Neuro Flashcards
What are the four main bones that make up the skull?
Frontal
Parietal
Temporal
Occipital
What are the 3 main cranial sutures of the skull?
Coronal suture (Bregma) Sagittal suture Lambdoid suture (lambda)
What are the three separate parts of the cranial base?
Anterior- alveolar arches of maxilla to posterior edge of hard palate
Middle- posterior edge of hard palate to anterior edge of foramen magnum
Posterior- behind middle part
What are some key features of the internal roof of the Calvaria?
Blood vessel imprints - MMA
Foramina for emissary veins
Groove for superior Sagittal sinus
Granular pits
What is the brain?
The brain is a bilateral structure (i.e. anatomically symmetrical), with some lateralisation of function with some aspects of its modality
What is the orientation of the brain?
Its orientation can be broken down into rostral and caudal, due to the embryological development of the brain
Forebrain orientation differs from brain stem orientation due to embryological development
Describe the cerebrum
The cerebrum includes the cerebral hemispheres (and the basal ganglia), separated by the falx cerebri within the longitudinal cerebral fissure, which are the dominant features of the brain.
Each cerebral hemisphere is made up of four lobes (corresponding to the overlying bones), frontal, temporal, parietal and occipital.
What are gyri?
Ridges or elevations in cerebral cortex
What are sulci?
Grooves or depressions in cerebral cortex
What are fissures?
Major sulci (grooves or depressions) in cerebral cortex
What is the frontal lobe and it’s importance?
Frontal lobe, which lies anterior to the central sulcus and extends inferiorly to the lateral sulcus; medially, the frontal lobe also extends to the corpus callosum. The most prominent structure of the frontal lobe is the precentral gyrus (bounded by central and precentral sulci), which has an important role in motor function. Contains Broca’s area, important for speech.
What is the parietal lobe and it’s importance?
Parietal lobe, which houses the functions that perceive and process somatosensory events, extends posteriorly from the central sulcus to the parieto-occipital sulcus. The parietal lobe contains the postcentral gyrus, bordered by the central sulcus and postcentral sulcus, which acts as the primary receiving area of somatosensory information from the periphery. The remainder of the parietal lobe can be divided into two sections, by the interparietal sulcus, into supramarginal gyrus and the angular gyrus. Wernicke’s area is found in the ventral aspect of these gyri and is vital for comprehension of spoken language.
What is the temporal lobe and it’s importance?
Temporal lobe which is separated via the transverse lateral sulcus and is vital in the perception of auditory signals. It consists of superior, middle, and inferior temporal gyri.
What is the occipital lobe and it’s importance?
Occipital lobe which is separated from the parietal and temporal lobes by the parieto-occipital sulcus. Involved in vision.
Describe the thalamus
The thalamus forms the central core of the brain. It is responsible for relaying and integrating information to different regions of the cerebral cortex from a variety of structures associated with sensory, motor, autonomic, and emotional processes.
Part of diencephalon
Describe the hypothalamus
The hypothalamus lies ventral and anterior to the thalamus and regulates visceral functions (temperature, endocrine functions, feeding, drinking, emotional states, and sexual behaviour) and links to the pituitary gland at the base of the brain.
Part of diencephalon
Describe the cerebellum
The cerebellum plays a vital role in integration, regulation, and co-ordination of motor processes. It contains two symmetrical hemispheres that are continuous by a midline structure (called the vermis), and the hemispheres are divided into anterior, posterior, and flocculonodular lobe, all of which vary in the inputs they receive.
Involved in balance, coordination and speech.
What are the three main parts of the brainstem?
Midbrain
Pons
Medulla (oblongata)
Describe the midbrain
The midbrain is involved in relaying information for vision and hearing. It is found caudal to the pons and rostral to the diencephalon (thalamus, hypothalamus etc.); it is composed of the tectum (which contains the superior and inferior colliculi) and the cerebral peduncle (which contains the substantia nigra). CNIII and CNIV are associated with the midbrain.
