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. 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 Parotid Duct Opening, Ventral Surface of Tongue, and Floor of Mouth

• Mucous membrane 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 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. Roof of Oral Cavity – Hard and Soft Palate

Incisive foramen Hard palate consists of two parts: Primary palate 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 Maxilla

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 Roof of Oral Cavity – Nerve and Blood Supply

Mucosal glands

Nasopalatine n., Branches of maxillary nerve Sphenopalatine a. 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. 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.) = “Chin” Mento (L.)

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. Extrinsic and Intrinsic Musculature of the Tongue

Muscle (Extrinsic) Bony Attachment Glossal Attachment Action

Genioglossus Superior mental spine Body of hyoid and tip of Depresses and protrudes (anterior attachment) tongue (posterior tongue attachment) Hyoglossus Greater horn of hyoid Posterolateral surface Depresses and retracts tongue Styloglossus Styloid process of temporal Side and inferior aspect of Retracts and elevates tongue bone tongue Palatoglossus Palatine aponeurosis Side of tongue Draws soft palate onto tongue Extrinsic muscles move the tongue, whereas the intrinsic muscles (having no bony attachments) alter its shape. All extrinsic and intrinsic muscles, EXCEPT palatoglossus, are innervated by the hypoglossal nerve. Palatoglossus is innervated by the vagus nerve. 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 Nerve Supply of the Tongue: Sensory, Motor, Taste

Including circumvallate papillae 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 Osteology of the Mandible

Edentulous Mandible Submandibular and Sublingual Salivary Glands

Note the classic spiral relationship of the Submandibular (Wharton’s) lingual nerve to the submandibular duct. Sublingual duct gland

Lingual n.

Submandibular Mylohyoid m. ganglion

Submandibular gland Geniohyoid m. Submandibular duct is narrowest at the sublingual caruncle, commonly the point of stone (sialolith) impaction. Parasympathetic nerve supply to submandibular and sublingual glands Blood Supply to Tongue

Lingual artery: Passes deep to hyoglossus • Dorsal lingual a. – to posterior region of tongue • Deep lingual a. – enters ventral surface of tongue • Sublingual a. – supplies floor of mouth and sublingual gland Lymphatic Drainage of Lips and Tongue Soft Palate

Torus tubarius Soft Palate • Fibromuscular; contains mucous glands • Mobile Torus • Attached to hard palate via a connective tissue levatorius palatine aponeurosis • Contains 5 prs of skeletal muscle (motor innervation: CN X, except TVP [CN V3]) Inferior concha • Depressed during chewing to keep foodstuffs in the oral cavity and maintain an open airway c • Elevated during swallowing to seal b LVP off nasopharynx from the oropharynx a

Palatoglossal fold

a = incisive canal b = palatine process of maxilla c = horizontal plate of palatine LVP = levator veli palatini

= Opening of auditory tube

Palatine tonsil Palatopharyngeal fold Muscles of the Soft Palate

Muscle Origin Insertion Innervation Action

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

Hamulus M P * P * MPP = Medial pterygoid plate

* = Scaphoid fossa

Opening of bony portion of auditory tube

Pharyngeal tubercle Cartilaginous portion of auditory tube Soft Palate

Muscles of the Soft Palate

• Tensor veli palatini

• Levator veli palatini

• Palatopharyngeus

• Musculus uvulae

• Palatoglossus Lateral Pharyngeal Wall – mucosa removed

Muscles of the Soft Palate

• Tensor veli palatini

• Levator veli palatini

• Musculus uvulae

• Palatoglossus

• Palatopharyngeus Soft Palate – posterior view Pharynx

Posterior pharyngeal wall covered by buccopharyngeal fascia

• Cranial end of the foregut • Dual function – respiratory/digestive 3 Parts: • Funnel-shaped from posterior view • Nasopharynx – from tip of soft palate to base of skull • Related to skull base and cervical spine • Oropharynx – from tip of soft palate to tip of epiglottis • Lateral walls have “gaps” • Laryngopharynx – from tip of epiglottis to lower border • Anterior wall “missing” of cricoid cartilage • 3 Parts: Nasopharynx, oropharynx, laryngopharynx 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 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 Posterior Pharyngeal Wall – view following disarticulation of head and cervical compartment from the cervical spine 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 Interior of Pharynx- posterior wall opened

