Clinical anatomy of interior skull Flashcards
Where is an area of bone weakness on the skull due to thin bone?
Pterion
Which borns join to form pterion?
Frontal, temporal, parietal, sphenoid
Where are areas of weakness on the skull due to openings?
Nasal apertures and orbit
Why does the structure of sutures make them immovable?
Joined by very strong collagen fibres
How does interdigitation make sutures stronger?
Increases SA of contact
What is bevelling and what is the effect of bevelling on sutures?
Overlapping of bone, makes the suture stronger
What is buttressing?
Thickened areas of bone that support fragile zones like the nasal cavity and orbit
Buttressing of the skull is in line with forces of mastication, why is this?
Dissipate forces of mastication so maxillary teeth don’t get forced into maxillary sinus
Name the buttresses on the anterior surface of face?
Supracilary bar, lower orbital margin, canine buttress, maxilla-zygomatic buttress
What type of forces does the buttressing not he anterior surface fo the face not resist?
Anterior
What buttressing does resist anterior forces?
Tuberosity pterygoid buttress
How do the dural reflections have a protective role?
Transmit weight to skull and absorb energy of impact
What allows the dural reflections to absorb energy of impact?
They are incompressible and flexible
Through what fo. do the venous sinuses drain blood?
Jugular fo.
What are the 3 protective roles of venous insulin drainage?
Drain 70% of blood through jugular fo.
Cooling mechanism
Protect abasing changes in BP by moving blood to emissary veins
What is the extradural space?
Between duramater and skull
What occurs during an extradural haemorrhage?
Blood strips dura away from skull and presses against brain
What artery does an extradural haemorrhage effect?
Middle meningeal
During a subdural haemorrhage where does blood drain into?
Superior cerebral vein
What is the subarachnoid space normally filled with?
CSF
What are the routes of infection spread?
Tissue plane, venous, lymphatics, direct erosion
If an infection is untreated it can?
Cause airway obstruction
Spread into brain
Cause septicaemia
What is the line of least erosion?
Spread through the tissue before thick - may spread in an unexpected way
During a periodical abbess the route of infection is determined by line of least residence, this changes in individuals deepening on the thickness of which bone?
Alveolar bone
Name the tissue spaces of the lower jaw
Sublingual Submandibular Submental Pteyrgomandibular Peritonsillar Retropharyngeal
Name the tissue spaces of the upper jaw
Parotid
Canine
Palatal
Infratemporal
If an infection spreads intraorally, which tissue plane does it infect?
Sublingual
If an infection spreads extra orally which tissue plane doe sit infect?
Submandibular
If an infection spreads to the neck which space does it infect?
Retropharyngeal
Paranasal sinuses are in direct contact with bone, how can infection spread from here?
Rapid erosion
Ludwigs angina can occur after a tooth infection. What is it?
Infection spread backwards towards posterior border of mylohyoid and infects mylohyoid, causes growth an pushes tongue pack to block airway
Why is cavernous sinus thrombosis an issue?
Cavernous sinus is deep seated so antibiotics cannot reach
Cavernous sinus thrombosis blocks what artery?
Internal carotid
