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223 Cards in this Set

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Describe a Unipolar Nueron
a single process extends from the soma
Not found in fully developed humans
Describe a Psuedo-unipolar Nueron
a single process extends from the soma and immediately divides into two

sensory nueron of spinal nerves and all cranial nerves except I, II and VIII

perpherial axon typically connects to sensory receptors
What type of neuron is the dorsal root ganglion composed of?
Psuedo-unipolar nuerons
Describe a Bipolar Nueron
2 process emerge from the soma

found only in the peripheral nervous system

associated with CN I, II, and VIII
Where is the location of the cell bodies for smell located (CNI)?
Olfactory mucosa
Where are the cell bodies of vision located (CNII)?
Retina
Where are the cell bodies of hearing located (CN VIII)?
Spiral ganglion
Where are the cell bodies of balance located (CN VIII)?
Vestibular ganglion
Describe a Multipolar Nueron
> 2 processes emerge from the soma

majority of all nuerons

functions in sensory, motor and autonomic systems

Ex. Purkinje Fibers and Pyramidal nuerons
Brain Stem
Medulla, Pons, Midbrain
Forebrain
Porsencephalon
Midbrain
Mesencephalon
Hindbrain
Rhombencephalon
Cerebellum & Pons
Metachephalon
Medulla
Myelencephalon
Describe the axis orientation of the forebrain
Dorsal = Superior
Caudal = Posterior
Ventral = Inferior
Rostral = Anterior
Describe the axis orientation inferior to the Midbrain, Diencephalic junction
Rostral = Superior
Dorsal = Posterior
Caudal = Inferior
Ventral = Anterior
Describe the Longitudinal Fissure
Midsagittal Section (splits the brain into halves)
What separates the Frontal Lobe from the Parietal Lobe
Central Sulcus
What separates the Frontal and Parietal Lobes from the Temporal Lobe
Sylvian Fissure (lateral Sulcus)
What does the Precentral Gyrus control and in what lobe is it located?
Motor and the Frontal Lobe
What does the Postcentral Gyrus control and in what lobe is it located?
Somato-sensory and the Parietal Lobe
In what lobe does the Calcarine Sulcus run?
Occipital Lobe
Decussation
Cross the midline
Collections of Cell bodies in the CNS
Gray matter, nucleus/nuclei, body, locus, substantia
What does the corpus callosum connect?
connects the R and L cerebral hemispheres
What does the Cerebral Aqueduct pass through to reach __________?
The midbrain (tectum and tegmentum) to reach the 4th ventrical.
Term for collection of cell bodies in the PNS
Ganglion/ganglia
Terms for bundle of axons in the CNS
White matter, capsule, brachium, peduncle, tract, commisure
Term for bundle of axons in the PNS
NERVE! (the only term)
What are the 4 types of supportive tissue of the CNS?
1. astrocytes
2. oligodendrocytes
3. microglia
4. Ependymal cells
Describe astrocytes
only in the CNS

functions: physical support, scar tissue, removes excess waste and ions (K+), remove neurotransmitter from synapse, blood brain barrier
Describe oligodendrocytes
only in the CNS mainly in white matter

functions: produce myelin around axons

1 oligodendrocyte can provide myelin segments to over 50 axons
The main constituents of myelin
70% lipids (cholesterol and cerebroside) and Protiens (mainly mylein basic protein)
Describe Microglia
function: macrophage (remove damaged tissue by phagocytosis)

