharynx as viewed from oral cavity Mucosal lining of oropharynx when infected/inflamed = pharyngitis or sore throat; acute pharyngitis (e.g. strep throat, URI) is one of the frequent common causes of physician visits

25 Posterior Pharyngeal Wall view following disarticulation of head and cervical compartment from the cervical spine

26 Retropharyngeal lymph nodes Drain the nasopharynx, adenoids, middle ear, and auditory tube Efferent channels to deep cervical chain of nodes Infections from areas drained may overwhelm these nodes leading to abscess formation Retropharyngeal abscess Most common in children between 2 and 4 yrs of age Can occur at any age

27 Interior of Pharynx- posterior wall opened Choanae Middle nasal concha Inferior nasal concha Nasal septum Soft palate Uvula Vallecula Palatine tonsil Tongue Median glossoepiglottic fold Lateral glossoepiglottic fold Soft palate Palatine tonsil * * Piriform recess Aditus of larynx Aryepiglottic fold Piriform recess Lamina of cricoid cartilage (beneath mucosa) Potential sites for lodgement of ingested foreign objects (e.g., fish bones) Valleculae Piriform recesses of larynx The palatoglossal arches and pharyngeal portion (posterior 1/3) of tongue represent the anterior wall of the oropharynx.

28 Muscles of the Pharynx Muscle Origin Insertion Innervation Action Constrictors of Pharyngeal Wall Superior constrictor Pterygomandibular raphe Pharyngeal tubercle (occipital bone) and pharyngeal raphe Middle constrictor Greater horn of hyoid Pharyngeal raphe Inferior constrictor Elevators of Pharyngeal Wall Lateral surfaces of thyroid cartilage (thyropharyngeus) and cricoid cartilage (cricopharyngeus) Pharyngeal raphe Vagus nerve (CN X, via pharyngeal plexus) Constricts pharynx during swallowing to direct bolus towards stomach Palatopharyngeus Palatine aponeurosis Pharyngeal wall Elevates pharynx during swallowing; also helps close the oropharyngeal isthmus Salpingopharyneus Auditory tube cartilage Pharyngeal wall Elevates pharynx during swallowing Stylopharyngeus Styloid process of temporal bone Posterior superior border of thyroid cartilage Glossopharyngeal nerve (CN IX) Elevates pharynx during swallowing

29 Pharyngeal Musculature circular layer (incomplete) Pharyngeal constrictors: superior, middle, inferior Pharyngobasilar fascia Pterygomandibular raphe

30 Pharyngeal Musculature longitudinal layer (incomplete) Pharyngeal tubercle Auditory tube Stylopharyngeus Pharyngobasilar fascia Superior pharyngeal constrictor Elevators of pharynx and larynx during swallowing. 1. Salpingopharyngeus 2. Palatopharyngeus 3. Stylopharyngeus Middle pharyngeal constrictor Inferior pharyngeal constrictor Weakness in hypopharyngeal wall; potential area of herniation of mucosal lining Esophagus

31 Hypopharyngeal/Zenker s Diverticulum Saccular herniation of mucosal lining through weakness of pharyngeal wall, between thyropharyngeus and cricopharyngeus muscles. Collects foodstuffs; progressively enlarges May cause dysphagia; lump in throat Regurgitation of food when in supine position Halitosis Surgically repaired Diverticulum containing barium post-swallow Inferior constrictor 2 portions: Thyropharyngeus Cricopharyngeus = upper esophageal sphincter o o o A physiological sphincter Relaxes during swallowing to allow passage of contents to stomach Failure of timely relaxation leads to increased intraluminal pressure and herniation of mucosal lining IC: CP MC TP

32 Gaps between muscles in the lateral pharyngeal wall + CN IX

33 Motor and Sensory Innervation of the Pharyngeal Wall All pharyngeal muscles supplied by vagus, except stylopharyngeus (=glossopharyngeal nerve)

34 Palatine Tonsil Rests against the superior constrictor muscle Has an abundant blood supply Its mucosal surface is supplied by a tonsillar branch of the glossopharyngeal nerve

35 Tonsillar Ring of Tissue in the Nasopharynx and Oropharynx Lymphoid masses that serve as antigen-sampling devices to assist in immunological surveillance and development of immunocompetence. Most prominent in early childhood.

