The Head and Neck

Upper Respiratory Tract

NoseNostrilNasal CavityOral CavityPharynx

pg 992

Nose

Nose is the only portion of the RT that is externally visible CT, bone, hyaline cartilage

Air enters here during breathingPasses through the external nares (nostrils)

pg 1023

VestibuleSuperior to nostrilsSkin lined with:

Sebaceous glandsGreasy secretionCollect dirtLubricate Kill bacteria

Sweat glandsAcidicSlows growth of bacteria

Hair folliclesTrap small particles of dirt

VibrissaeNose hairsFilter large particles (insects)

pg 1013

Nasal Cavity

Functions:Provides airway for respirationMoistens and warms airFilters inhaled airResonating chamber for speechHouses olfactory receptors

2 divisions:External noseInternal nasal cavity

pg 1023

Nasal Cavity

Divided into R and L by nasal septumContinuous with the nasopharynx

through the internal nares (choanae)

pg 992

Nasal Cavity

Boundries:Roof – ethmoid bone (cribiform plate)Floor – maxilla (palatine process)

palatine (horizontal plate)Lateral walls – nasal bones, superior and middle nasal

conchae of ethmoid bone, inferior nasal conchae, maxilla, palatine bone

Hard palatePalatine bones and maxillary bone

Soft palateSkeletal muscle posterior portionEnd in uvula

Lining of the Nasal Cavity

Respiratory Mucosa Pseudostratified ciliated columnar epithelium Goblet cells Lamina propria

Mucous and serous cells Venous plexus Function is to filter and warm inhaled air Highly innervated

Sneeze!

Olfactory Mucosa Roof of nasal cavity Houses smell receptors No goblet cells Cilia modified for olfaction

www.mc.vanderbilt.edu/.../Respiratory03.htm

Nasal Conchae

Project medially from each lateral wall3 structures:

Superior of ethmoid boneMiddle of ethmoid boneInferior

Functions:Create turbulence to increase:

Filters air Heats airMoistens airReclaim heat and moisture during exhalation

pg 1023

Paranasal Sinuses

Air filled cavities that surround the nasal cavity

Lined by mucosaPerform same function

as nasal cavity and lightens skull

Located in Frontal, Ethmoid, Sphenoid, Maxilla bonespg 1018

Pharynx

Connects the nasal cavity and mouth to larynx and esophagus

Extends from base of skull to level of C6

vertebraCommon passage for food and air Lined with skeletal muscleDivided into:

NasopharynxOropharynx Laryngopharynx

pg 992

Tonsils

Lymphoid organMALT

Swellings of the mucosa lining the pharynxForm ring around the entrance to the pharynx4 groups:

PalatineLingualPharyngealTubal

Remove pathogens pg 992

Nasopharynx

Location: Posterior to nasal cavity Inferior to sphenoid bone Superior to level of soft palate

ONLY an air passageway Closed off during swallowing by the soft palates’ uvula

Giggling! Ciliated pseudostratified epithelium Contain:

Pharyngeal tonsils (adenoids) Tubal tonsils

pg 992

Oropharynx

Location: Posterior to the oral cavity Extends inferiorly from level of the soft palate to level of

the esophagus Swallowed food and inhaled air pass through hereStratified squamous epitheliumContain:

Palatine tonsils Lingual tonsils

pg 992

Laryngopharynx

Location:Lies posterior to larynxContinuous with the esophagus and larynx

Common passageway for food and airFood – esophagusAir - larynx

Stratified squamous epithelium

pg 992

Larynx “Voice box”Extends from C4 to C6

Attachments:Hyoid bone superiorlyContinuous with trachea inferiorly

Functions:VocalizationProvides open airwaySwitches to route air and food into proper channels

Innervation: VagusSuperior part = stratified squamous epitheliumBelow vocal cords= ciliated pseudostratified columnar

pg 1001

Larynx All hyaline cartilage except epiglottis Composed of 9 cartilages connected by membranes and ligaments:

