NEUR 0010 - Chapter7 Flashcards
What separates the two cerebral hemispheres?
Sagittal fissure
What hemisphere of the cerebrum controls right vs left sensation/movement?
Left cerebral hemisphere controls right sensation/movement, and right cerebral hemisphere controls left sensation/movement
What is the difference between rostral and caudal?
Nose and tail :)
What is the cerebellum primarily used for?
Movement control center: connects with cerebrum and spinal cord
What hemisphere of the cerebellum controls right vs left movement?
Left cerebellum controls left movement, right cerebellum controls right movement (contrasts the contralateral control of the cerebrum)
What does the brain stem do, and why does that contribute to its nickname?
Most primitive part of the mammalian brain: regulation of vital functions (breathing, consciousness, control of body temperature, etc.)
How does the spinal cord communicate with the body?
Via spinal nerves (part of the PNS)
Are spinal nerves part of the PNS or CNS?
PNS!
What is the difference in functioning between dorsal and ventral roots of the spinal nerves?
Dorsal roots from information into the spinal cord; ventral roots carry information out from the spinal cord
What is the somatic PNS?
All the spinal nerves that innervate the skin, joints, and muscles that are under voluntary control
What is the location difference between soma and axons of somatic motor neurons?
Soma lie in the spinal cord (CNS), but axons are part of the PNS
What is the difference in location between soma and axon for somatic sensory axons?
Soma lie outside the spinal cord in the dorsal root ganglia (PNS), but axons enter the dpinal cord through the dorsal roots
What is the autonomic PNS?
Controls involuntary, vegetative neurons: internal organs, blood vessels, glands
What are the meninges?
The three membranes covering the CNS against the bone
What are the three meninges, from outermost to innermost?
Dura mater, arachnoid membrane, pia mater
What separates the arachnoid membrane from the pia mater?
The subarachnoid space: filled with cerebrospinal fluid
Where and by what is CSF created?
By the choroid plexus in the ventricles of the cerebral hemispheres
What is gray matter?
Generic term for a collection of neuronal cell bodies in the CNS
What is cortex?
Any collection of neurons that form a thin sheets, usually at the brain’s surface
What is a nucleus?
A clearly distinguishable mass of neurons usually deep in the brain
What is a substantia?
A group of related neurons deep within the brain, but usually with less distinct borders than a nucleus
What is a locus?
A small, well-defined group of cells
What is a ganglion?
A collection of neurons in the PNS
What is a nerve?
A bundle of axons in the PNS; the only “nerve” in the CNS is the optic nerve
What is the only “nerve” in the CNS?
The optic nerve
What is white matter?
A general term for a collection of CNS axons
What is a tract?
A collection of CNS axons having a common site of origin and a common destination
What is a bundle?
A collection of axons that run together but don’t necessarily have the same origin and destination
What is a capsule?
A collection of axons that connect the cerebrum with the brain stem
What is a commissure?
Any collection of axons that connect one side of the brain with the other
What is a lemniscus?
A tract that meanders through the brain like a ribbon
How does an embryo begin? What are the three components called?
Flat disc with three distinct layers: endo derm, mesoderm, and ectoderm
What does the endoderm become?
Lining of many internal organs (viscera)
What does the mesoderm become?
Bones of skeleton and muscles
What does the ectoderm become?
Nervous system and skin
What part of the ectoderm gives rise to the nervous system?
The neural plate
How does the neural plate become the nervous system?
Neural plate develops the neural groove (walls are called the neural folds); the neural groove eventually fuses to form the neural tube (becomes the entire CNS), and the neural folds eventually pinch off to form the detached neural crest (becomes the entire PNS)
Where does the CNS develop from?
The neural tube (formed from a fused neural groove)
Where does the PNS develop from?
The neural crest (formed from pinched-off neural folds)
How does the mesoderm develop with the neural crest? What does that become?
Forms bulges on the sides of the neural tube (somites); develop into vertebrae and skeletal muscles
What is neurulation?
The process by which the neural plate becomes the neural tube; occurs very early in embryonic development (22 days after conception, approximately)
What is differentiation, in neural development?
The process by which structures become more complex and functionally specialized during development
What is the first step of the differentiation of the brain?
Development of the three primary vesicles, at the rostral end of the neural tube
What are the three primary vesicles that develop during brain differentiation?
Prosencephalon, mesencephalon, and rhombencephalon (fore, mid, and hindbrain)
What does the rhombencephalon connect to? What does that become?
The caudal neural tube: gives rise to the spinal cord
What are the secondary vesicles that sprout from the prosencephalon?
Optic vesicles and telencephalic vesicles
What is the diencephalon?
The unpaired structure that remains after the secondary vesicles have sprouted off the prosencephalon during forebrain development
What do the optics vesicles become, derived from the prosencephalon?
Optic stalks and optic cups: become optic nerves and retinas
What part of the NS are the retinas and optic nerves, CNS or PNS? Why?
CNS: derived from the prosencephalon (forebrain)
What is the telencephalon?
The “endbrain,” which is the fused two telencephalon vesicles derived from the prosencephalon; consists of two cerebral hemispheres
What are the four components of telencephalon development from the prosencephalon?
