Flashcards in Test 1 Deck (574)
Loading flashcards...
0
3 stages of prenatal motor development
germinal- 0 to 2 weeks
embryonic- 2 to 8 weeks
fetal- 8 to 40 weeks
1
germinal period
2 weeks in length
migration of zygote (fertilized ovum) to uterus:3-4 days
rapid increase in cell number
by day 9-12 the blastocyst embeds itself in the endometrium
2
gastrulation
embryo transforms from bilaminar to trilaminar day 15-16
3
Neurulation
-process by whereby the neural plate forms the neural tube
-lateral edges of the neural plate become elevated and form the neural folds; depressed mid region becomes the neural groove
-gradually the neural folds approach each other in midline, where they fuse
-closure of cranial and caudal neuropores
4
closure of cranial neuropore
day 25
5
closure of caudal neuropore
day 28
6
neurulation-week 3
-the notocord (dorsal cord) appears at the end of gastrulation
- notocord sends signals that causes cells of the ectoderm just above it to thicken
- neural plate begins to invaginate to form neural groove
-neural groove rises from embryos surface and closes to form neural tube
7
what defines the rostral- caudal axis
notocord, cylinder of cells, in the mesoderm
extends along entire length
8
neural crest cells
cells break away from epithelial layer of the developing dorsal neural tube and subsequently migrate as mesenchymal cells
9
crest cells travel to many areas of the developing embryos and give to rise to
dorsal root ganglion
ANS ganglia
ganglia to CN V, VII, IX, X
schwann cells
meninges
pigment cells
MS components of head
10
brain development
begins at day 28
superior neuropore closes, neural tube expands to form 3 enlargements (2 subsequent enlargements also appear)
enlargements are hollow
11
3 main divisions of the brain
prosencephalon (forebrain)
mesencephalon (midbrain)
rhombencephalon (hindbrain)
12
prosencephalon (forebrain)
telencephalon- cerebral hemisphere
diencephalon- thalamus, hypothalamus, epithalamus
13
mesencephalon (midbrain)
connects forebrain to hindbrain
14
rhombencephalon (hindbrain)
pons, medulla, cerebellum
15
spinal cord develops from
caudal end of neural tube. continuous with rhombencephalon
16
organization of gray/white matter
white matter: marginal zone
grey matter: dorsal cell bodies from alar plates. ventral cell bodies/ lateral grey columns from basal plates
17
when does myelination occur
throughout the first year of life
18
somites
cells formed in segmental pairs along the neural tube from mesoderm layer
give rise to vertebrae, muscles of back and body wall, and dermis of skin
19
development of somite
paraxial mesoderm cells (from neural crest) undergo further differentiation to develop into segment series of tissue blocks (somitomeres/somites) on either side of the neural tube
20
somites develop into 2 things
1) myotome- cells in dorsolateral regions from muscle cells; migrate beneath dorsal epithelium (dermatome)
2) sclerotome: cells in ventromedial wall lose epithelial arrangement; become mesenchymal
21
embryonic CT
1) fibroblasts
2) chondroblasts
3) osteoblasts
22
each somite gives rise to and differentiates into 3 things
1. ventromedial sclerotome (vertebrae and ribs)
2. myotome (muscles)
3. dermatome (skin)
23
where do the first pair of somites develop
a short distance posterior to cranial end of the notochord. the rest form caudally
24
how many pairs form during the somite perior of development?
what is the final number?
38 pairs (days 20-30)
overall 42-44 pairs
25
mycocoele
a cavity that forms within each somite but disappears
26
how can the age of an embryo be determined?
by the number of somites
27
embryonic period length
6 weeks and then continues to gastrulation
28
organogenesis
defining of cells
29
at 3 weeks cells differentiate into what 3 layers
ectoderm
mesoderm
endoderm
30
endoderm becomes what
digestive/respiratory systems
31
mesoderm becomes what
muscles, skeleton, circulatory system, reproductive system, dermis
32
ectoderm becomes what
CNS, PNS, eyes, ears, outerskin
33
embryo week 4
neural folds fuse, folding of embryo into human-like shape
arm and leg buds appear
heart pumps blood
pharyngeal arches visible
length 4-5mm
4-12 pairs of somites
34
Embryo week 5
Lens placodes appear
Primitive mouth
Digital rays on hands
Forebrain,midbrain, hindbrain form
35
Embryo week 6
Primitive nose
Primary palate
Auricular hillocks form-precursor to visible auricle of ear
Reflex response to touch
Digital rays being to develop
Length 21-23mm
36
Embryo week 7
Eyelids begin to form
Motor behavior first appears as slow neck extensions
Limbs undergo considerable change
Notches appear between digital rays
37
Embryo week 8
Length 3-5cm
Weight 2g
Ovaries and testes distinguishable
Eyes ears nose mouth digits formed
Muscle contraction appear- lateral flexion movement
Can see startle, hiccup, isolated arm/leg movement
38
Summary of embryonic development
By end of eight weeks embryo is distinctly human in appearance
Had more round/erect but still large
Neck established
Eyelids more obvious
Auricle s of ears begin to take shape
39
Prenatal development week 9
Increased activity and rapid growth
5cm in length
Sensory organs developing
Bone ossification begins
Head retro flexion
Head rotation
40
Prenatal development-week12
11.5cm 19g
Sex is externally recognizable
Head large for body
Brain configuration nearly complete
Blood forming in marrow
Sucking/swallowing
Yawn
41
Prenatal development weeks13-16
Breathing and swallowing motion appears
Tactile stimulation elicits movements
Growth very rapid
Limb movements increasingly coordinated
42
Prenatal development week 16
19cm
100g
Motor activity begins
Scalp hair present
Trunk size increasing relative to head size
Heart muscle developed
Sense organs formed
43
Prenatal development week 17
Grasp reflex appears
44
Prenatal development week 20
22cm
300g
Lower extremities have grown appreciably
Myelination of spinal cord begins
Fetus turns and moves easily
45
Prenatal development week 24
32 cm
600g
Lungs become viable organs
Cerebral cortex layers formed
Midgestation- full range of newborn movements can be observed
46
Prenatal development week 25
Third trimester
47
Prenatal development 26
Eye opening
48
Prenatal development week 28
36cm
1100g
Increasing fat tissue development
Retina layered and light receptive
Fetus turns head down
49
Prenatal development week 32
41cm
1800g
Weight increasing more than length
Taste sense operative
50
Prenatal development week 36
46cm
2200 grams
Body more rounded
Ossification begins distal femur
51
Prenatal development week 38
Term
52
Prenatal development week 40
52cm
3200 grams
Skin smooth and pink moderate head hair
Proximal tibia ossification
Myeloma tin of brain begins
Pulmonary breathing 2/3 complete
53
When do portions of skeletal system form
During the first few weeks post conception
54
What has occurred in skeletal development by the end of the embryonic period?
Skeletal pattern has been formed in cartilage and connective tissue- ossification begins
55
Two types of skeletal development
Intramembranous and endochondral
56
Intramembranous ossification
Replacement of ct membranes with bony tissue
Forms flat bones of skull and irregular shaped bones
First formed as connective tissue membranes
Osteoblasts migrate to membranes and deposit bony matrix
57
Endochondral ossification
Replacement of hyaline cartilage with bony tissue
Most bones formed this way
Future bones formed as cartilage models
After 12 weeks post conception the surface surrounding the models is infiltrated with blood vessels and osteoblasts
Surface becomes periosteum
Osteoblasts form collar of bone around diaphysis
Cartilage at center disintegrates
Osteoblasts penetrate center and replace cartilage with spongy bone (becomes primary ossification center)
Ossification continues from center to distal ends
When spongy bone reaches diaphysis osteoclasts break down new bone to open medullary cavity
Cartilage at epiphyses continue to grow to increase bone length
After birth secondary ossification centers form in epiphyses
Spongy bone retained in epiphyses
58
After 12 weeks post conception what happens to the surface surrounding the models
Is infiltrated with blood vessels and osteoblasts
Surface becomes periosteum
59
In endochondral ossification what do the osteoblasts penetrate?