Choanae

Middle nasal concha

Inferior nasal concha Nasal septum

Soft palate Uvula

Soft palate Palatine tonsil Tongue Palatine tonsil Median glossoepiglottic fold Vallecula Lateral glossoepiglottic fold

Aditus of larynx Piriform recess Aryepiglottic fold * * Piriform recess

Lamina of cricoid cartilage (beneath mucosa)

Potential sites for lodgement of ingested foreign objects (e.g., fish bones) • Valleculae The palatoglossal arches and • Piriform recesses of larynx pharyngeal portion (posterior 1/3) of tongue represent the “anterior wall” of the oropharynx. Muscles of the Pharynx

Muscle Origin Insertion Innervation Action

Constrictors of Pharyngeal Wall Superior constrictor Pterygomandibular Pharyngeal tubercle raphe (occipital bone) and pharyngeal raphe Constricts pharynx Middle constrictor Greater horn of hyoid Pharyngeal raphe during swallowing to direct bolus towards stomach Inferior constrictor Lateral surfaces of Pharyngeal raphe thyroid cartilage Vagus nerve (CN X, via (thyropharyngeus) and pharyngeal plexus) cricoid cartilage (cricopharyngeus) Elevators of Pharyngeal Wall 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 Posterior superior Glossopharyngeal nerve Elevates pharynx during temporal bone border of thyroid (CN IX) swallowing cartilage Pharyngeal Musculature – “circular” layer (incomplete)

Pharyngeal constrictors: superior, middle, inferior

Pharyngobasilar fascia

Pterygomandibular raphe Pharyngeal Musculature – “longitudinal” layer (incomplete) Pharyngeal tubercle

Auditory tube

Elevators of pharynx and larynx during swallowing. Stylopharyngeus 1. Salpingopharyngeus 2. Palatopharyngeus Pharyngobasilar fascia 3. Stylopharyngeus Superior pharyngeal constrictor

Middle pharyngeal constrictor

Inferior pharyngeal constrictor

Weakness in hypopharyngeal wall; potential area of herniation of mucosal lining Esophagus 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” Diverticulum containing • Regurgitation of food when in supine position barium post-swallow • Halitosis • Surgically repaired

Inferior constrictor – 2 portions: • Thyropharyngeus MC • Cricopharyngeus = upper esophageal sphincter o A physiological sphincter o Relaxes during swallowing to allow passage of contents TP to stomach o Failure of timely relaxation leads IC: to increased intraluminal pressure and herniation of mucosal lining CP “Gaps” between muscles in the lateral pharyngeal wall

+ CN IX Motor and Sensory Innervation of the Pharyngeal Wall

All pharyngeal muscles supplied by vagus, except stylopharyngeus (=glossopharyngeal nerve) 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 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. Adenoid Facies 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” 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). 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 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 Cartilages of the Larynx

Epiglottis Arytenoid cartilages

Corniculate and Cuneiform cartilages

Cricoarytenoid joints Cricothyroid joint Fibroelastic membranes Actions at synovial joints: • Quadrangular membrane – in aryepiglottic fold • Cricothyroid – enable thyroid cartilage o Inferior thickening = vestibular ligament to tilt forward and downward toward • Conus elasticus (cricothyroid ligament) cricoid arch resulting in increased length and tension on vocal cords o Superior thickening = vocal ligament • Cricoarytenoid – arytenoid cartilages slide toward or away from each other Ligaments + mucosal covering = folds or cords 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. Interior of Larynx

Divided into 3 regions in reference to the glottis

Space between vestibular folds Space between vocal folds/cords Interior of Larynx Coronal view Laryngocele – air-filled dilation of laryngeal saccule that extends through the thyrohyoid membrane Intrinsic Muscles of the Larynx

Muscle Origin Insertion Innervation Action

Cricothyroid Superior lateral margin Inferior border and External laryngeal Tilt thyroid cartilage of arch of cricoid inferior horn of thyroid nerve (CN X) downward toward cartilage cricoid arch; Stretches and tenses vocal cords

