Oral Cavity Flashcards
State the functions of the oral cavity.
- Prehension
- Mastication
- Imbibition (drinking)
- Deglutition (swallowing)
- Heat exchange
- Grooming
- Respiration during exercise
Define the boundaries of the oral cavity.
- Oral cavity extends from lips to pharynx. Palatoglossal arch is caudal
- Vestibule is the space between the lips/cheeks and teeth
- Oral cavity proper is the space within teeth
- Bounded dorsally by hard and soft palate
What are 4 clinical conditions of the oral cavity?
- Periodontal disease
- Dental disease
- Trauma
- Neoplasia
What are some clinical signs of oral cavity disease?
- Salivation
- Inappetence
- Halitosis (bad breath)
- Quidding (dropping food and not be able to eat)
Describe the function and features of the lips.
Involved in prehension, communication and suckling.
- Sensitive and mobile in horses and rabbits
- Less sensitive and less mobile in cats and cows
Orbicular muscle innervated by facial nerve.
Philtrum – separation between upper lips
State the functions of the tongue.
- Taste using papillae
- Prehension in the rabbit and cow
- Lapping
- Manipulation of food
- Swallowing
- Grooming in cats
- Vocalisation
- Thermoregulation
Describe the structure of the tongue.
- Apex is the rostral free end
- Body is attached to the mandible by the frenulum – this can be too tight sometimes and can cause issues with suckling for example, so is surgically incised to release some of this tension.
- Root is attached to the hyoid bone
- Lingual process in ruminants of the basihyoid bone that supports the tongue
- Torus linguae in cattle
- Lyssa in carnivores
Name the intrinsic tongue muscle.
Lingualis proprius – transverse, longitudinal and perpendicular fibres allow tongue to move in all different directions
Name the extrinsic tongue muscles.
- Genioglossus – mandibular symphysis to body of tongue and protracts the tongue
- Hyoglossus – basihyoid bone to root of the tongue and retracts and depresses tongue
- Styloglossus – stylohyoid bone to body and root of tongue and retracts and elevates the tongue to move it laterally
- Geniohyoideus and stylohyoideus
Describe the innervation of the tongue.
Motor: hypoglossal nerve (XII)
Sensory:
- Facial nerve (VIII) for taste
- Trigeminal nerve (V) for sensation
- Glossopharyngeal nerve (IX)
What is the blood supply to the tongue?
Lingual artery is paired and is a branch of the external carotid artery.
- Lingual pulse from the artery
- Venepuncture from the lingual vein.
What are the major salivary glands?
Long ducts, which may block.
- Parotid: duct opens by 4th upper premolar in dogs
- Mandibular: duct along floor of the oral cavity and opens behind lower incisors
- Sublingual: duct along side of mandibular and shares common opening
What are the minor salivary glands?
In wall of the oral cavity and oropharynx.
Labial, lingual and buccal are short ducts.
Describe the hard palate, the soft palate, and clefts.
Hard palate – rostral with hard ridges.
Soft palate – caudal and forms palatoglossal arch, the soft palate connecting with the tongue, involving the palatinus muscle.
Clefts can occur in either palate and cause issues with openings into the nasal cavity and respiratory infections and issues suckling, so is surgically closed.
Describe the voluntary stage of swallowing.
Tongue pushes bolus against hard palate, forcing it towards the pharynx using the hyoglossus and styloglossus muscles.
Describe the involuntary stage of swallowing.
- Epiglottis closes over the glottis by drawing the hyoid rostrally and drawing the epiglottis back using the geniohyoid muscle.
- Soft palate elevates to close off nasal cavity.
- Bolus passes over/around epiglottis into pharynx.
- Pharynx constricts to propel into oesophagus using pharyngeal constructors.
What is the innervation of the pharynx?
Motor: vagus nerve (X)
Sensory: glossopharyngeal (IX) involved in gag reflex
Describe the oesophagus’ structure and function.
A muscular tube which conveys food from the pharynx down to the stomach.
- Proximal part also has skeletal muscle
- Smooth muscle distally
- Lumen lined by a thick protective stratified squamous epithelium
- The epithelium is highly folded to allow expansion as the bolus passes
Describe how teeth are classified by their attachment to the mandible/maxilla.
Implies there is a socket that the tooth attaches to via the roots.
- Acrodonts, such as teleost fish, do not have this root so have a firm ankylosis to the mandible.
- Pleurodonts, such as lizards, do not have this route and have some attachment to the medial aspect of the mandible.
- Thecodonts have this socket like structure that the root of the tooth attaches to the mandible with.
Describe how teeth are classified by number.
- Polyphyodont – have multiple numbers of teeth developed. Toothed fish and reptiles
- Diphyodont – most mammals have milk/deciduous/temporary teeth followed by eruption of permanent teeth.
Describe how teeth are classified by morphology.
- Homodonts – all teeth are the same. Such as lizards
* Heterodonts – most mammals have 4 recognised types of teeth: incisors, canines, premolars and molars.
Describe how teeth are classified by crown length.
- Brachydonts – carnivores and omnivores. The crown in above the gingival surface.
- Hypsodont – herbivores. The crown will extend below the gum line so can continue to erupt. Can be radicular (open rooted) or aradicular (closed rooted).
Describe the teeth typically found in carnivores.
- Incisors for snipping at food before it enters the mouth
- Well-developed canine teeth for tearing and grasping
- Sectional carnassial teeth for shearing. These are always upper 4th premolars and lower 1st molars
- Pointed molars for crushing bones
State 3 skull shapes and give a dog breed example for each.