The center and replace the cartilage with spongy bone
Ossification that continues from this center to distal ends of the bones
61
How does ossification continue??
From center to distal ends of bone
62
What happens once spongy bone reaches diaphysis?
Osteoclasts break down the new bone to open medullary cavity
63
Where and when do secondary ossification centers form
After birth in epiphyses
64
Where is spongy bone retained?
Epiphyses
65
When do limb buds appear
Week 4
66
When do upper limbs begin to develop
1-2days prior to lower limbs
67
What do buds consist of
Mass of mesenchyme derived from mesoderm covered by layer of ectoderm
68
What do ends of buds develop into
Quickly into paddle like hand or footplates
69
What occurs at the end of the 6th week
Digital rays are formed in hands. Week 7 for feet
70
What occurs by the end of the 8th week
Apoptosis to complete formation of digits
71
What occurs early in the 7th week
Limbs extend and rotate in opposite directions
72
Initially how do flexor aspect of limbs lay
Ventrally
73
Initially how do extensor aspect of limbs lay
Dorsally
74
How do the upper and lower limbs rotate
Upper limb 90 degrees laterally
Lower limb 90 degrees medially
75
What are the radius/ulna homologous to?
The great toe?
Tibia/ fibula
Thumb
76
Where do most muscles develop from
Mesoderm
77
Origin of skeletal muscle
Most from myotomal cells of somites
78
Cranial somites (4 occipital somites) -->
Tongue
79
What do the remaining caudal myotomes become?
Dorsal column epimere--> deep extensor muscles of back
80
What do the remaining ventral-lateral myotomes become
Hypomere--> muscles to the body wall
81
Spinal nerves
Posterior primary ramus (to the epimere)
Anterior primary ramus (to the hypomere)
82
What do some body wall muscles and limb bud muscles develop in situ from
Local mesenchyme
83
What do embryonic pharyngeal arches become
Muscles in head and neck
84
Skeletal muscle derived from?
Paraxial mesoderm
Somites: occipital--> sacral region (33)
Somitomeres: head (7)
85
Smooth muscle derived from
Differentiates from visceral splanchnic mesoderm surrounding gut
And ectoderm (pupillary, mammary gland, sweat gland muscles)
86
Cardiac muscle derived from
Differentiates from visceral splanchnic mesoderm surrounding heart tube
87
Teratogens
Congenital infection
Alcohol
Smoking
Drugs
Poor nutrition
88
Basics of somatic nervous system
Voluntary
Skeletal muscles
Sensation
89
What does the somatic nervous system consist of
Skeletal muscle
Nervous system components that control them
Generates behavior
90
What is the starting point of the CNS?
Spinal cord
91
What passes through the spinal cord
Motor neurons, autonomic efferents
92
Where does the spinal cord receive all afferent info from
Periphery
93
Segmental organization
Axons of LMNs bundle to form the ventral roots
Ventral roots join with dorsal roots to form spinal nerves (31 pairs of mixed)
Spinal segments
94
What are spinal segments
Motor neurons that make up one spinal nerve
95
Dermatome
Area of skin innervated by a single posterior root
96
Myotome
Group of muscles innervated by single anterior root
97
3 regions of gray matter
Dorsal horn (column)
Lateral horn (column)
Ventral horn (column)
98
Dorsal horn
Contains sensory nerve fibers
Interneurons and projection neurons that ascend to CNS
Pain
Temperature
Somatic and visceral information
99
Lateral horn
Contains cell bodies of autonomic neurons
Cells body's of preganglionic sympathetic neurons (ANS)
Seen only from T1-L3
100
Ventral horn
Contains cell bodies of motor neurons
Large cell bodies (LMNs) of skeletal motor neurons
101
Rexed's laminae
Named for bror rexed
Swedish neuroscientist who discovered and mapped the areas in the 1950s
Laminae=layers
102
Laminae 1 and 2
Marginal layer
Substantia gelatinosa
Dorsal horn
Process noxious stimuli
103
Laminae 3 and 4
Nucleus Proprius
Dorsal horn
Proprioception and 2 point discrimination
104
Laminae 5
Dorsal horn
Noxious stimuli from viscera
105
Laminae 6
Dorsal horn
Proprioceptive input
106
Laminae 7
Nucleus dorsalis
Intermediate zone
Receives proprioceptive input
Relays unconscious proprioceptive information to cerebellum
107
Laminae 8
Commissural nucleus
Ventral horn
Connects contralateral cord and the brain
108
Laminae 9
Ventral horn
Motor nuclei
Contains cell bodies of LMNs
109
Laminae 10
Grey matter
Grisea centralis
Axons that cross cord to opposite side
110
What types of columns of axons does white matter contain
Ascending tracts (afferent)
Descending tracts (efferent)
111
Ascending tracts
Carry sensory information to the brain
112
Descending tracts
Carry motor signals from brain to body
113
Upper motor neuron originates where?
In the cortex and synapses with lower motor neurons in the spinal cord
114
Lower motor neurons
Directly command muscle contraction
Originate in the ventral horn of spinal cord
Part of the PNS
include the cranial nerves, spinal nerves, cauda equina, and ventral horn
115
Distribution of lower motor neurons
Axial muscle lower motor neurons medial
Distal muscle lower motor neurons lateral
116
Alpha motor neurons
Tigger generation of force
Innervate extrafusal fibers
117
Gamma motor neurons
Regulate sensitivity of muscle to stretch
Innervate intrafusal fibers
118
3 sources of input/control for alpha motor neurons
Dorsal root ganglion
Upper motor neurons
Spinal cord interneurons
119
Motor unit
Alpha motor neuron and all muscle fibers it innervates
Vary in size
Recruited in order from smallest to largest
120
Motor neuron pool
Alpha motor neurons that innervate a single muscle
121
Function-graded control
Determine correct amount of force necessary to complete activity
Picking up/ holding a fragile item
Lifting neuroscience texts from desk
Sprinting in a race
122
Grading muscle contraction
CNS varies the firing rate
CNS recruits additional motor units
123
How does the CNS vary firing rates in grading muscle contractions
Alpha motor neuron releases AcH at neuromuscular junction
Causes excitatory post synaptic potential
Rapid succession of action potentials can create desired strength of contraction
124
Fast motor units
Rapid fatigue white
Escape muscles; jumping, upper extremity
125
Slow motor units
Slow
Fatigue
Red
Antigravity muscles of lower extremity
126
ALS
Amyotrophic lateral sclerosis
Enzyme superoxide dimutase is mutated
Causes increase in superoxide radicals that destroys cells especially motor neurons
Creates muscle weakness and paralysis due to the degeneration of large alpha motor neurons
127
Muscle contraction
Alpha motor neurons release ACh
ACh produces large EPSP in muscle fiber
EPSP evokes muscle action potential
Action potential triggers Ca2+ release
Fibers contract
Ca2+ reuptake
Fiber relaxes
128
Proprioception
Muscle spindles- stretch receptors
Golgi tendon organs- strain gauge
129
Gamma motor neurons
Muscle spindles contain intrafusal fibers innervated by gamma motor neurons
130
Reflexes
Involuntary stereotypical response to sensory input
Typically involve one or more interneuron
131
Myotatic reflex (stretch)
Mono synaptic
Examples:
Biceps c5/c6
Brachioradialis c6
Triceps c7
Quads L3/L4
Achilles s1/s2
132
Diminished reflexes
Result of abnormalities in muscles, sensory neurons, lower motor neurons, and neuromuscular junctio
133
Increased reflexes
Result of upper motor neuron lesions
134
Reverse myotatic reflex
Regulates muscle tension in normal range
135
Spinal interneurons
All actions of Golgi tendon and alpha motor neurons mediated by interneurons
Reciprocal inhibition
136
Reciprocal inhibition
Contraction of agonist with simultaneous relaxation of antagonist
137
Withdrawal reflexes
Interneurons are excitatory
Slower response than myotatic
Combines with crossed-extensor reflex to keep balance
138
Upper motor neurons-ascending tracts
Somatosensory
Anterolateral spinothalamic
Dorsal column medial lemniscal
Spinocerebral
139
Upper motor neurons- descending tracts
LATERAL
Motor;
Corticospinal
Rubrospinal
