The Head and Neck

1
The Head and Neck
2
Upper Respiratory Tract

• Nostril
• Nasal Cavity
• Oral Cavity
• Pharynx

pg 944
3
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

4
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)

5
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

6
Nasal Cavity
pg 965

• 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)

7
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
8
Nasal Conchae
pg 973

• 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

9
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

10
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

11
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

12
Nasopharynx
pg 944

• 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

13
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

14
Laryngopharynx
pg 944

• Location
• Lies posterior to larynx
• Continuous with the esophagus and larynx
• Common passageway for food and air
• Food esophagus
• Air - larynx
• Stratified squamous epithelium

15
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

16
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

17
Laryngeal Cartilages
pg 950

• Thyroid Cartilage
• Large
• Shield shaped
• Formed by 2 plates
• Contains laryngeal prominence
• Adams Apple!!

18
Laryngeal Cartilages
pg 952

• Cricoid
• Inferior to thyroid cartilage
• Forms a complete ring
• Directly superior to trachea

19
Laryngeal Cartilages
pg 951

• 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

20
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)

21
Thyroid Gland
pg 917

• 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

22
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

23
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

24
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,

25
Oral Cavity and Associated Organs
pg 944

• Mouth
• Tongue
• Teeth
• External Salivary glands

26
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

27
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

28
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)

29
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

30
Salivary Glands
pg 820
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

31
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

32
Teeth From Eruption to Edentate
pg 1008

• 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

33
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)

34
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

35
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

36
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

37
Teeth at Birth

• Number of erupted teeth 0
• Jaws covered by gingiva (gums)
• Lots of drooling!!!

38
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

Deciduous teeth dental formula
X 2 20
No premolars!
39
Adolescence Adult
pg 1008

• 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
40
Tooth Troubles

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

41
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 toToothlessness!

42
Triangles of the Neck

• Neck subdivided into two triangles
• Separated by the sternocleidomastoid muscle
• Anterior triangle
• Posterior triangle

43
Triangles of the Neck Posterior
pg 905

• Boundries
• Anterior - sternocleidomastoid
• Posterior - trapezius
• Inferior clavicle
• Contents
• Nerves accessory nerve, phrenic nerve, brachial
  plexus
• Artery Subclavian
• Vein External jugular

44
Triangles of the Neck Anterior
pg 762

• 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