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