140
Upper motor neurons- descending tracts
Ventralmedial
Reticulospinal (medullary and pontine)
Vestibule spinal
Tectospinal
Motor
141
Dorsal column medial lemniscus
Fasciculus gracious (medial) carry lower extremity
Fasciculus cuneatus (lateral) carry upper extremity
Proprioception and discriminative touch
142
Anterolateral spinothalamic
Immediate degustation of axons in spinal cord at levels of input
Fibers project upward directly to thalamus
Pain, temperature contralaterally
143
Damage to spinal cord at dorsal column/spinothalamic creates what impairments
Contralateral pain and temperature deficits
Ipsilateral touch deficits
144
Spinocerebellar tract
Conveys unconscious proprioceptive information
145
Spinocerebellar tract impairments: friedreichs ataxia
Inherited degenerative disease leading to profound incoordination of the arms (intention tremor) and wide based, reeling gate (ataxia)
Begins in childhood leaving child wheelchair bound by age 20
146
Descending pathways- lateral system
Fine precise motor skills in hands
Lateral corticospinal tract
Rubrospinal tract
147
Descending pathways- medial system
Trunk movement and stance
Reticulospinal tract
Vestibulospinal tract
Tectospinal tract
148
Tract
Bundles of upper motor neuron axons that travel together in the white matter of the brain stem and spinal cord
149
Percentage of fibers from lateral corticospinal tract
90%
150
Percentage of fibers from anterior/medial corticospinal tract
10%
151
Lateral corticospinal tract
Fine control of distal extremities and coarse regulation of proximal flexors
Allows fractionation of movement
Enables us to tie knots, press individual keys of a piano, pick up small objects
Longest, largest tract in cord
152
Lateral corticospinal tract pathway
Arise primary motor, premotor, and supplementary motor cortex
Course through internal capsule
Through basis pedunculi of midbrain, basis pontis of pons, and pyramid of medulla
Decussates at pyramidal decussation of cervicomedullary junction
Courses through lateral white matter of spinal cord and synapses in lateral intermediate zone of spinal cord
153
Anterior (medial) corticospinal tract function
Axons synapse cervical and thoracic regions only
Conveys info to lower motor neurons that control neck, shoulder, and trunk muscles
154
Anterior (medial) corticospinal tract pathway
Originates in motor cortex (frontal lobe) and somatosensory area of parietal lobe
Internal capsule
Base of cerebral peduncle (midbrain)
Pons
Medulla
Crosses at pyramidal decussation
Spinal cord
161
What do osteoblasts penetrate in endochondral ossification
Center and replace cartilage with spongy bone and becomes primary ossification center
162
Rubrospinal tract
Originates red nucleus of midbrain
Rubio means red in latin
Axons decussate in the pons and join with axons of corticospinal tract in lateral column of spinal cord
163
Corticospinal/rubrospinal impairments
Poor fractionated movements of arms and hands- use all fingers at once
Voluntary movements slower- less accurate
Baseball pitcher analogy- can stand on mound but not throw accurately
164
Medial tracts
Reticulospinal
Vestibulospinal
Tectospinal
Corticobulbar
165
Reticulospinal tract
Arise from reticular formation of brain stem
Pontine tract (ipsilateral)
Lateral (medullary) tract (bilateral)
166
Pontine tract
Ipsilateral
Facilitates extensor motor neurons
Enhances antigravity reflexes of spinal cord
Helps maintain standing posture
167
Lateral (medullary) tract
Bilateral
Facilitates flexor motor neurons
Liberates antigravity muscles from reflex control
168
Vestibule spinal tract
Responds to stimuli from the vestibular apparatus
Medial vestibulospinal tract
Lateral vestibulospinal tract
Damage to these tracts leads to ataxia and balance problems
169
Medial vestibulospinal tract
controls neck and upper back muscles for positioning
170
Lateral vestibulospinal tract
Facilitates extensors and inhibits flexors for balance
171
Tectospinal tract
Originates in midbrain- superior colliculus- which receives direct input from the retina and projections from the visual cortex
Directs head movements toward novel visual and auditory stimuli
172
Tectospinal tract course
Superior colliculus occipital lobe
Crosses at tectobulbospinal junction
Travels with vestibulospinal tract ending cervical region
173
Corticobulbar tract
Arises in motor areas of cerebral cortex and projects to the cranial nuclei in brainstem
Voluntary control drive to brainstem
174
Central cord syndrome tracts involved
Corticospinal
Spinothalamic
175
Symptoms of central cord syndrome
Falls
Upper/lower extremity weakness
Sensory loss (pain, temperature, light touch, position) below level of the lesion
176
Anterior cord syndrome
Tracts- ascending spinothalamic
Pain and temperature sensation altered
Motor control impaired
177
Brown sequard syndrome
Below level of the lesion:
Ipsilateral voluntary motor control
Ipsilateral conscious proprioception
Ipsilateral discriminative touch
Contralateral pain
Contralateral temperature
178
Posterior cord syndrome
Loss of proprioception
Variable loss of motor function, pain, temperature
179
What kind of structure is the cerebral cortex
Convoluted
Folds help increase surface area of the brain and allow more neurons to be compacted into a smaller cranial space
180
Gyrus/gyri
Elevated ridges winding around the brain
181
Sulcus/sulci
Small grooves dividing the gyri
Central sulcus divides the frontal lobe from the parietal lobe
182
How is the cerebral hemisphere divided
In 2 by falx cerebri
183
Each hemisphere contains 4 lobes
Frontal, parietal, temporal, occipital
184
What sulcus separates the temporal lobe from the frontal and parietal lobes
Lateral (sylvian) sulcus
185
Which sulcus separates the frontal and parietal lobes
Central sulcus and is separated by 2 important parallel gyri
186
What fissure separates the cerebral hemispheres
Median (longitudinal)
187
Cerebrum
Largest division of the brain. It is divided into 2 hemispheres each of which is divided into 4 lobes
188
Cerebral cortex
The outermost layer of gray matter making up the superficial aspect of the cerebrum
189
Functions of cerebral cortex
Cognition
Memory
Language
Perception
Control of complex movement
190
Total surface area of cerebral cortex
2200 cm
About 1/3 is surface area
About 2/3 is hidden in the sulci
191
Thickness of cerebral cortex
1.5 mm-4.5mm
Thickest over the crest of the convolution and thinnest in the depth of the sulci
192
Weight of cerebral cortex
600gm=1.3 lbs
40%of total brain weight
180g --> neurons
420g --> glial cells
193
Number of neuronal cells in cerebral cortex
Neurons 10-15 billion
Glial cells 50 billion
194
Fissure
Deep grooves generally dividing large regions/ lobes of the brain
195
Transverse fissure
Divides two cerebral hemispheres
196
3 divisions of the cortex
Archicortex (allocortex)
Mesocortex (juxtallocortex)
Neocortex (isocortex)
197
Archicortex (allocortex)
3 layers
Hippocampus/ dentate gyrus
198
Mesocortex (juxtallocortex)
3-5 layers
Parahippocampal gyrus
199
Neocortex (isocortex)
6 layers
Primary motor/ sensory cortex
Association area
200
Anterior cerebral artery
Cortex (anterior medial surface)
Anterior medial surface frontal and parietal lobes
201
Middle cerebral artery
Cortex superior to sylvian fissure
Internal capsule
Globus pallidus
Putamen
Caudate
202
Posterior cerebral artery
Midbrain
Occipital lobe
Portions of medial and inferior temporal lobes
203
Ventricles
Contain CSF produced by choroid plexus
2 lateral ventricles (one in each cerebral hemisphere)
Third ventricle (in diencephalon)
4th ventricle surrounded by pons, medulla, cerebellum
204
3 divisions of the cortex
Archicortex (allocortex)
Mesocortex (juxtallocortex)
Neocortex (isocortex)
205
Archicortex (allocortex)
3 layers
Hippocampus/ dentate gyrus
206
Mesocortex (juxtallocortex)
3-5 layers
Parahippocampal gyrus
207
Neocortex (isocortex)
6 layers
Primary motor/ sensory cortex
Association area
