Outcome 6 - Central Nervous System Flashcards
What are the two types of protection that the spinal cord has?
- vertebral column
- spinal meninges
What is the spinal meninges?
- three layers of connective tissue that surrounds the spinal cord for support and protection
What is the spinal cord structure?
- bone-vertebral column
- epidural space
- dura mater - meninx
- subdural space
- arachnoid mater - meninx
- subarachnoid space
- pia mater - meninx
- spinal cord
Is epidural space found between the dura mater and the brain?
Nope. Just between the dura mater and the spinal cord.
What are denticulate ligaments?
- extensions from the Pia mater into the arachnoid mater and the inner layer of the dura mater to protect it from displacement
- extension to adhere Pia mater to spinal cord as well
- located between the anterior and posterior nerve roots of each spinal nerve
What is the arachnoid mater?
it is the middle avascular layer of the spinal meninges made up of collagen and elastic fibres
Where is the starting point of the spinal meninge?
a hole in the occipital
Where does the spinal cord start and end?
medulla oblongata to L2
What is the epidural space?
it is the space between the bone and the dura mater and acts as protection for the spinal cord
What does the epidural space contain?
adipose tissue and blood vessels
What is the dura mater?
it is the thick, strong outer most layer of the meninges; forms a sac from the foramen magnum to S2
What is the dura mater made up of?
dense irregular connective tissue
What is the subdural space?
interstitial fluid-filled area between the first two layers of the spinal meninges
What is the difference between the dura mater of the cranial and the spinal cord?
cranial - two layers of dura mater
spinal - one
What are the two layers of the cranial dura mater called?
- periosteal layer (external)
- meningeal layer (internal)
What is the subarachnoid space?
CSF-filled space
What is the Pia mater?
thin, transparent inner most layer that is made up of interlacing collagen fibres and elastic fibres
What is significant about the Pia mater?
it adheres directly to the spinal cord and is very vascular
What is the filum terminale?
it is the extension of the Pia mater inferiorly to adhere the cord to the coccyx
Where are the 2 enlargements of the spinal cord found?
- cervical: C4-T1
- Thoracic: T9-T12
Where do nerves to the upper limbs originate on the spinal cord?
C4-T1
Where do nerves to the lower limbs originate on the spinal cord?
T9-T12
What is the conus medullaris? Where does it occur?
tapering of the cord - L1 and L2
What is the caudal equine?
the root of nerves extending from the end of the spinal cord
How many pairs of spinal nerves are there? What is the breakdown of the spinal nerves?
31.
cervical - 8 pairs
Thoracic - 12 pairs
Lumbar - 5 pairs
Sacral - 5 pairs
coccygeal - 1 pair
What is the gray commissure?
the cross of the “H”
- has the central canal that is filled with CSF
- extends the length of the cord + superiorly into the 4th ventricle
What are the 4 major parts of the brain?
- cerebrum
- cerebellum
- diencephalon
- brain stem
What makes up the cerebrum?
2 hemispheres
What makes up the cerebellum?
2 hemispheres
What makes up the diencephalon?
thalamus, hypothalamus and the epithalamus
What makes up the brain stem?
midbrain, pons, and medulla oblongata
What is the structure of cranial meninges?
- cranium (bone)
- 2 layers of dura mater WITHOUT epidural space
- subdural space
- arachnoid mater
- subarachnoid space
- pia mater
- brain tissue
What are the three extensions of the dura mater within the cranium?
- falx cerebi - separates the two cerebral hemispheres
- falx cerebelli - separates the two cerebellar hemispheres
- tentorium cerebelli - separates the cerebrum and the cerebellum
Where does the inferior portion of the brain stem start and end?
at the foramen magnum to the pons
What is the desuccation of the pyramids?
when 90% of the tract crossing over to the other side; occurs right before medulla oblongata joins the spinal cord
What is the medulla oblongata responsible for?
controlling vital reflex functions such as heart beat + contraction strength, resp rate, coughing, sneezing, swallowing, hiccuping and vomiting
What is the pons responsible for?
