The Brain And Spinal Cord Flashcards
The central nervous system encompasses what?
- The brain
- The spinal cord
- Cavities (containing cerebrospinal fluid)
- Nerves
The brain is enclosed by what?
White matter and grey matter
The brain can be divided into three main sections, what are they?
- Cerebrum
- Cerebellum
- Brain stem
What is white matter?
- Composed of nerve axons, which are covered in myelin
What does axons do?
Carry the nerve impulses between neurons
What is Grey matter?
Composed of nerve cell bodies which is unmyelinated.
The nerve cell bodies of the grey matter are what?
Control centres
The route sensory and motor stimuli of grey matter do?
Creates a response
What is the cerebrum?
Largest part of the brain
How do we divide the cerebrum?
Into left and right hemispheres
The hemispheres are connected in the midline by what?
Corpus callosum
The hemispheres are separated from one another by what?
Fall cerebri
Each hemisphere can be divided into what?
Another 4 lobes
The cerebrum consists of what materials?
Both white and grey matter
Where does the grey matter lie in the cerebrum?
The Cortex and basal nuclei
Where does the white matter lie in the cerebrum?
Lies deep in the cortex
What are the four cerebral lobes?
- Frontal lobe
- Parietal lobe
- Occipital lobe
- Temporal lobe
The cerebrum has numerous what?
Folds and grooves
What are gyri?
Small folds
What are sulci?
Shallow grooves
What are fissues of the cerebral?
Deep grooves, booth longitudinal and lateral
What is the corpus callosum?
- Bundle of white matter located in the midline
- Connection between R and L cerebral hemispheres
- Forms the roof of the lateral ventricles
What are the basal nuclei or ganglia?
- Distinct regions of grey matter deep (Deep within we have cerebral white matter)
- Relay stations for sensory stimuli
Where does the basal nuclei or ganglia lie?
Adjacent to lateral ventricles
What is included in the basal nuclei or ganglia?
- Caudate nucleus
- Lentiform nucleus (includes the putamen and globes pallidus)
What is the thalamus?
- Ovoid masses of grey matter
- At the base of cerebral hemispheres
- Relay station for nerve impulses
Where is the R and L thalami located?
On either side of the 3rd ventricle
1. Form the lateral walls of the third ventricle
2. Massa intermedia
What is the massa intermedia?
- Tissue bridge between right and left thalamus
- Passes through the third ventricle in the midline
What is the brain stem?
- Connects the brain to the spinal cord
- Controls vital function such as breathing and heart rate
What are the major parts of the brain stem?
- Midbrain
- Pons
- Medulla oblongata
What is the midbrain?
- Superior and smallest portion of the brain stem?
- Located superior to the pons
- Surrounds the cerebral aqueduct
What are the Pons?
- Prominent anterior bulge
- Between midbrain and medulla oblongata
- “Bridge” between cerebrum and cerebellum
- Forms Anterior wall of the fourth ventricle
What does the Pons do?
Controls involuntary functions
1. Sleep
2. Hearing
3. Balance
What is the medulla oblongata?
- Inferior portion of brain stem
- Extends from pons to foramen magnum
- Continuous with the spinal cord
What does the medulla oblongata do?
Regulates vital functions
1. Heart rate
2. Respiratory rhythm
3. Blood pressure
4. Breathing
Where is the cerebellum located?
- Right and left hemispheres
- Sits posterior to the pons and medulla oblongata
- Forms the posterior wall of fourth ventricle
What does the cerebellum do?
Centre for motor functions
What is the tentorium cerebelli?
Separates the cerebrum and cerebellum
What is the vermis?
- Midline structures
- Connects the two hemispheres of the cerebellum
What is the cerebella peduncles?
- Nerve tracts that connect the cerebellum to other parts of the brain stem
- Superior, middle, and inferior
What are the ventricles?
- Fluid filled cavities in the brain
- Production and pathway of CSF
What are the parts of the ventricles?
- Right and left lateral ventricles
- 3rd ventricle
- 4th ventricle
All four ventricles are what?
Interconnected by channels
What is Cerebrospinal fluid?
- Clear, colourless fluid
- Produced by choroid plexus of ventricles
- Acts as protective cushion
- Provides buoyancy to support weight of brain
Where does CSF drain into?
Into the blood via rural sinuses
Where does CSF circulates?
Subarachnoid space
What are the lateral ventricles?
- Paired
- Largest in size
- C shaped
- Located within each cerebral hemisphere
Each one of the lateral ventricles is positioned where?
- Lateral to the midline
- Separated medically by septum pellucidum
- Communicates with the third ventricle
What are some features of the lateral ventricles?
- Body
- Horns
- Trigone or atria
- Interventricuar foramen
What is the body of the lateral ventricles?
Central portion of the lateral ventricle
What are the horns of the lateral ventricles?
- Frontal/ Anterior
- Occipital/ Posterior
- Temporal/ inferior
What are the trigone or Arita of the lateral ventricles?
Triangular area of body connected to all horns
What is the interventricular foramen of the lateral ventricles?
Channeled between each lateral ventricle and 3rd ventricle
What is the Cavum septum pellucidum?
- Thin, triangular membrane
- Midline, inferior to the corpus callosum
What does the cavum septum pellucidum do?
Separates medial walls of lateral ventricles
What is the choroid plexus?
