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118 Cards in this Set

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Silver Stain
stains all neuron fibrils
Golgi
his stain only stained certain kinds of neurons (approximately 1%), so he showed that there were specific types of neurons
Ramon y Cajal and Neuron Doctrine
used Golgi stains extensively and found that each neuron was an autonomous unit instead of all connected
Palade and Palay
1950's, used electron microscope to show there was a gap in between neurons (synaptic cleft), proving Cajal correct
Soma/Somata
-variable in size, 5-135 microns in diameter
- house numerous organelles like rough ER
Nissl stain
stains cell bodies of neurons only (really stains ribosomes there)
amacrine cell
neuron with no axons
teldendria/axonal branches
where axon branches on another neuron near the terminal bouton
collateral axons
axon branches out to another neuron before it gets near the end
Golgi type I cell/projection neurons
axon that goes a long way
Golgi type II cell/projection neurons
axon that goes a short distance before ending on its destination
nucleus
neuronal cell bodies in CNS
ganglia/ganglion
neuronal cell bodies in PNS
tract
bundles of axons in CNS with common origin and common target, usually named by origin and target
nerve
bundles of axons in PNS, not necessarily with same origin or taget
cortex/cortices
"bark," neurons stratifying themselves, successive layers different from one another but homogeneous within a layer
"Neuron A projects to Neuron B" or "Nucleus A projects to Nucleus B"
shows polarity and direction of AP
2 types of Myelinating Glia
1) Schwann Cells- PNS
2) Oligodendrocytes- CNS
Why is myelin beneficial?
1) Allows for higher speed of conduction (saltatory conduction)
2) Allows for axons with small diameter to increase in diameter and thus increase speed (ex: Optic nerve is only 2mm in diameter but adding myelin makes it 100mm)
Obersteiner-Redlich Zone
the place where Schwann and oligodendrocytes must switch when one axon goes from the CNS to the PNS or vice versa
Schwann cells
- in PNS
- double-layered, wrap around cell with nodes of Ranvier
Satellite cells
like astrocytes in PNS, but not so sophisticated
Oligodendroglia
- in CNS
- 2 lamellae (flattened sheaths of cytosol) and each will myelinate one or more axons
- few branches compared to astrocytes
2 Types of Astrocytes
1) Fibrous- in gray matter
2) Protoplasmic- in white matter, shorter and thicker

BOTH IN CNS
Glia Limitans
where astrocyte end feet surround surface of NS
Functions of Astrocytes
1) take up space between neurons and so have important roles in where neurons are
2) important during development (ex: neurons can travel along astrocytes for guidance)
3) presence of these can trigger cells to go along a particular path of maturation
4) keep ionic balance in EC medium (esp. K+) relatively consistent by soaking up excess K+ ions and can also be a source of K+, Na+, and sometimes Cl-
5) envelope synapses and confine NT’s
6) take up NT’s from synapse similar to presynaptic reuptake
7) have receptors on them for certain NT’s and can trigger electrical and chemical reactions in astrocyte
8) glial scar
glial scar
when have damage or a lesion, astrocytes surround dying neuron to wall it off
18 days into development of embryo
embryo flattens out and forms into 3 layers
1) endoderm---lining of gut, inner organs
2) mesoderm---muscles, bones, dermis of skin, reproductive and excretory system
3) ectoderm- skin, has neural plate which begins to think in center (rostral bigger than caudal)
21 days into development of embryo
- neural plate's neural grooves fold into eachother, 2 sides of future neck come together (caudal- spine, rostral- forebrain) and "zipper"
- when sealed, non-neural ectoderm on top of it and tube sinks into area between ectoderm and mesoderm
- neural tube- has CSF inside, ependyma begins to thicken
ependyma/ependymal lining
lining of ventricular system (on neural tube)
30 days/3-vesicle stage
1) Prosencephalon (forebrain)- most rostral
2) Mesencephalon (midbrain)- middle
3) Rhombencephalon (Hidbrain)- most caudal
- Behind that- spinal cord
- There is some bending too- cervical flexure in neck region and cephalic flexure in midbrain region
Lamina Terminalis
end of neural tube (most rostral)
40 days/5-vesicle stage
- Forebrain becomes 1) Telencephalon/ Lateral ventricle and 2) Diencephalon/ Third Ventricle
- Retinas and connection to brain are outpouchings of diencephalons, so optic nerve is actually a tract
- Ventral growth in diencephalons than produces the posterior pituitary
- Midbrain becomes 3) Mesencephalon (Midbrain/Cerebral Aqueduct)
- Hindbrain becomes 4) Metencephalon (Pons) and 5) Myelencephalon (Medulla) / Fourth Ventricle
- Spinal Cord/Central Canal- growth of spinal cord actually makes the central canal very very thin in humans
- Bending: get a pontine flexure between cephalic and cervical flexure happens; the bending requires making different kinds of cross-section at different angles
Spinal Cord function
- Ascending/descending pathways; motor and s sensory centers for trunk
- Motor pathways go from a motor center/nucleus in the CNS and innervate PNS on a gland or muscle, etc.