Always present in the CNS
Describe Ependymal cells
line cavities of the brain and spinal cord

circulate cerebrospinal fluid
Types of support cells of the PNS
1. Schwann Cells
2. Satellite Cells
Describe Schwann Cells
only in the PNS

functions: support, macrophage, protects axon, myelination

1 Schwann cell can provide only 1 myelin segment
What is the difference between a myelinated axon and an unmyelinated axon with regard to Schwann cells?
a schwann cell is able to myelinate one segement of one axon or engulf several axons
Describe a satellite cell
protects neuronal cell bodies (bascially covers the soma) in the PNS
Describe the location of the Diencephalon
rostral to the brainstem
Major subdivisions of the diencephalon
Epithalamus
Subthalamus
Hypothalamus
Thalamus
Third Ventrical
Anterior border of the diencephalon
Lamina Terminalis
Roof of the diencephalon
Body of the fornix
Structure that connects the R and L thalamus
Massa Intermedia
What separates the thalamus from the hypothalamus
hypothalamic sulcus
What 2 structures are located in the midbrain tectum
Superior and Inferior Colliculus
The dienephalon is bound laterally by...
posterior limb of the internal capsule
What separates the diencephalon into 2 symmetrical halves
third ventrical
What structure is found in the epithalamus?
Pineal Gland
Describe the location of the pineal gland
attached to the roof of the third ventricle near the posterior commissure
Pinealocytes
glia cells found in the epiphysis
Functions of the epiphysis
circadian rhythmicity, spontaneous locomotor activity, feeding and drinking patterns, initiation of puberity
What do pinealocytes secrete
hormone, melatonin
Percocious puberity
caused by tumors of the pineal gland
Brain Sand
calcification of the epiphysis

(ID midline in a radiograph)
Describe the Subthalamus
located rostral to the midbrain

contains the subthalamic nucleus (crucial relay of the basal ganglia, organize movement)
What separates the thalami
Third ventrical
Thalamic Radiations
afferent fibers to the cortex from the thalamus

(specifically from lateral thalamus to the internal capsule then to the cortex)
Thalamus is a relay center to...
cortex, cerebellum, and basal ganglia
Internal Medullary Lamina
Y shaped structure within the thalamus
Name the 3 groups created by the internal medullary lamina
1. anterior nuclear group
2. medial nuclear group
3. lateral nuclear group
Where is the centromedian nucleus nuclei of the thalamus located?
within the internal medullary lamina
What 3 structures does the posterior region of the thalamus contain
1. pulvinar
2. lateral geniculate body
3. medial geniculate body
Reticular Thalamic Nucleus
surrounds the lateral portion of the thalamus and contains inhibitory nuerons
What is unique about the Reticular Thalamic Nucleus
1. all of its projections terminate in the thalamic nuclei
2. purely GABAergic (inhibitory)
Thalamocortical Circuit
nearby points in the thalamus project to nearby points in the cortex (topological)

excitatory (glutamatergic)

reciprocated by a topological and excitatory corticothalamic projection
Function of the Reticular Thalamic Nucleus
prevent recprical feedback between the thalamus and cortex)
Name some of the functions of the thalamus
maintenance and regulation of consciousness, alertness and attention

conscious perception and interpretation of pain

synaptic input for all sensory impulses (except olfaction signals)
Name the structures ovserved in the area of the hypothalamus
mammillary bodies, tuber cincereum, infundibulum, neurohypophysis, optic chiasm
Bounderies of the hypothalamus
anterior = lamina terminalis
superior = hypothalamic sulcus
Inferior = optic chiasm and tracts
posterior = posterior edge of mammillary bodies
Tuber Cinereum
imaginary area on the inferior border of the hypothalamus between the optic chiasm and mammillary bodies.
General functions of the hypothalamus
regulates: heart rate, blood pressure, water metabolism, general metabolism, sexual behavior, temperature, GI activity

elaboration of emotional responses

modulates autonomic responses
2 Afferent inputs to the hypothalamus
1. forebrain (limbic system, retina and others)
2. brain stem/spinal cord (sensory input via dorsal longitudinal fasciculus (DLF))
Associated pathways of forebrain afferent input to the hypothalamus
hippocampus to hypothalamus via fornix

amygdala to hypothalamus via stria terminalis
Hypothalamic efferents
sends out to same areas from which recieved input

