Central Nervous System III Flashcards
What’s the composition of the CSF?
- Clear and transparent fluid
- Alkaline and does not coagulate
- Pressure = 6-150mm of H2O
- Pressure of CSF is increased in standing, coughing, sneezing, crying, compression of internal Jugular vein
What was Oueckenstedt’s sign?
Used to be used to test for lumbar spinal stenosis (narrowing of the spinal canal, compressing the nerves traveling through the lower back into the legs)
- Now an MRI or CT scan is used
What’s the circulation of CSF?
- Formed in Choroid Plexus of the lateral ventricle
- CSF passes from the lateral ventricle to the 3rd ventricle through FORAMEN OF MONRO
- Passes from the 3rd to the 4th ventricle through the CEREBROL AQUEDUCT (this is aided by the arterial pulsations of the Chroid Plexuses
- 4th ventricle CSF passes to the sub arachnoid space around the brain and spinal cord though the FORAMEN OF MAGENDIE & FORAMINA OF LUSCHKA
What are Arachnoid granulations?
- Projections of the arachnoid membrane (villi) into the dural sinuses that allow CSF to pass from the subarachnoid space into the venous system.
What is the Blood Brain Barrier?
- Protective mechanism that helps maintain a stable environment for the brain and prevents harmful Amino-acids and Ions present in the bloodstream and Blood-cells from entering the brain
What’s the composition of the BBB?
- Endothelium - tight junction
- Thick basal lamina
- Foot processes of Astrocytes
What are the characteristics of the BBB in terms of permeability?
- Water soluble molecules (glucose) are pump mediated
2. Lipid soluble molecules (drugs must be lipid soluble to move into the CNS), Oxygen and H2O can move through
What’s the Cerebrum?
- Largest part of the brain
- Situation in the anterior and middle cranial fossae and the whole concavity of the vault of the skull
What are the 2 parts of the Cerebrum?
- Cerebral hemispheres - left and right
- Diencephalon
- Thalamus, hypothalamus
What are Sulci and Gyri?
- The Cerebral hemispheres are thrown into folds called Gyri in increase the surface area of the brain
- Ssulci are fissures which separate the Gyri
- The Cerebral hemispheres are divided into lobes according to the cranial bones under
1. Central
2. Parieto-occiptial
3. Lateral
What does Grey matter consist of?
- Nerve cells
What does White matter consist of?
Nerve fibres
What are the 5 types of cells within the Grey matter of the Cerebral cortex?
- Horizontal cells
- Stellate cells
- Fusiform cells
- Cells of Martinotti
- Pyramidal cells
What are the 6 Cortical layers of the Cerebral Cortex?
Top
- Molecular layer
- External granular layer
- External pyramidal layer
- Internal grandular layer
- Ganglionic layer (internal pyramidal layer)
- Multiform layer
What is the composition of White matter?
- Myelinated nerve fibres
- Supported by Neuroglia
- Classified into 3 groups according to their connections
1. Commissural fibres
2. Association fibres
3. Projection fibres
What are Commissural fibres?
- Connects corresponding regions of the 2 hemispheres
- Corpus callosum
- Fornix
- Anterior and posterior Commissures
- Corpus Callosum is the largest commissure of the brain - divided into Rostrum, Genu, Body and the Splenium
What are Association Fibres?
Connects various cortical regions within the same hemispheres
- Divided into:
Short fibres = lie immediately beneath the cortex and connect adjacent Gyri
Long fibres = arranged into named bundles = Fasciculi
What are projection fibres?
- Afferent and efferent nerve fibres passing to and from the brain stem to the cerebral cortex
- Internal capsule, corona radiata, optic radiation
What is the Diencephalon?
- Locatedd within the cerebral hemispheres around 3rd Ventricle
- Develops from Ddiencephalic vesicle (part of forebrian vesicle)
- Consists of paired structures:
1. Thalamus
2. Hypothalamus + pituitary
3. Epithalamus (pineal gland)
What are the characteristics and functions of the Thalamus?
- Egg shaped body on either side of 3rd ventricle
- Makes up 80% of Diencephalon
- Consists of groups of nucleii:
1. Anterior
2. Medial
3. Lateral - Recieves main sensory tracts except olfactory pathway (SENSORY RELAY STATION)
- Integrates information it receives and relays to the cerebral cortex and subcortical regions
- Intergrates visceral and somatic functions
What are the characteristics and functions of the Hypothalamus?
- Extends from the Optic Chiasma to the posterior border of the mammillary body
- Lies below the thalamus separated from it by the Hypothalamic sulcus
- Main visceral control centre + essential for overall homeostasis
- Autonomic control centre
- Body temp reg
- Regulation of food intake
- Regulation of body water balance and thirst
- Regulation of sleep-wake cycle
- Control of endocrine system functioning
What are the characteristics and functions of the Pituitary gland?
- Pituitary gland (hypophysis) has a stalk (infundibulum), an anterior part (adenohypophysis) and a posterior part (neurohypophysis)
- Pituitary stalk and posterior pituitary are derived form the Diencephalon
- Anterior pituitary is derived from the ectodermal part of the oral cavity
Contains: Supraoptic Nucleus & Paraventricular Nucleus
What are the characteristics and functions of the Pineal gland?
- Projects backwards from the Diencephalon to lie posterior to the midbrain
- Progressive calcification with age (visible in x-ray)
- Produces Metatonin hormone = in a circadian rhythm influenced by light
- Indirectly controls the function of other endocrine organs, including the pituitary
What’s the Basal Ganglia?
- Subcortical nuclei deep within each cerebral hemisphere
- Made up of:
1. Caudate nucleus
2. Globus Pallidus
3. Putamen
4. Lentiform nucleus
5. Substantia Nigra
6. Subthalamic nucleii
