Lecture 3 - Neuroanatomy I - Ventricles, Meninges and Blood Flow Flashcards
What are the 5 layers of the scalp? Superficial to deep
- skin
- connective tissue
- aponeurosis
- loose connective tissue
- periosteum
Which layers make up the scalp proper?
The first three:
- skin
- connective tissue
- aponeurosis
What is unique about the scalp proper?
They are the only layers that you can move and they all move together
What does the aponeurosis do?
- helps prevent stretching
What are the three sections of the aponeurosis?
- frontalis
- epicranial aponeurosis
- occipitalis
What are the three sections of the aponeurosis in?
the occipitofrontalis
What is the loose connective tissue referred to as sometimes and why?
The “danger zone” because the emissary vein passes through it and provides a potential infection pathway into the cranial vault
Where is periosteum found?
on the surface of all bones
What do the meninges do?
provide protection and support to the CNS
What are the layers of meninges? from superficial to deep
- dura mater
- arachnoid mater
- pia mater
What is the dura mater and what does it do?
- thick layer deep to the skull cap (calvarium)
- encloses dural venous sinues and major structures that drain the cranial vault
What does the dura mater form?
- three invaginations (folds) within the cranial vault
What are the three folds that the dura mater forms within the cranial vault?
- falx cerebri (vertical, before tentorium cerebelli)
- tentorium cerebelli (horizontal)
- calx cerebelli (vertical, after tentorium cerebelli)
Where does the falx cerebri attach to?
anteriorly to the crista gallii of the ethmoid bone
What are the layers of the dura mater?
- periosteal layer
- meningeal layer
The two layers of the dura mater are always right beside each other except for when…
they split to help form the dural venous sinuses
What is a “potential space”?
a space that is not found unless trauma/disease cause seperation of layers
What are the two potential spaces of the dura mater
- epidural space
- subdural space
Where is the dura mater?
at the edge of the skull
where do the dura mater layers split?
at the foramen magnum
Where do the layers of the dura mater continue after they split at the foramen magnum?
- the periosteal layer continues around the edge of the skull
- the miningeal layer continues around the spinal cord
What is the subarachnoid space?
the space between the arachnoid mater and the pia mater which contains cerebrospinal fluid (CSF)
What does cerebrospinal fluid do?
helps to metabolically (exchange medium) and physically (buoyancy and cushion) the brain
What are two features of the arachnoid mater?
- arachnoid granulations
- arachnoid trabeculae
What do arachnoid granulations do?
drain CSF through the dura
What do arachnoid trabeculae do?
support the arachnoid mater
What does the pia mater cover?
cortical sulci and gyri
What is subpial space
potential space between pia and cortex
what are the spinal meninges?
- dura mater
- arachnoid mater
- pia mater
(same as brain)
Which meningues cover the spinacl nerve roots?
the dura and arachnoid meningues
What are the denticulate ligaments?
- come from pia
- connect to dura for cord stability
What are the 4 spaces of the spinal cord?
- epidural space
- subarachnoid space
- subdural space
- subpial space
What is the epidural space?
contains fat and venous plexuses
What is the subarachnoid space?
contains CSF
What is the subdural space?
potential space
What is the subpial space?
potential space
What are vrentricles witin the brain?
4 cavities responsible for deep CSF flow
- Lateral ventricles (2)
- third ventricle
- fourth ventricle
Features of the lateral ventricles (6)
- anterior horn
- inferior horn
- posterior horn
- body
- atrium
- interventricular foramen (of Munro)
What are the lateral ventricles associated with?
various lobes of the cerebrum (the telecephalon)
Features of the third ventricle
*** like a cube
- anterior wall
- posterior wall
- lateral walls
- roof
- floor
- interthalamic adhesion (not a space… its a band of tissue passing through ventricle)
What is the third ventricle associated with?
the thalamus and hypothalamus (the dicephalon)
What is the cerebral aqueduct?
it connects the third and fourth ventricles, passing through the midbrain into the pons
Features of the fourth ventricle
- 3 apertures (hole or opening)
- 2 lateral and 1 median
What are lateral apertures called?
Foramina of Luschka
What is the median apertures called?
Foramen of Magendie
What is the fourth ventricle associated with?
the pons (the myelencephalon)
What is beyound the fourth ventricle?
the central canal
What is the central canal?