(exception: mammillary bodies to thalamus via mammillothalamic tract)
Hypophysis
connection between the hypothalamus with the pituitary gland
Neurohypophysis
porterior portion of the pituitary gland
Adenohypophysis
anterior portion of the pituitary gland
Hypothalamic Areas
Lateral
Medial
Periventricular (most medial surrounding the third ventricle)
Hypophyseal portal vessels
blood vessels that connect the hypothalamus to the adenohypophysis
2 Nuclei connecting with the posterior pituitary (neurophypophysis)
1. Supraoptic nucleus (SON)
2. Paraventricular nucleus (PVN)

both release neuroendocrine products into the general circulation via the nuerohypophysis
Infindibulum & Pars Nervosa
axons and axon terminals of the neurohypophysis, respectively
3 parts of the adenohypophysis
1. pars tuberalis
2. pars distalis
3. pars intermedia
Median eminence
ventral portion of the hypothalamus, where hypothalamic axons converge to secrete releasing/inhibiting hormones with act on cells in pars distals as signals to release/store hormones
Function of Anterior Hypothalamus
Detects an increase in blood temperature
Activated cutaneous vasodilation and sweating
(lesion results in hyperthermia)
Function of Posterior Hypothalamus
Detects decrease in blood temperature
Activiates cutaneous vasoconstriction and shivering to raise temperature
(lesion results in hypothermia)
Function of Lateral Hypothalamus
feeding center
(lesion: anorexia)
Function of the Ventromedial Hypothalamus
satiety center
(lesion: overeating and rage)
CN I
Olfactory nerve
(olfaction)
CN II
Optic nerve
(vision)
CN III
Oculomotor nerve
(eye movement, pupil constriction)
CN IV
Trochlear nerve
(eye movement)
CN V
Trigeminal nerve
(facial sensation, muscles of mastication)
CN VI
Abducens nerve
(eye movement)
CN VII
Facial nerve
(muscles of facial expression, taste, lacrimation, salivation)
CN VIII
Vestibulocochlear nerve
(hearing, equilibrium sense)
CN IX
Glossopharyngeal nerve
(pharyngeal muscles, carotid body reflex, salivation)
CN X
Vagus nerve
(parasympathetic to most organs, laryngeal muscles, pharyngeal muscles, aortic arch reflexes)
CN XI
Spinal Accessory nerve
(head turning)
CN XII
Hypoglossal nerve
(tongue movement)
Dysnosmias: Anosmia & Hyposmia
Anosmia = no smell
Hyposmia = decreased function
Cacosmia
hallucination of unpleasant smells
Olfactory pathway
1. odorants must dissolve in mucosa
2, olfactory receptors (metabotropic chemoreceptors) on dendrites of first order nuerons are activated
3. axons collect and penetrate the cribiform plate of ethmoid bone
4. first synapse occurs in teh olfactory bulb between first order bipolar neurons synapse with second order mitral cells
Lateral Olfactory Stria
one olfactory tract
projects to the pyriform and entorhinal regions of the cerebral cortex, and amygdala
Medial Olfactory Stria
one olfactory tract
projects to the contralateral olfactory bulb via the anterior commissure
Is the thalamus involved with the olfaction
NO
The layers of the eye from innermost to outermost
Retina (Nueral)
Choriod (vascular)
Sclera (fiberous)
Of the 10 layers of the retina is 1 the innermost or outermost?
1 is the outermost and layer 10 is the innermost
What are the 5 types of nuerons in the retina and which are involved in the visual pathway?
Receptor, Bipolar, Ganglion -> involved with the visual pathway
horizontal and amacrine -> not involved
2 types of receptor neurons of the retina
Rods (night vision)
Cone (color)
Describe the Rod receptor nueron
-low intensity of illumination and subserve twilight and night vision
-when only rods activated, we cannot see color
-contain more visual pigment and are more sensitive than cones
-total loss of rods = night blindness
Describe the Cone receptor nueron
-higher threshold of excitability (stimulated by light of relatively high intensity)
-sharp vision
-color discrimination
-day vision
-3 types of cones (encompass the visual spectrum)
Layer 1 of the retina
pigment epithelium, absorbs light not captured by retina
Layer 2 of the retina
contains the receptor portion of rods and cones
Layer 6 of the retina
contains cell bodies of horizontal, bipolar, and amacrine neurons
Layer 8 of the retina
contains cell bodies of the ganglion cells
Layer 9 of the retina
next to innermost layer

