head
DESCRIPTION
TRANSCRIPT
The Head and Neck
Upper Respiratory Tract
Nasal Cavity Nostril Oral Cavity Larynx Pharynx
Nose
Only portion of the RT that is externally visible
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
Nasal Cavity
Air enters here during breathing Passes through the
nares (nostrils)
Divided into R and L by nasal septum
Continuous with the nasopharynx through the internal nares
Nasal Cavity
Boundries: Roof – ethmoid bone (cribiform plate) Floor – maxilla (palatine process)
palatine (horizontal plate) Lateral walls – nasal bones, superior and middle nasal
conchae (ethmoid bone), inferior nasal conchae, maxilla, palatine bone
Hard palate Palatine bones and maxillary bone
Soft palate Muscular posterior portion
Nasal Cavity Vestibule
Superior to nostrils Skin 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
Vibrissae Nose hairs Filter large particles
(insects)
Lining of the Nasal Cavity
Olfactory Mucosa Roof of nasal cavity Houses small 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
Nasal Conchae
Project medially from each lateral wall 3 structures:
Superior of ethmoid bone Middle of ethmoid bone Inferior
Functions: Filters air Heats air Moistens air Reclaim heat and moisture during exhalation
Paranasal Sinuses
Air filled cavities that surround the nasal cavity
Lined by mucosa Perform same function
as nasal cavity and lightens skull
Located in Frontal, Ethmoid, Sphenoid, Maxilla bones
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 (throat)
Lined with skeletal muscle Divided into:
Nasopharynx Oropharynx Laryngopharynx
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
Oropharynx
Location: Postreior to the oral cavity Extends inferiorly from
level of the soft palate to level of the esophagus
Swallowed food and inhaled air pass through here
Stratified squamous epithelium
Contain: Palatine tonsils Lingual tonsils
Tonsils
Lymphoid organ Swellings of the mucosa
lining the pharynx Form ring around the
entrance to the pharynx 4 groups:
Palatine Lingual Pharyngeal Tubal
Remove pathogens MALT
Laryngopharynx
Location: Lies posterior to larynx Continuous with the
esophagus and larynx
Common passageway for food and air
Stratified squamous epithelium
Larynx “Voice box” Extends from C4 to C6
Attachments: Hyoid bone superiorly Continuous with trachea inferiorly
Functions: Vocalization Provides open airway Switches to route air and food into proper
channels Innervation: Vagus Superior part = stratified squamous epithelium Below vocal cords= ciliated pseudostratified
columnar
Larynx Composed of 9 cartilages connected by membranes and ligaments:
1 Thyroid 1 Cricoid 1 Epiglottis 2 Arytenoid 2 Corniculate 2 Cuneiform
Laryngeal Cartilages
Thyroid Cartilage Large Shield shaped Formed by 2 plates Composed of laryngeal
prominence Adam’s Apple!!
Laryngeal Cartilages
Cricoid Inferior to thyroid
cartilage Forms a complete ring Perched on top of the
trachea
Laryngeal Cartilages
Epiglottis Composed of elastic
cartilage Covered by mucosa Projects upward from
anterior wall of laryngeal inlet to level of base of tongue
Vocal Cords
Located in the larynx Mucosal 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)
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 TH
Increases metabolic rate Calcitonin
Depresses excess levels of Ca+ in blood
Thyroid Gland
Internally, composed of follicles Follicular cells
TH Parafollicular cells
Calcitonin
Blood supply Superior thyroid arteries
Branches of external carotids
Inferior thyroid arteries Branches of subclavians
Parathyroid Gland
Two pairs Located on the deep
surface of the lateral lobes of the thyroid gland
Produce parathyroid hormone Increases blood
calcium levels
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, larynx
Composed of: Body 2 pairs of horns
Functions: Moveable base for tongue Points of attachment for larynx
and neck muscles Sternohyoid, thyrohyoid,
Triangles of the Neck
Neck subdivided into two trianglesSeparated by the sternocleidomastoid
muscleAnterior trianglePosterior triangle
Triangles of the Neck: Posterior
Boundries: Anterior - sternocleidomastoid Posterior - trapezius Inferior – clavicle
Contents: Nerves: accessory nerve,
cranial plexus, phrenic nerve, brachial plexus
Artery: Subclavian Vein: External jugular
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: Carotid Vein: Internal jugular, External
jugular Nerve: Acccessory
Mouth and Associated Organs
Mouth Tongue Salivary glands Teeth
Mouth - Oral Cavity
Food enters alimentary canal through here
Mucosa-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
Mouth
Lips (labia) and Cheeks Keep food inside mouth during chewing Composed of skeletal muscle surrounded by skin Lips formed by orbicularis oris muscle Cheeks; 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 mouth Soft palate (posterior) rises to close off nasopharynx
during swallowing; made of smooth muscle Hard 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)
Swallowing
Voluntarily initiated (pharynx) 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
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:
Parotid Submandibular sublingual
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
Teeth – From Eruption to Edentate Lie in sockets (alveoli) in
gum-covered margins in mandible and maxilla
Have 2 sets of teeth (dentitions) Primary dentition /
deciduous (milk) teeth Permanent dentition
Incisors: rip, cut Canines: tear and pierce Premolars: grinding Molars: grinding
Teeth
Function: Ingestion and mechanical
breakdown of food Periodontal ligaments
(collagen fibers) anchor tooth in bony socket Gomphosis - form of
immovable articulation; a peglike part fits into a cavity
Continous with gingiva (gum)
Teeth
Regions: Crown
Covered with enamel Area above gingiva
Neck (gumline) Root
Area below 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 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 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 – Adult Permanent 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, 3M2I, 1C, 2P, 3M
X 2 = 32
Tooth Troubles
Cavities (caries) Demineralization of
enamel by bacteria In severe cases, erodes
the dentin of tooth Most severe cases
erosion penetrates pulp cavity
Tooth Troubles
Gingivitis Inflammation of the
gingiva caused by plaque accumulation
Leads to……. Periodontitis
Infection of periodontal ligament leading to its destruction along with the bone around the teeth
Leads to……………
Toothlessness!!!!!!