36 Adenoid Facies

37 Peritonsillar Abscess Usually complication of tonsillitis; poor response to antibiotics Usually unilateral Pus forms btn tonsil + sup constrictor Uvula pushed toward opposite side Hot potato voice (muffled); painful to open mouth wide Potential of infection to enter retropharyngeal space Tonsillitis Usually bilateral sore throat Viral/bacterial infection Painful swallowing Tenderness of JD/tonsillar lymph node May compromise airway Ear pain (referred) common sensory innervation of oropharynx and middle ear cavity by CN IX Adenoiditis Swelling may obstruct Eustachian tube Patient mouth breathes

38 Nerve Tests Gag reflex Sensory limb: Glossopharyngeal nerve Motor limb: Vagus nerve Lesion of left vagus nerve In the normal open mouth, the soft palate should appear symmetric and when asked to say AHAA, it should elevate smoothly in the midline. If the vagus nerve is damaged, the soft palate will appear asymmetric (flaccid and slightly lower on side of lesion). During elevation, the uvula will deviate to the opposite side of the lesion due to unopposed pull of the intact palatal muscles (origins of principal elevator muscles are posterior and lateral to their insertions).

39 Larynx Functions of Larynx: Protection of the airway via adduction of the vocal cords/folds Phonation = sound production Respiration via transfer of air to/from lungs through an open glottis

40 The larynx ( voicebox ) is an integrated structure composed of cartilage (mostly hyaline in type), connected by membranes and skeletal muscles, and two sets of synovial joints (cricothyroid and cricoarytenoid) whose actions are to modify the glottic opening and tension on the vocal ligaments. Cartilages of the Larynx Thyroid cartilage Cricoid cartilage - The only complete ring of cartilage in the respiratory tree Signet ring : Arch anteriorly Lamina posteriorly Angle between the two laminae: ~90 adult men; creates greater laryngeal prominence ~120 adult women Oblique line attachment site for: Sternothyroid muscle Thyrohyoid muscle Inferior constrictor muscle

41 Cartilages of the Larynx Epiglottis Arytenoid cartilages Corniculate and Cuneiform cartilages Cricoarytenoid joints Cricothyroid joint

42 Fibroelastic membranes Quadrangular membrane in aryepiglottic fold o Inferior thickening = vestibular ligament Conus elasticus (cricothyroid ligament) o Superior thickening = vocal ligament Ligaments + mucosal covering = folds or cords Actions at synovial joints: Cricothyroid enable thyroid cartilage to tilt forward and downward toward cricoid arch resulting in increased length and tension on vocal cords Cricoarytenoid arytenoid cartilages slide toward or away from each other and rotate so that vocal processes pivot either toward or away from the midline so as to adduct or abduct the vocal cords Note: Vestibular ligament/fold/false vocal cord is superior and lateral to vocal ligament/fold/true vocal cord.

43 Interior of Larynx Divided into 3 regions in reference to the glottis Space between vestibular folds Space between vocal folds/cords

44 Interior of Larynx Coronal view Laryngocele air-filled dilation of laryngeal saccule that extends through the thyrohyoid membrane