Describe the pons
The pons lies caudal to the medulla, rostral to the midbrain, and ventral to the cerebellum. It contains tracts passing through it as well as numerous nuclei for functioning in sleep, respiration, bladder control, and many others. CNV is associated with the pons.
(CNVI-VIII are associated with the junction of the pons and medulla)
Describe the medulla oblongata
The medulla oblongata controls autonomic function (such as respiration, cardiac centre and baroreceptors, and vomiting, coughing, sneezing, and swallowing centres) and connects the higher levels of the brain to the spinal cord. It is found rostral to the pons.
The pyramids of the descending fibres can be seen in the medulla, on the anterior surface; the medulla contains all the ascending and descending tracts of the CNS. The inferior olivary nucleus is found on the rostral half of the medulla and is important in relaying information from the spinal cord and other regions of the brainstem to the cerebellum. CNIX, X and XII
(CNVI-VIII are associated with the junction of the pons and medulla)
What are the basal ganglia?
Basal Ganglia play an important role in the regulation and integration of motor functions. (ADD TO LATER)
What is the precentral gyrus?
Elevation of the frontal lobe of the brain, in front of the central sulcus, involved in motor functions
What is the postcentral gyrus?
Elevation of the parietal lobe of the brain, behind the cental sulcus, involved in sensory functions
What is the central sulcus?
Groove/depression found between the frontal and parietal lobe of the brain. Separates precentral (motor) and postcentral (sensory) gyri.
What is the lateral fissure/sulcus?
Groove/depression found between the frontal and temporal lobes of the brain
What is the cingulate gyrus?
Elevation of the cerebral cortex around the corpus callosum
What is the Limbic system of the brain?
The limbic system (or paleomammalian brain) is a complex set of brain structures located on both sides of the thalamus, right under the cerebrum. It is not a separate system but a collection of structures from the telencephalon, diencephalon, and mesencephalon. It includes the olfactory bulbs, hippocampus, amygdala, anterior thalamic nuclei, fornix, columns of fornix, mammillary body, septum pellucidum, habenular commissure, cingulate gyrus, parahippocampal gyrus, limbic cortex, and limbic midbrain areas.
What are the brain ventricles?
Communicating network of cavities filled with cerebrospinal fluid (CSF) 2 lateral ventricles Third ventricle Cerebral aqueduct Fourth ventricle
The ventricular system is embryologically derived from the neural canal, forming early in the development of the neural tube. The 3 brain vesicles (prosencephalon or forebrain, mesencephalon or midbrain, and rhombencephalon or hindbrain) form around the end of the first gestational month. The neural canal dilates within the prosencephalon, leading to the formation of the lateral ventricles and third ventricle. The cavity of the mesencephalon forms the cerebral aqueduct. The dilation of the neural canal within the rhombencephalon forms the fourth ventricle.
The lateral ventricles communicate with the third ventricle through interventricular foramens, and the third ventricle communicates with the fourth ventricle through the cerebral aqueduct (see the image below). During early development, the septum pellucidum is formed by the thinned walls of the 2 cerebral hemispheres and contains a fluid-filled cavity, named the cavum, which may persist.
Tufts of capillaries invaginate the roofs of prosencephalon and rhombencephalon, forming the choroid plexuses of the ventricles. Cerebrospinal fluid (CSF) is secreted by the choroid plexuses, filling the ventricular system. CSF flows out of the fourth ventricle through the 3 apertures formed at the roof of the fourth ventricle by week 12 of gestation.
Where are the lateral ventricles derived from?
Prosencephalon- telencephalon
Where is the 3rd ventricle derived from?
Prosencephalon- diencephalon
What is the cerebral aqueduct derived from?
Mesencephalon
What is the fourth ventricle derived from?
Rhombencephalon- metencephalon and myelencephalon
Describe the spinal cord
The spinal cord forms as a continuation of the brainstem, at the medulla. It is around 42-45cm long and extends from the foramen magnum to around the L2 level, where it tapers as the conus medullaris. As a result, the spinal cord occupies only the superior two-thirds of the vertebral canal.
