TMJ Flashcards
What are the articular surfaces of the TMJ?
condyle, articular eminence and mandibular fossa
Which two articulating surfaces of the TMJ are part of the temporal bone?
Mandibular fossa and articular eminence
What is the bony lateral boundary of the TMJ?
zygomatic process of temporal bone
What is the medial bony boundary of the TMJ?
spine of the sphenoid
What is the anterior bony boundary of the TMJ?
articular eminence
What features of the skull make up the the posterior bony boundary of the TMJ?
squamotympanic and petrotymapnic fissures and the tympanic plate
Where does the loose capsule surrounding the entire joint attach?
It attaches the joint from the temporal bone to the neck of the mandible
What are the superior attachments of the capsule?
Anteriorly arraches to the articular eminence and posteriorly attaches to the squamotympanic fissure
What is the inferior attachment of the capsule?
the neck of the condyle
What is the temporomandibular ligament?
A thick part of the capsule that forms the lateral ligament and prevents posterior and inferior displacement
Extrinsic ligament (1 of 2)
Stylomandibular ligament-styloid process to the angle of the mandible
Extrinsic ligament (2 of 2)
Sphenomandibular ligament-spine of the sphenoid to lingula of mandible
Articular disc
A BI-concave disc made of fibrous tissue that separates the joint into UPPER and LOWER compartments with a synovial membrane lining EACH ONE
Articular disc (characteristics)
avascular and possibly receives nourishment from the synovial fluid
Posterior thickening
larger and sits atop the condyle when at rest
Anterior thickening
smaller and sits below the articular eminence
Intermediate zone
thin and lies between the posterior and anterior thickenings
Articular disk attachment to capsule via…
superior and inferior sheets or lamellae that blend with the walls of the capsule
The superior attachment of the capsule is (loose or tight)?
loose
The inferior attachment of the capsule is (loose or tight)?
tight
Rotation, or simple rotation of the condyles occurs in…
the lower compartment during the first 20-27 mm of opening
Translation, or sliding of the condyles AND the disk onto the articular eminence always occurs for any except the most minimal opening of the mouth in…
the upper compartment
Translation causes…
posterior recess of the inferior compartment to increase in size and anterior recess to decrease in size
Sliding of the condyle onto the articular eminence causes…
the mandible to open
Innervation of the TMJ
General sensory-V3 (auriculotemporal, masseteric and temporalis nerves)
Blood supply of TMJ
External carotid (superficial temporal) and branches of the maxillary artery
Muscles causing protrusion of the mandible
lateral pterygoid, medial pterygoid, superficial head of the masseter
Muscles causing retrusion of the mandible
Temporalis and deep head of the masseter (from a protruded position)
Muscles causing depression of the mandible
Lateral pterygoid (inferior head) and supra and infrahyoid muscles (gravity is the strongest depressor)
Muscles causing elevation of the mandible
Temporalis, masseter and medial pterygoid
Muscles causing right lateral excursion of the mandible
right masseter, right temporalis, left medial pterygoid and left lateral pterygoid
Muscles causing left lateral excursion of the mandible
left masseter, left temporalis, right medial pterygoid and right lateral pterygoid
Note on excursive movements of the mandible (1 of 2)
the masseter and temporalis will pull the mandible to the same side becuase their origines are slightly LATERAL to their insertions
Note on excursive movements of the mandible (2 of 2)
The medial and lateral pterygoids will pull the mandible to the opposite side becuase their origins are slightly MEDIAL to their insertions
Swallowing and deglutition
Stage one (voluntary) Stages two through four (involuntary)
Stage one of swallowing
Voluntary-food pressed into bolus on dorsum of tongue against hard palate. The swallow is initiated by pushing the food posteriorly into the oropharynx by the tongue
Stage two of swallowing
Involuntary-Soft palate elevates to seal the oropharynx from the nasopharynx and prevents regurgitation of food into the nasal cavity. The stylopharyngeus and palatopharyngeus muscles and the suprahyoid muscles contract to raise the larynx
Stage three of swallowing
Involuntary-The three constrictor muscles contract in a sequential fashion as peristaltic waves. From superior to inferior, each pair of muscles contracts for approx. .33 second. Just as the muscles physically overlap, so do their contractions overlap from superior to inferior.
Stage four of swallowing
Involuntary-Bolus enters esophagus and is propelled downward by peristaltic action. Cricopharyngeus muscle is in a constant state of contraction and prevents passage of air to the esophagus below. During the act of swallowing, the cricopharyngeus relaxes to allow passage of the bolus into the esophagus below. The bolus is propelled to the stomach by peristaltic waves of the esophagus.