208
Anterior cerebral artery
Cortex (anterior medial surface)
Anterior medial surface frontal and parietal lobes
209
Middle cerebral artery
Cortex superior to sylvian fissure
Internal capsule
Globus pallidus
Putamen
Caudate
210
Posterior cerebral artery
Midbrain
Occipital lobe
Portions of medial and inferior temporal lobes
211
Ventricles
Contain CSF produced by choroid plexus
2 lateral ventricles (one in each cerebral hemisphere)
Third ventricle (in diencephalon)
4th ventricle surrounded by pons, medulla, cerebellum
212
Roles of frontal lobe
Memory formation
Emotions
Decision making/ reasoning
Personality
Movement
213
5 major functional regions of frontal lobe
Motor cortex
Premotor cortex
Supplementary motor area
Broca's area
Prefrontal cortex
214
Motor planning areas
Primary motor cortex
Premotor area
Supplementary motor area
Broca's area
Analogous area to Broca's in opposite hemisphere
215
Primary motor cortex
Area of voluntary controlled movements
Source of most neurons in corticospinal tract
Controls contralateral movements
Motor homunculus
216
Supplementary motor area
Brodmanns area 8
Just medial to the premotor cortex
217
Functions of supplementary motor area
Motor planning ( initiation of movement) planning bimanual and sequential movements
Stores motor programs
Directs activity of primary motor cortex
Orientation of the eyes and head
218
Premotor area
Controls trunk and girdle muscles
Stabilizes the shoulders during upper limb tasks and hips during walking
219
Broca's area
Usually in left hemisphere
Planning movement of mouth during speech and grammatical aspects of language
220
Area analogous to Broca's
Opposite hemisphere to Broca's
Plans nonverbal communication
Emotional gestures
Tone voice
221
Phineas gage (1823-1860)
Railroad construction foramen
Accident in 1848
Iron road 1 1/4 inch diameter 3ft 7in long and 13 1/4 lb passed completely through his head and landed 80ft away
Passed behind left eye and through the left frontal lobe
Frontal lobe injury
222
Parietal lobe
Located deep to the parietal bone of the skull
Major role in senses and integrates sensation
Spatial awareness and perception (proprioception)
223
Proprioception
Awareness of body and body parts in space and in relation to each other
224
Parietal lobe- cortical regions
Primary somatosensory cortex (post central gyrus)
Somatosensory (parietal) association cortex
Primary gustatory cortex
225
Primary somatosensory cortex (post central gyrus)
Site involved with processing of tactile and proprioceptive informtion
226
Somatosensory (parietal) association cortex
Assists with the integration and interpretation of sensations relative to body position and orientation in space
May assist with visuo-motor coordination
227
Primary gustatory cortex
Primary site involved with the interpretation of the sensation of taste
228
Primary sensory areas of cortex
Primary somatosensory
Primary auditory
Primary visual
Primary vestibular
229
Primary somatosensory
Discriminates shape, texture, size of objects
230
Primary auditory
Conscious discrimination of loudness and pitch of sounds
231
Primary visual
Distinguishes intensity of light, shape, size, location of objects
Color, dimensions
232
Primary vestibular
Discriminates among head positions and head movements
233
Occipital lobe
Deep to occipital bone of the skull
Processing, integration, interpretation, etc of vision and visual stimuli
234
Occipital lobe cortical regions
Primary visual cortex
Visual association area
235
Lateral ventricle structure
Frontal (anterior horn)
Body
Atrium
Occipital (posterior horn)
Temporal (inferior horn)
236
Frontal (anterior) horn
Extends to the frontal lobe of the brain
237
Occipital (posterior) horn
Extends to occipital lobe of brain
238
Temporal (inferior) horn
Extends inferiorly and anteriorly to temporal lobe
239
Third ventricle
Slit like cavity between right and left halves of diencephalon
240
Interventricular foramen (foramen of Monro)
Communication point between lateral ventricles and third ventricle
241
Cerebral aqueduct (aqueduct of sylvius)
Communication between the third ventricle and fourth ventricle
242
CSF flow
Produced in choroid plexus
Flows to lateral ventricles
To IV foramen (foramen of Monro) into third ventricle
To cerebral aqueduct into fourth ventricle
Through foramina of Lushka and magendie into subarachnoid space
To arachnoid granulations and reabsorbed into the blood stream
251
Roles of frontal lobe
Memory formation
Emotions
Decision making/ reasoning
Personality
Movement
252
5 major functional regions of frontal lobe
Motor cortex
Premotor cortex
Supplementary motor area
Broca's area
Prefrontal cortex
253
Motor planning areas
Primary motor cortex
Premotor area
Supplementary motor area
Broca's area
Analogous area to Broca's in opposite hemisphere
254
Primary motor cortex
Area of voluntary controlled movements
Source of most neurons in corticospinal tract
Controls contralateral movements
Motor homunculus
255
Supplementary motor area
Brodmanns area 8
Just medial to the premotor cortex
256
Functions of supplementary motor area
Motor planning ( initiation of movement) planning bimanual and sequential movements
Stores motor programs
Directs activity of primary motor cortex
Orientation of the eyes and head
257
Premotor area
Controls trunk and girdle muscles
Stabilizes the shoulders during upper limb tasks and hips during walking
258
Broca's area
Usually in left hemisphere
Planning movement of mouth during speech and grammatical aspects of language
259
Area analogous to Broca's
Opposite hemisphere to Broca's
Plans nonverbal communication
Emotional gestures
Tone voice
260
Phineas gage (1823-1860)
Railroad construction foramen
Accident in 1848
Iron road 1 1/4 inch diameter 3ft 7in long and 13 1/4 lb passed completely through his head and landed 80ft away
Passed behind left eye and through the left frontal lobe
Frontal lobe injury
261
Parietal lobe
Located deep to the parietal bone of the skull
Major role in senses and integrates sensation
Spatial awareness and perception (proprioception)
262
Proprioception
Awareness of body and body parts in space and in relation to each other
263
Parietal lobe- cortical regions
Primary somatosensory cortex (post central gyrus)
Somatosensory (parietal) association cortex
Primary gustatory cortex
264
Primary somatosensory cortex (post central gyrus)
Site involved with processing of tactile and proprioceptive informtion
265
Somatosensory (parietal) association cortex
Assists with the integration and interpretation of sensations relative to body position and orientation in space
May assist with visuo-motor coordination
266
Primary gustatory cortex
Primary site involved with the interpretation of the sensation of taste
267
Primary sensory areas of cortex
Primary somatosensory
Primary auditory
Primary visual
Primary vestibular
268
Primary somatosensory
Discriminates shape, texture, size of objects
269
Primary auditory
Conscious discrimination of loudness and pitch of sounds
270
Primary visual
Distinguishes intensity of light, shape, size, location of objects
Color, dimensions
271
Primary vestibular
Discriminates among head positions and head movements
272
Occipital lobe
Deep to occipital bone of the skull
Processing, integration, interpretation, etc of vision and visual stimuli
273
Occipital lobe cortical regions
Primary visual cortex
Visual association area
274
Lateral ventricle structure
Frontal (anterior horn)
Body
Atrium
Occipital (posterior horn)
Temporal (inferior horn)
275
Frontal (anterior) horn
Extends to the frontal lobe of the brain
276
Occipital (posterior) horn
Extends to occipital lobe of brain
277
Temporal (inferior) horn
Extends inferiorly and anteriorly to temporal lobe
278
Third ventricle
Slit like cavity between right and left halves of diencephalon
279
Interventricular foramen (foramen of Monro)
Communication point between lateral ventricles and third ventricle
280
Cerebral aqueduct (aqueduct of sylvius)