Vesicles grow posteriorly to lie over/laterally to diencephalon; another vesicle pair sprouts ventrally (olfactory bulbs); cell walls differentiate into various structures; white matter systems develop: axons to and from neurons of the telencephalon
What are the olfactory bulbs derived from?
Sprout off from the developing telencephalon (which is itself derived from the prosencephalon)
Where are the lateral ventricles and third ventricle located?
Lateral ventricles are in the telencephalon within the two cerebral hemispheres; third ventricle is in the center of the diencephalon
What are the two types of gray matter in the telencephalon?
Cerebral cortex and basal telencephalon
What are the two structures that the diencephalon becomes?
Thalamus and hypothalamus
When the neurons of the developing forebrain extend axons to other parts of the NS, what three white matter systems develop?
Cortical white matter, corpus callosum, and internal capsule
What is cortical white matter, made of axons from the developing forebrain?
Axons that run to/from neurons in the cerebral cortex (one of the gray matter types of the telencephalon)
What is the corpus callosum, made of axons from the developing forebrain?
Continuous with the cortical white matter; axonal bridge between cortical neurons of the two cerebral hemispheres
What is the internal capsule, made of axons from the developing forebrain?
Connects to the cortical white matter; links the cortex with the brain stem, particularly the thalamus
What is the gateway to the cortex?
The thalamus: all sensory information passes through
How do thalamic neurons send axons to the cortex?
Via the internal capsule, usually about the contralateral side of the body
What role does the corticospinal tract play in cortically-controlled voluntary movement?
Cortex sends axons to spinal cord through the internal capsule, which allows for control
What are the three landmark structures that develop from the mesencephalon?
Tectum, tegmentum, and cerebral aqueduct
What is the tectum, derived from the mesencephalon?
The dorsal surface of the mesencephalon
What is the tegmentum, derived from the mesencephalon?
The floor of the mesencephalon
What is the cerebral aqueduct, derived from the mesencephalon?
CSF-filled narrow channel between the tectum and tegmentum; connects rostrally with the third ventricle of the diencephalon
What are the two structures of the tectum?
Inferior colliculus and superior colliculus
What does the superior colliculus of the midbrain’s tectum do?
Receives direct input from the eye (optic tectum)
What is the function of the optic tectum?
Control eye movements; some of the axons that supply the eye muscles bundle together to form cranial nerves III and IV
What does the inferior colliculus of the midbrain’s tectum do?
Receives sensory information from the ear; serves as relay station for auditory info en route to the thalamus
What are the two components of the tegmentum of the midbrain?
Substantia nigra and red nucleus
What do the substantia nigra and the red nucleus in the tegmentum do?
Involved in control of voluntary movement
What are the three structures that the rhomboencephalon differentiates into?
Pons, medulla oblongata, and cerebellum
From which regions of the hindbrain do the pons/cerebellum/medulla develop?
Pons and cerebellum from the rostral end (metencephalon), medulla from the caudal (myelencephalon)
What is the fourth ventricle, from the hindbrain?
The CSF-filled tube; continuous with the cerebral aqueduct of the midbrain
What is the major function of the pons?
Serves as a switchboard to connect the cerebral cortex with the cerebellum
What are the two options for axons going down from the cerebral cortex?
Synapse in the pons (90%) or go through the medullary pyramids
What is the pyramidal decussation?
Near where the medulla joins the spinal cord: each pyramidal tract crosses sides; explains why cortical control is contralateral for movement
What are the different functions of the dorsal horn cells, ventral horn cells, and intermediate zone cells?
Dorsal horn cells (receive sensory input from dorsal root fibers), ventral horn cells (project axons into ventral roots to innervate muscles), intermediate zone cells (interneurons that shape motor output in response to sensory input, descending commands from the brain)
What are the three zones of spinal cord gray matter?
Dorsal horn, ventral horn, intermediate zone
What does the dorsal column of the spinal cord do? Where does decussation occur?
Carries somatic sensory info to the brain on the ipsilateral side (and then postsyn neurons in the medulla are where decussation occurs)
What does the lateral column of the spinal cord do?
Contains axons of descending corticospial tract: decussate in the medulla, just like in the dorsal column; innervate neurons of the intermediate zone and ventral horn; communicate signals that control voluntary movement
What are the main characteristics of cerebral cortex cytoarchitecture?
Cell bodies often arranged in sheets parallel to the brain surface; layer of neurons closes to the surface is separated from pia mater by “layer 1” which lacks neurons; at least one layer contains pyramidal cells that emit large dendrites (apical dendrites) that extend to later 1
What part of the cortex only has one layer of cells?
The hippocampus
What part of the cortex only has two layers of cells?
Olfactory cortex: continuous with the olfactory bulb
What structure delineates the olfactory cortex from the rest of the cortex?
Rhinal fissure
What part of the cortex has lots and lots of cell layers?
Neocortex: found only in mammals!
According to Krubitzer, working off of Brodmann’s ideas, what are the three types of cortex?
Primary sensory (first to receive signals from ascending sensory pathways), secondary sensory areas (heavy interconnections with primary sensory areas), motor areas (intimately involved with control of voluntary movement)