Lateral cricoarytenoid Upper lateral surface of Muscular process of Recurrent laryngeal Rotate muscular arch of cricoid arytenoid cartilage nerve (CN X) processes of arytenoids medially; Adduct the vocal cords Posterior Posterior surface of Muscular process of Recurrent laryngeal Rotate muscular cricoarytenoid lamina of cricoid arytenoid cartilage nerve (CN X) processes of arytenoids laterally; Sole abductors of the vocal cords Transverse arytenoid Posterior surface of one Posterior surface of Recurrent laryngeal Draws medial surfaces arytenoid cartilage other arytenoid nerve (CN X) of arytenoid cartilages cartilage toward each other; Adducts the vocal cords Thyroarytenoid Posteroinferior surface Anterolateral surface of Recurrent laryngeal Draws arytenoid of thyroid cartilage near arytenoid cartilages nerve (CN X) cartilages slightly midline forward to relax the vocal cords Vocalis Lateral surface of vocal Lateral surface of Recurrent laryngeal Adjusts tension along process of arytenoid ipsilateral vocal nerve (CN X) vocal cords cartilage ligament Intrinsic Muscles of the Larynx Muscle Actions Tensors: cricothyroid – raises pitch of voice

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 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. Nerve and Blood Supply to Larynx

“Guardian of the airway” 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 Development of the Face and Palate

Face and Palate Development Animation (4:06 mins) http://youtu.be/DgZ_tqucdI4

• Occurs between 4th and 8th 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 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 Development of the Palate (Primary and Secondary) Intermaxillary segment is formed by merged Secondary palate MNPs. Gives rise to: philtrum of upper lip, maxilla Formed by fusion of with 4 incisor teeth, and primary palate. palatine shelves of maxillary processes

Maxillary processes grow toward each other and fuse to form secondary palate

N a s a l s e p t u m Development of the Palate (Primary and Secondary) Development of the Nasal Cavity 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) 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 Orofacial Clefting

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

Oblique facial cleft Median cleft lip • Failure of fusion • Failure of fusion between lateral between the two medial nasal prominence nasal processes and maxillary process Cleft Lip and Cleft Palate

Bifid uvula 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 Phases of Swallowing

“We eat with our eyes first” Anticipatory Phase Experiential Information

Visual Information Olfactory Stimulation Phases of Swallowing

Oral Preparatory Preparation of Phase bolus size and Indeterminant length of time consistency for First step in safe swallowing

digestive A “pureed” diet process Airway is open; active Involves: . Taste and general sensory perception of nasal breathing tongue and oral structures continues . Actions of muscles of mastication . Saliva production . Lip closure and increased tone in cheek . Soft palate is pulled down and forward wall to keep foodstuffs on occlusal by palatoglossus muscles to seal oral surfaces of teeth cavity from oropharynx and the airway . Auger action of the tongue Phases of Swallowing

Oral Phase Lateral portions of tongue contact the 1-1.5 sec duration palatoglossal folds terminating this Bolus is moved phase

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

Pharyngeal Sequential Phase contraction of pharyngeal 1 sec duration constrictors and relaxation of the Begins with elevation UES of the soft palate to seal nasopharynx from . Produces a “clearing wave” the oropharynx that strips the entire bolus from the pharynx in Hyolaryngeal anticipation of airway Involves: elevation and airway opening; protects airway . Elevation and tensing of soft palate from post-swallow aspiration . Anterior movement of posterior pharyngeal protection of residual foodstuffs wall by the superior constrictor muscles . Within milliseconds of SP elevation, posterior Involves: tongue retracts to propel bolus into oropharynx . 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 Phases of Swallowing

Esophageal Phase Relaxation of LES and entrance of 8-20 secs duration bolus into the (increases with age) stomach Active closure of UES to prevent air from entering esophagus Peristalsis along

Involves: esophagus; respiration . Tonic contraction of cricopharyngeus (UES) normal through nose and mouth

• Transports bolus to reach the LES and then the stomach