contains axons of the ganglion cells, these axons become the optic nerve
Ganglion nuerons of the retina
axons project to become the optic nerve
Bipolar nuerons of the retina
neuronal "link" between the receptor nuerons and ganglion neurons
Amacrine and Horizontal nuerons of the retina
internuerons in the retina that make synapses on other neurons

Involved with visual processing
Optic disc
one area of specialization of the retina

axons of the ganglion nerves converge here to form the optic nerve
Fovea Centralis
area of the retina containing only cones

inner layers are shifted to the side so light may hit the photoreceptors without any distortions

[sharpest vision and most acute color discrimination]
Central visual pathway -
Pupillary pathways -
Visual association pathway -
Reticular pathway -
Hypothalamic pathway -
Central visual pathway - produces vision
Pupillary pathways - one to iris (constricts pupil), one to ciliary body (lens accommodation)
Visual association pathway - via super colliculus
Reticular pathway - produces alertness
Hypothalamic pathway - circadian rhythm
The path from light to optic nerve
light -> photoreceptor -> bipolar neuron -> ganglion nueron -> optic nerve
Which neurons are 1st and 2nd order in the visual pathway
1st order = bipolar neuron
2nd order = ganglion nueron
What is the difference between Optic Nerve and Optic Tract
Optic nerve is before the optic chiasm and optic tract is after
What information does the Right optic tract contain
contralateral visual field

aka. Left visual field
Central Visual Pathway
80% of optic tract -> lateral geniculate body -> primary visual cortex in occipital lobe
Does that lateral geniculate body receive information from both eyes?
Yes, but from the contralateral visual field
How many cellular layers does the lateral geniculate body have, and how are they arranged?
6 layers

3 devoted to contralateral axons
3 devoted to ipsilateral axons
What order are the neurons in the lateral geniculate body?
3rd order
Where does information from the fovea project to on the occipital lobe?
occipital pole (most posterior portion)
Where does the superior half of the visual field project to?
area inferior to the calcarine fissure
Where does the inferior half of the visual field project to?
area superior to the calcarine fissure
Meyer's Loop
optic radiations conveying info to the inferior occipital lobe
Will a person be able to see if there is a lesion to V1 in the central visual pathway
No

V1 = visual awareness

A person would be aware enough to move out of the way if a ball was thrown at them
Agnosia
inability to recognize objects
Prosopagnosia
inability to recognize faces

(right occipitoparietal cortex, grandmother cells)
Refraction
bending of light at an angled surface
What does a Convex lens do to light?
causes light rays to converge to a focal point
What does a Concave lens do to light?
causes light rays to diverge
Does a green car absorb the green light or reflect it?
The green car will absorb all the colors of white light except green, which it reflects
Spectrum
ROYGBIV
Red (longest wavelenght, less energy)
Orange
Yellow
Green
Blue
Indigo
Violet (short wavelength, more energy)
Photopic Vision
daytime vision
[Cones]
Purpose and contents of photopigment
transduce light into receptor potential

contains: retinal and Opsin
Retinal + Scotopsin =
Rhodopsin
Retinal + Blue Opsin =
Blue photopigment
Retinal + Green Opsin =
Green photogpigment
Retinal + Red Opsin =
Red photopigment
In the dark (at rest) the photoreceptor is _____________
depolarized
In the presence of light, the photoreceptor _______________
hyperpolarizes
Are the Na+ channels in the photoreceptor OPEN or CLOSED in the presence of cGMP?
OPEN

cAMP is present at rest (in the dark) keeping the photoreceptor depolarized at rest
Does light INCREASE or DECREASE the intracellular concentration of cGMP
Decrease