- acts as a bridge between cerebellum and other parts of the brain
- helps control breathing (contains the pontine respiratory group)
What is the cerebral aqueduct?
it is situated in the midbrain
- where the csf flows from the 3rd ventricle to the 4th ventricle
What is the midbrain responsible for?
- reflex enters for visual an auditory activities and helps control muscle activities
How is the cerebellum and cerebrum separated?
by the transverse fissure
What is the superficial layer of gray matter called in the cerebellum?
cerebellar cortex
What is the deeper white matter called in the within the arbor vitae?
cerebellar nuclei
What is the arbor vitae?
tracts of white matter deep to the gray matter in the cerebellum
What are the 2 major functions of the cerebellum?
- learning and performing rapid, coordinated, highly skilled movements
- maintain posture and balance
What does the diencephalon do?
it connects the brainstem to the cerebrum
What are the three parts of the diencephalon?
- thalamus (~80%)
- epithalamus
- hypothalamus
What is the interthalamic adhesion?
it is the bridge of gray matter that joins R and L halves
What does the thalamus do?
it is the relay station for impulses that travel throughout the brain
What does the hypothalamus do?
it controls and integrates activities of the ANS-major regulator of homeostasis
- hormone production and regulation, body temp, emotional and behavioural patterns, regulation of eating, thirst and circadian rhythms
What is the hypothalamus composed of?
12 nuclei in four major regions
What are the 4 major regions of the hypothalamus?
- mammillary
- puberal
- supraoptic
- preoptic
What are the 2 components of the epithalamus?
- pineal gland
- habenular nuclei
What does the pineal gland do?
secretes melatonin
What does the habenular nuclei do?
it is involved in olfaction — emotions related to smells
What is the cerebrum?
it is the largest part of your brain that allows you to read, write, calculate, speak, remember, plan and imagine!
What is the longitudinal fissure?
it is the type of deep grooves that separates the cerebral hemispheres
What are the 3 parts of the cerebrum?
- cerebral cortex
- cerebral white matter
- basal nuclei
What do you call the folded ridges in the cerebrum?
GYRI
What are the shallow grooves between gyri called?
SUCLI
What are the deep grooves between gyri called?
fissures
What does the cerebral cortex do?
it processes sensory information, execute voluntary motor movements and deal with complex integrative functions
What is the cerebral white matter?
internal region of the cerebrum that conducts nerve impulses between different areas of the cerebrum (including between gyri) and lower parts of the CNS
Where do you find the basal nuclei?
it is deep within the white matter of the cerebrum
What role does the basal nuclei do?
- it plays a primary role in motor function (initiation of movements, suppression of unwanted movements, regulation of muscle tone)
- also help initiate and terminate some cognitive processes (attention, memory, and planning)
What does the corpus callosum do?
bridge that allows for the communication between the right and left hemisphere
What does the internal capsule do?
it allows for the communication between superior and inferior parts of the brain
What are the association tracts?
it is the ridges on the cerebral cortex – it runs from gyri to gyri
What are the 4 lobes in each hemisphere?
- frontal
- parietal
- temporal
- occipital
What is the insula?
It is the 5th part of the brain and lies within the lateral cerebral sulcus
What are the 3 sulci? What lobes do they separate?
- parieto-occipital sulcus - parietal + occipital
- central sulcus - parietal + frontal
- lateral cerebral sulcus - temporal + frontal
What is the basal nuclei also known as?
corpus striatum
What are the 3 groups of nuclei that make up the basal nuclei?
- caudate nucleus
- globus pallidus
- putamen
What basal nuclei make up the lentiform nucleus?
globus pallidus + putamen
What are some disorders that arise from the degeneration of the basal nuclei or the tracts that link them with other areas of the brain?
parkinson’s, Huntington, Tourettes, schizophrenia, OCD
What is the limbic system?
the “emotion brain”
plays a role in emotion, smell and memory
Where do you find the limbic system?
it encircles the upper part of the brain stem and corpus callosum
Where are most of the sensory area found in the cerebral cortex?
posterior to the central sulcus
Where do you find the motor area in the cerebral cortex?
anterior to the central sulcus
What is the difference between the Broca’s area and wernicke’s area?
broca = speech
wernicke - interpreting speech and translating words into thoughts; adding emotions into your speech
What area is found on the insula?
the gustatory and olfactory cortex
What is hemispheric lateralization?
functional differences between the hemispheres
Why does the brain suffer permanent injury if blood flow stops for >4 minutes?!
there isn’t any glucose stored in the brain
What is the difference between a stroke and TIA?
