Cranial Meninges, Dural Infoldings, and Dural Venous Sinuses Flashcards
Where do cranial meninges lie?
Deep to the cranium
What are functions of the cranial meninges?
Protect the brain
Form supporting framework for vasculature and venous sinuses
Enclose the cerebrospinal fluid filled subarachnoid space
Where is CSF formed?
Choroid plexuses of ventricles of the brain
How does CSF travel?
Leaves the ventricular system and enters the subarachnoid space, where it cushions and nourishes the brain
What is the role of the pia mater?
Attachment site for fibers of arachnoid mater
What comprises the leptomeninx?
Arachnoid and pia
What is the dura mater? What is another name for it?
Thick, dense, bilaminar membrane
Pachymeninx
What are the two layers of dura mater?
Outer periosteal layer
Inner meningeal layer
What roles do the dural infoldings play?
Compartmentalize cranial cavity
Support parts of the brain
Where are the four dural infoldings?
Falx Cerebri
Tentorium Cerebelli
Falx Cerebelli
Diaphragma Sellae
Where does Falx Cerebri lie?
Lies in longitudinal cerebral fissure
Separates the left and right cerebral hemispheres
Where does the Tentorium Cerebelli lie?
Separates the occipital lobes of cerebrum from cerebellum
Divides cranial cavity into supratentorial and infratentorial compartments
Where does the Falx Cerebelli lie?
Lies inferior to tentorium cerebelli, in posterior aspect of posterior cranial fossa
Partially separates the cerebellar hemispheres
Where does the Diaphragma Sellae lie?
Horizontal shelf of meningeal dura mater - suspended between the clinoid processes, forming the ‘roof of the sella turcica’ that covers the pituitary gland
Which bony landmarks are associated with the falx cerebri anteriorly?
Frontal crest of frontal bone and crista galli of ethmoid bone
Which bony landmarks are associated with the falx cerebri posteriorly?
Internal aspect of occipital protuberance
Which bony landmarks are associated wtih tentorium cerebelli?
Clinoid processes of sphenoid bone
Petrous part of temporal bone
Parietal bones
Occipital bone
What are dural venous sinuses?
Dural venous sinuses are endothelial-lined spaces, located within the dura, between the periosteal and meningeal dural layers
Principle venous channels of brain; veins from brain’s surface empty into dural venous sinuses to internal jugular veins
What are arachnoid granulations?
Outward bulges of dura mater
Prolongations of arachnoid mater that protrude through meningeal layer of dura into dural venous sinuses
What is the role of arachnoid granulations?
Transfer CSF to venous system
Where is the superior sagittal sinus? Where does it end?
Lies in superior border of falx cerebri
Begins at crista galli; ends near internal occipital protuberance at confluence of sinuses
Where is the inferior sagittal sinus? Where does it end?
Lies in inferior border of falx cerebri
Ends in straight sinus
Where is the straight sinus? Where does it end?
Runs along the line of attachment of the falx cerebri and tentorium cerebelli
Joins confluence of sinuses
Where is the occipital sinus? Where does it end?
Lies in posterior border of falx cerebelli
Ends superiorly at confluence of sinuses
Where do the transverse sinuses run?
Run laterally from confluence of sinuses in posterior margin of tentorium cerebelli
Continuous with sigmoid sinus
Where do the sigmoid sinuses run?
Continuation of transverse sinus
S-shaped course
After passing through jugular foramina, continue as internal jugular veins
Where is the cavernous sinus located?
Located bilaterally on sides of sella turcica on body of sphenoid
Where does the confluence of sinuses receive venous blood from?
Superior sagittal sinus
Occipital sinus
Straight sinus
Which arteries supply blood to the brain?
Internal carotid arteries
Vertebral arteries
Describe the path of the internal carotid arteries
Arise in the neck from common carotid arteries
Ascend vertically in the neck to the cranial base
Pass through the external opening of the carotid canal and the internal opening of the carotid canal - within petrous portion fo temporal bone
What are the 4 parts of the internal carotid artery?
Cervical part
Petrous part (in carotid canal within petrous portion of temporal bone)
Cavernous part (S-shaped path in cavernous sinus)
Cerebral part (intradural)
Describe the path of the internal carotid artery in the cavernous sinus?
ICA exits the petrous part of temporal bone and enters the cranial cavity
ICA ascends to posterior clinoid process
ICA passes anteriorly, along the lateral aspect of the body of the sphenoid bone
ICA curves upward on medial side of anterior clinoid process
ICA pierces dura mater; the cavernous part of the ICA ends and the cerebral part of the ICA begins
Where are the vertebral arteries found?
Arise in the neck from subclavian arteries
Ascend vertically in neck, passing through transverse foramina of cervical vertebrae (C6 - C1)
Enter cranial cavity via foramen magnum
Left and right vertebral arteries meet at midline to form Basilar artery
Which vessels does the basilar artery provide?
Posterior cerebral arteries
Branches to brainstem
Superior cerebellar artery
Anterior inferior cerebellar artery
What is the role of the posterior communicating arteries?
Small communicating arteries that provide a link between posterior cerebral arteries and internal carotid arteries
What branches do the internal carotid arteries provide?
Middle cerebral arteries
Anterior cerebral arteries
What is the role of the anterior communicating artery?
Connects both anterior cerebral arteries