causing a closure of Na+ channels
Light __________ the photoreceptor
hyperpolarizes
Sequence of events leading to degradation of cGMP
1. light detected by a photopigment
2. conformational change in retinal
3. change in opsin structure
4. activate G-protein (tranducin)
5. transducin activated phosphodiesterase (eat up cGMP)
Does hyperpolarization lead to an increase or decrease of glutamate release?
decrease onto the bipolar nueron
1 Rhodopsin molecule absorbs ____ photon
One -> leading to an amplification of response
What does glutamate do to bipolar cells?
inhibits them
Reduction of glutamate levels leads to DEPOLARIZATION or HYPERPOLARIZATION of the bipolar cell, which leads to _________ of the ganglion cell.
Depolarization

Activation
What do nuclei of CN III, IV and VI have in common
nuclei of ocular motion
What are the 2 nuclei associated with CN III
1. Oculomotor Nucleus
2. Edinger-Westphal Nucleus

(both in the midline in the midbrain)
CN IV nucleus
Troclear Nucleus

(midline in midbrain)
CN VI nucleus
Abducens Nucleus

(midline in caudal pons)
Direct pupillary light reflex
constriction in the eye stimulated
Consensual light reflex
constriction in the opposite eye
Neurons in the Pupillary Pathway from the bipolar neuron to the pupillae muscle
1. bipolar n.
2. ganglion n.
3. neurons in the pretectal area
4. Edinger - Westphal nucleus
5. ciliary ganglion
6. pupillae muscle
What causes the consensual light reflex in pupillary pathway?
The pretectal area sends two axons out, one to each Edinger-Westphal nucleus
Is pupil constriction a sympathetic or parasympathetic response?
parasympathetic

Parasympathetic CN (3,7,9,10)
Where does pupillary dilation initiate from and what path does it follow?
Initiates in the hypothalamus then travels down the spinal cord. It passes through the white rami communicantes to the superior cervical ganglion onto the carotid plexus and lastly to the pupillary dilator muscle.
Pupillary Pathway for lens accommodation and convergence
visual info -> visual cortex -> axons to pretectal area -> axons to oculomotor nucleus and Edinger-Westphal nucleus

oculomotor nuclues -> contraction of the medial recti muscle (convergence)
Edinger-Westphal -> ciliary ganglion -> contraction of ciliary muscle -> adjust tension in lens
Accommodation
[change in refractive power of lens]
At rest is the lens thin or thick?
thin
What happens upon contraction of the ciliary muscle?
tension is relieved from the zonule fibers and the lens thickens
Where is the oculomotor nuclei located?
Midbrain - level of superior colliculus
Where is the Trochlear nucleus located?
Midbrain - level of inferior colliculus

Note: CN leaves dorsally and projects contralaterally
Where is the Abducens nucleus located?
Pons - dorsal in the brainstem

exits ipislaterally at the pons-medullary junction
Is CN VII a mixed nerve?
Yes

4 Nuclei
-2 efferent (motor) components
-2 afferent (sensory) components
Facial motor nucleus
(1 of 2) efferent nucleus of CN VII

-> innervates the facial muscles
Superior Salivatory Nucleus
1 efferent nucleus of CN VII

parasympathetic innervation to mediate lacrimation and salvation
Describe the location of the facial motor nucleus and it's exiting axons
nucleus - caudal pons

axons travel inward and wrap around the abducens nucleus then travel ventrally
What input does the upper 1/2 of the facial motor nucleus receive?
bilateral input from the cerebral cortex
What input does the lower 1/2 of the facial motor nucleus receive?
only contralateral input from the cerebral cortex
Lesion to the facial motor nucleus
ipsilateral paresis of the entire half of face
Lesion to the corticobulbar tract
contralateral lower face paralysis
Through what tract does the facial motor nucleus receive input from?
cortex -> Corticobulbar tract -> facial motor nucleus
Bell's Palsy
Lesion facial nerve

paralysis to half of face on ipsilateral side of lesion
the facial nerve contains ___________ preganglionic axons that arise from the superior ________ nucleus.
Parasympathetic