45 Intrinsic Muscles of the Larynx Muscle Origin Insertion Innervation Action Cricothyroid Superior lateral margin of arch of cricoid Inferior border and inferior horn of thyroid cartilage External laryngeal nerve (CN X) Tilt thyroid cartilage downward toward cricoid arch; Stretches and tenses vocal cords Lateral cricoarytenoid Upper lateral surface of arch of cricoid Muscular process of arytenoid cartilage Recurrent laryngeal nerve (CN X) Rotate muscular processes of arytenoids medially; Adduct the vocal cords Posterior cricoarytenoid Posterior surface of lamina of cricoid Muscular process of arytenoid cartilage Recurrent laryngeal nerve (CN X) Rotate muscular processes of arytenoids laterally; Sole abductors of the vocal cords Transverse arytenoid Posterior surface of one arytenoid cartilage Posterior surface of other arytenoid cartilage Recurrent laryngeal nerve (CN X) Draws medial surfaces of arytenoid cartilages toward each other; Adducts the vocal cords Thyroarytenoid Posteroinferior surface of thyroid cartilage near midline Anterolateral surface of arytenoid cartilages Recurrent laryngeal nerve (CN X) Draws arytenoid cartilages slightly forward to relax the vocal cords Vocalis Lateral surface of vocal process of arytenoid cartilage Lateral surface of ipsilateral vocal ligament Recurrent laryngeal nerve (CN X) Adjusts tension along vocal cords

46 Intrinsic Muscles of the Larynx

47 Tensors: cricothyroid raises pitch of voice Muscle Actions Relaxors: Thyroarytenoid lowers pitch of voice Vocalis selectively tenses/relaxes vocal folds during speech/singing Adductors: Lateral cricoarytenoid Transverse and oblique arytenoids Abductor (sole): Posterior cricoarytenoid

48 Positions of the vocal folds and shapes of rima glottidis Valsalva maneuver forced expiration against a tightly closed glottis. Used to stabilize trunk during heavy lifting or increasing intraabdominal pressure during defecation.

49 Nerve and Blood Supply to Larynx Guardian of the airway

50 Vocal Cord Lesions Vocal Cord Lesions: Any pathologic process that alters the mass of the vocal cords or their ability to adduct will affect voice quality, i.e., produce hoarseness. Unilateral complete section of right recurrent laryngeal nerve Inspiration Phonation Bilateral section of recurrent laryngeal nerves Inspiration

51 Development of the Face and Palate Face and Palate Development Animation (4:06 mins) Occurs between 4 th and 8 th weeks of gestation Develops from 5 primordia of NCC enriched mesenchyme: - frontonasal prominence >> forehead, nose, primary palate, nasal septum, and philtrum of upper lip - maxillary prominences (2) >> cheeks, maxillary bone, secondary palate, and lateral portion of upper lip - mandibular prominences (2) >> lower jaw and lip

52 Development of the Face and Palate Nasal placodes are bilateral thickenings of ectoderm (become the future nostrils) They become surrounded by horsehoe-shaped ridges of mesenchyme and recessed as nasal pits These ridges divide into medial and lateral nasal processes Medial nasal processes elongate, fuse (form philtrum of upper lip) and will form the intermaxillary segment and tip of nose Lateral nasal processes will form the alae of the nostrils and merge with maxillary prominences to form lateral part of upper lip

53 Development of the Palate (Primary and Secondary) Intermaxillary segment is formed by merged MNPs. Gives rise to: philtrum of upper lip, maxilla with 4 incisor teeth, and primary palate. Secondary palate Formed by fusion of palatine shelves of maxillary processes Maxillary processes grow toward each other and fuse to form secondary palate N as a l s e p t u m

54 Development of the Palate (Primary and Secondary)

55 Development of the Nasal Cavity

56 Orofacial Clefting Anterior vs Posterior Clefts (incisive foramen landmark) Anterior clefts due to partial or complete lack of fusion of maxillary prominence with the medial nasal prominence on one or both sides (lateral cleft lip, cleft of upper jaw, cleft between primary and secondary palates) Posterior clefts result from lack of fusion of the palatine shelves (cleft secondary palate, cleft uvula)

