The Head and Neck

Upper Respiratory Tract Pg 583

The Nose Only external part of respiratory tract Made of nasal bones, connective tissue and hyaline cartilage External Nares = Nostrils: openings into nasal cavity Internal Nares = Choanae: openings between nasal cavity and nasopharynx

Entrance to the Nasal Cavity Vestibule –space just inside external nares Skin lining contains: Sebaceous glands -greasy secretion collect dirt, lubricate, kill bacteria Sweat glands -acidic, slows growth of bacteria Hair follicles –trap smaller particles of dirt and dust Vibrissae – nose hairs filtering larger particles from air

Nasal Cavity Part of respiratory passage Boundaries Roof = ethmoid bone (cribiform plate) Floor = hard palate & soft palate Hard palate = maxilla (palatine process) + palatine (horizontal plate) Soft palate = skeletal muscle ending in uvula Lateral walls = nasal bones, superior+ middle nasal conchae (ethmoid bone), inferior nasal conchae, maxilla, palatine bone Nasal Septum = divides cavity into 2 Vomer & Perpendicular Plate of Ethmoid Cartilage

Nasal Cavity Pg 584

Nasal Cavity Functions Airway of respiratory tract Moisten and Warm air Filter air Resonating chamber for speech Houses olfactory receptors

Nasal Cavity (continued) Respiratory Mucosa–lines cavity walls, septum Ciliated psuedostratified columnar epithelium w/lamina propria Mucous cells + serous cells Highly vascularized Moistens + warms inhaled air Highly innervated Cause sneeze reflex Olfactory Mucosa – on roof of nasal cavity, contains the olfactory (smell) receptors

Nasal Conchae Project medially from each lateral wall of nasal cavity Superior, Middle (ethmoid) Inferior nasal conchae Covered with Mucosa Functions Increase surface area Create turbulance Reclaim heat from exhaled air Pg 584

Paranasal Sinuses Air-filled sacs surrounding nasal cavity Extensions of nasal cavity, continuous with it Same respiratory mucosal lining In Frontal, Ethmoid, Sphenoid, Maxillae bones Function: Warm + Filter air, Lightens skull Pg 16

Mouth = Oral Cavity Opening of alimentary canal Lined with mucosa Thick, stratified squamous epithelium (slightly keratinized in some parts) Boundaries Anterior = lips Lateral = cheeks Posterior = oropharynx Superior = palate Inferior = tongue Pg 617

Some Muscles of Face Lips (labia) + Cheeks: Keep food in mouth during chewing Lips: Orbicularis oris Cheeks: Muscles of Mastication Temporalis Masseter Buccinator Digastric Pterygoids

Muscles of Mastication Name Origin Insertion Action Innervation Pterygoids (med & lat) Pterygoid plate (sphenoid), Maxilla, Palatine bone Mandible Elevate & Protract Mandible Trigeminal N. (branch V3) Digastric Mandible, Mastoid process (temporal) Hyoid bone (indirectly) Elevate hyoid, Depress mandible Masseter Zygomatic arch and bone Mandible (angle and ramus) Elevates mandible Temporalis Temporal bone Coronoid process of mandible (indirectly) Elevates & retracts mandible

Palate Hard palate (anterior 2/3) Soft palate (posterior 1/3) Made of bone Covered with mucosa Tongue pushes food against it during chewing Soft palate (posterior 1/3) Made of skeletal muscle Covered by mucosa Ends in the uvula Closes nasopharynx during swallowing

Tongue bitter sour salty sweet Pg 618 Functions Creates floor of mouth Grips and moves food between teeth during chewing Mixes food with saliva = BOLUS Moves bolus down pharynx Speech production Houses taste buds (= gustation) Creates floor of mouth Attachments: hyoid, mandible, styloid process, soft palate Made of Skeletal muscle w/CT septum Intrinsic muscles Extrinsic muscles Innervation Motor = Hypoglossal (CN XII) Sensory = Mandibular (CN V3), Facial (CN VII), Glossopharyngeal (CN IX) sour salty sweet Pg 618

