Muscles of mastication + oral cavity M7 Flashcards
what are the four muscles of mastication?
- temporalis
- masseter
- medial pterygoid
- lateral pterygoid
temporalis - origin
temporal fossa
temporalis - insertion
coronoid process and ramus of mandible
temporalis - actions
elevates and retracts mandible
masseter - origin
zygomatic arch
masseter - insertion
angle and lateral surface of ramus and mandible
masseter - actions
elevates (and slightly protrudes) mandible
medial pterygoid - origin
- superficial head = pyramidal process of palatine bone and tuberosity of maxilla
- deep head - medial surface of lateral pterygoid plate of sphenoid bone
medial pterygoid - insertion
medial surface of ramus of mandible
medial pterygoid - actions
- bilaterally - elevates and protrudes mandible
- unilaterally ( with lateral pterygoid) - laterally deviates mandible to contralateral side
lateral pterygoid - origin
- upper head - greater wing of sphenoid bone
- lower head - lateral surface of lateral pterygoid plate of sphenoid bone
lateral pterygoid - insertion
neck of condylar process of mandible, TMJ capsule and articular disc (that divides cavity into 2)
lateral pterygoid - actions
- bilateral - protrudes mandible (and assists gravity in depressing mandible)
- unilaterally (with medial pterygoid) - laterally deviates mandible to contralateral side
what are the muscles of mastication innervated by?
these are all innervated by the mandibular division (motor and sensory functions) of the trigeminal nerve (main sensory nerve of the face)
what does the oral region include?
- oral cavity
- palate
- teeth
- gun - gingivae
- tongue
- oropharyngeal isthmus (fauces)
what is the oral cavity divided into?
two parts:
1. oral cavity proper - internal to the teeth and gingivae
2. oral vestibule - between teeth and gingivae and the lips and cheeks
what are the functions of the oral cavity?
- passage for ingested material: hold/ collect ingested material prior to swallowing + begin digestion
- accessory airway - entrance to respiratory tract (indirectly when breathing through the mouth)
- articulation and resonance for speech
what are the boundaries of the oral cavity?
- roof - palate
- floor - muscles (tongue isn’t the floor but sits on it)
- walls - anterior (lips), lateral (cheeks), posterior (oropharyngeal isthmus (fauces))
mucous membranes (mucosa)
- lining of oral cavity - it is continuous with mucosa of oropharynx
- contains mucous glands for lubrication
- called gingivae whe it surrounds the teeth
- gigivae + mucosa of the hard palate and tongue are tougher than the mucosa lining the lips and cheeks - allows for greater withstanding of abrasion from ingested material
lips (labia) - oral cavity
- from anterior wall of the oral cavity
- opening bw then is called oral fissure - formed by musculofibrous tissue
- orbicularis oris muscle + labial muscles
- skin - external surface
- mucosa - internal surface - anchored to the gingivae by the labial frenula ( singular=frenulum)
lips (labia) - what are the functions?
- articulation of sound and speech
- smiling and sucking liquids
- holding food
oral cavity - cheeks (buccae)
- form the lateral walls of the oral cavity
- movable walls of the oral cavity and continuous with the lips
- lined by mucosa
- contains fat pads, muscles, nerves and the duct of the parotid gland
cheeks (buccae) - function?
allow filling of the oral vestibule
two types of palates
soft and hard palate
soft palate
- posterior muscular portion (uvula hanging from end)
cleft palate
- birth defect that occurs when the maxillae don’t fuse in utero
- has implications for speech and swallowing
- often associated with cleft lip (incomplete formation of upper lip)
- cleft palate and lip are collective called ‘orofacial clefts’ and are classified according to location (uni or bilateral) and sverityy ( complete or incomplete)
hard palate
-anterior bony portion which covers w mucosa
- has a midline ridge called palatine raphe
- has irregular folds of connective tissue
called palatine rugae > these extend
from anterior palate to area of first
premolar/ highly sensitive/ assist with
speech and swallowing
- has a bony ridge called the alveolar process (or ridge)
alveolar ridge - what is it? why have it?