Where are the enlargements of the spinal cord and why?
The spinal cord is enlarged in two regions:
· The cervical enlargement extends from C4 to T1 segments, with most of the anterior rami at this region form the brachial plexus
· The sacral enlargement extends from T11 to S1 segments of the spinal cord (i.e. inferior to the conus medullaris), with most of the anterior rami at this region forming the lumbar and sacral plexuses of nerves.
How does the spinal cord differ in the embryo? How does this give rise to the cauda equina and filum terminale?
In embryos, the spinal cord occupies the full length of the vertebral canal, so the spinal nerves pass out laterally to exit the corresponding IV foramina. Yet during the foetal period, the vertebral column grows faster than the spinal cord so appears to ascend; at birth, the tip of the conus medullaris is at L4-L5 level and gradually ascends until it lies at L2 level in adults. The lumbar and sacral nerve roots are therefore the longest, extending beyond the termination of the cord at L2 level, in order to reach the remaining lumbar, sacral, and coccygeal IV foramina. This group of nerve roots running in the lumbar cistern is known as the cauda equina.
The filum terminlae is a remnant of the caudal part of the spinal cord of the embryo and descends amongst the cauda equina. It attaches to the dorsum of the coccyx, acting to anchor the inferior end of the spinal cord and spinal meninges.
What is cauda equina syndrome?
Cauda Equina Syndrome results from dysfunction to the lumbar and sacral nerve roots in the lumbar vertebral canal, affecting the cauda equina. Cauda equina syndrome presents with dysfunction of the bladder, bowel, or sexual function, and sensory changes in saddle or perianal area, as well as potential back pain (with or without sciatic-type pain), sensory changes or numbness in the lower limbs, lower limb weakness, reduction or loss of reflexes in the lower limbs , or unilateral or bilateral symptoms.
Whilst it is commonly caused by large central IV disc herniation at L4/5 or L5/S1 level, it can also be caused by tumours, direct trauma, spinal stenosis, or inflammatory disease. It is a medical emergency as if left untreated, patients can be left incontinent, affects motor function, and many other possible complications. Treatment is treating the underlying cause.
How are dural compartments formed?
Dura mater sends inward reflections into the cranial cavity, dividing the cavity into freely communicating spaces, and securing the brain in place restrict displacement of brain in acceleration/ deceleration when head is moved
What is the falx cerebri?
The falx cerebri, also known as the cerebral falx, so named from its sickle-like form, is a strong, arched fold of dura mater that descends vertically in the longitudinal fissure between the cerebral hemispheres. It divides the supratentorial compartment into left and right.
It is narrow in front, where it is attached to the crista galli of the ethmoid; and broad behind, where it is connected with the upper surface of the tentorium cerebelli.
What is the tentorium cerebelli?
The tentorium cerebelli is an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes. It divides the cranial cavity into the supra and infra tentorial compartments.
What are the three neuronal classes?
Afferent neurones- arise from sense organs, axons diverge in the CNS onto other neurones
Efferent neurones- cell body in CNS upon which other nerve cells converge
Inter neurones- ~99% neurones entirely within the CNS (some exceptions in autonomic) - integrate input with output
What are some examples of glial cells found in the CNS?
Astrocytes
Oligodendrocytes
Ependymal cells
Microglial cells
Describe neurulation and the notochord
The notochord forms when a solid core of cells formed by prenotochordal cells migrate from the primitive pit cephalically, acting to form the midline and driving neurulation. Neurulation is initiated whereby the overlying ectoderm differentiates to form the neural plate; the neural plate thickens and its lateral edges rise up and the midline depresses (the neural groove). The lateral edges approach each other at the midline, fusing to form the neural tube.
The fusion of these neural folds themselves starts at the cervical region. The fusion then spreads cephalically and caudally, producing neuropores anteriorly and posteriorly. The anterior neuropore closes on day 25 and the posterior neuropore closes on day 28, yet any defect in their closure can cause serious neural tube defects (NTDs).
What is spina bifida?