- Lines areas within each ventricle
- Produces supply of CSF
Where is the choroid plexus located?
- On the floor of the lateral ventricles
- On the roof of the 3rd ventricle
- Posterior wall of the 4th ventricle
What is the third ventricle?
- Midline, slit like cavity
- Sits inferior to the lateral ventricles
- Lateral walls are formed by the right and left thalami
Where does the massa intermedia of the thalamus run?
Through the third ventricle
What is the cerebral aqueduct?
- Connection between the third and fourth ventricles
- The aqueduct extends posterior from the third ventricle
What is the fourth ventricle?
- Located inferior and posterior to the third ventricle
- Diamond shaped cavity
- Located anterior to the cerebellum and posterior to the pons
How is the fourth ventricle drained?
Three channels drain it
What is the foramen of magendie?
- Single, posterior, midline opening
- Connects fourth ventricle to the spinal cord
What is the foramen of luschka?
2 lateral openings
All three openings in the fourth ventricles communicate how?
Within the subarachnoid space
What are the meninges?
Three distinct membranes that cover the brain and spinal cord
What are the functions of the meninges?
- Protect the neural cells
- Provide support for vessels
- Creates venous sinuses in the head
- Form partitions in the brain
- Allows for circulation of CSF
What are the layers of the meninges?
- Dura matter (outer)
- Arachnoid (middle)
- Pia matter (Inner)
What is the dura matter?
- Strong out covering
- Double layered membrane
What are the two layers of the dura matter?
- Periostea layer
- Meninges layer
What is the periostea layer?
Adheres to the bone
What is the Meningeal layer?
Adheres to the brain and spinal cord
What lies inferior to the dura matter?
Subdural space
What are some associated features of the dura mater?
- Dura partitions
- Dura venous sinuses
What are three dura mater partitions?
- Falx cerebri
- Falx cerebelli
- Tentorium Cerebelli
What is the Falx cerebri?
- Projects inward between cerebral hemispheres
- Along longitudinal fissures
What is the Falx Cerebelli?
- Separates cerebellar hemispheres
- Inferior and posterior to Falx cerebri
What is the tentorium cerebelli?
- Horizontal fold in transverse fissure
- Separates cerebrum and cerebellum
What are the dura venous sinuses?
Dural layers separate along fissure to form sinuses
Where are some major dural sinuses?
- Superior sagittal
- Inferior sagittal
- Straight
- Transverse
- Sigmoid
What are the jugular veins?
Blood from venous sinuses returns to the heart via the internal jugular vein
What is the arachnoid layer?
- Middle layer of the meninges
- Cobweb appearance
What does the Arachnoid villi or granulations do?
- Outgrowths of arachnoid mater penetrate the dura
- Outgrowths project into the venous sinuses
- Allow for reabsorption of fluid into the venous system
What is the subarachnoid space?
- Important area for the circulation of CSF
- Surrounds both the brain and the spinal cord
- Receives CSF from ventricles
Where does the subarachnoid space lie?
Between the arachnoid and pia layers
What are Cisterns?
- Widened ares located within the subarachnoid space
- Pools of CSF
- Located mainly at the base of the skull
What is the cisterna Magna
- Largest pool
- Continuous with the spinal space
What is the Pia mater?
- Delicate connective tissue
- Adheres to surface of brain
- Membrane sfollow brain contour
- Highly vascular
What the two main arterial routes from the heart to the brain?
- Internal carotid arteries
- Vertebral arteries
What is the internal carotid arteries?
- Branches of the common carotid arteries
- Take a tortourus route within the brain
- Connect with the middle cerebral arteries
What are the vertebral arteries?
- Branches off the subclavian arteries
- Ascend cranial through the transverse foramina of the vertical spine
- Enter the skull through the foramen magnum
- Unite to form the basilar artery in the posterior of the brain
What is the circle of Willis?
- Arterial circle of major vessels at the base of the brain
- Unites anterior and posterior arteriosclerosis blood supplies
- Collateral blood flow between hemispheres
- Allows continuous flow to brain in cases of damage in one area
What are the parts of the circle of Willis?
- Posterior cerebral arteries (R and L)
- Posterior communicating arteries (R and L)
- Middle cerebral arteries (R and L)
- Anterior Cerebral Arteries (R and L)
- Anterior communicating artery (1)
What is the posterior cerebral arteries (R and L)?
Branch from basilar artery
What is the Posterior communicating arteries (R and L)?
Run between the posterior cerebral arteries and middle arteries
What is the middle Cerebral Arteries (R and L)?
Branch from the internal carotid arteries
What is the anterior Cerebral Arteries (R and L)?
Bilateral anterior arteries
What is the Anterior communicating arteries (1)?
- Single midline artery
- Connects the R and L anterior cerebral arteries
What is the spinal cord?
- Nerve cable
- Continuation of the brain medulla
- Extends down to the level of L2
- Cords tapers distally
What is associated with each vertebra?
Nerves
What are some features of the spinal cord?
- Conus medullaris
- Cauda equine
- Film terminals
- Denticulate ligaments
What is the conus medullaris?
- Distal tapering of cord
- Tip should never be below L2
What is the cauda equina?
- Nerve bundles inferior to Conus medullaris
- Horses tail appearance
What is the film terminale?
- Slender strand from conus medullaris to coccyx
- Anchors cord