Salivatory
Pterygopalatine Ganglion
receive axons from the superior salivatory nucleus via the facial nerves

leads to lacrimination via the lacrimal glands
Submandibular Ganglion
receive axons from the superior salivatory nucleus via the facial nerves

leads to salivation via the sublingual and submandibular glands
What carries gustatory (sensory) info from the anterior 2/3 of the tongue
CN VII

cell bodies in the geniculate ganglion, and synapse in the solitary nucleus
What carries somatic sensations from the small area within the pinna (external ear)
CN VII

cell bodies in the geniculate ganglion, and synapse in the spinal trigeminal nucleus
What is the spinal cord continuous with?
medulla
Term for the end of the spinal cord
conus medullaris
segments of the spinal nerves
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
Where does the spinal nerve C8 emerge from?
between the seventh cervical vertebrae and the first thoracic vertebrae
Arrangement of the 10 layers within the gray matter
Lamina (layer) I is dorsal
Lamina IX is ventral
Lamina X surrounds the central canal
3 paired funiculi of White Matter in the spinal cord
Posterior funiculus
Lateral funiculus
Anterior funiculus
Anterior median fissure
midline on the spinal cord on anterior surface

contains anterior spinal artery
Posterior median sulcus
posterior midline in the spinal cord

contains posterior spinal vein
Posterior Intermediate sulcus
divides the posterior funiculus into 2 on the spinal cord

only present T7 and above
Does the sacral spinal cord contain more gray or white matter?
large amounts of gray and small amounts of white matter
Why does the amount of white matter increase as you move up the spinal cord?
gain more sensory axons
Where is the dorsal nucleus of Clarke located?
Thoracic spinal cord - within the posterior horn
What separates the fasiculus gracilis and fasiculus cuneatus?
posterior intermediate septum (sulcus)

above T7
Alpha peripheral neuron
proprioception, somatic motor

largest is diameter and conduction velocity (myelinated)
Beta peripheral neuron
touch, pressure

(myelinated)
Gamma peripheral neuron
Motor to muscle spindles

(myelinated)
Delta peripheral neuron
pain, temperature, touch

(myelinated)
B peripheral neuron
preganglionic autonomic
C peripheral neuron
-dorsal root
-sympathetic
dorsal root - pain, reflex response
sympathetic - postganglionic sympathetis

(unmyelinated)
Relative fiber diameter and conduction velocity of fibers of type A
Diameter and conduction velocity:
alpha > beta > gamma > delta

(all myelinated)
Ascending Spinal Pathways
somatosensory pathways for the entire body except orofacial complex
1. Dorsal column/ medial lemniscus pathway
2. Anterior Lateral System (ALS)
Where do the central process of the DRG go in the Dorsal Column/ medial lemniscus pathway?
enter into the spinal cord in the posterior horn
What is the organization of the posterior funiculus?
sacral fibers are most medial
cervical fibers are most lateral
Fasciculus Gracilis: where and what it carries
present in all spinal levels

ascending fibers from sacral, lumbar and lower 6 thoracic dorsal roots
Fasciculus Cuneatus: where and what it carries
appear around T7

ascending fibers from upper 6 thoracic and all cervical dorsal roots
Where do the internal arcuate fibers cross the midline is the Dorsal column pathway?
in the medulla
What sensory information does the dorsal column/medial lemniscus pathway carry?
fine touch, proprioception, vibration
What sensory information does the anterior lateral system carry?
pain, temperature, crude touch
What are the 3 neurons in the Anterior Lateral System?
1. DRG neurons (A-delta and C fibers)
2. neuron in dorsal horn to VPL
3. VPL to somatosensory cortex
Where do the neurons of the lissauer's tract synapse in the dorsal horn?
Laminae I, II, and V
Where does the Anterior Lateral system cross the midline?
upon entry into the spinal cord via the ventral white commissure