- Spina Bifida is failure in the caudal neuropore fusion. Whilst it can occur anywhere along the along its length, it nearly always occurs in the lumbosacral region. Neurological deficits occur, yet rarely associated with mental retardation; hydrocephalus nearly always occurs (this is due to the lengthening of the vertebral column, causing the cerebellum to be pulled into the magnum foramen, cutting off the CSF). Two main types of spina bifida can occur:
· Spina bifida occulta is a defect in the vertebral arches whereby there is a lack of fusion of the vertebral arches
· Spina bifida cystica is a severe NTD whereby neural tissue and / or meninges protrude through the skin to form a cyst like sac. If only fluid-filled meninges are in the sac, it is termed meningocele, whereas if neural tissue is in the sac, it is termed meningomyelocele.
What is anencephaly?
Anencephaly is failure of the cranial neuropore to close properly, resulting in an absence of brain structures, including the brain, so is incompatible with life.
What is rachischisis?
- Rachischisis occurs when the neural folds do not elevate but remain as a flattened mass of neural tissue.
How can NTD’s be diagnosed and prevented?
Neural tube defects can be detected through raised serum α-fetoprotein or on USS. Increased folate intake in first trimester has been to reduce incidence by 70%.
How does the spinal cord develop?
Most of the length of the neural tube goes to forming the spinal cord. At 3 months, the spinal cord is the same length as the vertebral column yet thereafter the vertebral column grows faster. Consequently, the spinal roots themselves must elongate to exit their original intervertebral foramina.
How does the brain develop?
During neural fold formation, three primary brain regions can be distinguished, known as the forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalom). As the neural tube closes at the end of the fourth week, these dilations at the cranial end become three primary vesicles; by 5 week development, 5 secondary brain vesicles have formed, known as the telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon. Each of these form mature derivatives.
What are the mature derivatives of the telencephalon?
Cerebral cortex
Basal ganglia
Hippocampus
Amygdala
What are the mature derivatives of the diencephalon?
Thalamus
Hypothalamus
What are the mature derivatives of the mesencephalon?
Tectum
Tegmentum
What are the mature derivatives of the metencephalon?
Pons
Cerebellum
What are the mature derivatives of the myelencephalon?
Medulla
How do the flexures develop?
The cranial end of the neural tube undergoes such rapid enlargement that it rapidly exceeds the available space, so consequently begins to fold up. A cervical flexure is seen at the spinal cord hindbrain junction and a cephalic flexure at the midbrain region. Consequently, the neuraxis does not remain straight and leads to the production of ‘caudal’ and ‘raustral’ ends.
How do the ventricles of the brain develop?
In the adult, the ventricular system act as a reservoir of CSF (produced by cells of ventricular lining), acting to cushion the brain and spinal cord within their bony cases. They develop from the neural tube lumen, which persists to form the 5 vesicle stage system.
Hydrocephalus is mostly common in newborns suffering from spina bifida. It can result if there is blockage of the ventricular system or impaired absorption of CSF fluid
How do neural crest cells mature?
Cells of the lateral border of the neuroectoderm tube become displaced and enter the mesoderm and undergo epithelial to mesenchymal transition. They have an input in a large number of different structures’ development, such as adrenal medulla, Schwann cells, or C cells of the thyroid gland. Neural crest cells are vulnerable to ‘environmental insults’, especially alcohol.
What cells produce CSF?
Choroid plexus cells of the lining of the ventricles
What is Hirschsprung’s Disease?
- Hirschsprung’s Disease (or congenital aganglionic megacolon) is a disorder of the gut which is caused by the failure of the neural crest cells to migrate completely during fetal development of the intestine. The affected segment of the colon fails to relax, causing an obstruction.
What are the two broad systems that the nervous system is made up of?
Central nervous system
Peripheral nervous system
What are the proportion of cells in the CNS?
Neurones from a small proportion
Glial cells make up 50% +
Ratio of about 10:1 glial cells to neurones
What are the three main types of glial cells that have been identified?