Communication between the third ventricle and fourth ventricle
281
CSF flow
Produced in choroid plexus
Flows to lateral ventricles
To IV foramen (foramen of Monro) into third ventricle
To cerebral aqueduct into fourth ventricle
Through foramina of Lushka and magendie into subarachnoid space
To arachnoid granulations and reabsorbed into the blood stream
282
Temporal lobe
Located on sides of the brain, deep to temporal bones of the skull
Hearing, organization/comprehension of language
Information retrieval (memory)
283
Temporal lobe structures
Primary auditory cortex
Inferotemporal cortex
Primary olfactory cortex
Wernickes area
Amygdala
Hippocampus
284
Inferotemporal cortex
Recognition of face, objects, colors
285
Damage to inferotemporal cortex
Prosopagnosia- inability to recognize people that one knows
Early sign of Alzheimer's disease
286
Arcuate fasciculus
White matter tract that connects Brock's area and wernickes area through the temporal, parietal, and frontal lobes. Allows for coordinated, comprehensible speech
287
Insular lobe
5th central cerebral lobe
Phylogenetically old
Involved in taste processing
288
6 layers of cerebral cortex
1. Molecular layer
2. External granular layer
3.external pyramidal layer
4. Internal granular layer
5. Internal pyramidal layer
6.multiform layer
289
How are layers of cerebral cortex layered
Columnar
Labeled from outer most to inner most
Differ in appearance and function throughout the cortex
290
Layer one of cortex
Molecular
Mainly axons and dendrites. Few cells
291
Layer two of cerebral cortex
External granular layer
Many small pyramidal and stellar cells which establish intracranial connections
292
Layer three of cerebral cortex
External pyramidal layer
Pyramidal cells
Medium sized neurons
293
Layer four of cerebral cortex
Internal granular layer
Site of termination of afferent fibers from specific thalamus nuclei
294
Layer five of cerebral cortex
Internal pyramidal layer
Origin of projection fibers to extra cortical targets ( basal ganglia, thalamus, brain stem, spinal cord)
295
Layer six of cerebral cortex
Multiform layer
Contains association and projection neurons
296
Variation in cerebral cortex layers
Relative thickness of each level varies depending on function of area
Primary cortex- large efferent projections, layer V thicker
Primary visual cortex- layer 4 thicker
297
Neurotransmission
Chemical signals sent electrically through dendrites to cell body- signals accumulate
Critical membrane potential reached and action potential produced
Signal transferred to atonal nerve end releasing transmitter from synaptic vesicles
Presynaptic release of transmitter
Transmitter binds to post synaptic receptors
Opens ion specific channels of post synaptic membrane
Cations (Na+, K+) and anions (Cl-) flow
Opening of cation channels causes excitation
Opening of anion channels causes inhibition
298
Neural communication in gray matter
Note communication between cortical layers
Note that specific cells send projections to subcortical structures
Sensory inputs activate neurons in layer 4
299
Association fibers
Afferent fibers that arise in the same hemisphere
300
Commisural fibers
Afferent a arising in the contralateral hemisphere
301
Short association fibers
Connect adjacent gyri
302
Long association fibers
Superior longitudinal fasc.
Arcuate fasciculus
Inferior longitudinal fasciculus
Cingulum- septal area, cingulate and para hippocampus gyri
Uncinate fasciculus-orbital frontal gyri to temporal pole
303
Anterior commisural fibers
Inferior and middle temporal gyri
Olfactory areas
304
Posterior commisural fibers
Preoptic nuclei (vision)
305
Habenular commisural
Habenular nuclei (olfaction)
306
Corpus callossum
Connects hemispheres
Rostrum, genu, body, splenium
Bundle of axons
Contains only 100 million axons
10-15 billion cells in cortex
307
Corona radiata
Axons, projection fibers form this structure
Contain both descending and ascending axons that carry nearly all of the neural traffic from and to the cerebral cortex
308
Emotions and behavior and MCA stroke impairments
If right sided stroke, easily distracted, poor judgement, impulsiveness
If left sided stroke, apraxia, compulsiveness, overly cautious
309
Association areas
Account for much of the cortical surface area, though there is blurred delineation between the 2
Two broad types:
Unimodal
Multimodal/heteromodal
310
Unimodal association areas
Elaborate on the functions of the primary cortex
311
Multimodal and heteromodal association areas
Neurons respond to multiple sensory modalities
May change response properties under different circumstances
312
Subcortical structures
Limbic system
Hippocampus
Thalamus
313
Anterior cerebral artery infarcted structures
White matter of inferior frontal lobe
Medial surface of frontal and parietal les
Anterior corpus callosum
Deep cerebrum
Diencephalon (thalamus, hypothalamus)
Limbic structures
Head of caudate
Anterior limb of internal capsule
314
Somatosensory and ACA stroke impairments
Loss sensation of lower limbs
315
ACA and stroke impairments
Apraxia
Hemiplagia (lower limb more than upper limb)
Impaired gait
316
Emotions and behavior and ACA stroke impairment
Flat affect
Impulsive
Perseveration
Confusion
317
Mentation, language, memory and ACA stroke impairments
Difficulty with divergent thinking
318
Other problems with ACA stroke impairments
Urinary incontinence
319
MCA structures
Most of cortex and white matter
Deep white matter
Diencephalic structures
320
Somatosensory and MCA stroke impairments
Hemianesthesia (face, UE >LE)
321
Motor and MCA stroke impairments
Face and UE impaired
322
Relay nuclei
Convey information from sensory systems (except olfactory), the basal ganglia, and cerebellum
Majority of the thalamic nuclei]
receive specific information and serve as relay stations
send info directly to specific localized area of cortex
323
Special senses and MCA stroke impairments
Homonymous hemianopsia
324
Nonspecific nuclei
Regulate consciousness, arousal, attention
receive multiple types of input and project to widespread areas of cortex
325
Mentation and MCA stroke impairments
Aphasia if language dominant hemisphere involved
Difficulty with spatial relationships, neglect if non language dominant hemisphere affected
326
somatosensory and PCA stroke impairments
Hemianesthesia
327
Motor and PCA stroke impairments
Hemiparesis
Oculomotor nerve palsy
328
Special senses and PCA stroke impairments
Homonymous hemianopsia
Cortical blindness
Lack of depth perception
329
Mentation and PCA stroke impairments
Memory loss
330
Other PCA stroke impairments
Thalamic syndrome
331
Diencephalon structures
Thalamus
Hypothalamus
Epithalamus-pineal gland
Subthalamus
Pretectum
332
Function of diencephalon
Relay station for majority of motor and sensory ocnnections
333
What does thalamus mean in Greek
Inner chamber or bed room
334
Function of thalamus
Major relay station for sensory and motor information from cortex, basal ganglia, cerebellum, limbic system
Regulates flow of information to cortex: selective filter of info, regulates the activity level of cortical neurons
All sensory pathways relay in the thalamus
Cerebellar, basal ganglia, limbic pathways have relays here
335
Shape of thalamus
Large egg shaped collection of nuclei located bilaterally above the brainstem
336
What divides the thalamic nuclei into 3 groups
A y shaped sheet of white matter
Anterior
Medial
Lateral
337
3 functional groups of thalamic nuclei
Relay nuclei
Association nuclei
Nonspecific nuclei
338
Association nuclei
Process emotional and some memory information or integrate different types of sensation
339
cerebellar functions
maintenance of balance and posture
coordination of voluntary movements
motor learning
cognitive function
does not direct movement
340
cerebellum means
little brain
341
cerebellum accounts what percent of brain volume
10%
342
what percent of neurons in the brain does the cerebellum account for?
