Oral Cavity, tongue, salivary glands Flashcards
Main functions of the oral cavity
- Prehension of food
- Mastication
- Insalivation of food
- Aggression and defense
- Breathing
- Vocalization
Components of the oral cavity
- Walls of the oral cavity
- Accessory structures that project into it (teeth and tongue)
- Structure that drain into it (salivary glands)
- Starts between lips and continues into pharynx
What are lips made of?
- Skin
- Intermediate layer of muscle
- Tendon
- Salivary Glands- scattered among muscles of mucosa
- Oral mucosa
Muscles and nerves of lips
- Mimetic muscles- allow lips to raise, depress or retract lips
- Facial nerve (cranial nerve 7)
Form of lips depending on diet and feeding
- Wide gap- when there is a need to use teeth in seizing prey or fighting
- Smaller opening- herbivores and rodents
- Newborn animals- lips form a seal around the teat for suckling
Dog lips
- Extensive but thin
- Can be drawn from teeth to show aggression
- Not that motile
- Have serrated margins
- Lower lip is loose but fastens to lower jaw at level of canine
Horse lips
- Lips are sensitive and mobile for food prehension
- Can have hair (vibrissae or whiskers) on their upper lip
Cattle lips
- Tongue used to collect food so lips are thick and insensitive
- Area above upper lip is modified hairless and moist skin called nasolabial plate (nose printing ID)
Sheep and goat lips
- Lips used for prehension of food so more motile
- Hairless skin above lip is smaller, called philtrum
- Have conical papillae that protect mucosa from roughage in ruminants
Oral cavity divisions
- Oral (outer) vestibule
- Oral cavity proper
- Cheeks (buccae)
Oral vestibule
- area between lips/cheek/jaw and teeth/oral cavity proper
Oral cavity proper
- internal area from teeth.
- Ends at caudal limit= palato-glossal arch
Palato- glossal arch
- Mucosal folds from soft palate to each side of tongue root
- Best seen when tongue pulled to one side
Cheeks (buccae)
- structurally similar to lips
- herbivores: have protective buccal papillae
- supported by buccinator muscle which helps return food into oral cavity proper
- has some buccal salivary glands
- buccal folds- allow occasional max opening of mouth while avoiding injury by teeth
Oropharynx
- starts when the oral cavity ends
- has palatine tonsils on the caudolateral sides
Tongue attachment to cavity
- Frenulum- attaches tongue to oral cavity floor
- Sublingual caruncle- on either side and has drainage to salivary glands
Palate
- Roof of oral cavity proper
- Flat in most species, vaulted in humans
Differences of hard palate for herbivores and ruminants
Herbivores
- Covered by heavily keratinized transverse ridges (rugae) which lays on either side of palatine raphe (middle line on roof of mouth)
Ruminants
- Have dental pad- a tough but yielding cushion in lieu of upper incisive teeth, as counterpart to lower teeth
- Incisive papilla is flanked by incisive canals that usually continue to the nasal cavity which is likely used for flehmens response
Functions of tongue
- Prehension
- Lapping
- Grooming
- Mastication
- Speech
- Heat loss
Parts of the tongue
- Apex
- Body
- Root
- Intrinsic and extrinsic muscles
Apex of tongue
- Freely moving tip
Body of tongue
Attached to mandibular symphysis and supporting muscles (myohyoideus)
Root of tongue
Attached to the hyoid bone
Intrinsic and extrinsic muscles of tongue
- Intrinsic muscles are not named, fibers go in different directions, have structural fat mixed with fibers
- Extrinsic muscles
o Genioglossus
o Styloglossus
o Hyoglossus
Genioglossus
- Form symphysis to median plane
- Some fibers through frenulum to apex (helps with retraction), to the body (helps depress tongue), or to root (to protract tongue)
Hyoglossus
- From hyoid to root of tongue to retract and depress
- More lateral
Styloglossus
- Fibers from stylohyoid to body of tongue to retract and elevate
- Most lateral
Supportive muscles of tongue
- Mylohyoideus- fibers go across inter mandibularly like a hammock to support and raise tongue. A thin layer
- Geniohyoideus- from symphysis to basihyoid to bring hyoid and hence base of tongue forward. Cord like
Tongue mucosa papillae
- Has mechanical and gustatory functions
- Types: filiform, conical, fungiform, vallate, foliate
Filiform
- Mechanical
- Most abundant
- Soft-thread like
- Covering most of tongue surface in humans, dogs
- More keratinized in herbivores
Conical
- Mechanical
- Larger and modified filiform
- Mostly on torus and caudal parts
Fungiform
- Gustatory
- Dispersed among filiform
- Become larger on each side
Vallate
- Gustatory
- Ox: a few on each side of caudal parts
Foliate
- Gustatory
- Absent in cattle
Size and shape of tongue
- Corresponds to the oral cavity
- Ox: has a torus
- Horse: spatula-like
Tongue papillae in dogs
- Soft, carpeted with fine papillae
- Tip spatulated
- Filiform enlarge toward caudal parts
- Can be pigmented
- Has a lyssa (J-shaped fibrous rod of ~3cm long embedded ventrosagittal to apex mucosa) that may aid in lapping
- A fibrous septum extending from lyssa is responsible for the conspicuous median groove on the upper surface
Tongue papillae in cat
- Modified filiform are highly keratinized (like rasp)
- When grooming, hair pushed to back of oral cavity which is why there are more hairballs in cats
Tongue papillae in horse
- Has a soft tongue
- No torus
- Vallates are lobulated and only one on each side
Tongue Papillae in llama
- Tip is soft like in a horse
- Body carries a torus like in ox
- Vallate papillae are very large, only a couple on each side
Tongue papillae in newborn piglets
- Tongue fringed with modified filiform that are lace-like called marginal papillae
o Seen up to ~2 weeks
o May help in fitting tongue around dam’s teat - Seen in piglets and some puppies
Salivary glands
- Parotid
- Mandibular
- Sublingual
- Zygomatic
Parotid
- Almost entirely serous in most species (mixed in dogs)
- Triangular and molds around base of ear
Parotid Duct
- takes a short cut across the masseter muscle in dog
- opens in vestibule caudal to 4th upper premolar tooth
Mandibular
- mixed but mostly mucous
- ovoid-shaped in dogs; looks like golf ball
- has a fibrous capsule around it
- drains close to the frenulum at sublingual caruncle
Sublingual
- present in some species
2 parts
1. Compact gland (monostomatic)- located close to mandibular gland
- Duct travels with mandibular and opens at sublingual caruncle
- Diffuse gland (polystomatic)
- Numerous small ducts which open directly under the tongue
Horses sublingual gland
Only has the polystomatic gland
Zygomatic
- A modified enlarged dorsal buccal gland that is covered by the zygomatic arch
- Duct opens behind that of parotid (4th premolar or 1st molar)
- Only termed this in carnivores
Salivary glands in ox
- Larger in herbivores
- Cattle produce 100-200 L of saliva daily (~40L in horses, ~15 L in pigs)
- Lymph nodes are often associated with salivary glands and are important in meat inspection
- Also have numerous buccal glands that are rather diffuse and have numerous openings into vestibule
