Cranial cavity - general arrangement (dave's notes) Flashcards
What invests the brain?
Pia mater, composed of fibrous vascular tissue
Describe the pia mater of the spinal cord - what does it form here?
Projected laterally in the spinal column to form the denticulate line
The arachnoid is …… proof
CSF
What lies between the arachnoid and dura?
A thin layer of lymph except at the cochlear aqueduct
What traverses the subarachnoid space? Does the subarachnoid space exist at all other areas surrounding the CNS?
Obliterated at times by fusion. Cranial nerves and spinal nerve roots traverse this space.
What are arachnoid villi?
Where the arachnoid herniates through the dura
What are incongruities in the bone/brain profile known as? List four.
Subarachnoid cisterns. Cerebromedullary Pontine Interpeduncular Chiasmic
Describe the dura
The dura withstands the hydrostatic pressure and is thick fibrous tissue often continuous with the periosteum.
May be thought of as an outer layer (periosteum) and an inner layer (dura proper)
What intervenes between the dura and bone?
No substance - the dura lies on congruity with the outer periosteum
Where may the dura be easily stripped from the bone?
Over the vault
What is the tentorium cerebelli? Where does it extend from?
A flange of the inner layer from the transverse sinuses and the margins of the superior petrosal sinuses
Describe the free margin of the tentorium cerebelli. What does it suspend?
The free margin is u shaped, with the central gap accommodating the mid-brain. The midline attachment of the falx suspends the tentorium.
What is the falx cerebri?
A sickle shaped flange in the mideline between the cerebral hemispheres
What do the two layers of the falx cerebri accommodate?
The superior and inferior saggital sinuses
Where does the falx cerebri extend from and to?
From the internal occipital protuberance to the posterior margin of the foramen magnum
What horizontal sheet of the inner layer of dura forms a roof for the pituitary fossa?
The diaphragmatic sellae
Describe the blood supply to the dura
The inner layer is poorly supplied. The outer layer is richly supplied with the adjacent bone.The arteries lie between the two layers
What is found between the two layers of dura?
The meningeal arteries:
Middle meningeal
Meningeal branches of ophthalmic and anterior ethmoidal arteries
Meningeal branches of the ICA and accessory meningeal
Meningeal arteries of the vertebral arteries
What meningeal artery is found in the supratentorial part of the dura?
The middle meningeal
What meningeal artery is found in the anterior cranial fossa?
The meningeal branches of the ophthalmic and anterior ethmoidal arteries
What meningeal artery is found over the cavernous sinus?
The meningeal branches of the internal carotid artery and accessory meningeal
What meningeal artery is found in the posterior fossa?
The meningeal arteries of the vertebral arteries.
What does the middle meningeal artery arise from? Where? How does it enter the cranial cavity?
The maxillary artery, in the infratemporal fossa
Foramen spinosum
What accompanies the middle meningeal artery?
Sympathetic nerves and veins
Where are the venous sinuses of the dura found? What blood do they receive?
Most lie between the inner and outer layers and receive all the blood from the brain and adjacent bone
What holds the venous sinuses open? How do they drain?
The underlying inner layer and drain via a siphonage system
List the venous sinuses of the dura
Superior sagittal sinus
Inferior sagittal sinus
Straight sinus
?cavernous sinus
What does the superior sagittal sinus drain? Where is it found?
Found between the falx, drains both the upper and posterior parts of the brain, then becomes the transverse sinus.
What does the inferior sagittal sinus drain? Where does it drain to?
The lower parts and drains into the straight sinus
What do the upper and posterior parts of the brain drain to?
The superior sagittal sinus in between the falx
What do the lower parts of the brain drain to?
The inferior sagittal sinus, then to the straight sinus
