3. Oral Cavity, Tongue, and Salivary Glands I Flashcards
Main functions of oral cavity:
-prehension=getting food
-mastication=chewing
-insalivation of food
-aggression and defense
-breathing
-vocalization
Oral cavity includes:
-walls of oral cavity
-accessory structures that project into it (teeth, tongue)
-structures that drain into it (salivary glands)
Oral cavity location:
-entered between lips and continues into pharynx
Lips are made of:
-skin
-intermediate layer of muscle
-tendon
-glands
-oral mucosa
Salivary glands: lips
-small ones are scattered among muscles below mucosa
Mimetic muscles:
-muscles that are not to do with chewing
-encircle mouth
-raise, depress or retract lips
*all supplied by facial nerve (cranial nerve 7)
What determine form of lips?
-diet and feeding habits
-wide gape vs. smaller opening
Wide gape lips:
-needed to use teeth in seizing prey or in fighting
Smaller opening lips:
-suffices in most herbivores and rodents
New born animals:
-lips form seal around the teat for suckling
Lips in dogs:
-extensive, but thin
-can be drawn back from teeth to show aggression
-not that motile, serrated margin
Lower lip of dogs:
-loose, but fastened to lower jaw at level of canine
Lips in horses:
-sensitive and mobile for food prehension
-some have hair on upper lip (vibrissae or whiskers)
Lips in cattle:
-thick and insensitive (tongue is used to collect food)
-area above lip is a nasolabial plate
Nasolabial plate: cattle
-area above upper lip
-modified hairless and moist skin
-can be used for nose-printing for ID
-conical papillae
Lips in sheep and goat:
-used for prehension of food=motile
-hairless skin is much smaller=philtrum
-conical papillae
Conical papillae:
-protect mucosa from roughage in ruminants
Oral cavity divided by:
-teeth and margins of jaws into outer vestibule
-bounded by lips/cheeks externally
-central oral cavity proper
Cheeks (buccae):
-are structurally similar to lips
-in herbivores: have protective buccal papillae
Buccinator muscle:
-main support of oral cavity to return food into oral cavity proper
Salivary glands in the oral cavity:
-buccal salivary glands
Buccal folds:
-allow occasional maximum opening of mouth while avoiding injury by teeth
Caudal limit of oral cavity:
-marked by Palato-glossal arch (palate-tongue)
>mucosal folds from soft palate to each side of tongue root
>seen best when tongue is pulled to one side
Beyond oral cavity:
-oropharynx starts
>has palatine tonsils on it’s caudolateral surfaces
Frenulum:
-joins the tongue to the floor of the oral cavity
>sublingual caruncle on each side
>drainage to some salivary glands
Palate:
-roof of oral cavity proper
Hard palate:
-flat in most species (vaulted in humans)
-dental pad
-rugae
-palatine raphe
-buccal papillae
Herbivores hard palate:
-covered by heavily keratinized transverse ridges (rugae), on either side or palatine raphe
Dental pad:
-ruminants
-tough but yielding cushion in lieu of upper incisive teeth, as counterpart to lower teeth
incisive papilla:
-flanked by incisive canals
>usually continue to the nasal cavity
Tongue is involved in:
-prehension
-lapping
-grooming
-mastication
-speech
-heat loss
Tongue:
-highly muscular
>capable of vigorous and precise movements
Parts of the tongue:
-apex
-base
-root
Apex of tongue:
-free moving tip (rostral)
Body of tongue:
-attached to mandibular symphysis and supporting muscles (mylohyoideus)
Root of tongue:
-attached to the hypoid bone (caudal)
Intrinsic and extrinsic muscles of the tongue:
*intermingle
Intrinsic muscles of the tongue:
-not named
-fibers go in different directions
-have structural fat mixed with fibers
3 extrinsic muscles of the tongue:
-enter tongue
-names end in ‘glossus’
1. Genioglossuss
2. Styloglossus
3. Hypoglossus
Genioglossus:
-from symphysis go in median plane
-some fibers thru frenulum to apex, body and root
Genioglossus to apex:
-retract the tongue
Genioglossus to body:
-depress tongue
Genioglossus to root:
-protract the tongue
Hypoglossus:
-from hyoid (thyrohyoid and basihyoid) to root of tongue
>retract and depress
-more lateral
Styloglossus:
-fibers from stylohyoid to body of tongue
>retract and elevate
-most lateral
Supportive muscles of the tongue:
-mylohyoideus
-geniohyoideus
Mylohyoideus:
-fibers go across inter-mandibular (like a hammock)
>support and raise tongue
-thin layer
Geniohyoideus:
-from symphysis to basihyoid
>bring hyoid and tongue forward
-cord like
