Week 6 - TMJ, Temporal & Infratemporal Region Flashcards
What forms the TMJ ?
Mandibular fossa of temporal bone and condylar process of mandible.
What type of joint is the TMJ ?
Modified hinge (atypical) synovial joint.
What makes the TMJ a synovial joint ?
Has a joint capsule.
What makes the TMJ a modified hinge ?
Permits gliding motions and some degree of rotation as well as elevation and depression.
What makes the TMJ an atypical joint ?
Surfaces of articulating surfaces are covered in fibrocartilage rather than hyaline cartilage - this is however more typical for synovial joint.
What are the names of the ligaments associated with the TMJ ?
2 extrinsic - sphenomandibular and stylomandibular ligament.
1 intrinsic - lateral ligament.
Where is the sphenomandibular ligament and what is its function ?
From spine of sphenoid bone to lingual of mandible.
Main passive support of mandible (with MOM).
Where is the stylomandibular ligament ?
From styloid process to angle of mandible - thickening of fibrous capsule of parotid gland.
What is the function of the lateral ligament ?
Strengthens the joint laterally and acts to prevent posterior dislocation.
What are the 5 movements of the TMJ ?
Protrusion, retraction, elevation, depression, lateral.
What muscles contribute to elevation of the mandible (closing of the mouth) ?
Temporalis.
Masseter.
Medial pterygoid.
What muscles contribute to depression of the mandible (opening of the mouth) ?
Lateral pterygoid.
Supra and infrahyoid muscles.
What muscles contribute to protrusion of the mandible (protrude chin) ?
Lateral pterygoid.
Masseter.
Medial pterygoid.
What muscles contribute to retrusion of the mandible (retrude chin) ?
Temporalis - posterior oblique and near horizontal fibres.
What muscles contribute to lateral movements of the mandible (grinding and chewing) ?
Temporalis of same side.
Pterygoids of opposite side.
Masseter.
When is the TMJ most unstable and results in anterior dislocation into Infratemporal fossa ?
Depression - when condylar processes move anteriorly.
What is the origin of the temporalis ?
Floor of temporal fossa and deep surface of temporal fascia.
What is the insertion of the temporalis ?
Medial surface of coronoid process of mandible.
Anterior border of the ramus of mandible near the last molar.
What area does the temporalis occupy ?
Temporal fossa.
What is the action of the temporalis ?
Retract and elevate mandible.
What is the innervation of temporalis ?
Deep temporal nerve from anterior trunk of CNV3.
What is the origin of masseter ?
Maxillary process of zygomatic bone and anterior 2/3 of inferior border of zygomatic arch.
What is the insertion of the masseter ?
Angle and lateral surface of ramus of mandible.
What is the action of the masseter ?
Elevates the mandible.
What is the innervation of masseter ?
Masseteric nerve from anterior trunk of CNV3.
What is the origin of the medial pterygoid ?
Deep head - medial surface of lateral pterygoid plate.
Superficial head - maxillary tuberosity and pyramidal process of palatine bone.
What is the insertion of the medial pterygoid ?
Medial surface of the ramus and angle of the mandible.
What is the innervation of the medial pterygoid ?
Nerve to medial pterygoid from main trunk of CNV3.
What is the origin of the lateral pterygoid ?
Upper head - infratemporal surface of greater wing of sphenoid bone.
Lower head - lateral surface of lateral pterygoid plate.
What is the insertion of the lateral pterygoid ?
Front of neck of the mandible.
What is the action of the lateral pterygoid ?
Protrude and depress mandible and assists medial pterygoid in lateral movement.
What is the innervation of the lateral pterygoid ?
Nerve to lateral pterygoid and buccal nerve from anterior trunk of CNV3.
What is the relevance to dentures of the mylohyoid line ?
Lower denture must stop short of mylohyoid otherwise contraction would lift it when speaking of chewing.
What is the relevance to Ludwig’s angina of the mylohyoid line ?
Infection spread from lower teeth below mylohyoid line into floor of submandibular region.
What is the relevance to prosthodontics of the oblique line ?
Buccal edge of the mandible should stop short of oblique line or buccinator will interfere.
What is the superior and posterior border of the temporal fossa ?
Superior and inferior temporal lines.
What is the anterior border of the temporal fossa ?
Frontal process of zygomatic bone and zygomatic process of frontal bone.
What is the inferior border of the temporal fossa ?
Infratemporal crest deep to zygomatic arch.
What is the floor of the temporal fossa ?
Frontal, parietal, temporal and greater wing of the sphenoid bone (including pterion).
What is the roof of the temporal fossa ?
Temporal fascia.
What is the temporal fascia ?
Tough layer of fascia to superior temporal line and splits into two layers inferiorly to attach to zygomatic arch.
What is the function of the temporal fascia ?
Provides the resistance to masseter.
What is the lateral boundary of infratemporal fossa ?