> 50%
343
Cerebellar hemispheres
2 hemispheres that communicate with eachother- degree of somatotopic organization.
hemispheres separated by vermis
344
Folia
small ridges that run medial to lateral on the surface (means leaves)
345
flocculonodular lobe of cerebellum
located underneath the posterior lobe
touches the brainstem
346
Anterior cerebellar lobe
superior
separated from posterior lobe by primary fissure
347
three cerebellar lobes
flocculonodular
anterior
middle/posterior
348
inputs to the vermis
spinocerebellar pathways terminate at vermis- subconscious proprioception
auditory and visual information from tectum
349
outputs from vermis
to fastigial nucleus which send to vestibular nucleus and motor nuclei in reticular formation
350
vermis may be linked to the ability to do what?
integrate and analyze inertial motion.
perkinje cells are now thought to receive sensory information from the vestibular system and use this to compute information about the body's movement through space
351
three cerebellar nuclei
fastigial
interposed nuclei
dentate
352
interposed nuclei- 2 parts
emboliform
globose
353
fastigial cerebellar nuclei
-most medially located
-receives input from the vermis and from cerebellar afferents that carry vestibular, proximal somatosensory, auditory, and visual information
-projects to the vestibular nuclei and the reticular formation
354
interposed nuclei
globose
emboliform
-receive input from the intermediate zone and from cerebellar afferents that carry spinal, proximal somatosensory, auditory, and visual information
- project to the contralateral red nucleus (origin of rubrospinal tract)
355
dentate nucleus
largest of the nuclei
receives afferent fibers from medulla
projects to the contralateral red nucleus and ventrolateral thalamic nucleus
356
vestibular nuclei location
located in the medulla
357
vestibular nuclei functionally like what?
cerebellar nuclei
connectivity patterns the same as cerebellar nuclei
358
where does the vestibular nuclei receive input from
flocculonodular lobe and vestibular labyrinth
359
where does the vestibular nuclei project to?
various motor nuclei and orginate in vestibulospinal tracts
360
cerebellar peduncles
form walls of 4th ventricle
inferior cerebellar peduncle
middle cerebellar peduncle
superior cerebellar peduncle
361
inferior cerebellar peduncle
restiform body
rope like body
afferent fibers from the medulla as well as efferents to the vestibular nuclei
mainly carry inputs
362
middle cerebellar peduncle
brachium pontis
massive connections to the pons
connect with pons, contain afferent fibers
mainly carry inputs
363
superior cerebellar peduncle
brachium conjunctivum
efferent fibers from the cerebellar nuclei as well as some afferents from the spinocerebellar tract
connect with midbrain, contain mostly efferent fibers
mainly carry outputs
364
3 cerebellar cell layers
molecular
purkinje
granule
365
cerebellar neuronal cell types
purkinje
granule
basket
stellate
golgi
366
purkinje cell layer
-extensive dendritic tree- dendrites extend only to molecular layer. numerous spines
-axons synapse with the deep cerebellar nuclei- axons of this type are the only ones that leave cerebellar cortex
-modify the output of the cerebellum
-GABA is neurotransmitter-inhibitory
367
what are the only output cells for the cerebellar cortex
purkinje
368
granule cells
axons project to the folia where they bifurcate and form the parallel fibers
higher density of parallel fibers relative to one purkinje cell
excitatory synapses with purkinje cells
369
basket cells
-found in molecular level
-dendrites extend into superficial molecular layer and receive excitatory input from parallel fibers
-axons extend across folia (perpendicular to parallel fibers) and send collateral branch to Purkinjes; inhibitory
370
stellate cells
found in molecular level
axons extend across the folia perpendicular to parallel fibers
stellate cells receive excitatory input from parallel fibers
inhibitory synapses on Purkinje
have discrete influence on dendrites
371
golgi cells
deep to purkinje cells
dendrites extend to molecular layer
excitatory connections with parallel fibers
axons enter granule layer
inhibitory to granule cells
372
cerebellar glomerulus
complex synaptic structure
373
what is the cerebellar glomerulus formed by
golgi cell axons
granular cell dendrites
Mossy fibers
374
4 cerebellar cellular fiber types
mossy fibers (majority)
climbing fibers (olivocerebellar)
paralle fibers (terminals of granule cells)
aminergic fibers from hypothalamus, pontine raphe nuclei, locus ceruleus
375
Mossy fibers
excitatory afferent fibers that determine the output of purkinje fibers
376
mossy fibers are formed by efferent axons from
pontine nucleus
spinal cord
vestibular nuclei
reticular formation (brain stem)
377
what do mossy fibers synapse with?
granule cell dendrites
378
2 branches of mossy fibers
spinocerebellar tracts
ascend to cerebellar cortex
379
what connection do mossy fibers make
excitatory connections with glomeruli
380
1 mossy fiber connects with how many granule cells
600 granule cells which in turn connects to greater than 5000 purkinje cells
381
climbing cell fibers formed by afferent axons from
inferior olivary nucleus in medulla
olivary nuclei act as a major staging area for motor and sensory information entering the cerebellum
enter through inferior cerebellar peduncle
382
what do climbing fibers synapse with?
purkinje cell dendrites
383
collateral branches of climbing fibers make what kind of connections?
excitatory within glomeruli
slow firing rate, strong enough to initiate action potential
open calcium channels affecting metabolism of purkinje cell
mechanism that is responsible for motor learning
384
1 climbing fiber connects to how many purkinje cells?
as many as 300
385
2 pathways that mossy fibers influence cerebellar output
a direct pathway to the cerebellar nuclei
a less direct pathway through the cerebellar pathway
386
climbing fibers are thought to convey what
error signals to purkinje cell
387
excitatory inputs from what?
