Anatomy W4 - The cranial Cavity Flashcards
In which hemisphere of the brain is the motor speech area located?
The left (frontal lobe)
What vessel is the middle cerebral artery a continuation of?
The internal carotid artery
Where does the maxillary artery (from the external carotid) branch into the middle meningeal artery?
In the infratemporal fossa
What are the 2 layers of the dura called?
The periosteal layer - outer
The meningeal layer - inner
What is the falx cerebri?
A sickle shaped layer of dura mater that separates the left and right hemispheres
What is the sellar diaphragm?
The layer of dura mater surrounding the pituitary gland
List the attachments of the falx cerebri. (3)
Anterior - crista galli
Attached to both sides of the groove of the superior sagital sinus
Posterior - tentorium cerebelli
List the attachments for the tentorium cerebelli (3)
Anterior - clinoid process
The superior border of the petrous portion of the temporal bone
Posterior - the occipital bone on both sides of the groove for the transverse sinus
What is the purpose of the tentorial notch?
A space in the dura that allows passage of the brain stem
What anatomical landmark helps you locate the optic nerve?
The anterior clinoid process
Where do the olfactory nerves CN 1 enter/exit the cranial cavity?
Through the cribriform plate of the ethmoid bone
Name a symptom a patient with an aneurysm in the internal carotid artery would experience?
The ICA runs close to the optic chiasm - so if there is a pathological swelling it can cause visual disturbances.
What nerves exit the cranial cavity in the middle cranial fossa under the lesser wing of the sphenoid bone and enter the orbit via the superior orbital fissure?
The oculomotor CN 3
Trochlear CN 4
Abducents CN 6
Opthalmic divison of CN 5
What muscles does the trochlear nerve supply?
The superior oblique muscles
Where does the opthalmic division of the trigeminal leave the cranial cavity?
The superior orbital fissure
Where does the maxillary division of the trigeminal leave the cranial cavity?
The foramen rotundum
Where does the mandibular division of the trigeminal leave the cranial cavity?
The foramen ovale
Where does CN 7 (facial) and 8 (vestibulocochlear) leave the cranial cavity?
The internal acoustic meatus
Where does CN 9, 10 and 11 leave the cranial cavity?
Through the jugular foramen
What does the spinal route of the accessory nerve supply?
The sternocleidomastoid and trapezius
What does the cranial route of the accessory nerve supply?
Why is this?
The larynx and the pharynx
When the cranial route of the accessory nerve leaves the skull it combines with the vagus nerve in the inferior ganglion of the vagus nerve.
Where is CSF produced?
In the ventricles of the brain
What is the function of CSF (along with the falx cerebri and the tentorium cerebelli)?
Cushioning the brain and resisting movement
What fills the subarachnoid space (between the arachnoid mater and the pia)?
CSF (that has escaped from the 4th ventricle )
What are arachnoid villi?
Projections of arachnoid mater through the wall of the superior sagittal sinus.
What is the function of arachnoid villi?
The allow CSF to be absorbed into the venous bloodstream. (constant turn over)
What vessels are involved in an extradural haemorrhage?
Middle meningeal artery
What vessels are involved in an subdural haemorrhage?
The cerebral veins
What vessels are involved in an subarachnoid haemorrhage?
Cerebral arteries in the circle of willis on the underside of the brain.
What age would a patient presenting with an extradural haemorrhage commonly be?
Any age
What age would a patient presenting with an subdural haemorrhage commonly be?
Elderly or very young children
What age would a patient presenting with an subarachnoid haemorrhage commonly be?
Middle aged
Describe what occurs in an extradural haemorrhage.
There is fracture to the side of the head, commonly at the pterion which is very weak bone. The MMA runs beneath the pterion and ruptures.
Blood accumulates between the dura and the bone stripping the dura from the bone = rising pressure in the cranial cavity.
Describe what occurs in a subdural haemorrhage.
Movement of the brain can cause the cerebral veins to tear away from the firm dura.
This causes blood to accumulate between the dura and the arachnoid mater.
Describe what occurs in a subarachnoid haemorrhage.
Berry aneurysms can form at the circle of willis - these can burst spontaneously or due to trauma.
Blood accumulates in the subarachnoid space on the underside of the brain.
Describe the deterioration of conscious levels in a patient with an extradural haemorrhage.
Blood accumulates over a few hours - deterioration of conscious levels = few hours.
Describe the deterioration of conscious levels in a patient with a subdural haemorrhage.
Since its venous blood, it accumulates less rapidly i.e. over a few weeks.
Deterioration of conscious levels = few weeks.
Describe the deterioration of conscious levels in a patient with a subarachnoid haemorrhage.
Sore head and immediate deterioration of conscious levels = sudden death.
How could you test to see if death was caused by a subarachnoid haemorrhage?
CSF would be blood stained
What vein leaves the cavernous sinus?
Sphenoidal emissary vein
Where does the sphenoidal emisssary vein exit the cranial cavity?
The foramen ovale alongside the mandibular div of the trigeminal
What are the symptoms of a cavernous sinus thrombosis?
Patient has a fever and a swollen eye
What can cause a cavernous sinus thrombosis?
Infection in the face that travels to the sinus via the opthalmic veins.
Veins don’t have valves so infection can travel freely.
Describe what occurs in Cavernous sinus thrombosis, why does this result in a swollen eye?
Infection in the face travels via the opthalmic veins to the cavernous sinus.
Blood travels slowly through the CS so this gives the bacteria from the infection time to multiply within the sinus.
The multiplying bacteria cause the blood to clot within the sinus.
The blood clots block the sinus and blood cannot leave the orbit to enter = swelling.
What are the symptoms of a pterygoid venous plexus thrombosis?
Same as cavernous VS thrombosis - Patient has a fever and a swollen eye
What can cause a pterygoid venous plexus thrombosis?
Same as cavernous VS thrombosis - infection in the face i.e. of the upper teeth
Why are the symptoms of a pterygoid venous plexus thrombosis the same as the CVS thrombosis?
Bacteria from infection can reach the pterygoid venous plexus and then travel to the cavernous venous sinus via the sphenoidal emissary vein/foramen.
Then same disease process as the CVS thrombosis:
Infection in the face travels via the opthalmic veins to the cavernous sinus.
Blood travels slowly through the CS so this gives the bacteria from the infection time to multiply within the sinus.
The multiplying bacteria cause the blood to clot within the sinus.
The blood clots block the sinus and blood cannot leave the orbit to enter = swelling
What bone is present between the outer and inner tables if the cranium?
Cancellous/ diploae bone
What is Padget’s disease?
A disease of bone remodelling = fragile and misshapen bones
What bone of the skull does Padget’s disease commonly affect?
The frontal bone = bulging
Where does the middle meningeal artery enter the cranial cavity from?
The foramen spinosum
What is the tentorium cerebelli?
A fold of dura mater that separates the cerebellum from the posterior hemisphere
Where does the optic nerves CN 2 enter/exit the cranial cavity?
Via the optic canal
Where does the hypoglossal nerves CN 12 enter/exit the cranial cavity?
Via the hypoglossal canal
Describe the course of CSF within the brain.
Travels from the lateral ventricle to the third ventricle then moves down the cerebral aqueduct to the 4th ventricle then enters the spinal canal.
What is the intraventricular foramen/foramen of munroe located?
Between the lateral ventricle and the 3rd ventricle