Astrocytes
Oligodendrocytes
Microglia
What are the general functions of glial cells in the body?
Provide structural support to neurones
Nourish neurones
Insulate neurones
Remove waste of neurones
What are astrocytes also known as?
Supporter cells
What are the 5 main functions of astrocytes?
Provide structural support Provide nutrition for neurones Remove neurotransmitters Maintain an ionic environment Help form the blood brain barrier
How do astrocytes provide nutrition for neurones?
Neurones cannot produce or store glycogen and thus require a constant supply of glucose.
Neurones can receive some glucose and lactose via a direct path from endothelium to the neurone but would not be sufficient alone.
Astrocyte surrounding the neurone provide a direct source of either glucose or lactose to be transferred to the neurone- allows for an additional source of energy (from the lactate) for the neurone and during any ischaemia the neurone has a store of lactose of about 5 minutes
Astrocyte functions via glucose-lactate shuttle where glucose/lactate produced or stored within the Astrocyte is shuttled from the Astrocyte into the neurone- so any area of the brain with high energy consumption can receive adequate additional energy via this system
How do astrocytes remove neurotransmitters?
Astrocytes contain transporters specific for neurotransmitters such as glutamate, which can remove the neurotransmitter following an AP, allowing extracellular concentrations of that neurotransmitter to remain low.
Glutamate can then be recycled back via the astrocytes by converting them to glutamine.
Maintaining of a low concentration allows for minimal glutamate spread to other receptors of other neurones and preventing any excessively high concentration of glutamate which can be toxic.
How do astrocytes help to maintain an ionic environment?
A high extracellular K+ concentration around a neurone can result in its depolarisation.
Consequently astrocytes remove K+ ions from the extracellular fluid to keep this ECF concentration low - so as a result astrocytes have a very negative resting membrane potential due to their high intracellular potassium levels (-85 - -90mV)
What are Oligodendrocytes also known as?
Insulators
How do Oligodendrocytes insulate?
They are responsible for the myelination of the neurones within the CNS.
They contain numerous processes that extend out and allow for the myelination of multiple neurones.
The ‘Schwann cells’ of the CNS.
What are microglia also known as?
Immune response cells
How do microglia act as immune response cells?
They are immunocompetent cells (involved in antigen presentation) and phagocytic - form the basis of the brains defence system as they can recognise foreign material and begin phagocytosis to remove debris and foreign material.
What is the importance of the blood brain barrier?
The blood brain barrier limits diffusion of substances from the blood to the extracellular substances of the brain meaning not everything from the blood can directly enter the brain. This acts to maintain the correct environment for the neurones to be produced in.
What are the three main features of the blood brain barrier that help with its function?
Tight junctions between endothelial cells (bound by clodin and occludin)- prevent hydrophilic molecules entering through capillaries
Basement membrane- limits diffusion of substances
Foot processes of astrocytes- sends signals to endothelial cells to form tight junctions
How do molecules gain access via the blood brain barrier?
There need to be specialised transporters because of the tight junctions that exist with the capillaries - under control of signals released from astrocytes.
Glucose, amino acids and potassium are transported transcellular le across the BBB allowing their concentrations to be controlled
Gaseous molecules, lipophilic molecules and H2O diffuse freely across the BBB
Why is the CNS termed immune privileged?
The CNS is termed immune privileged - it has a specialised immune function.
CNS has a regulated inflammatory response whereby T cells are able to enter the CNS but their inflammatory T cell response is significantly limited- because any inflammatory expansion in the CNS would not be tolerated due to the rigidity of the skull- therefore allografts of the brain are not rapidly rejected
What is a neurone composed of?
Dendrites
Soma/cell body
Myelinated axon
Terminals
Where is an action potential generated to pass along an axon?
Axonal hillock
What two things does a post synaptic response depend on?
