The Head and Neck

Upper Respiratory Tract

NostrilNasal CavityOral CavityPharynx

pg 944

Nasal Cavity

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

Functions: Provides airway for respiration Moistens and warms air Filters inhaled air Resonating chamber for speech Houses olfactory receptors

2 divisions: External nose Internal nasal cavity

pg 973

Nasal Cavity

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

Divided into R and L by nasal septumContinuous with the nasopharynx through

the internal nares (choanae)

pg 944

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

Nasal CavityVestibule

Superior to nostrilsSkin lined with:

Sebaceous glands• Greasy secretion• Collect dirt• Lubricate • Kill bacteria

Sweat glands• Acidic• Slows growth of bacteria

Hair follicles• Trap small particles of dirt

VibrissaeNose hairsFilter large particles (insects)

pg 965

Lining of the Nasal CavityOlfactory Mucosa

Roof of nasal cavity Houses smell receptors

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!

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 973

Paranasal Sinuses

Air filled cavities that surround the nasal cavityLined by mucosaPerform same function as nasal cavity and

lightens skullLocated in Frontal, Ethmoid, Sphenoid, Maxilla

bones

pg 970

Pharynx

Connects the nasal cavity and mouth to larynx and esophagus

Extends from base of skull to level of C6 vertebra

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

NasopharynxOropharynx Laryngopharynx

pg 944

Tonsils

Lymphoid organMALT

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

PalatineLingualPharyngealTubal

Remove pathogens

pg 944

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 944

Oropharynx

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

epiglottisSwallowed food and inhaled air pass through hereStratified squamous epitheliumContain:

Palatine tonsils Lingual tonsils

pg 944

Laryngopharynx

Location:Lies posterior to larynxContinuous with the esophagus and larynx

Common passageway for food and airFood – esophagusAir - larynx

Stratified squamous epithelium

pg 944

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 949

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 952-3

Laryngeal Cartilages

Thyroid CartilageLargeShield shapedFormed by 2 platesContains laryngeal

prominenceAdam’s Apple!!

pg 950

Laryngeal Cartilages

Cricoid Inferior to thyroid

cartilageForms a complete ringDirectly superior to

trachea

pg 952

Laryngeal Cartilages pg 951

Vocal Cords

Located in the larynxMucosal folds formed by vocal ligaments

Composed of elastic fibers Run from arytenoid cartilages to the thyroid cartilages

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 960

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 917

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 917

Hyoid Bone

Location: 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 755

Oral Cavity and Associated Organs

MouthTongueTeeth

External Salivary glands

pg 944

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 993

Mouth

Lips (labia) and CheeksKeep food inside mouth during chewingComposed of skeletal muscle surrounded by skinLips formed by orbicularis oris muscleCheeks; Muscles of Mastication (pg 266-67)

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 989

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

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 820pg 997

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 998

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 1008

Teeth

Gomphosis Synarthrosis Peg in socket with ligament

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

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

Teeth

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

Regions: Crown

Covered with enamelArea projecting beyond gingiva

Neck (gumline) Root

Area beyond neck in alveolus

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 SubstancesEnamel

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 at Birth

Number of erupted teeth = 0

Jaws 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:

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 yearsMay be absent!!

Adult dental formula:

2I, 1C, 2P, 3M2I, 1C, 2P, 3M

X 2 = 32

pg 1008

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 teeth

Leads 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 905

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 762