Temporomandibular joint and Infratemporal Fossa Flashcards
What is the temporomandibular joint and where does the articulation take place?
The Temporomandibular Joint (the ‘jaw joint’) is a modified synovial hinge joint between the cranium and the mandible. Articulation: – The condyle of the mandible and the articular tubercle of the temporal bone and the mandibular fossa. The articular disk divides the TMJ into superior and inferior joint compartments.
How is the joint stabilised?
The TMJ has a joint capsule which is relatively loose – Movement > Stability. The joint is supported by 3 ligaments: – The lateral Ligament (Temporomandibular ligament), Stylomandibular Ligament and the Sphenomandibular ligament.
What movement are available at this joint and which muscles facilitate this movement?
Elevation – Temporal, masseter and medial pterygoid
Depression – Lateral pterygoid, Supra/infrahyoid – (but mainly done by gravity)
Protrusion – Lateral pterygoid mainly
Retrusion – Temporal
Lateral Movements – (e.g. Chewing) Temporal on same side, pterygoids of opposite side and masseter.
What is the innervation of the muscles of mastication?
Temporalis, masseter and pterygoids are muscles of mastication and supplied by the mandibular branch of Trigeminal nerve (V3).
What is locked jaw?
Jaw becomes displaced from the inframandibular fossa and passes anteriorly.
Describe dislocation of the temporomandibular joint
Commonly a sideways blow to the chin when the mouth is open causes anterior dislocation of the same side – Head of mandible anterior to articular tubercle – Need to check for fracture on the opposite side of the affected jaw.
What other disorders can occur at the TMJ?
Pain around the TMJ joint is a common presenting complaint. Branches of V3 are the articular supply of the TMJ (Auriculotemporal nerve). Be careful – Temporal arteritis is a differential diagnosis, this is a type of vasculitis and can result in loss of eyesight.
Conditions include: – Bruxism (teeth grinding) – Osteoarthritis of TMJ – Inter-articular disk derangement. Exact pathophysiology is poorly understood. Commonly multifactorial causes e.g. – Anatomical, Psychological and Social.
What is the infratemporal fossa?
An irregularly shaped space deep and inferior to the zygomatic arch and deep to the ramus of the mandible.
What are the contents of the infratemporal fossa?
3 muscles: – Temporal muscle (inferior part) – Lateral and medial pterygoid muscles
1 artery: – Maxillary artery
1 venous plexus: (plus maxillary vein, Obvs.) – Pterygoid venous plexus which has a communication with cavernous sinus.
Lots of nerves: – Mandibular, Inferior alveolar, Lingual, Buccal, chorda tympani and the otic ganglion.
Descirbe the functions of all the nerves passing through the infratemporal fossa?
Mandibular branch of trigeminal gives off: Inferior alveolar nerve which supplies innervation of lower teeth and continues as the mental nerve supplying innervation to the skin of the chin and bottom lip. The
Lingual nerve is a branch of the Mandibular nerve which supplies sensory to the anterior 2/3 of tongue
and carries chorda tympani fibres from facial nerve for special sensory supply of same area.
The Buccal nerve is a branch of teh mandibular nerve and supplies sensory to cheek and gum.
Otic ganglion: parasympathetic supply of parotid.
What is the clinical relevance of the infratemporal fossa?
Fossa can be a site for isolated infections e.g. diabetic patients and tumours rarely.
If infection is present there is a risk of cavernous sinus thrombosis due to the venous communication with pterygoid venous plexus.
This fossa can be used as a site for mandibular nerve blocks.