The nature of the transmitter
The nature of the receptor
Describe the neurotransmitter of the CNS
Whilst over 30 different neurotransmitters have been identified, three main categories of neurotransmitter can be recognized:
· Amino acids, such as glutamate, GABA, or glycine
· Biogenic amines, such as NA, dopamine, serotonin (5-HT), or histamine, and ACh
· Peptides, such as dynorphin, enkephalins, substance P, somatostatin, cholecystokinin, and neuropeptide P
Describe the action of glutamate in the brain
In the CNS, the main neurotransmitters to cause an excitatory response are amino acids; the main receptors are for glutamate, with 70% of all CNS receptors being glutamatogenic.
Glutamate Receptors
Glutamate receptors can be either ionotrophic (integral ion channel, increasing the Na+ and K+ permeability and sometimes the Ca2+ permeability as well) or metabotrophic (GPCR, allowing for changes in IP3 or cAMP levels). Of the ionotrophic receptors, there are three main types:
· AMPA – acts to increase K+ and Na+ permeability- fast response
· NMDA – acts to increase Na+, K+, and Ca2+ permeability- slower response
· Kainate receptors- acts to increase Na+ and K+ permeability
All these three will cause depolarisation and subsequently allow more APs to fire (Excitatory PostSynaptic Potential (EPSP))
The glutamate receptors are also thought to have a role in memory, whereby activation of the NMDA and mGluRs can lead to upregulation of AMPA receptors.
Entry of Ca2+ during NMDA receptor activation can cause cell damage if intracellular Ca2+ levels become too high. Consequently, excessive amounts of glutamate can cause cell death, known as excitotoxicity. (hence why astrocytes are important in removing excess neurotransmitter)
Describe the action of GABA in the brain
GABA is the main inhibitory neurotransmitter in the brain and glycine mainly acts as an inhibitory neurotransmitter mostly in the brainstem and spinal cord. GABAA and glycine receptors are integral Cl- ion channels. Opening the channels results in hyperpolarisation, and this results in decreased action potential firing (Inhibitory PostSynaptic Potential (IPSP)). GABAB receptors have a modulatory role.
What drugs act on GABA receptors and cause sedation and anti anxiety actions?
Barbiturates and Benzodiazepines
What are the three categories of neurotransmitter found in the brain?
Amino acids- glutamate, GABA, glycine
Biogenic amines- NA, ACh, serotonin, dopamine
Peptides- cholecystokinin, Neuropeptide p
Describe the action of acetylcholine in the brain
Acetylcholine not only acts at the NMJ, ganglionic synapse of the ANS, and postganglionic neurone for the PNS, but also acts as a central neurotransmitter. It mainly acts as excitatory, on both nicotinic and muscarinic receptors, and receptors also present on presynaptic terminals to enhance the release of other neurotransmitters. ACh receptors are widely distributed throughout the brain, acting for arousal, memory, learning, and motor control, and the degeneration of cholinergic neurones in the nucleus basalis of Meynert is associated with Alzheimer’s disease.
ACh neurones originate in basal forebrain and brainstem and have diffuse projections to many parts of cortex and hippocampus.
Describe the action of dopamine in the brain
Dopamine receptors are found in regions for motor control and involved in mood, arousal, and reward. Loss of dopamine receptors has been associated with Parkinson’s Disease and release of too much dopamine has been associated with Schizophrenia.
Describe the action of noradrenaline in the brain
Noradrenaline receptors are found on postganglionic effector synapses on the SNS and also found in the CNS. Operating as GPCR, they can be found throughout the cortex, hypothalamus, amygdala, and the cerebellum.
Activity increases during behavioural arousal and amphetamines increase the release of noradrenaline and dopamine, whereas depression has been associated with a decrease in NA
Which neurotransmitter is involved in fast excitatory neurotransmission in the brain?
Glutamate
Which neurotransmitter is involved in fast inhibitory neurotransmission in the brain?
GABA
Which neurotransmitter is involved in neuromodulation ( regulation of diverse population of neurones) in the brain?
ACh
Dopamine
Noradrenaline
What is the pathogenesis in Alzheimer’s?
Degeneration of cholinergic neurones in nucleus basalis of Meynert
What is the pathogenesis of Parkinson’s?
