Lecture 28: Oral Cavity Flashcards
What bones form the roof and floor of the oral cavity?
Roof - maxilla
Floor - mandible
What does the mandible articulate with?
The temporal bone at condylar region of mandible - temporomandibular joint
What are the features of the temporomandibular joint?
Sliding hinge joint that allows chewing
What muscles help in chewing?
Masseter and temporalis
What are the features of orbicularis oris?
Muscle that goes around the lips - brings lips together
What are the features of buccinator?
Embedded in the cheek and closes off the space between the mandible and maxilla to form the lateral wall of the oral cavity
Where does the temporals tendon attach and what happens when it contracts?
Temporalis tendon attaches to coronoid process. When temporalis contracts it pulls condyloid process and elevate mandible when chewing
What bones form the roof of the mouth/hard palate?
Maxilla, palatine and horizontal process of palatine
Where is the soft palate?
Connective tissue and muscle suspended from posterior end of hard palate
What is deep to the mucosa lining the mouth?
Palatine glands
Where do the lesser palatine vessels go?
Posterior to soft palate
Where do the greater palatine vessels go?
Along hard palate
Where is the mandible deficient and what fills this?
Inferiorly, mylohyoid muscle
Where does the inferior alveolar nerve enter the mandible?
Mandibular foramen on medial aspect of mandibular foramen
Where does the hyoid bone sit?
Crease between floor of mouth and neck
What is the oral vestibule?
Space lateral to dental arches where mucosa projects upwards - space to store food
What is significant about the vessels in the mucosa in the floor of the mouth?
Important for rapid absorption of drugs
Why will there be profuse bleeding and nerve damage if the floor of the mouth is injured?
Lingual nerve, submandibular duct and hypoglossal nerve present here
How is the tongue split?
Tongue is split into anterior 2/3 and posterior 1/3 by v-shaped groove (sulcus terminalis) - apex of the v is directed posteriorly (towards back of oral cavity) - classic landmark for sensory nerve supply
What is the depression at the apex of sulcus terminalis and what is it remnant of?
Foramen caecum - remnant of thyroglossal duct in development
What is present between the palatoglossal and palatopharyngeal arches?
Palatine tonsils
Where are the papillae on the tongue?
Valate papillae are anterior to sulcus terminalis in a row, foliate papillae are grooves on lateral sides of tongue, fungiform papillae over rest of mucosa of tongue - scattered all over anterior 2/3 of the tongue
Why are papillae important?
Papillae are important because the tastebuds are imbedded in the walls of the papillae. Tastebuds are connected to sensory nerves that run in the chordae tympani (branch of 7th cranial nerve - info about taste from tongue to CNS)
What papillae doesn’t have tastebuds?
Filiform
Why are filiform papillae important?
Rough, allow tongue to grip food
What innervates extrinsic tongue muscles and what do they do?
Alter position of tongue, CNXII (except for palatoglossus – pharyngeal branch of CNX)
What are the extrinsic tongue muscles?
- Palatoglossus - from palate towards tongue - elevate
- Styloglossus - styloid process to posterior tongue (more horizontal) - retract
- Hyoglossus - hyoid to tongue – depress
- Genioglossus - mid mandible to back end of tongue - protract
What nerve innervates the intrinsic tongue muscles, what are they and what do they do?
Alter shape of tongue, CNXII
Superior and inferior longitudinal, transverse and vertical
What is the sensory innervation for the tongue?
Posterior 1/3 innervated by glossopharyngeal (taste and general sensory)
Anterior 2/3 innervated by lingual nerves (general) and chorda tympani (CNVII) (special)
How many adult teeth?
32
What are the number of teeth and their type and features?
- 2 incisors – central and lateral, sharp flat edges for biting
- 1 canine – sharp pointy edge for anchoring onto food
- 2 premolars and 3 molars – flat cusps important for grinding
What is the nerve innervation for the upper teeth?
Upper teeth innervated by superior alveolar nerve (branch of V2 trigeminal – maxillary)
What is the nerve innervation for the lower teeth?
Lower teeth innervated by inferior alveolar nerve (branch of V3 trigeminal – mandibular) - access into mandible via mandibular foramen on medial side of ramus
What is the structure of the tooth?
Outer enamel later (protective) and inner core of pulp - significant neurovascular supply - through bone and roots into pulp
What is dentin?
Layer between enamel and pull - little tubules to transmit fluid, temp or electrical energy
What is a toothache?
Activation of highly sensitive pulp
What is the vascular supply to the teeth?
Branches of external carotid artery
When do the teeth erupt, and how do they normally erupt?
Teeth erupt from about 6/7 years of age, usually anterior to posterior
What are the exceptions to normal teeth eruption?
Lower canine and upper canine erupt a bit later and out of sequence, first molar erupts very early
What are the features of the parotid salivary glands?
Anterior to external auditory meatus, superficial to masseter and ramus of mandible - has a single duct emerging from anterior aspect that runs over masseter and opens in oral vestibule opposite 2nd molar tooth
What are the features of the sublingual salivary glands?
In floor of mouth on either side of tongue under mucosa - opens via multiple ducts into mucosa on floor of mouth
What are the features of the submandibular salivary glands?
Sits on both sides of posterior oral cavity, wraps around posterior edge of diaphragm muscle (mylohyoid) - bit inside and bit outside oral cavity - duct projects all the way forward and opens via small papilla lateral to lingual frenulum