granule cells (parallel fibers)
mossy fibers
climbing fibers
aminergic fibers
388
inhibitory inputs from what
purkinje cells
stellate and basket cells
golgi cells
389
mossy,granule, and climbing cells what kind of input
excitatory
390
purkinje, basket, and golgi are what kind of input
inhibitory
391
functional divisions of cerebellum
based on connections made with CNS
Vestibulocerebellum- congruent with flocculonodular lobe and vermis
spinocerebellum
cerebrocerebellum
392
vestibulocerebellum receives afferent input from
vestibular nuclei, vestibular apparatus
393
vestibulocerebellum projects to what
vestibular nuclei
394
vestibulocerebellum output reaches LMNs via
vestibulospinal tract
395
function of vestibulocerebellum
regulates equilibrium
396
example of vestibulocerebellum
person reaches for a book from a high shelf, vestibulocerebellum provides anticipatory contraction of lower limb and back muscles to maintain balance. if absent person will fall forward
397
spinocerebellum is function name for what region
vermis and paravermal
398
spinocerebellum receives input from
spinal cord
vestibular nuclei
auditory and vestibular info from brainstem nuclei
399
spinocerebellum projects output to
vestibular nuclei
reticular nuclei (via fastigial nucleus)
Motor cortex (via fastigial nucleus)
Red nucleus (via globose and emoliform nuclei)
400
what does the spinocerebellum regulate
gross limb movement
401
example of spinocerebellum
coordinates the upper limb movement as the person reaches for the book. without this inpu the movement would be jerky and inaccurate
402
cerebrocerebellum receives input from
cerebral cortex via pontine nuclei
403
cerebrocerebellum projects output to
motor and premotor cortices via dentate nucleus and motor thalamus
red nucleus
404
cerebrocerebellum extends to LMNs via
lateral corticospinal tract
corticobulbar tract
405
what does the cerebrocerebellum regulate
distal limb voluntary movements
406
example of cerebrocerebellum
would coordinate the finger and thumb movements necessary to grasp the book
407
cerebellar vasculature
branches of basilar and vertebral arteries
SCA
AICA
PICA
408
superior cerebellar artery supplies
middle cerebellar peduncle
superior cerebellar peduncle
deep cerebellar nuclei
cerebellar white matter
409
infarction of superior cerebellar artery causes
limb and gate ataxia
abnormal saccades
nystagmus
410
anterior inferior cerebellar artery supplies
medulla
pons
inferior middle peduncle
inferior peduncle
flocculus
vermis
inferior cerebellar cortex
411
infarctions of anterior inferior cerebellar artery causes
limb and gait ataxia
412
posterior inferior cerebellar artery supplies
dorsolateral medulla
inferior/ posterior vermis
inferolateral surface of cerebellum
dentate nucleus
413
posterior inferior cerebellar artery infarcions cause
rotatory dizziness
nausea
vomitting
imbalance
nystagmus
414
cerebellum clinical disorders
lesions of cerebellum affect the ipsilateral side of the body
415
signs of cerebellar dysfunction
ataxia/ataxic gait
nystagmus
dysdiadochokinesia
dysmetria
decomposition of movment
416
ataxia
area involved: any lesion causes ataxia
ataxia is voluntary, normal-strength, jerky and inaccurate movements
vermal and focculonodular lesions lead to truncal ataxia
paravermal lesions result in gait and limb ataxia
lateral cerebellar lesions cause hand ataxia
417
signs of vestibulocerebellar lesions
ataxic gait- patient will fall toward side of the lesion, cerebellar gait
nystagmus
vertigo
418
spinocerebellar/cerebrocereballar lesions
dysdiadochokinesia
dysmetria
decomposition
419
dysdiadochokinesia
loss of timing between agonist and antagonist
cannot perform rapid alternating movements
sequnce of individual muscle contraction is impaired
420
dysmetria
performance deteriorates as the motor act progresses
421
decomposition
performance of motor activity by moving only one joint at a time because of an inability to control the entire movement
helps improve movement
ataxia- disruption in the recision of motor acts
422
ganglion
collection of nerve cell bodies
outside of CNS
423
peripheral nerve
collection of nerve fibers
connect CNS with peripheral structures
spinal or cranial nerves
424
basal ganglia
group of closely related nuclear masses:
corpus striatum (caudate and putamen)
globus pallidus
substantia nigra
subthalamic nuclei
425
what do the basal ganglia participate in
complex networks that influence the descending motor systems
Modulate the output of these systems
426
basal ganglia function
govern the initiation and cessation of movement
regulate muscle contraction
regulate muscle force
regulate multi joint movements
sequencing of movements
creating and executing motor plans
427
output of basal ganglia is conveyed to UMNs via what
cerebral cortex and pedunculopontine nucleus in brainstem
428
striatum (neostriatum) in basal ganglia
caudate nucleus and putamen
principally involved in the control of movement
receive virtuall all inputs to BG
important connects with the thalamus and subthalamic nucleus of diencephalon
429
caudate nucleus
important in learning and memory functions (feedback processing)
highly innervated by dopamine neurons
consists of a large globular head; tapering body; long thin tail
430
putamen
disk shaped nucleus on the lateral border of the basal ganglia
receives input from the premotor and sensorimotor cortex
431
caudate and putamen function
-caudate and putamen contains similar neuronal circuitry
-both receive fibers from the ipsilateral neocortex
-GABAergic fibers from the caudate-putamen innervate the ipsilateral globus pallidus
432
GABA
gamma aminobutyric acid
433
rostral caudate related to what cortex
prefrontal- controls behavioral and cognitive function
434
putamen connects to what
premotor and motor cortex- influences the motor operation of distal limb musculature
435
caudate and putamen principle neurons
medium spiny neurons
make up 96% of space
dendrites have smooth surfaces up to or near their first branch
at this point they become profusely covered in spines
axons are observed to emit several collaterals before the primary branch extends beyond the striatum
436
caudate and putamen local circuit neurons
medium spiny neurons
giant spiny neurons
437
caudate and putamen- lesions or degeneration of neurons
leads to hyperkinetic states such as chorea, athetosis, dystonia
behavioral changes
cognitive chages
438
chorea
rapid jerky aimless and constant motion of limbs
439
athetosis
slow sinous motion of limbs
440
dystonia
slow sustained contorting of the body
441
lesions restricted to putamen
motor dysfunction in contralateral limbs
putamen connects to the premotor and motor cortex
442
basal ganglia output pathways are inhibitory
using GABA
pathway is through the VL and VA nuclei of the thalamus
thalamic nuclei convey information to entire frontal cortex (mainly the premotor cortex, supplementary motor area, primary motor cortex)
443
lesions restricted to caudate
behavioral defects; apathy, disinhibition, major affective disturbance
444
globus pallidus
wedge shaped structure between putamen and internal capsule
consists of medial (internal) segment and lateral (external) segment
445
globus pallidus: medial/internal
output region of corpus striatum
projects primarily to the thalamus [ventral anterior ventrolateral, centromedian nuclei]
part of direct pathway through basal ganglia
446
where does the medial/internal globus pallidus receive GABAergic projections from?