Loss of dopamine receptors
What is the pathogenesis of schizophrenia?
Too much dopamine
Describe the blood supply of the cerebral cortex
Brachiocephalic trunk (R), subclavian artery (L&R), vertebral arteries (L&R), basillar artery, 2 posterior cerebral arteries
Brachiocephalic trunk (R), CCA (L&R), ICA (L&R), middle and anterior cerebral arteries (L&R)
Also posterior and anterior communicating arteries which anastamose to form the circle of willis
Where are the cerebral and cerebellar arteries given off?
In the subarachnoid space
Why is anastamoses of arteries supplying the brain important?
Any blockage of one of the arteries will allow sufficient blood supply to reach and perfuse the region of the brain affected- collateral circulation
Where does the ICA run through?
The carotid canal of the petrous temporal bone, passing through the cavernous sinus to enter the middle cranial fossa
Where do the vertebral arteries run through?
Ascend through the transverse foramen in upper 6 cervical vertebrae and enter the posterior cranial fossa via the foramen magnum
Where do the two vertebral arteries unite to form the basilar artery?
Lower border of pons
Which part of the cerebrum does the anterior cerebral artery supply and what functions does this involve?
Medial frontal and parietal lobes up to the parietal-occipital sulcus
Leg area of the somatosensory cortex
Which part of the cerebrum does the middle cerebral artery supply and what functions does this involve?
Lateral parietal and frontal lobe and temporal lobes
Motor and sensory area of central sulcus, except leg
Speech and language
Which part of the cerebrum does the anterior cerebral artery supply and what functions does this involve?
Inferior surface of brain and occipital lobes
Vision
What arteries supply the cerebellum?
Vertebral arteries, posterior inferior cerebellar artery
Vertebral arteries, basilar artery, anterior inferior cerebellar artery
Vertebral arteries, basilar artery, superior cerebellar artery
What arteries supply the pons?
Vertebral arteries, basilar artery, pontine arteries
Describe the venous drainage of the cerebrum
Internal cerebral veins (emerge from transverse fissure), external cerebral (bridging) veins (subarachnoid space), venous sinuses, IJV
Describe the blood supply to the spinal cord
Anterior spinal artery ——–>
Paired posterior spinal arteries ——–>
Both run in pia mater
Both reinforced by radicular branching arteries
* large radicular artery in the lower thoracic/ upper lumbar region known as arteria radicularis Magnus of Adamkiewicz - occlusion of which can lead to neural dysfunction
What are the three meningeal layers from outside in?
Dura mater
Arachnoid mater
Pia mater
What are the three important spaces formed by the meninges?
Extradural space
Subdural space
Subarachnoid space
Describe the dura mater
Consistent of 2 layers:
- outer periosteal layer that is continuous with cranial foramina
- inner meningeal layer, a strong fibrous membrane which is tightly adherent to periosteal layer except where there are dural venous sinuses present
Infold of the dura mater between the cerebral hemispheres forms the falx cerebri
What is the falx cerebri?
Infold of the dura mater between the cerebral hemispheres attaching the crista galli (anteriorly) to the tentorium cerebelli (posteriorly)
What is the tentorium cerebelli?
Horizontal sheath at posterior edge of falx cerebri, forming the roof of posterior cranial fossa, providing vertical reinforcement of cerebrum and separates the cerebellum from the occipital lobe
Divides the brain into infratentorial (cerebellum) and supratentorial (occipital lobe) compartments
Antero-medial border - tentorium notch - brain stem extends from the posterior to middles cranial fossa
What is the extradural space?
Potential space bound between the bone of the skull and the periosteal layer of the dura mater- only becomes an actual space in pathology (EXTRADURAL HAEMORRHAGE)
What is an extradural haemorrhage?
Collection of blood in the extradural space
Arterial blood (Pterion fracture and MMA)
Lenticular shape on CT Scan
What is the Subdural space?
Potential space between the meningeal layer of the dura mater and the arachnoid mater- only becomes an actual space in pathology (SUBDURAL HAEMORRHAGE)
