skull base Flashcards
What is the skull divided into?
- Anterior cranial fossae
- Middle cranial fossae
- Posterior cranial fossae
Where does the frontal lobe of the brain sit?
anterior cranial foassae
Where does the cerebellum sit?
Posterior cranial fossae
What are the fossae divided by?
Ridges
What are the components of the Anterior cranial fossae?
- Foramen caecum
- Crista Galli
- Cribrifoirm plate
What is the role of foramen caecum?
- Transmit emissionary vein
2. Drain nasal cavity into superior sagittal sinus
What is the role of cribriform plate?
- Transmit sensory nerve fibre from nasal mucosa transmitting smell to olfactory bulb of CN I
What are the components of middle cranial fossae?
- Optic Canal
- Superior Orbital fissure
- Foramen Rottundum
- Foramen Ovale
- Foramen Spinosum
What are the 2 structures that the optic canal transmit?
- CN II - Optic nerve
2. Opthalmic artery
What is the superior orbital fissure?
Transmit structure from cranial cavity to orbit
What are the cranial nerves of superior orbital fissure?
- CN III - Occulomotor nerve
- CN IV - Trochlear nerve
- CN VI - Trigeminal
- CN VI - Abducens
Superior opthalmic vein
What structure passes through the superior orbital fissure?
Superior opthalmic vein
What is the superior orbital fissure?
Communication between cavernous sinus and apex of orbit
It is a cleft lying between lesser and greater wings of sphenoid bone
What cranial nerve is found in the foramen Rotundum, and what is the vein called?
CN V2 - Trigmeninal
Maxillary nerve
What are the structures found in the Foramen Ovale?
O - Otic Ganglion V - V3 (Trigeminal) A - Accessory Meningeal Artery L - Lesser petrosal nerve E - Emissary vein
Where is Foramen Spinsosum found and what is it’s role?
More lateral to the foramen ovale
Transmits middle meningeal artery
What is the role of Foramen Spinosum?
Allows the passage of middle meningeal artery, the middle meningeal vein and meningeal branch of CN V3
What are the 5 bones of normal skull base?
- Frontal
- Ethmoid
- Sphenoid
- Temporal
- Occipital
What does Ethmoid bone form?
Part of nasal cavity + orbits
What is the role of Ethmoid bone?
Main mechanical support structure of nasal cavity
What does Lesser wing of sphenoid separate?
Anterior cranial fossa from middle cranial fossa
It forms the lateral border of optic canal
What do Anterior Cranial Fossa contain?
- Orbital plate of frontal bone
- Ethmoid bone
- Lesser Wing of Sphenoid
- Frontal Crest
- Crista Galli
- Foramen caecum
- Cribriform plate
What does the middle cranial fossa contain?
- Sphenoid bone
- Squamous temporal
- Petrous temporal
What anatomical structures does the middle cranial fossa accomodate?
- Pituitary gland
2. Temporal lobes of the cerebral cortex
What are examples of openings in the middle cranial fossa?
- Optic canal
- Superior orbital fissure
- Foramen rotundum
- Foramen ovale
- Foramen spinosum
- Foramen lacerum
- Carotid canal
What is the role of foramen lacerum in middle cranial fossa?
Transmits artery and nerve of pterygoid canal
What is the sphenoid bone?
- Mid-section of the skull base
2. Anterior wall of middle cranial fossa
What are important for identifying structures?
- The petrous portion of the temporal bone
2. Greater wings of sphenoid bone