Cranial cavity Flashcards
(41 cards)
What are the 3 cranial fossae ?
- anterior cranial fossa
- middle cranial fossa
- posterior cranial fossa
Describe the bones and contents of the anterior cranial fossa
- smallest and shallowest cranial fossa
- made up of the frontal bone, ethmoid bone and sphenoid bone
- contains the frontal lobe of the brain
Describe the bones and contents of the middle cranial fossa
- made up of the sphenoid bone and temporal bone
- contains the temporal lobe and pituitary gland
Describe the bones and contents of the posterior cranial fossa
- it is the deepest and largest fossa
- made up of the occipital bone and a little bit of the sphenoid and temporal bone
- contains the cerebellum and brainstem
What are the 3 meninges of the brain ?
- the meninges are the surrounding layers of the brain
- outermost layer = dura mater
- middle layer = arachnoid mater
- innermost layer = pia mater
Describe the dura mater of the brain
- tough parchment like
- double layer : inner meningeal layer and outer periosteal layer
Describe the arachnoid mater of the brain
- very thin
- avascular
- lies above the subarachnoid space which contains the cerebrospinal fluid
Describe the pia mater of the brain
- thin
- adherent to the brain surface
- enters the contours on the surface of the brain
What is the difference between the dura mater of the of the brain and the spinal cord ?
- the cranial dura mater has 2 layers whereas the spinal dura mater has 1 layer
- the meningeal layer of the cranial dura mater descends down to the vertebra and becomes spinal dura mater
What forms when the 2 layers of the cranial dura separate ?
- dural venous sinuses
- dural partitions
What is a dural venous sinus ?
- the space between the 2 layers of cranial dura mater when they separate
- filled with venous blood
What is a dural partition ?
When the meningeal layer of the dura mater invaginates between regions of the brain
What happens of damage occurs to the middle meningeal artery ?
- the middle meningeal artery lies deep to the pterion
- if the artery is damaged then an extradural haematoma will occur
- this is when blood fills between the skull periosteum and dura mater
List the dural partitions
- falx cerebri
- tentorium cerebelli
- falx cerebelli
- tentorial notch
- diaphragma sellae
- infundibulum of hypophysis cerebri
What is the diaphragma sellae ?
It is a sheet of dura mater that forms the roof of the pituitary fossa
Describe the position of the falx cereberi
- it is sickle shaped
- separates the right an left hemispheres of the cerebrum
Describe the position of the tentorium cerebelli
- lies transversely
- superior to the cerebellum
- lies between the occipital lobe and cerebellum
Describe the position of the falx cerebelli
- lies below the tentorium cerebelli
- found between the left and right hemispheres of the cerebellum
Describe the tentorial notch
- it has a sharp edge
- found on the medial margin of the tentorium cerebelli
Describe the supply and drainage of the dural venous sinuses
- dural venous sinuses receive blood from diploic veins and emissary veins
- blood from the dural venous sinuses drain into the internal jugular veins
- venous blood of the brain drains into dural venous sinuses
What is meningitis ?
If infection is present in the dural venous sinuses this can lead to inflammation of the meninges - meningitis
Describe the structure of the bone of the skull
- flat bone
- the outer and inner tables are made from compact bone
- the area between the tables is bone marrow and spongy bones and it is known as diploe
List the dural venous sinuses
- superior sagittal sinus
- inferior sagittal sinus
- straight sinus
- transverse sinus
- sigmoid sinus
- inferior petrosal sinus
- superior petrosal sinus
- cavernous sinus
- sphenoparietal sinus
What is the confluence of sinuses ?
The point at which the superior sagittal sinus, straight sinus and transverse sinus meets