Flashcards in Week 1: Overview of nervous system: development, adult structures and ventricles Deck (13)
1
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
2
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)
3
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)
4
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)
5
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
6
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
7
What are the subdivisions of the brain stem?
-midbrain
-pons
-medulla oblongata
8
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
9
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
10
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
11
Explain the flow of CSF
lateral ventricle-->3rd ventricle-->cerebral aqueduct-->4th ventricle-->median and lateral apertures-->subarachnoid space around brain and spinal cord
12
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
13