- Sensory pathways go from PNS and terminates on a CNS neuron/ sensory center
Medulla function
Motor and sensory centers for head; ascending and descending pathways
Pontine Tegmentum Function
continuation of Medulla, more motor/sensory center
Decussation
crossing (like an “X”)- ex: Corticospinal tract which goes from cortex to spinal cord on left and right, axons cross at the junction between the medulla and spinal cord
Pons function
relay station btw cerebral cortex and cerebellum (gets input from cerebral cortex and goes to the cerebellum)
Cerebellum function
regulates balance, muscle tone, and motor coordination
Basis Pedunculi Function
also known as the cerebral peduncle, descending fibers from cerebral cortex en route to brainstem and spinal cord
Midbrain tegmentum function
same as medulla
Inferior Colliculus Function
relay center for auditory info
Superior Colliculus Function
center for visual reflexes and visuo-motor linkage
Ventricular System by Regions of the Brain
1) Central Canal---Spinal Cord
2) IV Ventricle---Metencephalon/Myelencephalon in Hindbrain
3) Cerebral Aqueduct---Mesencephalon
4) Third ventricle---Diencephalon
5) Lateral Ventricles---Telencephalon
Parts of Brain by Region
- Prosencephalon:
1) Telencephalon- amygdala, basal ganglia, cerebral cortices
2) Diencephalon- hypothalamus, thalamus
- Mesencephalon
1) Mesencephalon- basis pedunculi, midbrain tegmentum, inferior/superior colliculus
- Rhombencephalon
1) Myelencephalon- medulla
2) Metencephalon- pons, pontine tegmentum, cerebellum
Commissure
-bundle of axons (tract) that interconnects 2 corresponding points (right and left side of brain)
- corpus callosum- largest commissure
2 Parts of PNS
1) Visceral= autonomic NS, innervation to smooth and cardiac muscle

2) Somatic= tends to be voluntary, innervates striated muscles
septum pallucidum
- thin membrane
- if poke hole in this would be in lateral ventricle and could see striatum below
interthalamic adhesion/masintermedia
where 2 parts of thalamus meet; "eye" of the duck in the ventricular system
ependyma
lines ventricles
pia mater
innermost meninges/meninx
arachnoid
-above subarachnoid space (btw pia mater and arachoid)
-fluid here is CSF about 100ml
- supports and surrounds brain to cushion it
- distributes chemicals throughout brain
sub-arachnoid cistern
enlargement of arachnoid space
dura mater
- outermost meninges
- surrounding arachnoid
- attached to the skull and compartmentalizes the brain
choroid plexus
- where all of these structures come together:
1) choroidal capillaries (leaky)
2) pia mater
3) ependyma
- 2 choroid plexus'- one on lateral side of 4th ventricle, one on roof of 3rd ventricle (shaped like a y from diencephalon to telencephalon)
- where CSF produced, about 500ml per day
Foramens of Magendie and Luschka
- holes in choroid plexus for CSF to "get out" in 4th ventricle
- Foramen of Magendie- large center one
- Foramen of Luschka- 2 on either side
Arachnoid villi/villus
sticks up through dura into superior sagittal sinus (large "drain" essentially, in top center of brain)
- lots of sinuses that come together in back of brain and drains back into blood
- acts as one-way valve in the sense that in can only go out not back into the villi
Meningitis
inflammation of meninges, arachnoid villi wouldn't have proper return
Hydrocephalus
water on the brain, causes babies' skulls to swell because skull not fully formed yet; put a shunt in to relieve pressure into thoracic cavity
What do crest cells give rise to?
