Theme 8c Flashcards
Interior of Skull
What is the skull composed of?
Cranium & Mandible
Neurocranium: Bones forming the protective cranial vault around the Brain & Brianstem
Cranial base: Bones making up the floor of the
What are the divisions of the interior of the skull?
What are their boundries?
Anterior cranial fossa:
- frontal bone
- lesser wing of sphenoid
Middle cranial fossa:
- Lesser wings of spenoid
- petroud temporal bone
Posterior cranial fossa:
- Petrous temporal bone
- Dorsum sellae
How do the Cranial nerves leave the skull?
V:
- V1 - Superior orbital fissue
- V2 - Fo. Rotundum
- V3 - Ovale
III, IV, VI: Cavernous sinus & superior orbital fissue
VII: Internal auditory meatus, facial canal, stylomastoid foramen
VIII: Internal auditory meatus
IX, X, XI: Jugular foramen
XII: Hypoglossal canal
Venous drainage of the Brain
What are the different Sinus’s involved?
Superior sagittal:
- Runs backwards attached to Falx cerebri
- Ends at metting of tentorium & cerebri in confluence of sinus’s
Inferior Saggital:
- Runs backwards in faux cerebri to drain into straight sinus
Straight:
Junction between falx cerebri & tentorium
Ends at confluence of sinuses
Transverse:
- Drains from Sup.Sagittal & Straight
- Turns & continues as sigmoid sinus into jugular foramen as Jugular Vein
Sigmoid:
- Greater & lesser petrosal sinus drain into here
Cavernous & petrosal:
- Cavernous sinus drains into superior & inferior petrosal sinus’s
What are the protective functions of the Meninges & Dura?
CSF: supports brain as a shock absorber & absorbs engery from impact - between arachnoid & pia layrs
Dural reflections: supports brain by transmitting its weight to the skull = shock absorber
What are the protective functions of the Venous sinus’s?
Drains 70% of venous blood
Temperature regulation: cools rterial blood
Protects against changes in venous pressure
Intercranial Haemorrhages
What is a intercranial haemorrhage?
What are the different intercranial haemorrages & where can they occur?
an escape of blood from a ruptured blood vessel
Extradural: middle meningeal artery
- Bleeding between dura & skull
Subdural: superior cerebral veins
- Bleeding into subdural space
Subarachnoid: angiomas, aneurysms
- Bleeding into subarachnoid space
Intracerebral: middle cerebral artery
- Bleeding into brain
In orofacial infections, what are the sites of infection?
Teeth dental pulp: due to caries lesion
Periodontium: destruction = bony pockets being formed around teeth where bacteria accumulate
Bone & TMJ joint
Soft tissue
In orofacial infections, what are the routes of infection spread?
- Tissue planes
- Venous drainage
- Lymphatic drainage
- Direct erosion of tissue
What is periapical abscess?
Chronic, localised infection at the root apex of a tooth
Passage: thin cortical bone to thick inner bone
Spread of Infection of 3rd Molar
Tissue spaces around jaw & neck, lymphatic drainage, venous drainage & intracranial spread
Intraorally: sublingual space
Extraorally: Submandibular space
Neck: parapharyngeal/retropharyngeal space
What are potential tissue spaces that can be infected by spread of infection
Lower Jaw
- Sublingual
- Submental
- Submandibular
- Pterygomandibular
- Peritonsillar
- Parapharyngeal
- Parotid
Upper Jaw
- Canine
- Palatal
- Infratemporal
Route of Intracranial spread of Dental Infection
- Paranasal sinuses
- Venous communicatons
- Tissue spaces in neck & direction ersion of skull base