Salivary Glands Exocrine, tubuloalveolar glands Produce Saliva H2O, Ions, Mucus, Enzymes Internal salivary glands are small In mucosa of tongue, lips, palate, cheeks Keep areas wet External salivary glands are large, have ducts External to mouth Provide saliva when necessary or anticipated 2 Submandibular, 2 Sublingual, 2 Parotid glands

Salivary Glands Moisten mouth, wet food Dissolve food to taste Bind food together Begin to break down starch Neutralize mouth acid Kill harmful microorganisms Promote beneficial bacteria Pg 618

The story of teeth from eruption to edentate Tiny Tabitha’s Teeth The story of teeth from eruption to edentate

Tiny Tabitha: Age 4 days Number of Erupted Teeth = 0 Ultimate Goal = 32 Teeth Incisors (8): rip, cut Canines (4): tear and pierce Premolars (8): grinding Molars (12): grinding Estimated Time of Completion = 15-25 years Currently jaws covered by gingiva (gum): is oral mucosa = lots of drooling

Tabitha’s First Tooth Deciduous (Milk) = 20 8 Incisors = 6-10 months 4 Canines = 16-20 months 4 1st Molars = 12-16 months 4 2nd Molars = 20-24 months Dental Formula: describes number, kind & position of teeth in ½ of the mouth canines premolars molars 2:1:0:2 Incisors X 2 = 20

Tabitha’s Teeth Function: Ingestion and mechanical breakdown of food Alveoli: sockets in mandible and maxilla teeth sit in Periodontal Ligament: collagen fibers anchor tooth in bony socket Gomphosis Cementum: calcified connective tissue attaching tooth to periodontal ligament Pg 620

Gross Anatomy of a Tooth Pg 620 Crown = area above gingiva Neck = (gumline) where crown and root meet Root = area below neck in alveolus

Tabitha’s Teeth Begin to Tumble Around 7 years of age the periodontal ligaments & roots of deciduous teeth are eroded = teeth fall out Permanent teeth begin to erupt between 7-13 years 3rd Molars (Wisdom Teeth) may not erupt until 17-25 years End Result: Adult Dental Formula premolars 2:1:2:3 X 2 = 32

Tabitha’s Tooth Troubles College --> too much junkfood = CAVITIES (caries) Bacteria erodes through the outer enamel covering of tooth Avascular, Acellular Mostly calcium salts Not renewed or replaced Hardest substance in body In severe cases it erodes the deeper dentin of tooth Made of minerals & collagen Is maintained during life Harder than bone Bulk of tooth Pg 620

Tabitha’s Tooth Trauma! Most severe cases erosion penetrates pulp cavity Center of tooth Pulp = loose CT w/ vessels & nerves Supplies nutrients to hard tissues Root canal: part of pulp cavity in root Apical Foramen: opening of pulp cavity into root canal Artery: Sup/Inf Alveolar aa, branches of Ext Carotid a Innervation: Maxilla = Superior Alveolar Nerves Mandible = Inferior Alveolar Nerves Pg 620

Tabitha’s Teeth: the later years Tabitha graduates college, begins to take better care of her teeth (i.e. consistent brushing, flossing & dental visits), and leads a normal happy tooth-filled life UNTIL……… GINGIVITIS…..(inflammation of the gingiva caused by plaque accumulation) leads to…..

Toodaloo Tabitha’s Teeth PERIODONTITIS Infection of periodontal ligament leading to its destruction and that of the bone around teeth Leading to…….. TOOTHLESSNESS!!!

Pharynx = “Throat” Connects nasal cavity & mouth to esophagus & larynx Runs from skull to C6 Carries food and air Lined with skeletal muscle Divided into 3 regions Nasopharynx Oropharynx Laryngopharynx Pg 617

Tonsils Swellings of mucosal lining of pharynx Simple lymph organs MALT: mucosa-associated lymphoid tissue Form ring around opening of pharynx 4 groups Palatine (pair) Lingual Pharyngeal Tubal (pair) Pg 570

Regions of the Pharynx Nasopharynx Oropharynx Laryngopharynx Pg 584

Nasopharynx: Only carries air Ciliated pseudostratified epithelium Location Posterior to Nasal Cavity Inferior to Sphenoid bone Superior to Soft Palate Closed off during swallowing by soft palate & uvula Pharyngeal tonsils (adenoids) Tubal tonsils

