Introduction to the Brain, Cranial Meninges and Blood Supply (Neuro) Flashcards
What are the names for the forebrain, midbrain and hindbrain when the brain is first developing respectively?
-Prosencephalon
-Mesencephalon
-Rhombencephalon
What are the two subdivisions of the prosencephalon?
Telencephalon and Diencephalon
What are the two subdivisions of the Rhombencephalon?
Metencephalon and Myelencephalon
What is White matter made up of? Why is it called white matter?
Nerve cell axons
due to presence of myelin sheaths
What is Grey matter primarily made up of? What 3 other cells are presen?
Nerve body cells
Other 3 cells- Astrocytes, oligodendrocytes and unmyelinated axons.
What four structures is the brain broadly consisted of?
Cerebrum, Cerebellum, Diencephalon and Brainstem
What is the largest part of the brain? What is it split up into?
Cerebrum
split into four lobes and two hemispheres
What is the frontal lobe mainly consisted of (2)?
What is the function of these structures?
-Primary motor cortex- Planning and executing conscious movement
-Prefrontal cortex- behavior, personality and decision making
What two structures does the Temporal lobe contain? What is the function of each?
-Primary auditory cortex, function is processing auditory information
-Hippocampus, formation of memories
What does the Parietal lobe contain? What is its function?
-Primary somatosensory cortex
Function is processing sensory information
What is the function of the Cerebellum?
Maintaining posture and balance and correcting fine movements
What is the Function of the Brainstem? (3)
1.Connects brain to spinal cord
2.Contains nuclei of cranial nerves
3.Contains vital centres for regulating breathing and cardiovascular function
What is a fold of tissue in the brain called? What is the groove called between the folds?
Gyri
Sulcus
What splits up the:
1. Frontal and Parietal lobes
2. Temporal and Parietal lobes
- Central sulcus
- Lateral sulcus
What is the part of the Cerebral cortex that can be seen when the lateral sulcus is opened?
Insula
What is the name of the structures that covers the insula? What does it consist of?
Opercula
Made up of parts of the Frontal, Parietal and Temporal lobe
What is the structure called that separates the left and right lobe of the brain?
Longitudinal fissure
What can you see when you open up the Longitudinal Fissure? What does it connect What is it made up of?
1.Corpus Callosum
2.Left and right hemispheres
3.Made up of white matter
What two nerve fibres are found on either side of both frontal lobes?
Function of the first one
Olfactory and Optic nerves
What direction do the optic nerves run?
What is the point called where they cross?
- Posteriorly and Medially
- Optic chiasm
What rounded structure is found behind the optic chiasm and Pituitary gland? What part of the brain does it belong to?
Mamillary body
Belongs to diencephalon
What structure and surface do the mamillary bodies lie on? Where is this structure visible behind?
Inferior surface of hypothalamus
behind optic chiasm
What is known as the ‘feet of the brain? What are they consisted of and what are they next to?
Crus cerebri
White matter next to mammillary bodies
What do the Crus cerebri make part of? What is this structure part of? What do they do?
Cerebral peduncles
Part of the midbrain
Connect the cerebrum to the brainstem
What 3 structures is the brainstem made up of?
Midbrain
Pons
Medulla oblongata
What structure is also known as the ‘little brain’? What is it made up of? What connects it together?
1.Cerebellum
2.Two hemispheres and lined with small fissures
3. Connected by central vermis
Where is the Primary motor cortex located in the frontal lobe? What is located anterior to this? What is the function of this structure?
1.Anterior to the central sulcus
2.Premotor cortex
3.Planning and preparing movements
What is the most anterior part of the frontal lobe?
Where is Broca’s area located? Function of Broca’s area?
- Prefrontal cortex
2.Inferior part of dominant hemisphere (usually left) - Speech production
In the parietal lobe what is immediately posterior to the central sulcus? What is each hemisphere of the Parietal lobe responsible for?
Primary somatosensory cortex
Left- important for perception, mathematical and language operations
Right- important for visuospatial functions
Where does the parietal lobe extend to and from?
Central sulcus to the parietooccipital fissure
What structure is Immediately below the lateral sulcus in the temporal lobe? Where is the hippocampus located in the temporal lobe?
Primary auditory cortex
Inferiorly and Medially
Where is Wernicke’s area located?
Most superior and Posterior part of the dominant temporal lobe
What system includes the hippocampus, amygdala and Various parts of the cortex?
Limbic system
What is the process of mapping specific parts of the cortex’s to different parts of the body called?
Homunculus
What do the lateral and superior parts of the Cortex represent respectively?
Lateral- face and mouth
Superior- Upper limbs and torso
What does the most medial parts of the cortex represent?
Feet
What are the meninges?
Three layers of tissue that envelop the brain and spinal cord
What are the three layers of meninges from superficial to deep?
Why does the middle layer have its name?
1.-Dura
-Arachnoid
-Pia
2.Arachnoid- resembles a spiders wed
Which is the thickest meninges and which is the thinnest?
Dura is thickest and pia is thinnest (arachnoid in the middle)
What are the two layers of the Dura called? What does the inner layer do when it folds inwards?
- Outer endosteal layer
- Inner meningeal layer
Folds into brain to separate certain parts of the brain
What is the name of the double dura layer that separates:
1. Two cerebral hemispheres
2. occipital and cerebellum
3. Two cerebellum lobes
- Falx cerebri
- Tentorium cerebelli
- Falx cerebelli
What are the small spaces/ channels where the outer endosteal and inner meningeal layer are separate from one another?
What are they filled with?
Dural venous sinuses
Venous blood
What are the two sinuses that run in the sagittal plane? What does the second one lie on top of?
