Lecture 1 - CNS Development and Introduction Flashcards
What are the parts of the tripartite brain?
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- prosencephalon
- mesencephalon
- rhombencephalon
What are the parts of the pentapartite brain and what division of the tripartite brain do they originate from?
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Prosencephalon:
- telencephalon
- diencephalon
Mesencephalon:
-mesencephalon
Rhombencephalon:
- metencephalon
- myelencephalon
What is anencephaly?
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Failure of the cranial end of the neural tube to close.
What is holoprosencephaly?
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Failure of he prosencephalon to divide into two cerebral hemispheres.
Can have associated facial deformities such as:
- single orbit w/ two eyes, one eye, or no eyes
- proboscis-type nose
- cleft lip/palate
What are the two main classifications of spina bifida?
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Spina Bifida Occulta:
- failure of caudal neural tube closure
- failed formation of caudal vertebral arches
- typically have normal spinal cord function
Spina Bifida Cystica:
- sac-like cyst at the caudal end of spine with spinal cord and/or meninges located in the cyst
- spinal cord function may be impaired including lower extremity, bowel, and bladder dysfunction
What are the different forms of spina bifida cystica?
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Meningocele:
- only meninges are present in the sac
- spinal cord function may be impaired
Meningomyelocele:
- meninges and spinal cord are present in the sac
- spinal cord function/growth impaired
- lower extremity paralysis/numbness
- bowel/bladder dysfunction
Myeloschisis:
- failure of caudal neural folds to close
- most severe form
What is the Arnold-Chiari deformity?
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- inferior cerebellum and medulla are elongated and protrude into vertebral canal
- medulla and pons are deformed
- hydrocephalus
- malformation in lower cranial nerves (results in deafness and tongue/facial muscle, and lateral eye movement weakness)
What are the major structures of the brain derived from the telencephalon?
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Roof:
-cerebral cortex
Floor:
- basal ganglia
- olfactory lobes/nerves
Lumen:
-lateral ventricles (I and II)
What are the major structures of the brain derived from the diencephalon?
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Roof:
-epithalamus
Walls:
-thalamus
Floor:
-hypothalamus
Lumen:
-third ventricle
What are the major structures of the brain derived from the mesencehpalon?
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Roof:
-tectum (superior/inferior colliculi)
Floor:
-tegmentum
Lumen:
-cerebral aqueduct
What are the major structures of the brain derived from the metencephalon?
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Roof:
-cerebellum
Floor:
-pons
Lumen:
-part of fourth ventricle
What are the major structures of the brain derived from the myelencephalon?
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Roof:
-choroid plexus
Walls:
-medulla oblongata
Lumen:
-part of fourth ventricle
What are the components of a reflex arc and indicate the differences in somatic and visceral (splanchnic) pathways.
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Afferent (sensory) pathways:
- somatic: sensation carried from structures such a s skin or skeletal muscle
- visceral: sensation from viscera
Efferent (motor) pathways:
- somatic: motor signals to skeletal muslce
- visceral: motor signals to smooth and cardiac muslce
Interneurons:
- intervening neurons in CNS that moderate reflex arc
- if reflex arc does not contain these the reflex cannot be stopped
What are the physiological states of a neuron?
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Resting:
-potential is ~-65mv
Excited:
- more positive than resting; ~-45mv
- caused by influx of sodium ions
Inhibited:
- more negative than resting; ~-70
- caused by influx of chloride ions or effluent of potassium ions
What are the components of the somatosensory axis?
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Primary afferent neurons:
-synapse in posterior horns of spinal cord or sensory nuclei of brain
Secondary afferent neurons:
-synapse in the thalamus
Tertiary afferent neurons:
-synapse in somesthetic areas of cerebral cortex
