L59: structure and function of oral cavity

what are the components of the ailementary canal?

1. esophagus

2. stomach

3. small intestine

4. large intestine

what are the accessory organs of the digestive tract?

1. salivary glands

2. teeth

3. gallbladder

4. pancreas

5. liver

what animals are considered hindgut fermenters?

horse and rabbit

what animals are considered foregut fermenters?

ruminants and deer

what is the alimentary tract/canal?

the transport, physical processing, and storage of the digestive system from mouth to anus

what is the process of food passage?

1. food chewed by mouth

2. food becomes bolus that will be swallowed

3. bolus reach stomach and becomes ingesta, when reaches small intestines called chyme

4. nutrients and water absorbed from ingesta, waste becomes feces that will exit via rectum

what will the feces of an animal living in a dry area appear as?

dry feces since most of the water is being reabsorbed into the body

what are the functions of the oral cavity?

1. ingestion

2. mastication

3. insalivation

oral fissure

opening of the mouth

palatale dorsal arch

located at the most caudal part of the oral cavity where both palatoglossal arches combine

mucosa of oropharynx

highly sensitive, can initiate swallowing reflex in animal

what is another name for lips?

oral fissure

angle of mouth/ oral comissure/ comissure of the lip

point where the upper and lower lip meet; used as a landmark in surgeries to gain entry into oral cavity

function of mouth

1. ensure proper closure of rima oris/oral fissure

2. sucking milk in young

3. prevent loss of saliva and food while chewing

what muscle provides support to the lips?

orbicularis oris muscle

what mucosa is present in the lips?

labial glands = minor salivary glands on the oral surface

what happens when the orbicularis oris muscle contract?

mouth will close but important to note DOES NOT have control over jaw movement

describe the surface of the outer skin of the lips

keratinization to protect against tough material

what is the composition of the lower lips?

1. stratified squamous epithelium

2. labial glands

which animals have prehensile upper lips?

1. horse

2. sheep 

3. goat

what do we mean when we say an animal has prehensile upper lips?

animal uses upper lip to bring food to the mouth

what is seen in animals with flews?

lots of drooling will be seen because oral fissure not closed as well, animal cannot contain as much saliva in oral cavity

lip fold

present between the lips and the gum, exclusive to dogs

lip frenulum

located at rostral part of lip fold, exclusive to dogs

what is this image showing in the dog?

lip fold dermatitis

what is the black line pointing to in the goat?

conical papillae 

what is the function of the conical papillae in ruminants?

1. reduce direct contact between mucous membrane and rough food material

2. prevent back flow of food outside of the oral cavity to be able to swallow

what direction do the conical papillae face?

backwards

where are conical papillae present?

labial and buccal mucosa

what structure forms the caudo-lateral boundary of the oral cavity?

the cheeks

what is another name for cheeks?

buccae

what muscle forms the major bulk of the cheeks?

buccinator muscle

what muscle is responsible for facial expression and closing of the jaw?

buccinator muscle

which species have narrow cheeks?

carnivores

which species have wider cheeks?

herbivores

what are the minor salivary glands of the cheeks?

buccal glands

what is different about the cheeks in cats and dogs?

zygomatic and molar salivary glands are major, normally they are minor glands in the cheeks

what provides sensory innervation to the lips and cheeks?

trigeminal nerve (CN 5)

what provides motor innervation to the lips and cheeks?

orbiculus muscle

skeletal muscle of the lips under voluntary control for facial expression

what is the muscle of the cheeks for facial expression?

velocinatory muscle

what does the facial artery branch from?

external carotid artery

what branches from the facial artery?

1. superior labial

2. angularis oris

what branches from the maxillary artery?

1. inferior alveolar then mental arteries

2. infraorbital then lateral nasal artery

what is the rostral limit of the oral cavity?

rima oris

what is the caudal limit of the oral cavity?

palatoglossal arch

what structure makes up the floor boundary of the oral cavity?

mylohyoideus muscles

what is the vestibule of the mouth?

Space outside the teeth

what is the oral cavity proper?

space inside the teeth

what are the organs of the oral cavity?

1. tongue

2. teeth

3. openings of salivary glands

what salivary glands are located in the vestibule of the oral cavity?

1. parotoid gland

2. zygomatic gland

MCQ: what animal has prehensile lips?

horse, sheep, and goat

what are the transverse ridges of the hard palate?

rugae

hard palate

rostral bony portion including incisive, maxillary, and palatine bones

incisive papilla

opening of the incisive ducts on both sides – ducts of the

vomeronasal organ

what is the pink box pointing to?

incisive papillae

what is the green box pointing to?

rugae

what is the purpose of rugae on the hard palate?

makes surface uneven to help prevent loss of food and push it back into oral cavity

what is the red?

incisor bone

what is the blue?

maxillary bone

what is the green?

palatine bone

what is something to note of the papillae of the cat and cow?

backward pointing papillae on the hard palatehelp in grasping food

what are the sublingual / buccal drugs?

1. buprenorphine

2. detomidine

which species is buprenophine effective in?

cats

what do we prescribe buprenorphine for?

pain relief and sedation

what species is detomidine effective in?

horses and calves

what is detomidine prescribed for?

pain relief and sedation

MCQ: which nerve innervates the muscles of the hard palate?

vagus and glossopharyngeal

describe the oral mucosa of ruminants?

1. keratinixation of oral mucosa

2. less sensitive lips and oral mucosa= dont feel abnormal objects in food

which species have a keratinized soft palate?

ruminants and horses

which species do not have a keratinized soft palate?

dogs and cats

what does this image show?

soft palate of a cow

what does this image show?

soft palate of a dog

which animal does not have salivary glands in the hard palate?

pigs

what is the histology of the hard palate?

Keratinized Stratified squamous epithelium

where are salivary glands located in the hard palate?

caudal portion only

what is number 7?

seromucous labial glands in propria submucosa of the lip

what is number 2?

keratinized stratified squamous epithelium of the lip

what does the tunica muscularis consist of in the lip?

skeletal muscle fibers of the orbicularis oris muscle

what is the outer layer of the lip?

cutaneous/skin

what is the middle layer of the lip?

Orbicularis oris muscle

what is the inner layer of the lip?

Stratified squamous epithelium

what structure is absent in the oral cavity but present in the cheek?

muscularis mucosae

what are signs of unilateral facial paralysis?

1. dullness of the face

2. drooped ears

3. loose lips

4. drooling

5. food and water loss with eating

which nerve is damaged in unilateral facial paralysis?

facial nerve (CN 7)

what is this dog suffering from?

unilateral facial paralysis

what nerves do you have to consider during a cleft palate repair?

1. greater palantine foramen

2. greater palatine nerve

3. maxillary nerve (branch of CN 5)

what does the image show?

primary cleft palate or “harelip”; more rostral

secondary cleft palate

the soft palate and hard palate have not fused on both sides leading to a gap along the midline

what is the green box?

rostral septal

what is the blue box?

major palatine

what is the pink box?

major palatine

what is the red box?

minor palatine

what blood vessels do you have to consider during a cleft palate repair?

1. major palatine

2. minor palatine

3. rostral septal

what action are the soft palate muscles important for?

swallowing

what are the palatine muscles?

1. palatinus muscle

2. tensor veli palatini muscle

3. levator veli palatini muscle

4. palatopharyngeus muscles

what innervates the soft palate?

vagus nerve and glossopharygneal nerve 

what is the green arrow pointing to?

soft palate

what are the blue arrows pointing to?

palatoglossal arch/fold

what is the yellow arrow pointing to?

palatine tonsils