HEAD/NECK II: Throat/ Pharynx Overview: Sagittal view of nose/mouth/throat Nasal Cavity and Breathing Mouth and Chewing Throat and Swallowing Larynx and Singing

Sagittal Section Head Cranial cavity Brain/Spinal cord Vertebral bodies Epaxial muscles Hard/soft palate Oral cavity Esophagus Trachea Epiglottis Naso- Oro- Laringo- pharynx

Nose/Nasal Cavity and Breathing Function: Inlet for air to lung Warm/filter air (mucous membranes on ethmoid conchae) Smell (nerve endings on nasal membranes)

Conchae of Ethmoid Bone Scroll-like bones Covered in mucous membrane for Smell Filter air Warm air

Sinuses All connected to nasal cavity All lined with mucous membranes Cold/allergies—fill with mucous=sinus headache Maxillary Ethmoid Frontal Sphenoid M&M, Fig. 7.11

Mouth/Oral Cavity and Chewing FUNCTION Bite and chew food Form words Taste Kiss COMPONENTS Lips Cheeks Palate Jaws and teeth Salivary glands Lined by thick stratified squamous epithelium (almost no keratin) Vestibule—in front of teeth Oral cavity proper—behind teeth

Lips FUNCTION Close mouth Keep food in Make speech sounds Tactile STRUCTURE Core of sphinchter-shape skeletal muscle (orbicularis oris) “Red margin” transition from keratinized skin to oral mucosa Red because clear color lets underlying vessels show through No sweat or sebaceous glands, thus needs to be wet (or lip balm) Lips

Cheeks FUNCTION Form side of moth STRUCTURE Buccinator muscle— instrumental in swallowing, connects back to pharyngeal constrictors

Palate Hard palate anterior Maxilla Palatine Soft palate is posterior extension, soft tissue Palatoglossal arch (palate to tongue) Palatopharyngeal arch (palate to pharynx) Tonsils between arches Uvula…???

Jaws FUNCTION Hold teeth Occlude in chewing STRUCTURE Upper jaw—maxillary bone Lower jaw--mandible

Teeth Key to healthy teeth and gums: Flossing Deciduous teeth—”milk” or “baby” teeth Emerge 6 mos. – 2 yrs. Replaced by permanent teeth 6-12 yrs. Wisdom teeth (3rd molar) erupts 17-25 yrs or remains in jaw Key to healthy teeth and gums: Flossing Visiting dentist regularly (every 6 mos.) and starting at young age (3-4 yrs.)

Structure of individual tooth—it’s alive!!

Jaw muscles Masseter, temporalis— elevate mandible (“close jaw”) Medial pterygoid—lateral (side-to-side) chewing Lateral pterygoid—translates mandible anteriorly (part of opening) Digastric (not shown)— depresses mandible (“opens jaw”) Chewing is circular motion

Tongue FUNCTION Position food between teeth Form words in speech STRUCTURE Intrinsic muscles (allow for shape change with fibers in various directions) Extrinsic muscles— attach tongue to skeleton Genioglossus Hyoglossus

Salivary glands Intrinsic—all over mucous membranes of tongue, palate, lips, lining of cheek Extrinsic—secrete more saliva when eating (or anticipating) Parotid Submandibular Sublingual

Saliva Moistens mouth Dissolves food to be tasted Wets and binds food Contains amylase to start starch digestion (saltine to sugar experiment) Contains bicarbonate to neutralize cavity-causing acids produced by bacteria Contains anti-bacterial and anti-viral enzymes and cyanide-like compound to kill harmful micro- organisms Contains proteins that stimulate growth of beneficial bacteria in the mouth

Throat/Pharynx and Swallowing Back of mouth to larynx Food and air mix and cross Food PHARYNX Air Trachea Esophagus STRUCTURES Entry—pharyngeal arches Exit—glottis (epiglottis is lid) Pharyngeal constrictors squeeze food through When it goes wrong—choking!!

Pharynx and Swallowing Focus on muscles and arrangement of mouth cavity, pharynx, larynx, epiglottis, trachea Pharynx/Swallowing in detail!!

Descent of the larynx

Larynx and Singing FUNCTION Channel air out of trachea Vibrate to produce sound for speech/song STRUCTURES External skeleton or frame (cartilage) Internal vocal cords and associated muscles

Skeleton of larynx M&M, Fig. 21.5 Cricothyroid ligament is usual site of emergency tracheotomy (feel on self—SURFACE ANATOMY)

Vocal cords M&M, Fig. 21.6