Superior and inferior sagittal sinuses
Lies on top of Corpus Callosum
What sinus forms when the falx cerebri connects to to the tentorium cerebelli? What sinus forms on both lateral aspects extending from the tentorium cerebelli?
- Straight sinus
- Transverse sinus
Which sinus connects the transverse sinus to the internal juguar vein?
Sigmoid sinus
Which sinus is this?
Transverse sinus (forms on both lateral aspects extending from the tentorium cerebelli)
Which sinus forms when the straight sinus meets the transverse and superior sagittal sinus’? Where is it found in the skull?
Confluence of sinuses
Most posterior aspect
What sinuses are found most anteriorly? What two structures is it to the side of? What important structure passes through it?
- Cavernous
- sphenoid bone and sella turcica
- Internal carotid artery and abducens
What is the space called between the arachnoid and the pia? What does it contain? What is it called when the arachnoid covers a gyri?
Subarachnoid space
Cerebrospinal fluid
Cisterns
As capillaries go into the brain what do their endothelial cells fuse with? What does this form
Fuse with the pia
forms blood-brain barrier
What are four specialised features of capillaries in the blood-brain barrier?
- Endothelial cells tightly bonded
2.basement membrane lacks fenestrations
3.pericytes wrap around endothelial cells
4.Astrocytes have projections called end feet that further wrap around capillaries
Which two arteries supply the brain? What do they form?
Internal carotid and vertebral arteries
Form the circle of willis
What % and parts of the brain do the internal carotid and vertebral arteries supply respectively?
Internal Carotid- 80% (rest of cerebrum and diencephalon)
Vertebral- 20% (posterior parts such as occipital lobe cerebellum and brainstem)
What direction is the circle of willis looking from? What does the formation of two vertebral arteries form? What arteries are given off by this artery formed?
Looking inferiorly
Basilar artery
Pontine arteries
What arteries form as a result of the basilar arteries bifurcating? What direction does it go?
Posterior cerebral arteries
Posteriorly
What arteries are the continuation of the Internal carotid arteries? What do they pass into?
- Middle cerebral arteries
- Pass into the lateral sulcus
What arteries branch of the internal carotid arteries? What is their course?
Anterior cerebral arteries
Pass anteriorly then wrap back towards the corpus callosum
Which artery joins the posterior cerebral artery to the middle cerebral arteries?
Which artery joins the left and right anterior communicating artery?
- Posterior communicating artery
- Anterior communicating artery
What are the three cerebellar arteries?
1.Anterior inferior cerebellar arteries
2.Posterior inferior cerebellar arteries
3.Superior cerebellar arteries
Which two parts of the brain Anterior cerebral artery supply?
What do these areas control?
- Medial aspects of the frontal and parietal lobes
- Strip of cortex on the superior aspect
3.Motor and somatosensory cortex responsible for lower limb
What part of the brain does the Middle cerebral artery supply?
What do these areas control?
1.Lateral and deep aspects of the hemispheres
2. Motor and somatosensory cortices for face, arms and trunks
Which two parts of the brain does the posterior cerebral artery supply?
Occipital lobe and small part of the inferior temporal lobe
What are the branches of the Basilar arteries called? What do they supply? What can damage to this artery result in?
- Pontine arteries
- The pons
- Loss of all motor function and sensation from the neck down
Other than the cerebellum what do the cerebellar arteries supply?
Parts of brainstem
What arteries make up the anterior and posterior circulation respectively?
two and three
Anterior- anterior and middle cerebral arteries
Posterior- Posterior cerebral, basilar and cerebellar arteries
What is the course of veins that venous blood flows?
First: internal cerebral veins
Second: External cerebral veins
Third: Dural Venous sinuses
What two routes can the Dural Venous sinuses drain blood into extracranial veins (veins outside the brain)?
- Sigmoid sinuses become Internal jugular veins and exit the skull
- Emissary veins cross the endosteal layer of dura and drain venous blood into the bones of the skull
What is the clinical relevance of the cavernous sinus and venous blood flow?
Venous blood draining from face can potentially drain into cavernous sinus, which could potentially allow superficial infection to get into intercranial structures.
What can superficial blood entering cavernous sinuses result in(2)?
What can the second one have an effect on?
Meningitis or thrombosis
Thrombosis can cause pressure on nerves in cavernous sinus
What is the Ventricular system of the brain? What is it filled with? What is it continuous with?
- Central Cavities within the brain
- CSF
- Subarachnoid space
Where is CSF produced? Where in the brain is this? What type of cells produce CSF?
- Lateral Ventricles
- Located within the cerebral hemispheres
- Choroid plexus
Where does CSF flow from out of the lateral ventricles? Where in the brain is this located? What structure does it go through?
Flows to the third ventricle which is in the midline and separates the diencephalon
Interventricular foramen
Where does CSF flow to from the third ventricle? What shape is this and where is it located? What structure does it pass through?
Fourth Ventricle
Diamond shape and posterior to brainstem
Passes through cerebral aqueduct
How does CSF travel from the ventricular system to the subarachnoid space around the spinal cord(1) and also around the brain (2)?
- Via the central canal
- Median aperture of Magendie (posteriorly)
- Lateral aperture of luschka (laterally)
What areas have larger pockets of CSF in the brainstem and diencephalon? How is CSF recycled into the bloodstream?
- Subarachnoid cisterns
- Recycled via arachnoid granulations
What are 9 structures that would need to be cut in order to get into the brain?
1.SKin
2. Fascia
3. Aponeurosis of scalp muscles
4. Connective tissue (fascia)
5. Periosteum (connective tissue that envelopes bone)
6. Skull
7. Dura Mater
8. Arachnoid mater
9. Pia mater