1 Thyroid 1 Cricoid 1 Epiglottis 2 Arytenoid 2 Corniculate 2 Cuneiform

pg 1000

pg 1001

Laryngeal Cartilages

Thyroid CartilageLargeShield shapedFormed by 2 platesContains laryngeal prominence

Adam’s Apple!!

pg 998

Laryngeal Cartilages

Cricoid Inferior to thyroid cartilageForms a complete ringDirectly superior to trachea

pg 998

Laryngeal Cartilages

EpiglottisComposed of elastic cartilageCovered by mucosaProjects upward from anterior wall of laryngeal inlet to

level of base of tongueClose off larynx during swallowing

pg 999

Vocal Cords

Located in the larynxMucosal folds formed by vocal ligaments

Composed of elastic fibers Run from arytenoid cartilages (posterior) to the thyroid cartilages

(anterior)

Exhaled air passes over them and causes vibration Force of air = volume Length & tension of folds = pitch

False vocal cords Vestibular folds (superior to true)

pg 1008

Thyroid Gland

Location: In anterior neck On trachea, inferior to larynx

2 lateral lobes Connected by the isthmus Butterfly shape

Largest endocrine gland in body Produces Thyroid hormone (TH)

Increases metabolic rate Calcitonin

Depresses excess levels of Ca+ in blood

pg 966

Thyroid Gland

Internally, composed of folliclesFollicular cells

TH

Parafollicular cellsCalcitonin

Blood supplySuperior thyroid arteries

Branches of external carotids

Inferior thyroid arteriesBranches of subclavians

Parathyroid Gland

Two pairsLocated on the deep surface of the lateral lobes

of the thyroid glandProduce parathyroid hormone

Increases blood calcium levels

pg 966

Hyoid BoneLocation:

Inferior to mandible In anterior neck

Associated with the skull Only bone in skeleton that does not articulate directly to

another bone!!!

Attaches via ligaments to temporal bone, larynxComposed of:

Body 2 pairs of horns

Functions: Moveable base for tongue Points of attachment for larynx and neck muscles

Sternohyoid, thyrohyoid, pg 803

Oral Cavity and Associated Organs

MouthTongueTeeth

External Salivary glands

pg 992

Mouth - Oral Cavity

Food enters alimentary canal through hereMucosa-lined

Thick stratified squamous epithelium, with keratinization in some areas

Boundaries: Lips anteriorly Cheeks laterally Palate superiorly Tongue inferiorly Oropharynx posteriorly

Mouth divided into 2 parts: Vestibule Oral cavity proper

pg 1041

Mouth

Lips (labia) and CheeksKeep food inside mouth during chewingComposed of skeletal muscle surrounded by skinLips formed by orbicularis oris muscleCheeks; Muscles of Mastication

Temporalis & Masseter (elevate mandible, close mouth) Buccinator (chewing) Digastric (lower mandible against resistance, opens mouth) Pterygoids (lateral movements)

Palate: forms the roof of the mouthSoft palate (posterior) rises to close off nasopharynx

during swallowing; made of skeletal muscleHard palate (anterior) provides surface for tongue to force

food against during chewing

Tongue

Functions 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 with a CT septum

Intrinsic muscles (change shape; rolling) Extrinsic muscles (movement; protrude, retract) Motor = Hypoglossal (CN XII) Sensory = Mandibular (CN V3), Facial (CN VII), Glossopharyngeal (CN IX)

pg 1037

Moving Bolus

Swallowing voluntarily initiated (pharynx)Peristalsis = propulsion

InvoluntaryAlternate waves of contraction and relaxation of muscles

in organ walls (e.g. esophagus)Squeezes food from one organ to nextSome mixing

www.answers.com

Salivary Glands

Compound tubuloalveolar glands Intrinsic salivary glands

In mucosa of tongue, palate, lips and cheeks Keeps mouth moist at all times

Extrinsic salivary glands Lie external to mouth Connected by ducts Secrete only during eating or prior to (“mouth watering”) 3 paired glands:

