Organization of CNS Flashcards
describe the contents of telencephalon
endbrain - derived from the rostral prosencephalon
- cerebral hemispheres
- cerebral cortex
- basal ganglia
- lateral ventricles
- Foramina of Monro which connect the lateral ventricles witht he diencephalic third ventricle
- closely tied to olfactory nerves
describe the contents of diencephalon
interbrain - derived from the caudal prosencephalon
- thalamus
- hypothalamus (and pituitary)
- subthalamus
- epithalamus
- third ventricle
- cranial nerve II
describe the contents of mesencephalon
midbrain
- tegmentum (floor: including cerebral peduncles or crus cerebri)
- tectum (roof: corpora quadrigemina or sup. and inf. colliculi)
- cerebral aqueduct
- CN III and IV
describe the contents of metencephalon
derived from the rhombencephalon
- pons
- cerebellum (cerebellar hemispheres and vermis)
- rostral fourth ventricle
- CN V-VIII
describe the contents of myelencephalon
derived from the rhombencephalon
- medulla oblongota
- caudal fourth ventricle
- Foramina of Magendi (medial) and Luschka (lateral) communicate between the fourth ventricle and the subarachnoid canal
- CN IX - XII
describe the function of diencephalon
- the thalamus modulates and relays sensory info. (from sensory systems) and motor info. (from basal ganglia and cerebellum) to cerebral cortex
- the hypothalamus subserves many functions concerned with repro. and homeostasis
- the subthalamus participates in motor and sensory fxn
- the epithalamus participates in endocrine fxn
describe the function of mesencephalon
- contains neurons forming part of the motor system
- regulates eye movements
- promotes alertness/arousal
describe the function of the pons in the metecephalon
- pons
- ventral region relays motor info. from cerebral cortex to cerebellum
- dorsal region involved in respiration, taste and circuits controlling sleep/wake cycle
- regulates motor function
describe the function of the cerebellum in the metecephalon
- cerebellum
- receives somatosensory info. from the spinal cord, motor info. from cerebral cortex (and other motor centers) and vestibular info. from organs of inner ear
- maintains posture and balance
- smoothes and coordinates movement by regulating motor centers
describe layer I of the cerebral cortex
molecular (plexiform) layer
- very few neuronal somata
- apical dendrites of cells located in deeper cortical layers
- axons passing through or making connections in this layer
- axons arising from within this layer often travel parallel to the pia
describe layer II of the cerebral cortex
external granular layer
- small granule cells (local interneurons that inhibit other cortical cells) and some slightly larger pyramidal cells
- communications with ipsilateral cortical areas (via association fibers)
describe layer III of the cerebral cortex
external pyramidal layer
- primary small-to-medium pyramidal neurons projecting from the cortex
- communications with homotopic contralateral cortices (via commissural fibers)
describe layer IV of the cerebral cortex
internal granular layer
- no pyramidal neurons
- interneurons receiving ascending sensory (thalamocortical) input and projecting to layer II/III
- contains dense band of tangential axons that form the outer band of Baillarger, which is hypertrophic and visible to the naked eye in a discrete occipital region
describe layer V of the cerebral cortex
internal pyramidal (ganglionic) layer
- medium-to-very-large pyramidal neurons
- a major source of cortical output to the brainstem and spinal cord
- contains a dense band of tangential axons