- thickened part of maxillae (+ mandible for lower jaw)
- containing tooth sockets
- covered with gingivae
- essential for healthy teeth and successful dental implants
- important for articulation of alveolar consonants (eg.d/l/n/s/t/z)
parts of the tooth
crown
neck
root
what is the crown? - tooth
exposed part of the tooth covered by enamel
what is the neck? - tooth
narrow part of the tooth bw crown and root - covered by gingivae root is the part of a tooth that is
what is the root? - tooth
the part of a tooth that is embedded in the tooth sockets in the alveolar processes/ridges of the maxillae and mandible.
what are the types of teeth?
incisors, canines, premolars
what are the incisors?
incisors are for cutting food. 2 incisors
in each quadrant of the mouth.
what are the canines for?
tearing/shredding food. 1 canine in each quadrant of the mouth.
what are the pre-molars for?
crushing/grinding food. 2 premolars in each quadrant of the mouth
what are the molars for?
crush/grind food. 3 molars in each quadrant of the mouth. third molars=wisdom
tongue - what are the 2 parts?
- can be divided into 2 parts, separated by a V shaped groove called sulcus terminalis
1. oral part - anterior 2/3
2. phrayngeal part - posterior 1/3
-anchored to the floor by the lingual frenulum
orophrayngeal isthmus (fauces)
- form from the posterior wall/ boundary of the oral cavity
- narrow passage bw velum and tongue
- boundary between oral cavity and oropharynx
- bound by pillars of fauces/ faucial pillars
what are the pillars of the oropharyngeal isthmus (fauces)?
- palatoglossal arch (anterior faucial pillar)
- palatoglossal muscles = covered in
mucosa- palatopharyngeal arch (posterior faucial pillar)
- palatopharyngeus muscle covered in
mucosa
- palatopharyngeal arch (posterior faucial pillar)
what are the palatine tonsils?
- aggregations of lymphoid tissues
- first line of defence against foreign substances that are ingested or inhaled
what are the salivary glands? what do they do?
- produce approx 1- 1.5 L of saliva per day (mostly water)
- cleans and moistens the oral cavity
- maintains oral hygiene - antibacterial properties and neutralises acids
- start digestion
- mechanical - moistens food for bolus production
- chemical - produces enzymes
- dissolves molecules in food for tasting
three pairs of major salivary glands
parotid gland
submandibular gland
sublingual gland
parotid salivary gland
- largest salivary gland
- located superficially on the face anterior to the ear
- produces mostly serous secretions
- drains its secretion via the parotid duct (crosses masseter muscle) into the oral vestibule, opposite the upper second molar
submandibular gland
- produces most of the total saliva
- located deep and inferior to the body of the mandible
- produces a mixture of serous and mucous secretions
- drains its secretions via submandibular duct into the oral cavity proper (under the tongue)
sublingual gland
- smallest of the major salivary glands
- located on the floor of the oral cavity under the tongue
- produces mainly mucous secretions
- drains its secretions via the several sublingual ducts into the oral cavity proper (under tongue)
salivary glands - innervation
- innervated by the autonomic nervous system
parasympathetic innervation increases salivation
- facial nerve - CN VII- submandibular and sublingual glands
- glossopharyngeal nerve -CN IX- parotid gland
- fibres are carried to the glands via branches of mandibular nerve - CN V3
sympathetic innervation decreases salivation - via vasoconstriction
- results in thicker saliva that is rich in mucous - dry mouth
what four cranial nerves that contribute to sensory innervation of oral cavity?
- trigeminal nerve - CN V
- facial nerve - CN VII
- glossopharyngeal nerve - CN XI
- vagus nerve - CN X
zooming in on the trigeminal nerve…. what parts of the face relate to the maxillary/ mandibular nerve?
- maxillary nerve - palate and upper lip and teeth
- mandibular nerve- lower lip and teeth, buccal mucosa, anterior 2/3 of tongue (general sensations)
CNs VII, IX, X Nerves
- facial nerve = taste to anterior 2/3 of tongue
- glossopharyngeal nerve = taste and general sensation to posterior 1/3 of tongue and pillars of fauces
- vagues nerve = taste and general sensation to epiglottis and small area of tongue near epiglottis