1) Schwann cells
2) Ganglia of spinal nerve (dorsal root ganglia)
3) Motor ganglia of ANS
4) Ganglia of cranial nerves
Placodes
-one at top that gives rise to anterior pituitary and one that gives rise to lens of eye
- all rest give rise to neural structures (ganglia of cranial nerves)
function of hypothalamus
regulates autonomic NS and endocrine system (through pituitary)
function of thalamus
relay of sensory and motor info to cerebral cortex
function of amygdala
"almond," pre-hypothalamic sensory relay center, projects axons into hypothalamus so it influences the endocrine and ANS
function of basal ganglia
regulates output of motor cortices (striatum)
function of cerebral cortices
analysis of sensory info, formulation of motor output patterns, substrate for higher cognitive function
interventricular foramen of Monro
passageway btw lateral ventricles
What regions make up the brainstem?
hindbrain + midbrain - cerebellum
Neurite
processes off the neuron (axon or dendrite)
What does the paraxial mesoderm give rise to and where is it?
gives rise to somatic muscles, lies on either side of notochord which defines axis of the embryo
What does the lateral plate mesoderm give rise to and where is it?
gives rise to involuntary muscles of gut and heart (visceral), located in interior potion of the laterally situated mesoderm
somites
-repeating units underlying the paraxial mesoderm
-become somatic muscles of trunk and limbs, innervated by spinal nerves
somitomeres
-primordial units of segmentation for paraxial mesoderm of head and truck
- during subsequent development, most of these condense to form somites, but the 7 most rostral ones don't
3 parts of a somite
1) sclerotome= give rise to certain skeletal elements
2) dermatome= forms dermis of skin
3) myotome= gives rise to somatic muscles including their connective tissue elements like fascia and tendons
What happens to the 7 somitomeres that don't become somites?
produce somatic muscles without connective tissue in the head and neck, innervated by cranial nerves
What do epibrachial placodes give rise to?
taste
What does the otic placode give rise to?
inner ear and vestibular system
What is the sulcus limitans and why is it important?
- separates dorsal portions from ventral portions of ependyma
- important because in subsequent development from basal plate (ventral) give rise to motor areas and alar plates (dorsal) give rise to sensory areas
the 31 segments of the spinal cord
1) Cervical- 8 segments
2) Thoracic- 12
3) Lumbar- 5
4) Sacral- 5
5) Coccygeal- 1

Total: 31
In the spinal cord, what represents the gray matter and the white matter visually?
butterfly= gray matter
space surrounding butterfly= white matter
Isthmus
narrowing of midbrain
What is different about C1?
It has no dorsal root.
Where are the enlargements in the spinal cord?
in the cervical and sacral regions
Where is the obex and what is its importance?
the obex is the place representing where the medulla becomes open (where dorsal alar plate thins, creates 4th ventricle choroid plexus)
What number nerve is the Hypoglossal Nerve and what is its function?
Cranial Nerve XII
-innervates muscles of tongue, most caudal of medially located SM nuclei of brainstem
What number nerves are the Abducens, Trochlear, and Oculamotor and what function do they have in common?
CN VI= Abducens
CN IV= Trochler
CN III= Oculamotor
all are SM that allow you to move your eyeballs around
What CN's do the nucleus ambiguus give rise to?
Gives rise to Glossopharyngeal and Vagus/Vagal nerve
What number nerves are the Glossopharyngeal and Vagus Nerves and what function do they have in common?
CN IX= Glossopharyngeal
CN X= Vagus
SM, innervate pharynx and larynx
What kind of receptors are visceral sensory?
-stretch receptors in visceral muscles
-baroreceptors and chemoreceptors in blood vessels
What kind of receptors are somatic sensory?
- lie within somatic muscles and tendons that attach them to bones (muscle spindles, golgi tendon organs) and in overlying skin where they respond to touch, pressure, temperature, and pain
Where are special sensory structures derived from?
-Derived from epidermal placodes
What do the epibranchial placodes give rise to?
taste buds
special visceral sensory structure
What do the otic placodes give rise to?
vestibular and auditory portions of inner ear
special somatic sensory
What innervates the somatic muscles of the trunk in the spinal cord and where does it go?
-large motoneurons (called alpha motoneurons) located in the ventral horn of the spinal cord gray matter
- course ventrally through gray matter into white matter and then across white matter into ventral root of spinal nerve, terminate in periphery on a somatic muscle-cell bodies form a continuous longitudinal column, enlarged at lumbo-sacral and brachial areas which provide innervation for muscles of hindlimb and forelimb respectively
What innervates the visceral motor areas in spinal cord and where does it go?