57 Orofacial Clefting Combination of clefts Oblique facial clefts due to failure of maxillary prominence to merge with corresponding lateral nasal prominence causing exposure of nasolacrimal duct Median cleft lip result from incomplete merging of the right and left medial nasal prominences

58 Orofacial Clefting Bilateral cleft lip and palate Unilateral cleft lip and complete cleft palate

59 Orofacial Clefting Oblique facial cleft Failure of fusion between lateral nasal prominence and maxillary process Median cleft lip Failure of fusion between the two medial nasal processes

60 Cleft Lip and Cleft Palate Bifid uvula

61 Swallowing disorders aka dysphagia (difficulty swallowing) Clinical Scenarios Helen, a 76-year-old with Alzheimer s dementia, lives in a nursing home. She needs minimal to moderate assistance while eating. Lately, she has not been finishing meals. She has gurgly voice quality during mealtime and has recently had severe coughing episodes while eating. This has been very upsetting and frustrating to her. Lee is a 43-year-old man who exhibits severe swallowing difficulty with frequent aspiration and now receives nutrition through a gastric tube. He has hoarse vocal quality. He had radiation therapy and neck dissection following cancer surgery in his right buccal space. Dysphagia is not a disease but a symptom of several etiologies (e.g., neurological injuries, progressive brain diseases) Prevalence: ~7% of elderly patients (>62 years of age) ~29 to 64% of stroke patients ~24 to 34% of people with multiple sclerosis ~81% of patients with Parkinson s disease ~30-35% of patients in rehabilitation facilities ~50% of residents in nursing home environments ~26 to 71% of patients with traumatic brain injury

62 Phases of Swallowing We eat with our eyes first Anticipatory Phase Experiential Information Visual Information Olfactory Stimulation

63 Phases of Swallowing First step in digestive process Involves: Taste and general sensory perception of tongue and oral structures Actions of muscles of mastication Saliva production Lip closure and increased tone in cheek wall to keep foodstuffs on occlusal surfaces of teeth Auger action of the tongue Oral Preparatory Phase Indeterminant length of time Airway is open; active nasal breathing continues Soft palate is pulled down and forward by palatoglossus muscles to seal oral cavity from oropharynx and the airway Preparation of bolus size and consistency for safe swallowing A pureed diet

64 Phases of Swallowing Bolus is moved to back of tongue Involves: Collecting the bolus within the center of the tongue while tongue contacts hard palate Tongue propels bolus to back of oral cavity in piston-like fashion Sensory information is gathered regarding bolus size and texture; bolus may be subdivided if perceived to be too large Oral Phase sec duration Airway is open; active nasal breathing continues Soft palate is pulled down and forward by palatoglossus muscles to seal oral cavity from oropharynx and airway Lateral portions of tongue contact the palatoglossal folds terminating this phase Triggers the Pharyngeal Phase

65 Phases of Swallowing Begins with elevation of the soft palate to seal nasopharynx from the oropharynx Involves: Elevation and tensing of soft palate Anterior movement of posterior pharyngeal wall by the superior constrictor muscles Within milliseconds of SP elevation, posterior tongue retracts to propel bolus into oropharynx Pharyngeal Phase 1 sec duration Hyolaryngeal elevation and airway protection Sequential contraction of pharyngeal constrictors and relaxation of the UES Produces a clearing wave that strips the entire bolus from the pharynx in anticipation of airway opening; protects airway from post-swallow aspiration of residual foodstuffs Involves: Contraction of suprahyoid muscles Adduction of vocal cords (breathing temporarily halted) Folding of the epiglottis over the laryngeal inlet and directing the bolus into the esophagus

66 Phases of Swallowing Active closure of UES to prevent air from entering esophagus Involves: Tonic contraction of cricopharyngeus (UES) Esophageal Phase 8-20 secs duration (increases with age) Peristalsis along esophagus; respiration normal through nose and mouth Relaxation of LES and entrance of bolus into the stomach Transports bolus to reach the LES and then the stomach