- Dolicocephalic – greyhounds
- Mesaticephalic – most breeds
- Brachycephalic – chihuahua, English bulldog, pug
State some effects of selective breeding on dentition.
- Prognathia – underbite
- Brachygnathia – overbite (parrot mouth)
- Dental crowding
- Rotation
Describe the teeth in horses as herbivores.
- Incisors for snipping
- Rudimentary canines
- Diastema
- Occasionally see 1st premolar, the wolf tooth, tends to be upper not lower
- Premolars and molars for grinding and chewing
- Hypsodont – large crown allowing wear
Occlusal surface of a lower cheek tooth in a horse will get worn down and expose a different enamel composition so can be used to age horses.
Describe the teeth in ruminants as herbivores.
- Have prehensile tongue so do not require upper incisors or canines, so have a dental pad instead
- ‘Cheek teeth’ and diastema is called ‘chewing the cud’ in regurgitation
- Canines integrated to incisors in lower jaw at 4th/corner incisors
- Hypsodont - large crown allowing wear
What are the 3 calcified tissues in teeth?
Cement
Enamel
Dentine
All have connective tissue pulp.
Name the bones that make up the skull.
Frontal bone Parietal bone Occipital bone Temporal bone Zygomatic bone Nasal bone Maxilla Incisive bone Palatine bone Mandible - made up of body and ramus, and varies in shape according to diet
What is the innervation of teeth?
Trigeminal nerve – V2&3
What is the blood supply to teeth?
Branches of the maxillary artery
What is dental formulae?
The number and classification of teeth in a particular species, young and adult.
Written with dental formula of one side of the mouth on one row and the other on another row, with 2x written on for the left and right. Incisors first, canines and then premolars.
What is the problem with notation systems to identify teeth?
Notation systems for identifying individual teeth, such as I1, P2, M3, but there are no ways of knowing whether this means the upper left or lower right, for example.
Describe the structure of incisors.
- Have 1 root
- Upper incisors have a trilobed crown
- Lower incisors have a bilobed crown
- In most mammals, 12 in total: 3 lower left, 3 lower right, 3 upper left, 3 upper right
Describe the structure of canines.
- Have 1 root
- Root is longer than the crown
- Laterally compressed
- Firmly implanted
- 4 in total
- Rule of 4 9s is used. This is the triadan system and canines will always end in 04.
Describe the structure of premolars.
- 16 in total
- 1st premolar can have 1 or 2 roots
- 2nd and 3rd premolars have 2 roots
- 4th upper premolar is enlarger to form a carnassial/sectorial tooth and has 3 roots
Describe the structure of molars.
- 10 molars in total
- Developed for crushing due to broader occlusal surface
- Upper molars have 3 roots
- Lower molars have 2 roots
- 1st lower molar is the carnassial tooth
Describe the structure of carnassial teeth.
- Enlarged sectional teeth for shearing
- 4th upper premolar has 3 roots
- 1st lower molar has 2 roots
- Useful landmark
Name and describe some common dental problems in cats.
Plaque deposition leading to gingivitis and periodontal disease, such as:
- Feline odontoclastic resorptive lesions (FORLs) – such as neck lesions, root resorptions, cavities and cervical line erosions. If the lesion enters the pulp, the tooth must be removed.
- Gingivostomastitis
State some common dental problems in horses.
- Malocclusion
- Distema
- Abscesses
- Canine caries
- Spur formation
What is the function of dental charts?
- To record the presence of health and/or disease in a form that can be used now and later
- For medico-legal protection, as it records what teeth and pathology was present before treatment started
- To gauge the success or otherwise of treatments over time
Describe the Triadan system.
Assigns each tooth a 3 digit number.
- The 1st digit refers to the arcade (top left = 1, top right = 2, bottom left = 3, bottom right = 4)
- The 2nd 2 digits refer to the tooth in sequence
Describe the hard and soft palates.
- Hard palate – forms part of the dorsal boundary of the oral cavity. Characteristic ridges are identifiable.
- Soft palate – continuous with the hard palate. In the horse, it is long and hangs down before the epiglottis. The palatoglossal arches in the horse therefore forms an airtight seal that closes the oropharynx. Horses are obligate nose breathers.
What is dorsal displacement of the soft palate?
A condition where the soft palate is displaced dorsally above the epiglottis. The soft palate will then obstruct the opening of the trachea, reducing the amount of air a horse can take in. this can occur during exercise and cause respiratory noise and poor performance. It is diagnosed via endoscope.
What is the torus linguae in the bovine oral cavity?
An adaptation of a ruminant tongue, which is a swollen area at the caudal/posterior portion of the tongue. It is used to help crush down grass and cellulose material.
What is a feature of the ruminant oral cavity?
One of the bones of the skull that houses the upper incisors. These are missing in ruminants and replaced by a dental pad.
Describe the 3 salivary glands.
- Zygomatic salivary gland – present in carnivores and found deep to the zygomatic arch.
- Parotid salivary gland – large gland found ventral to ear and opens caudal to the 4th upper premolar. Has a superficial duct.
- Mandibular salivary gland – found caudoventral to mandible. Duct runs along the ventral floor of the oral cavity and opens at the sublingual caruncle behind the lower incisors.
Describe the difference in feline and canine dentition.
The upper molars in the dog have 3 roots, whereas the lower molars have 2 roots. Cats only have cutting action and have 2 roots only.
What 3 nerves could be damaged if an animal has an inability to swallow and why?
Vagus supplies motor innervation to pharynx
Hypoglossal provides motor innervation to the tongue
Glossopharyngeal provides sensory innervation to the tongue and phraynx