Ramus of the mandible.
What is the medial boundary of infratemporal fossa ?
Lateral pterygoid plate of sphenoid bone.
What is anterior boundary of infratemporal fossa ?
Posterior aspect of maxilla.
What is posterior boundary of infratemporal fossa ?
Tympanic plate, mastoid and styloid processes.
What is superior boundary of infratemporal fossa ?
Infratemporal crest of sphenoid bone.
What is inferior boundary of infratemporal fossa ?
Angle of mandible.
What 3 muscles are found in infratemporal fossa ?
Medial, lateral pterygoid and inferior part of temporalis.
What are the two terminal branches of external carotid artery ?
Superficial temporal and maxillary.
What are the 6 most relevant branches of maxillary artery ?
Middle meningeal.
Inferior alveolar.
Anterior and posterior deep temporal.
Masseteric.
Buccal.
Superior alveolar.
What foramen does the middle meningeal artery pass through to enter middle cranial fossa ?
Foramen spinosum.
What foramen does inferior alveolar artery pass through to enter mandible ?
Mandibular foramen.
What branch of the maxillary artery passes through mandibular notch ?
Masseteric artery.
What does the middle meningeal artery supply ?
Dura matter of the brain.
What anatomical landmark can be seen from the inside of the skull relevant to the middle meningeal artery ?
Middle meningeal groove.
The middle meningeal artery passes through a split in what nerve ?
Auriculotemporal nerve branch of CNV3.
What route does the anterior and posterior deep temporal arteries take in the infratemporal fossa ?
Pass superiorly and laterally across roof of infratemporal fossa.
The masseteric artery supplies the masseter via what surface ?
Deep surface.
What does the buccal artery supply ?
Buccinator, cheek and buccal oral mucosa.
What is the 1st part of the maxillary artery called ?
Mandibular part.
What is the 2nd part of the maxillary artery called ?
Pterygoid part.
What is the 3rd part of the maxillary artery called ?
Pterygopalatine part.
What muscle is the maxillary artery divided into parts in relation to ?
Lateral pterygoid.
What two main arterial branches are associated with the mandibular part of the maxillary artery ?
Middle meningeal and inferior alveolar arteries.
What three main arterial branches are associated with the pterygoid part of the maxillary artery ?
Anterior and posterior deep temporal, masseteric and buccal arteries.
What main arterial branch is associated with the pterygopalatine part of the maxillary artery ?
Superior alveolar artery.
What fissure and then fossa does the third part of maxillary artery enter (pterygopalatine part) ?
Pterygomaxillary fissure and into pterygopalatine fossa.
What artery runs deep between lateral and medial pterygoid muscles ?
Maxillary artery - first part i.e. mandibular part with branches - middle meningeal and inferior alveolar.
What fossa does the trigeminal ganglion lie ?
Middle cranial fossa.
What foramen does the mandibular nerve (CNV3) pass through ?
Foramen ovale.
What is the corticobulbar tract responsible for ?
Voluntary motor control of head (skeletal muscle) - including muscles of facial expression, infra/suprahyoids, intrinsic and extrinsic muscles of the tongue and muscles of mastication.
Where is the primary motor cortex located ?
Anterior to central sulcus.
What fibres run from primary motor cortex to internal capsule ?
Corona radiata.
What area of the internal capsule does the corticobulbar tract run through towards the brainstem ?
Genu (central point of the triangle made by the internal capsule).
What is the genu ? And where is it located ?
Tunnel of white matter through middle of basal ganglia beneath corona radiata.
What motor cranial nerves are associated with the midbrain ?
CNIII (oculomotor) and CNIV (trochlear).
What motor cranial nerves are associated with pons ?
CNV (trigeminal), CNVI (abducens), CNVII (facial).
What motor cranial nerves are associated with medulla ?
CNIX (glossopharyngeal), CNX (vagus), CNXI (accessory, CNXII (hypoglossal).
The ‘nucleus ambiguwus’ is a shared nucleus in the corticobulbar tract by what 2 cranial nerves ?
CNX and CNIX.
What is pseudobulbar palsy ?
Mild form of weakness in associated muscles.
What two cranial nerves are an exception to “bilateral rule of innervation” in corticobulbar tract ?
CNVII and CNXII.
Explain why facial nerve’s motor innervation differs from the “bilateral rule of innervation” in corticobulbar tract.
- Facial nuclei split into upper and lower.
- Upper nuclei UMN - innervated bilaterally for ipsilateral side.
- Lower nuclei UMN - single contralateral innervation to nucleus.
Explain why hypoglossal nerve’s motor innervation differs from the “bilateral rule of innervation” in corticobulbar tract.
Single contralateral innervation to nucleus.
What makes trochlear nerve unusual in the corticobulbar tract ?
UMN innervation - bilateral.
LMN innervation - contralateral.
LMN crosses to opposite sides.
