Download The Head and Neck

The Head and Neck
Upper Respiratory Tract
 Nostril
 Nasal Cavity
 Oral Cavity
 Pharynx
pg 944
Nasal Cavity
pg 973
 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
Nasal Cavity
pg 944
 Air enters here during breathing
Passes through the external nares (nostrils)
 Divided into R and L by nasal septum
 Continuous with the nasopharynx through
the internal nares (choanae)
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 palate
Palatine bones and maxillary bone
 Soft palate
Skeletal muscle posterior portion
End in uvula
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)
pg 965
Lining of the Nasal Cavity
 Olfactory 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 wall
 3 structures:
Superior of ethmoid bone
Middle of ethmoid bone
Inferior
 Functions:
Create turbulence to increase:
 Filters air
 Heats air
 Moistens air
 Reclaim heat and moisture during exhalation
pg 973
Paranasal Sinuses
pg 970
 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
pg 944
 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 muscle
 Divided into:
Nasopharynx
Oropharynx
Laryngopharynx
Tonsils
pg 944
 Lymphoid organ
MALT
 Swellings of the mucosa lining the pharynx
 Form ring around the entrance to the pharynx
 4 groups:
Palatine
Lingual
Pharyngeal
Tubal
 Remove pathogens
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
pg 944
 Location:
 Posterior to the oral cavity
 Extends inferiorly from level of the soft palate to level of the
epiglottis
 Swallowed food and inhaled air pass through here
 Stratified squamous epithelium
 Contain:
 Palatine tonsils
 Lingual tonsils
Laryngopharynx
 Location:
Lies posterior to larynx
Continuous with the esophagus and larynx
 Common passageway for food and air
Food – esophagus
Air - larynx
 Stratified squamous epithelium
pg 944
Larynx
pg 949
 “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
pg 952-3
 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
Laryngeal Cartilages
 Thyroid Cartilage
Large
Shield shaped
Formed by 2 plates
Contains laryngeal
prominence
 Adam’s Apple!!
pg 950
Laryngeal Cartilages
 Cricoid
Inferior to thyroid
cartilage
Forms a complete ring
Directly superior to
trachea
pg 952
Laryngeal Cartilages
 Epiglottis
Composed of elastic
cartilage
Covered by mucosa
Projects upward from
anterior wall of
laryngeal inlet to level
of base of tongue
Close off larynx during
swallowing
pg 951
Vocal Cords
pg 960
 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 Thyroid hormone (TH)
 Increases metabolic rate
 Calcitonin
 Depresses excess levels of Ca+
in blood
pg 917
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
pg 917
 Two pairs
 Located on the deep surface of the lateral
lobes of the thyroid gland
 Produce parathyroid hormone
Increases blood calcium levels
Hyoid Bone
pg 755
 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,
pg 944
Oral Cavity and Associated Organs
 Mouth
Tongue
Teeth
 External Salivary glands
Mouth - Oral Cavity
pg 993
 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 skeletal muscle
Hard palate (anterior) provides surface for tongue to force
food against during chewing
Tongue
pg 989
 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)
Moving Bolus
 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
pg 997
 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
pg 820
Salivary Glands
pg 998
 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 1008
Teeth – From Eruption to Edentate
 Function:
 Ingestion and mechanical
breakdown of food
 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
 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 enamel
 Area 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 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)
Deciduous teeth dental formula:
2I, 1C, 2M
X 2 = 20
2I, 1C, 2M
****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 X 2 = 32
2I, 1C, 2P, 3M
pg 1008
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!
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,
phrenic nerve, brachial plexus
Artery: Subclavian
Vein: 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