ParotidSubmandibularsublingual

pg 863

pg 1043

Salivary Glands

Produce saliva Mixture of water, ions, mucus and enzymes Moistens mouth Dissolves food for taste Binds food into a bolus Enzymes digest starch Bicarbonate buffer neutralizes acids Kill microorganisms Contains proteins to promote growth of beneficial bacteria

pg 1046

Teeth – From Eruption to EdentateFunction:

Ingestion and mechanical breakdown of food

Have 2 sets of teeth (dentitions)Primary dentition / deciduous (milk) teethPermanent dentition

Incisors: rip, cutCanines: tear and piercePremolars: grindingMolars: grinding

pg 1056

Teeth

GomphosisSynarthrosisPeg in socket with ligament

The sockets (alveoli) are in gum-covered margins in mandible and maxilla

Periodontal ligaments (collagen fibers) anchor tooth in bony socketContinous with gingiva (gum)

Teeth Substances

Enamel Made of calcium salts Avascular, acellular Not renewed or replaced HARDEST substance in body!!!!

Dentin Underlines enamel Forms bulk of tooth Made of minerals and collagen Maintained during life Harder than bone

Cementum Calcified external surface Attaches tooth to periodontal ligament

Teeth

Regions: Crown

Covered with enamelProjecting into oral cavity

Neck (gumline) Root

Area beyond neck in alveolus

Pulp cavity Center of tooth Loose CT with vessels and nerves Supplies nutrients to hard tissues

Teeth

Root Canal Portion of the pulp cavity in the root

Apical foramen Opening into the root canal at the tip of each root

Blood supply Superior/Inferior Alveolar artery, branches of External Carotid artery

Innervation Maxilla = Superior Alveolar Nerves Mandible = Inferior Alveolar Nerves

Teeth at Birth

Number of erupted teeth = 0Jaws covered by gingiva (gums)

Lots of drooling!!!

First Teeth – 6 Months

Lower central incisors first to appear 8 Incisors = 6-10 months 4 Canines = 16-20 months 4 1st Molars = 12-16 months 4 2nd Molars = 20-24 months

20 deciduous teeth emerge by age 2 Dental formula

Describes the number and position of classes of teeth (half of the mouth)

2I, 1C, 2M 2I, 1C, 2M X 2 = 20

****No premolars!

Deciduous teeth dental formula:

pg 1056

Adolescence – AdultPermanent teeth enlarge and develop

Roots of deciduous teeth reabsorbed Teeth loosen and fall out Begin to erupt from 7-13 years of age Third molars (wisdom teeth) emerge from 17-25 years

May be absent!!

Adult dental formula:

2I, 1C, 2P, 3M

2I, 1C, 2P, 3MX 2 = 32

pg 1056

Tooth Troubles

Cavities (caries)Demineralization of enamel by bacteria In severe cases, erodes the dentin of toothMost severe cases erosion penetrates pulp cavity

Tooth Troubles

Gingivitis Inflammation of the gingiva caused by plaque

accumulationLeads to…….

Periodontitis Infection of periodontal ligament leading to its

destruction along with the bone around the teethLeads to toothlessness!

Triangles of the Neck

Neck subdivided into two trianglesSeparated by the sternocleidomastoid

muscleAnterior trianglePosterior triangle

Triangles of the Neck: Posterior

Boundries:Anterior - sternocleidomastoidPosterior - trapezius Inferior – clavicle

Contents:Nerves: accessory nerve, phrenic nerve, brachial

plexusArtery: SubclavianVein: External jugular

pg 948

Triangles of the Neck: Anterior

Boundries: Anterior - midline Posterior - sternocleidomastoid Superior – inferior margin of the mandible

Contents: Glands: Submandibular Muscles: Suprahyoid and infrahyoid muscles Artery: Common carotid Vein: Internal jugular, External jugular Nerve: Accessory

pg 954