HISTEM W8 Oral Mucosa and Tongue

Describe the Oral mucosa. What are the 3 main types?

• Stratified squamous epithelium on top of lamina propria (CT proper/dermis layer)

• May be a deeper layer of submucosa present (hypodermis)

3 types:

1. Masticatory mucosa – keratinized; gingiva & hard palate

2. Lining mucosa – non-keratinized; cheeks, lips, floor of mouth, soft palate

3. Specialized mucosa – on tongue; contains taste buds

What lies between the epithelium and lamina propria in the oral mucosa?

basement membrane → lamina lucida, lamina densa, reticular lamina

Describe Lining mucosa.

Lining mucosa:

• soft, pilable, moist, stretchable, cushioned

• NON-KERATINIZED stratified squamous epithelium

• Lamina propria is smoother (less rete ridges/CT papillae

• contains elastic fibers and submucosa

Where is Lining mucosa located in the oral cavity? (3)

1. floor of the mouth

2. buccal, labia, alveolar mucosa, ventral surface of the tongue

3. soft palate

Describe the lining mucosa in the Floor of the Mouth.

• non-keratinized, thin

• Lamina propria → highly vascularized, not very many rete ridges/CT papillae

• Submucosa → loosely attached to bone/muscles; submand. and sublingual salivary glands found here

Describe the lining mucosa in the Cheeks

• Non-keratinized

• Lamina propria → highly vascular

• Submucosa → contains adipose tissue and minor salivary glands

• May have Fordyce granules, melanin pigmentation

Describe the lining mucosa of Alveolar Mucosa.

• Non keratinized

• Extremely mobile, lines vestibules the spaces between the lips/cheeks and the teeth/gums.) of the oral cavity

• Lamina propria → highly vascularized; lots of elastic fibers

• Submucosa → loosely attached for mobility

Describe the lining mucosa of the Lips

• Non keratinized squamous epithelium (iinner lips)

• Lamina propria → contains minor seromucous salivary glands

• Submucosa → contains orbicularis oris muscle

  • muscle encircles the lips → “kissing muscle”

• Contains eleidin (clear, semi fluid, intracellular protein)

  • transparent = blood vessels in papillary layer can show through giving lips their colour

Describe the lining mucosa of the Soft Palate

• Non-keratinized stratified squamous epithelium

• Lamina propria → highly vascularized

• Submucosa → contains muscles of the soft palate and mucous glands (minor salivary glands)

Describe Masticatory Mucosa

• Parakeratinized or Orthokeratinized stratified squamous epthelium

• Thicker, rubbery surface texture, more resilience, firm base

• Abundant and pronounced rete ridges (prickle cell layer) = firm base

• Thin or absent submucosa

Where can you find Masticatory mucosa in the oral cavity?

1. Attached gingiva

2. Dorsal surface of tongue

3. Hard palate

What is the difference between Parakeratinized and Orthokeratinized

Presence (parakeratinized) or absence (orthokeratinized) of nuclei in the keratinized layer.

• Parakeratinized has a thinner keratin layer than orthokeratinized

Draw and label the Gingiva and the junctions between each “zone”

Gingiva = Free gingiva, attached gingiva, interdental gingiva/papilla

What is keratinized and smooth, has its inner margin at the gingival sulcus and outer margin as the oral cavity?

Free Gingiva

What is between the free gingival groove and mucogingival junction? What is its appearance?

Attached gingiva → keratinized and stippled appearance

Why does hyperkeratinisation occur in the oral cavity?

Its the tissue’s response to frictional or chemical trauma (chronic trauma)

Examples:

linea alba = a line where max and mand teeth occlude

frictional keratosis = tissue response to teeth grinding or cheek biting (looks white, thickened, textured)

gingival fibrosis = toughing of the gums

nicotine stomatitis = damage to tissues from heat of smoking

The anterior 2/3rds of the tongue is composed of what kind of muscle? What about the posterior 1/3rds? What are the names of these regions of the tongue?

Anterior aka body of tongue = skeletal muscle

Posterior aka root of tongue = skeletal muscle + anchored to the hyoid bone and covered with lingual tonsils.

What is the condition that is a short lingual frenum?

Ankyloglossia (tongue-tied)

What is the function of the lingual papillae

provide friction for handling food and contains taste buds

Describe Filiform Papillae and its function

• most common, make up majority of the dorsal surface of tongue

• fine pointed cones, tips pointing towards the throat

• slender and threadlike

• lined with a THICK layer of ortho/parakeratinized epithelium overlying core of lamina propria

• no taste buds

Fx: is to provide mechanical grip for food manipulation

Describe Fungiform papillae

• reddish dots on the tongue

• mushroom shaped

• thin layer of orthokeratinized or parakeratinized epithelium over lying the highly vascular lamina propria

• has taste buds

Fx: taste

Describe Foliate Papillae

• 4-11 (amount)

• Located on the vertical and parallel ridges on the lateral side of the posterior 1/3rd of tongue

• Leaf-shaped

• Lined with ortho/parakeratinized epithelium over core of lamina propria

• has taste buds

Fx: taste

Describe Circumvallate papillae (vallate papillae)

• 7-15 raised, mushroom shaped papillae

• located on the posterior 1/3rd of tongue in a V shape alignment

• ortho/parakeratinized epithlium overlying lamina propria

• has surrounding groove where von ebner gland is located

Fx: taste

Describe the structure of Taste buds.

Microscopic barrel shaped bodies derived from epithelium and 30-80 spindle shaped cells

What is the turn over rate for taste buds?

~ 10 days

How do we taste/perceive taste?

• Dissolved molecules of food touch taste receptors at the taste pore (opening of the taste bud)

Taste cells have a sensory neuron that will send impulses to the CNS (central nervous system) to be identified

4 types of taste sensation = sweet, sour, salty and bitter

Why is turn over time an important piece of information for cells in the oral cavity?

Helps us determine healing rates and recovery times from damage

• JE = 4-6 days

• Hard palate = 24 days

• Lining mucosa faster than masticatory mucosa

• Taste buds = ~ 10 days