- visceral motoneurons lie in lateral horn of spinal cord grey matter, from T1-L2, S2-S4
- goes through ventral horn and white matter and into a ventral root, synapse on other neurons in peripheral ganglia which might synapse on visceral target organs
What portions of the visceral motor areas are sympathetic and parasympathetic?
T1-L2= sympathetic
S2-S4= parasympathetic
Which part of the visceral motor areas are specifically for smooth and cardiac muscles?
T5-L2
Which part of the visceral motor areas are specifically for salivary and lacrimal glands and intrinsic eye muscles?
T1-T4
How and where is visceral sensory info from the trunk carried
carried by distal neurites of primary sensory neurons (cell bodies in PNS, specifically dorsal root ganglia of the spinal nerves)
- enter spinal cord and enter gray matter of the dorsal horn where they synape
How and where is somatic sensory info from the trunk carried?
- cell bodies lie within dorsal root ganglion and then go out to CNS via a dorsal root and end on the dorsal horn
primary motor neurons
-neurons with cell bodies within the CNS and leave CNS to synapse directly on muscles or other neurons that influence muscles and glands
- collections of these within spinal cord and brainstem make primary motor centers or motor nuclei
primary sensory neurons
neurons with cell bodies in PNS
The brainstem has how many cranial nerves attached to it?
10
CN III-XII from rostral to caudal
What are the different parts of the special visceral motor column?
1) Nucleus Ambiguus--CN X and CN IX
2) Facial nucleus= CN VII, innervates facial muscles for facial expression
3) Trigeminal motor nucleus= CN V, innervates muscles used in chewing
4) spinal nucleus of XI
How many cranial nerves innervate muscles of the neck and and head
8- Hypoglossal, Glossopharyngeal, Laryngeal, Trigeminal Motor Nucleus, Facial Nucleus, Abucens, Trochlear, Oculamotor
Which cranial nerves are classified as visceral motor neurons?
X- Vagus
IX- Glossopharyngeal (inferior salivatory nuclei)
VII- facial nerve (superior salivatory nuclei)
III-oculamotor (control intrinsic muscles of eye with Edinger-Westphal control
What is the tract and the cranial nerves that innervate the special visceral sensory area?
Nucleus Solitaris- innervated by vagus (X) and glossopharyngeal (IX)
What are the cranial nerves that innervate the somatic sensory receptors of the head and neck?
V- trigeminal
X, IX, VI- Vagus, Glossopharyngeal, Facial
What is the mesencephalic nucleus of V and why is it significant?
where the somatic sensory fibers terminate in the trigmeinal nerve, only example of a primary sensory neuron having its cell body in the CNS
What cranial nerve innervates the special somatic sensory column?
VII- stato-acoustic
vestibular info from inner ear from dorsal and ventral cochlear nuclei
What is the special visceral motor/ branchial motor column?
composed of cell masses that give rise to axons innervating a set of muscles evolutionarily derived from the muscles of the gill arches found in fish
Why was the special visceral motor/branchial motor column called this and what's changed about the interpretation?
1) the origin of the special visceral muscles has been traced to rostral extensions of the lateral plate mesoderm (tissue in the trunk that gives rise to general visceral muscle)
2) motor neurons innervating these muscles seen to form a separate column ventrolateral/lateral to the somatic motor columns
3)special visceral motor components of cranial nerves were known to exit brainstem in a dorsolateral position along with the general visceral motor components

BUT they actually arise from the paraxial mesoderm and innervate striated muscle unlike visceral columns, so considered somatic
What is the primitive streak?
a centrally located linear line of the epiblast where the embryo forms, defines future longitudinal axis of the embryo
What 2 things does the ependyma produce?
neurons and glia
Where does the CSF go once it's gone out the foramens of Magendie or Luschka?
It goes into the subarachnoid space and then out the arachnoid villi into the sinus which drains back into the blood and circulates again
How quickly is CSF made?
0.8 liters/day
What is the function of CSF?
- fluid cushion
- maintains a chemically stable environment
Some destinations for crest cells
- TRUNK: btw epidermal ectoderm and somites, give rise to pigment cells in dermis
- most move along inner surface of somite and give rise to sensory neurons in dorsal root ganglia or give rise to peripheral motor neurons and form gamglia of ANS or make up Schwann cells and satellite cells
- HEAD: pigment cells, sensory neurons in ganglia of cranial nerves, Schwann and satellite cells, cartilage, bone, connective tissue from ectodermal placodes