Oropharynx: Carries Food & Air Thick, protruding stratified squamosal epithelium due to great friction Location Posterior to Oral Cavity Runs from Soft Palate to Epiglottis Palatine tonsils Lingual tonsils

Laryngopharynx: Carries Food & Air Stratified squamosal epithelium Location Posterior to Larynx Continuous with esophagus (digestive system) Continuous with larynx (respiratory system)

Moving the Bolus Swallowing Peristalsis = propulsion Voluntarily initiated (pharynx) Suprahyoid, Infrahyoid, Pharyngeal constrictors Peristalsis = propulsion Involuntary Alternate waves of contraction and relaxation of muscles in organ walls (e.g. esophagus) Squeezes food from one organ to next Some mixing Pg 611

Hyoid Bone Only bone not directly articulated with other bones Attaches via ligaments to temporal bone, larynx Components Body Pair of Greater Horns Pair of Lesser Horns Functions Moveable base for tongue Attachment for sternohyoid, thyrohyoid Superior attachment for larynx Pg 163

Larynx = “voicebox” Location: C4-6 Attachments Innervation = vagus Low in neck for speech Attachments Superiorly = hyoid bone Inferiorly = trachea Innervation = vagus Functions Voice production Airway Routes food/air Pg 570

Laryngeal Cartilages 9 Cartilages connected by ligaments & membranes 1 Epiglottis 1 Thyroid 1 Cricoid 2 Arytenoid 2 Corniculate 2 Cuneiform Superior part = stratified squamosal epithelium Below vocal cords= ciliated pseudostratified columnar

Laryngeal Cartilages Epiglottis Thyroid Cartilage Cricoid Cartilage Elastic cartilage; Mucosa covering Projects upward from anterior wall of laryngeal inlet to level of base of tongue Thyroid Cartilage Large, shield shaped, made of 2 plates Laryngeal prominence Cricoid Cartilage Shaped like signet ring Between thyroid cartilage and trachea

Laryngeal Cartilages Pg 587

Vocal Cords Located in larynx Vocal ligaments run from arytenoid and thyroid cartilages Elastic fibers covered by mucosa True vocal cords = Mucosal folds Exhaled air passes over them causing vibration Force of air = volume Length & tension of folds = pitch “False” vocal cords = Vestibular folds lie superior to true pair, no role in voice production Pg 588

The Vocal Cords Thyroid cartilage True Vocal Folds Aretynoid cartilage False Vocal Folds True Vocal Folds

Thyroid Gland Location: Endocrine Gland Blood Supply: Along trachea, just inferior to larynx “Butterfly” shape Endocrine Gland Thyroid hormone (TH): increases basal metabolic rate Calcitonin: depresses excessive levels of Ca2+ in blood Blood Supply: Superior thyroid arteries (branches of ext. carotids) Inferior thyroid arteries (branches of subclavians) Pg 718

The Parathyroid Glands Usually 4 Posterior thyroid Parathyroid hormone, parathormone or PTH Increases Ca++ levels in blood

Triangles of the Neck Each half of the neck can be divided into 2 triangles: 1 Anterior and 1 Posterior

Anterior Muscles of the Neck Name Origin Insertion Action Innervation Sternocleido-mastoid Manubrium, clavicle Mastoid proc. (temporal bone), nuchal line (occipital bone) Flex or rotate head Accessory n. Sternohyoid Hyoid bone Depress larynx & hyoid C1-C3 spinal nerves Sternothyroid Manubrium Thyroid cartilage of larynx Moves thyroid cartilage, larynx, hyoid inferiorly

Anterior Triangle of the Neck Boundaries Superior = Inferior margin of Mandible Anterior = Midline of Neck Posterior = Sternocleidomastoid muscle Contents Muscles: Suprahyoid, Infrahyoid Artery: Carotid Vein: Internal Jugular, External Jugular Nerve: Accessory Glands: Submandibular

Posterior Triangle of the Neck Boundaries Anterior = Sternocleidomastoid muscle Posterior = Trapezius muscle Inferior = Clavicle Contents Nerves: Phrenic, Accessory, Cervical Plexus,Brachial Plexus Artery: Subclavian Vein: External Jugular

Triangles of the Neck pg 739