- it runs all the way down the spinal cord
- provides metabolic support to the deep spinal cord
What is the choroid plexus?
- collection fo ependymal cells
- found on walls of all 4 ventricles, in specific area
What is the purpose of the choroid plexus?
produces CSF which flows into the ventricles
Flow of CFS within ventricles (starting at lateral ventricle)
lateral ventricle -> interventricular foramen -> third ventricle -> cerebral aqueduct -> fourth ventricle -> (oprtion 1): foramina of Luschka, (option 2): central canal, (option 3): foramen of magendie
How does the CSF exit the ventricles?
CSF exits into small subarachnoid spaces called cisterns (small cavities)
Where does the CSF go after entering the cisterns?
CSF flows along the outer cortices (plural for cortex) of the cerebrum and cerebellum
What does CSF exit the subarachnoid space through?
Arachnoid granulations
What do arachnoid granulations do?
They pierce through the dura to drain CSF into the dural venous sinuses
Cranial CSF flow (12) from choroid plexus to heart
- Choroid plexus
- lateral ventricle
- interventricular foramen
- third ventricle
- cerebral aqueduct
- Fourth ventricle
- Median/lateral apertures
- subarachnoid cisterns
- bathes superficial brain
- arachnoid granulations
- dural venous sinuses
- heart
Spinal CSF flow (12) from choroid plexus to central canal (7)
- Choroid plexus
- lateral ventricle
- interventricular foramen
- third ventricle
- cerebral aqueduct
- Fourth ventricle
- Central canal
What are the three major branches off the aorta?
- brachiocephalic trunk
- left subclavian artery
- left common carotid artery
What does the brachiocephalic trunk bifurcate (end and split) into?
the right subclavian arteryand the right common carotid artery
What are the four major arteries to the brain?
- common carotid artery -> internal carotid artery
- subclavian artery -> vertebral artery
Where do the arteries pass through the skull? (continuing from previous question)
- internal carotid artery -> carotid canal
- vertebral artery -> anterior portion of foramen mahnum
What do the left and right vertebral arteries join to form?
the basilar artery
Where does the basilar artery sit?
in the basilar groove of pons
What arteries branch off of the basilar artery?
the pontine arteries
What do the pontine arteries sypply?
the pons
What does the basilar artery bifurcate into?
the 2 posterior cerebral arteries
What do the cerebral arteries supply?
the posterior cerbral cortex (right supplies right, left supplies left)
What is the circle of willis?
junction of arteries providing major cerebral blood supply
hat arteries make up the circle of willis? (7)
- basilar artery
- posterior cerebral arteries
- posterior communicating arteries
- internal carotid arteries
- middle cerebral arteries
- anterior cerebral arteries
- anterior communicatign artery
Trajectory of the circle of willis
- basilar artery bifurcates into posterior cerebral arteries
- internal carotid artery gives off the anterior and middle cerebral arteries and posterior communicating artery
What do communication arteries provide?
connections
What does the posterior communicating artery connect?
the internal carotid artery with posterior cerebral artery
What does the anterior communicating artery connect?
anterior cerebral arteries
What is the purpose of the circle of willis?
it maintains cerebral blood flow throughout the brain in the case of a clot in a vertebral or internal carotid artery
What does venous drainage consist of?
dural venous sinuses that drain the inner structures of the cranial vault
Where is the superior sagittal sinus?
lies along mid-sagittal plane (anterior to posterior right in the middle), in falx cerebri
Flow of sinuses
superior sagittal sinus -> confluence (joining) of sinuses -> transverse sinuses
Where does the transverse sinus sit?
in the tentorium cerebelli
What does the transverse sinus become when exiting the tentorium cerebelli?
the sigmoid sinus
What does the sigmoid sinus drain into?
the internal jugular vein
What is the jugular bulb?
a superior enlargment of the internal jugular vein
What is the cavernous sinus?
a venous plexus
Where is the cavernous sinus?
lateral to the body of the sphenoid bone
What does the cavernous sinus do?
drains eye, parts of cerebral cortex, and pituitary glrand
What is the cavernous sinus pierced by?
the internal carotid artery
Where does the internal carotid artery then go?
curves up to exit the dura, and contributes to the circle of willis
