Oral Cavities Flashcards
Three Diets and Two further divisions?
Ominvores - plant & meat
Carnivores - meat
Herbivores - plant
Monogastric - simple stomach
Ruminants - mixing & fermenting, multiple chambers
General features/structure of Oral Cavity (mouth) of dog?
-Composed of walls and accessory structures (tongue, teeth, salivary glands)
-Boundaries are lips, and pharynx (region at the back of cavity and shared with respiratory and digestive systems)
-Function: generates bolus of food
In depth structure of bones and muscles of oral cavity (dog)?
Bone Support:
-Incisive (front)
-Maxilla (top middle near lacrimal(bottom of eye) bone)
-Mandible (bottom jaw)
-Palatine (dorsal surface, hard top of inside mouth)
-Zygomatic (cheek bone ig)
Three Layers of Tissue:
-Outer - skin
-Middle - muscle, tendons, connective/adipose(storage of fat) tissue e.g. mylohyoideus(under chin) muscle on ventral surface
-internal labial mucosa covers oral cavity
Boundaries and functions of Oral Cavity (dog)?
Diagram on slide 5
MAIN:
Lips (Rostrally-imagine an angled arrow protruding from forehead)
-skin, muscle, tendons, mucosa
-forms angle of mouth (commissures)
-suckling (young)
-prehension
-aggression
Cheeks (Laterally)
-supported by buccinator muscle
-returns food to central cavity
-loose to allow stretching
-firm to prevent damage by teeth
Palatoglossal arch (where tonsils are)
-tissue extends from root of tongue to soft palate
-marks exit of mouth
Vestibule (cheek pouch)
-large in rodents, some monkeys
-can be storage
Hard Palate
-palatine bone and processes of incisive, maxillary bones
-covered in mucosa, bony ridges = rugae
-guides food caudally (moves it back)
Soft palate
-caudally from hard palate
-consists of connective tissue aponeurosis (a sheet of pearly white fibrous tissue that takes the place of a tendon in flat muscles having a wide area of attachment.)
-replaces bone of hard palate
Buccal Mucosa in cattle
-contains papillae (white arrows)
-assists w rough diet
What are the steps of consuming food?
- Prehension - holding firmly
- Selection
- Mastication (mechanical breakdown of food by chewing)
- Insalivation
- Taste buds for palatability/poison (appeal to senses)
Dentition adaptations of Carnivores?
-Catch and hold prey
-Tear flesh and grind bones
-Defensive/Aggression
-High energy
Dentition adaptations of Herbivores?
-Plant material
-Break down cellulose layer
-Grind material
-Low energy
Organisation of dental arch in carnivores?
Restricted lateral(horizontal) movement
Upper arch is longer & wider hence overlap of lower arch
Limited chewing
Aids shearing of food
Dogs & cats gulp food
Premolars do not make contact
Diestima (space) between canine and molars
Tooth structure?
Crown:
-encased in enamel (formed during development)
-white calcified material
-cannot be repaired
Root encased in cementum (softer and yellow)
Dentine (protective feature):
-can be replaced
-has central cavity
-lined with cells named ondontoblasts that replace dentine
-canaliculi (narrow channels in tooth that supply blood)
-houses central pulp
Tooth socket structure and function?
Gums (Gingivae)
-embraces neck of tooth
-lined by thin lamina
-perforated (holed) for passage of nerves/vessels
-outer layer has spongy bone to merge with jaw
Support
-attached to socket by tough fibrous periodontal ligament
-rich in collagen fibres
-attach to cement and alveolar bone
-acts as sling to permit limited movement
-stops tooth being driven into socket
3 Classifications of teeth?
Diphydont:
-two sets of teeth
-deciduous (baby teeth) and perma
Brachydont:
-short/low crowned
-distinct crown & roots
-stop growing after eruption
-humans/dogs/cats
-incisors & canines of ruminants
Hypsodont:
-Large crown (body) that extends below gum line
-small root that is formed late
-cotninues to grow for no. of years
-cheek teeth of ruminants
-canines of pigs
-all horse teeth except P1*
4 Functional relationship to teeth?
(I,C,P,M)
INCISORS (I)
Nibbling and grooming (carnivore)
CANINE (C)
Deep wounds, punching and holding
PREMOLARS (P)
Serrated, slicing, and cutting
MOLARS (M)
Crushing and cutting, no chewing
*Herbivore incisors have flat surface, suitable for tearing plant mats
Dental formula (dog/cat)?
Dog:
I3 C1 Pm4 M2 (upper arcade)
I3 C1 Pm4 M3 (lower arcade)
also written as:
3-1-4-2
3-1-4-3
Cat: (reduced Pm)
3-1-3-1
3-1-2-1
Attrition in herbivores?
The layer of tooth named ‘plate’ waste that gets worn down by 2-3mm every year.
Infundibulum?
Compartment generated by outer enamel coating and inner enamel ring.
Horse dentition?
Cutting action causes constant wear down.
Continuous eruption.
Long crown reserve.
Secondary dentine
-exposure of pulp prevented by formation of new dentine
-laid down by odontoblasts
-called ‘dental star’
-Never look a gift horse in the mouth* wear pattern estimates age of horse.
Young to Old horse dentition changes?
High crowns when young.
Embedded teeth almost fill maxmillary sinus.
Reserve crowns become smaller, root forms.
Older horse - roots close.
Alignment of upper and lower arcade change.
Maximillary sinus has greater size.
Bovine dental formula?
Lacks upper incisors, replaced by dental pads (heavily cornified).
Had lower canine tooth lateral to the incisor.
0-0-3-3
3-1-3-3
Damage limited by tongue.
Articulation of carnivore?
Requires maximum gape and power.
Smaller masseter, larger temporalis.
Articular condoyle - articulation in similar plane as teeth.
Articulation?
A temporomandibular joint.
Association of mandible with temporal bone of skull.A
The contact relationships of maxillary and mandibular teeth as they move against each other.
Articulation of herbivore?
Sustained rotary grinding, more flexibility.
Larger masseter, smaller temporalis. (for lateral and rotational movement)
Articular condoyle - high above the teeth line.
-allows force on lateral line.
-aids in grinding.
4 Muscles of Mastication?
TEMPORALIS
Lateral surface of cranial
Pulls up mandible
Insertion of coronoid process of mandible (helps stabilise jaw w chewing)
MASSETER
Origin in maxillary surface and zygomatic arch
Insertion on caudal aspect
Raises mandible and draws towards active side (restricted to one side)
PTERYGOID
Medial and lateral
Pulls up mandible
Draws mandible inward
Can work w masseter for ‘side to side’
DIGASTRICUS
Opens mouth
Contraction raises hyoid apparatus
Role of Pharynx and Soft Palate?
Both for respiratory and digestive systems.
Located between oral cavity and esophagus.
Oral (oropharhynx) - between soft palate and root of tongue.
Nasal (nasopharynx) - caudal border of soft palate.
Laryngeal part - dorsal to larynx.
Process of Deglutition? (Swallowing mechanism)
Soft palate lies on tongue.
When swallowing, soft palate raises.
Involves two phases and movement of the larynx. (In)/voluntary
Process must occur but prevent food or fluid entering trachea.
Otherwise choking will occur - normally prevented by epiglottis.
