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.