Temporomandibular Joint Flashcards
Describe how mastication works
Movement of the TMJ
- synovial joint, head covered with articular disc
- allows incisors to bite, molars to grind
Muscles of tongue keep food between molars
What movements is the mandible capable of
Gliding, hinge joint
Elevation, depression
Protrusion, retrusion
Lateral excursion
What is the significance of the infratemporal fossa
Space behind maxilla, deep to zygomatic arch, mandible ramus
-allows for the passage of the temporalis, pterygoid muscles, maxillary artery, pterygoid venous plexus
Describe the
- arterial
- venous
- nervous supply of the muscles of mastication
Arteries
ECA => maxillary artery (largest of 2 terminal branches)
-subdivided into mandibular, pterygoid, pterygopalatine regions (NOT BRANCHES)
Veins
- Pterygoid venous plexus => facial vein/cavernous sinus) => IJV (tributaries match maxillary branches)
- found between temporslis, pterygoid muscles
Nerves
-Anterior trunk of mandibular nerve (same as muscular and mucosal innervation of oral cavity and cheeks)
What are the main branches of the ECA
ECA main terminal branches
- superficial temporal
- maxillary
Some Anatomists Like Freaking Out Poor Medical Students
- superior thyroid
- ascending pharyngeal
- lingual
- facial
- occipital
- posterior auricular
- maxillary
- superfical temporal
What are the 4 masticators
Masseter
Temporalis
Lateral, medial pterygoid
What is the
- attachement
- fibre direction
- actions of the masseter
Attachment
- zygomatic arch => anterior border, rmandibular ramus
- superficial fibres => oblique
- deep fibres => vertical
Actions
- bilateral => elevation, clench teeth
- unilateral => ipsilateral excursion
- superficial only => retrusion
What is the
- attachment
- fibre direction
- actions of the temporalis
Attachment (fan muscle)
- 2 heads => temporal bone (at inferior temporal line) and temporal fascia (at superior temporal line) => zygomatic arch and coronoid process
- also attaches to the zygomatic arch, frontal process of zygomatic and frontal bone
Fibre direction
-converge onto coronoid process
Actions
- resting tonus => normal mandibular rest positions when upright
- bilateral => elevation or retrusion (posterior horizontal fibres)
- ipsilateral => ipsilateral excursion
What is the
- attachment
- fibre direction
- actions of the medial pterygoid
Attachment
- found in infratemporal fossa
- superficial head => maxillary tuberosity => mandibular ramus
- deep head => lateral pterygoid plate of sphenoid => mandibular ramus
Fibre direction
-mirrors masseter on inner mandibular surface
Actions
- bilateral => elevation, protrusion
- unilateral => contralateral excursion
What is the
- attachment
- fibre direction
- actions of the lateral pterygoid
Attachment
- superior head => greater sphenoid wing => neck of mandible
- inferior head => lateral pterygoid sphenoid => neck of mandible
Fibre direction
-both almost horizontal
Actions
- bilateral => protraction, depression when combined with hyoids
- unilateral => contralateral excursion
What is the
-actions of the supra and infrahyoid muscles
Name the supra and infrahyoid muscles
Suprahyoid (floor of the oral cavity)
- stylohyoid
- geniohyoid
- mylohyoid
- digastric
Actions (ALWAYS BILATERAL)
- raise hyoid and larynx
- can depress mandible in combination with infrahyoid and lateral pterygoids
Infrahyoid (superficial)
-omohyoid, sternohyoid
Infrahyoid (deep)
-sternothyroid, thyrohyoid
Actions (ALWAYS BILATERAL)
-depress hyoid and larynx when swallowing
Describe the process of eating
Incisors, canines take up small portions of food
Drenched in saliva and ptyalin
Mandible opened and closed => molar, premolar mastication
Tongue moves food towards molars, cheeks stop it from entering vestibule
Orbicularis oris contracts to stop food falling out of mouth
BIlateral contraction of palatoglossus narrows oropharyngeal isthmus => prevent entry into airway, continue food breakdown when swallowing
Describe how boluses are formed
Tongue gathers food into bolus, pushes it towards oropharynx => raising it against hard palate, palatoglossus relaxes to open oropharyngeal isthmus
Describe the buccal phase of swallowing
Compression of bolus against hard palate by tongue => raising of soft palate (levator muscles)
Describe the pharyngeal phase of swallowing
Swallowing in brain stem activated
- inhibits respiration
- raises larynx
- close glottis
- open upper esophageal sphincter
Soft palate elevated to close nasopharynx
True vocal cords close to prevent aspiration
Bonus moved to esophagus via pharyngeal peristaltic muscles
