Oral Mucous Membrane

Question 1

Oral mucous membrane

Answer 1

Forms principal barrier against physical and chemical trauma. Forms a continuous layer lining the oral cavity ( pierced by ducts and glands).
2 layers : - epithelium( stratified squamous keratinised/non)
- lamina propria( fibrous/elastic connective tissue)
In some regions these two layers attached directly to periosteum of bone. This whole combination is called the mucoperiosteum. In other regions oral mucous membrane seperated from underlying tissue by a layer of loose areolar connective tissue known as submucosa.
Salivary glands in deepest part of lamina propria or submucosa.

Question 2

Epithelium

Lamina propria

Answer 2

Epithelium - same layers as epidermis of skin however where non keratinised it won’t have stratum granulosum. Cells held together by desmosomes . Main difference to skin is that epithelium of mucosa is lubricated and protected by secretion of mucus. This mucus is contained in saliva. Contour of junction between epithelium and lamina propria may be flat or wavy with rete pegs.
Lamina propria - similar to dermis. Some areas a dense fibrous connective tissue others elastic . Has excellent blood supply and lymphatic drainage. Nerve fibres mainly touch and pain.
Other associated structures - salivary glands, sebaceous glands in lamina propria of lining of cheek known as fordyce spots.
Pigmentation - relation to degree of skin pigmentation.

Question 3

Anatomy of oral mucous membrane

Answer 3

Provides continuous covering including vestibule and mouth cavity. In the vestibule the membrane commences at buccal gingival margins to surround and cover cervical region of teeth and bone. Continues over bone and alveolar mucosa to reach labial/buccal sulcus . At the base of each labial buccal sulcus , membrane turns to like lip and cheeks.
In mouth cavity oral mucous membrane commences at the lingual gingival margin to surround lower cervical margin of teeth and bone. Continues over bone to reach lingual sulcus. At base of lingual sulcus turns to cover floor of mouth then ventral surface then dorsum of tongue. In upper arch it commences at palatal gingival margin to surround and cover cervical region of teeth and bone. Continues to cover hard and soft palate . Teeth are the only place in the body where mineralised structure outside epithelium .

Question 4

3 types of oral mucosa

Answer 4

1. LINING MUCOSA- flexible, allows distension of the oral cavity and adapts to muscle movement. Has a non keratinised stratified squamous epithelium and elastic connective tissue. Sites include labial/buccal mucosa,floor of mouth, soft palate, ventral surface of tongue.
2. MASTICATORY MUCOSA - resist greater forces. Keratinised stratified squamous epithelium and dense fibrous collagen rich connective tissue. Sites include hard palate mucosa and gingivae( mucoperiosteum ) with direct attachment to bone and cementum.
3. SPECIALISED MUCOSA - same structure as masticatory but carries specialised structures eg taste buds . Sites include dorsum of tongue.

Question 5

Functions of oral mucous membrane

Answer 5

Sensory, protection , excretion , absorption

Functions of skin not applying to oral mucous membrane : manufacture vit D, regulating body temperature.

Question 6

Renewal of healthy tissues

Answer 6

Most tissues undergo continual renewal of all cells in health. Epithelium is one of the most active tissues in this process.
STEADY STATE - number of cells formed will exactly balance the number of cells shed from the surface. If steady state is not maintained there will be clinically obvious differences in the area of the tissue. If more new cells than shed it will be swollen , overgrown , pink/ white if keratinised. If less new cells there will be an ulcer and red.
TURNOVER TIME - time taken for an area of tissue to be completely replaced. Time taken to form a number of cells equal to total number of cells in the tissue.
Skin epithelium - 20-40 days
Keratinised oral epithelium( gingiva) 10-14 days
Non keratinised oral epithelium 5-7 days