Week 1: Overview of nervous system: development, adult structures and ventricles Flashcards Preview

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Describe the basic events involved in embryological development of the CNS

-week 4: formation of neural crest and tube
-neural tube develops into spinal cord, brain, and brain stem
-day 25: 3 vesicle stage- tube has three dilations, the forebrain (prosencephalon), midbrain (mesencephalon), hindbrain (rhombencephalon)
-5 weeks: 5 vesicle stage.
forebrain: telencephalon and diencephalon
midbrain: Mesencephalon
hindbrain: metencephalon and myelencephalon


List the major components of the adult CNS and its subdivisions

-cortex, brain stem, and spinal cord
-transition between brain stem and spinal cord is at foramen magnum (through which you can have tonsilar herniation due to intracranial pressure increases)


Explain the production the CSF

-formed by choroid plexus: pial connective tissue and capillaries
-in body, inferior horn, and atrium (glomus) of lateral ventricles
-in roof of 3rd and 4th ventricles
-500mL/day, only 150mL capacity in ventricles and subarachnoid (3x turnover/day)


Know the sites of occlusion along the CSF pathways that can lead to hydrocephalus

1. obstructions within ventricular system
-turmor of choroid plexus can occlude 3rd ventricle , cause stenosis of aqueduct
-results in ventricle enlargement proximal to obstruction
2. obstructions in subarachnoid space impairing CSF absorption
-tumor causes lateral shift of brain due to unilateral mass (post infectious or post hemorrhagic meningitis)


List the adult derivatives of the CNS from the 5 vesicle stage

-Telencephalon: cerebral cortex and basal ganglia
-Diencephalon: retina, Thalamus, hypothalamus, subthalamus
-Mesencephalon: midbrain, sup and inf collicullus
-Metencephalon: Pons and cerebellum
-Myelencephalon: medulla


What are the subdivisions of the diencephalon?

-Thalamus: relays sensory info from PNS to cortex. Integrates motor fxns of cortex with cerebellum and basal ganglia
-hypothalamus: regulating homeostasis
-Subthalamus: motor control
-epithalamus (pineal gland): circadian rhythms


What are the subdivisions of the brain stem?

-medulla oblongata


What is the cerebellum for and what are its subdivisions?

-coordinates motor activity and involved in motor learning
-divided into two hemispheres and a midline vermis


How does the ventricular system develop?

-at around 5 weeks
-telencephalon expands, lateral ventricles enlarge with it
-third ventricle forms from central cavity of diencephalon and cerebral aqueduct from lumen of mesencephalon
-4th ventricle from shape change in floor of met encephalon and myelencephalon to form diamond like depression


Describe the ventricular system.

Lateral ventricles
-divided into anterior, body, posterior, and inferior horn
-lateral ventricles communicate with third ventricle through inter ventricular foramen
Third ventricle:
-extends into optic chasm, infundibulum, pineal body-called recesses
cerebral aqueduct
-connects 3rd and 4th ventricles
fourth ventricle:
-between cerebellum and pons, upper medulla ventrally
-communicates with subarachnoid space through 3 openings


Explain the flow of CSF

lateral ventricle-->3rd ventricle-->cerebral aqueduct-->4th ventricle-->median and lateral apertures-->subarachnoid space around brain and spinal cord


Explain the drainage of CSf

-CSF flows in upward direction form base of brain toward superior sagittal sinus. Absorbed via arachnoid granulations into cerebral venous sinuses


Explain the functions of CSF

-prevent injury
-blood-CSF barrier by epyndemal cells in chord plexus
-transports micronutrients, e.g. vitamins, trace elements to brain
-remove products of metabolism of some neurotransmitters

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