TIA - symptoms can resolve within a few minutes to 24 hours
How does the brain get blood?
- internal carotid arteries
- vertebral arteries
What three arteries splits from the internal carotid arteries?
- anterior cerebral arteries
- middle cerebral arteries
- posterior communicating arteries
What is the Circle of Willis?
vertebral arteries (2) –> basilar artery (1) –> posterior cerebral arteries (2) –> posterior communicating arteries (2) –> internal carotid arteries (2)/middle cerebral arteries (2) –> anterior cerebral arteries (2) –> anterior communicating artery (1)
Why is the circle of willis so important?
collateral circulation
Veins in the brain have no muscle tissue and no valves. T/F
True.
What pathway does brain brain blood drainage?
blood drains into dural venous sinuses –> internal jugular veins
What is the purpose of the blood brain barrier?
it protects the brain from pathogens by preventing substances from passing from the blood into the brain tissue
What are the three things that help the BBB with its purpose?
- tight junctions to seal and prevent leaks
- thick basement membrane to surround the capillaries to prevent leaks
- astrocytes secrete chemicals to maintain permeability of tight junctions
What passes through the BBB?
- lipid-soluble solutions can EASILY pass through (ex. alcohol, O2, CO2, anaesthetics)
- few water-soluble substances (such as glucose by facilitated transport)
What CANNOT get through the BBB?
proteins and antibiotics
What diffuses very slowly in the BBB?
substances like urea, creatinine and ions
What are the 3 T’s that disrupt the BBB?
- Trauma (inflammation)
- Tumors
- Toxins
NM + BBB
________ can’t pass through while _______ can pass through.
can’t = hydrophilic (water soluble)
can = lipophilic (lipid soluble)
Describe the CSF.
- It is a clear, colourless liquid.
- it protects the brain from chemical and physical injury.
- carries small amounts of O2 and glucose and other nutrients from blood to neurons and neuroglia.
What is the normal volume of CSF in an adult?
~80-150 mL
What is found in the CSF?
- glucose
- proteins
- lactic acid
- urea
- cations (Na+, K+, Ca2+, Mg2+)
- anions (Cl-, HCO3)
- WBCs
What are the 4 CSF filled cavities?
1/2. lateral ventricle
3rd ventricle
4th ventricle
Where do you find the CSF filled cavities (ventricles)?
1/2 - Lateral ventricles are found in each hemisphere of the cerebrum
3 - along the midline/between the R/L halves of the thalamus
4 - between the brain stem and cerebellum
What is the septum pellucidum?
a thin membrane that separates the two lateral ventricles
What are the 3 CSF function?
- mechanical protection - shock absorber
- chemical protection - perfect environment for neural signalling
- circulation - transport of nutrients and waste
What is the choroid plexuses?
it is a network of blood capillaries in the walls of the ventricles covered by ependymal cells
- responsible for CSF production
What is the blood-cerebrospinal fluid barrier?
ependymal cells – materials entering CSF can’t leak between cells they have to go through the ependymal cells to filter the plasma
What is the CSF circulation?
- formed in the chord plexuses of lateral ventricle
- flows in the 3rd ventricle through inter ventricular foramina (2)
- more CSF added by chord plexus of 3rd ventricle
- flows through the aqueduct of the midbrain into 4th ventricle
- choroid plexus of 4th ventricle contributes more fluid
- CSF enters subarachnoid space through 3 openings of 4th ventricle (1 median aperture + 2 lateral apertures)
- CSF circulates in the central canal + subarachnoid space (spinal cord); CSF circulates in the subarachnoid space of the brain
- CSF absorbed into blood through arachnoid villi that is projected into the dural venous sinuses
What is the normal absorption/production of CSF?
20 ml/hr
