L2 Organization of the Nervous System I Flashcards
what makes up the PNS?
neuronal processes + Glia outside the CNS
what makes up the somatic nervous system?
afferent and efferent structures of the PNS that communicate between skin, skeletal muscles, or joints and the CNS
what makes up the autonomic nervous system?
parasympathetic, sympathetic, enteric
what makes up the boundary between the PNS and the CNS?
- shift from oligodendrocytes - CNS to schwann cells - PNS = Redlich Obersteiner’s zone
- the axons here cannot regenerate - they can in limbs sometimes etc.
what are the 5 parts of the brain?
- telencephalon - cerebrum (and cortex)
- diencephalon (between 2 hems = 3rd ventricle with CSF
- mesencephalon - midbrain
- metencephalon - pons + cerebellum
- myelencephalon - medulla oblongata
what are the lobes of the brain?
- frontal
- temporal
- parietal
- occipital
- limbic - only seen from medial surface, joins the other lobes together
- insular - hidden from view
where is the grey and white matter in the brain?
grey is outside/surface
white is inside
*opposite of spinal cord
when a person shows back extended and arms outstretched/extended, what should I suspect?
midbrain injury
what makes up the myelon and what is its function?
spinal cord
-contains cells and axonal pathways related to somatosensory, motor and autonomic function
What are the 6 layers of the cerebral cortex?
- molecular layer
- external granular layer
- external pyrimidal layer (small pyrimidal cells)
- internal granular layer
- ganglionic layer (large pryamidal cells)
- multiform layer (polymorphus layer)
what do pyrimidal cells do?
- yield output pathway from cortex
- layers 2,3,5,6
- largest pyrimidal cells (Betz cells) found in layer 5 of primary motor cortex making synaptic connections with lumbar spinal motor neurons
what are all other neurons with cortical cell bodies?
local interneurons
All local interneuron have an _____ action?
inhibitory - except spiny stellate cells in layer 4
What are thalamic neurons?
most end in layer 4
axons of some thalamic neurons and other neurons regulating cortical excitability end in all layers.
what makes up the telencephalon (endbrain derived from rostral prosencephalon)?
-cerebral hemispheres cerebral cortex basal ganglia lateral ventricle + foramina of Monro closely tied to CN I olfactory n.
what makes up the diencephalon (inter brain - derived from the caudal prosencephalon)?
thalamus hypothalamus + pituitary subthalamus epithalamus third ventricle CN II Optic n.
what makes up the mesencephalon (midbrain)?
tegmentum - floor
tectum - roof
cerebral aqueduct
CN III and IV - oculomotor and trochlear n.
what makes up the met encephalon (derived from rhombencephalon)?
pons
cerebellum
rostral fourth ventricle
CN V-VIII - trigeminal, abducens, facial, vestibulocochlear
what makes up the myelencephalon (derived from rhombencephalon)?
medulla oblongata
causal fourth ventricle - foramen of Magendi and Luschka - central canal of medulla is continous with spinal cord
CN IX-XII glossopharyngeal, vagus, spinal accessory, hypoglossal.
what is the function of the cerebral hemisphere (cortex, white matter, BG, amygdala, hippocampal formation)?
motor activity - also perceptual, cognitive, visceral and emotional functions
commonly divided into lobes
what does the frontal lobe do?
motor planning and execution, language production, judgement, and working (ST) memory
what does the parietal lobe do?
somatosensory processing
what does the occipital lobe do?
visual processing
what does the temporal lobe do?
auditory processing
what does the limbic lobe do?
functionally tied to emotion and memory.
what is the function of the insular lobe?
varied function - autonomic and interoceptive
what does the thalamus do?
modulates and relays sensory info and motor info from BG and cerebellum to the cerebral cortex
what does the hypothalamus do?
homeostasis and reproduction
what does the subthalamus do?
motor and sensory function
what does the epithalamus do?
endocrine function
what does the midbrain do?
contains neurons forming part of the motor system
regulates eye movements
promotes alertness/arousal
what does the pons do?
ventral - relay motor info from cerebral cortex to cerebellum
dorsal - respiration, taste, circuits controlling sleep/wake cycles
regulates motor function
what does the cerebellum do?
receives somatosensory info from spinal cord, motor info from cerebral cortex and vestibulo info from organs of inner ear
maintains posture and balance
smoothes and coordinates movement by regulating motor centers
what does the medulla oblongata do?
some nuclei control respiration, BP and motor activity of mouth
other nuclei receive sensory info from chemoreceptors and mechanoreceptors
whats in the molecular layer?
- few neuronal sonata
- apical dendrites located in deeper cortical layers
- axons passing through or making cnx
- axons arising from this layer travel parallel to pia
whats in the external granular layer
- small granule cells (local interneurons that inhibit other cortical cells) and some slightly larger pyrimidal cells
- communcations with opsilateral cortical areas (via association fibers)
whats in hte external pyramidal layer?
- small to med pyramidal neurons projecting from cortex
- communications with homotopic contralateral cortices (via commisural fibers)
whats in the internal granular layer?
- no pyramidal neurons
- interneurons receive ascending sensory input and projecting to layers II and III
- contains dense band of tangenital axons that form the outer band of Baillarger - hypertrophic and visible to naked eye in a discrete occipital region
whats in the internal pyramidal layer
med to lrg pyramidal neurons
- major source of cortical output to brainstem and SC
- contains dense band of tangenital axons
whats in the multiform layer?
- assortment of cell types, few pyramidal cells
- small cells receive input from thalamus and from layers II, III, and V
- axons of the cells project to superficial cortical layers and to the thalamus
what does the Golgi stain reveal?
morpholog of some neurons
what does the Niddl stain reveal?
rough ER of the nerve cell bodies
what does the Weigert stain reveal?
myelin of axons
what layer are pyramidal cells found and where are the largest ones found?
II, III, V and IV
largest found in V of primary motor cortex and can make synaptic cnx with caudal spinal motor neurons
where do most thalamo-cortical neurons end?
layer IV
