Download The Head and Neck

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
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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:
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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 triangles
Separated by the sternocleidomastoid
muscle
Anterior triangle
Posterior 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)
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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
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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
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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)
Deciduous teeth dental formula:
2I, 1C, 2M
2I, 1C, 2M
X 2 = 20
****No premolars!
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, 3M
2I, 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!!!!!!