caudate
putamen
447
Globus Pallidus- Lateral/external
projects to the subthalamic nucleus (STN)
receives GABAergic prokections from caudate and putamen- part of an indirect pathway through the basal ganglia
448
globus pallidus leasions
lead to profound hypokinesia
similar to parkinsonian rigidity without the tremor
surgeons have used carefully placed lesions to reduce unwanted movements
449
carbon dioxide or carbon disulfide intoxication
causes profound rigidity and catatonic posture
450
substantia nigra
composed of 2 nuclei- pars reticulata (output nucleus of BG), and pars compacta
contains melanin- byproduct of dopamine metabolism
axons from S.N innervated the ipsilateral caudate and putamen
451
substantia nigra impairments
destruction of dopamine containing cells in pars compacta- results in parkinsonian signs and symptoms in the contralateral side of body
-synthetic heroin containing MPTP caused significant parkinsonism in youg users
452
subthalamic nuclei
thin elongated wedge of gray matter
receives inhibitory fibers from external globus pallidus
excitatory projections to internal GP
source of excitation to the internal GP that can be modulated by the external GP
453
input to BG
all regions of cerebral cortex project to basal ganglia
454
output to BG
directed towards the frontal lobe, particularly premotor and supplementary motor cortex
455
main recipient of input to BG
Striatum (caudate and putamen)
-from cerebral cortex:
frontal lobe to caudate head an putamen
parietal/occipital lobes to caudate body
temporal lobe to caudate tail
primary motor cortex and primary somatosensory cortex project to putamen
premotor cortex and supplementary motor areas to caudate head
-intralaminar nuclei of thalamus to putamen
456
basal ganglia outputs arise from 2 structures
globus pallidus interna- body output except head and neck
substantia nigra pars reticulata- outputs for head and neck
457
neurotransmitters in basal ganglia circuit (3)
glutamate
Gamma-aminobutyric acid (GABA)
Dopamine
458
glutamate
excitatory
released my cortical motor areas
459
GABA
inhibitory
460
dopamine
excitatory in direct pathway
inhibitory in indirect pathway
461
direct pathways
overall excitatory
Cortex-movement initiated
Excitation of direct inhibitory pathway of putamen and globus pallidus (striatum)
Disinhibition of thalamus
facilitation of cortex
movement occurs
462
indirect pathways
overall inhibitory
corticostriatal pathway stimulated
subthalamic nuclei releases input to globus pallidus
increases inhibition of thalamic nuclei
reduces thalamocortical output
463
Direct pathway is inhibition of what?
globus pallidus
GP stops signal to thalamus
thalamus now free to excite cortex
action continues forward from the cortex
464
what system stimulated in indirect pathway
corticostriatal pathway
465
what does the indirect pathway cause the subthalamus to do?
activate GP suppressing thalamic activation
suppressing unwanted movements
466
motor channel
cortical inputs travel to putamen
outputs from GP and SN to reach VA and VL of thalamus
from thalamus to SMA, premotor cortex, and primary motor cortex
467
occulomotor channel
input from body of caudate nucleus
output is to frontal eye fields and supplementary eye fields (for eye movement)
468
prefrontal channel
important in cognitive processes involving frontal lobes
input from head of caudate
output reaches prefrontal cortex
469
limbic channel
regulation of emotions and motivation
inputs from limbic cortex, hippocampus, amygdala
outputs to anterior cingulate and orbital frontal cortex
appear to play an important role in psychiatric disorders
470
basal ganglia impairment
BG inhibit thalamus typically
hypokinetic disorders
hyperkinetic disorders
471
hypokinetic disorders
too little movement
parkinsons disease
excessive inhibition from BG
472
hyperkinetic disorders
excessive movement
huntingtons disease
dystonia
some types of cerebral palsy
inadequate inhibition from BG
473
parkinsons disease characterized by
muscular rigidity
shuffling gait
drooping posture
rhythmical muscular tremors
masklike facial expression
474
parkinsons functional impairments
poor transition from standing to sitting
gait with flexed posture, shuffling of feet, decreased/absent arm swing
475
parkinsons rigidity
-increased resistance to movement in all muscles
-caused by direct UMN facilitation of alpha motor neurons without appropriate inhibition from BG circuit
476
parkinsons pathology
-degeneration of dopamine neurons in the SN
- one can lose about 80% of dopaminergic cells in the SN without symptoms
477
huntingtons chorea
increased in choreiform movements
involuntary continuous movements of body
lose striatal inhibition of GPe
subthalamic nuclei no long facilitate GPi and SN
ultimately disinhibition of the thalamus occur
478
nuclei of thalamus project where?
to the ipsilateral cerebral cortex
EXCEPT reticular nucleus
479
Relay nuclei-Sensory (4)
VPL
VPM
MG
LG
480
VPL
receives input from trunk and limbs from spinothalamic and medial lemniscus
projects to primary somatosensory cortex
481
VPM
receives taste information from medulla and vestibular information from vestibular nuclei
482
MG
auditory system
receives fibers from midbrain
projects to auditory cortex of temporal lobe
483
LG
visual system
termination site of optic tract
projects to internal capsule and optic radiation
484
Relay Nuclei- motor
VA and VL
485
VA and VL
receive fibers from BG and cerebellum
project to motor area of frontal lobe
486
4 association nuclei
AN and LD
MD
LP
P
487
AN and LD
part of the limbic system
involved in control of instinctive drives, emotional aspects of behavior and memory
488
MD
extensive reciprocal connections with the cortex of frontal lobe
controls modds and emotions
489
LP
connects with sensory association area of parietal lobe
490
P
connections with association cortices of parietal, temporal, and occipital lobes
491
blood supply of thalamus
primary blood supply is from branches of the PCA
492
thalamic impairment
-lesions interrupt ascending pathways
-compromises or eliminates (depending on size and severity) contralateral sensation- usually proprioception
rarely- thalamic pain syndrome
493
thalamic pain syndrome
rare
produces severe contralateral pain with or without external stimuli
494
Hypothalamus
small
less than 1% of brain weight
influences viscera and ANS
regulates endocrine function
chief effector of limbic system
Eating, reproductive, and defensive behaviors
495
what does the hypothalamus integrate behaviors with
visceral functions
- coordinates eating with digestive activity
496
how the hypothalmus maintains homeostasis
adjusts body temperature
metabolic rate
blood pressure
water intake and excretion
digestion
497
hypothalamus- emotional expression of what?
pleasure, rage, fear, aversion
498
what do the hypothalamus and pineal gland do together?
regulate circadian rhythms
499
endocrine function of hypothalamus
growth, metabolism, reproductive organs
500
functions of hypothalamus are carried out through regulation of what secretions
pituitary gland secretions (hormones)
and through efferent neural connect with the cortex
-via the thalamus, limbic system, brainstem, spinal cord
501
anterior hypothalamus
anterior area influences PSNS through projections to brainstem PSNS nuclei
502
anterior hypothalmus nuclei (4)
preoptic- maintain constant body temperature
supraoptic/paraventricular- regulate water balance
anterior- regulate appetite and food intake
suprachiasmatic
503
preoptic lesions
central hypothermia
504
supraoptic/paraventricular lesions
diabetes insipidus
decreased thirst response leading to hyponatremia
505
anterior nuclei lesions
obesity (medial)
anorexia and emaciation (lateral)
506
posterior hypothalamus
influences SNS through projections to lateral gray horn
507
posterior hypothalamus nuclei
mammillary body- play role in memory
posterior nucleus- thermoregulation
508
hypothalamic nuclei functions
temperature regulation- posterior nucleus conserves heat, anterior nucleus dissipates heat. (fever starts, sweating. fever ends, chills)
feeding function- lateral nucleus induces eating. ventromedial nucleus inhibits eating
509
output from hypothalamus
neural output is widespread to cerebral cortex, hippocampus, amygdala, pituitary gland, thalamus, brainstem, spinal cord
510
blood supply of hypothalamus
penetrating branches of ACA and anterior communicating arteries supply ANTEROMEDIAL regions
penetrating branches of PCA and posterior communicating arteries supply POSTEROMEDIAL regions
511
projection fibers
fibers that run between the cortex and subcortical structures
internal capsule
512
epithalmus
forms roof of third ventricle
houses pinneal gland
includes choroid plexus- involved in CSF productions
513
Pineal Gland
endocrine gland associated with seasonal cycles
innervated by sympathetic fibers
regulates circadian rhythms
secretes melatonin
influences secretions of pituitary gland, adrenals, parathyroids, and islets of langerhans
514
subthalamus
located superior to SN of midbrain
part of BG circuit
involved in regulating movement- rhythmic
facilitates BG output nuclei
contains bundles of projection fibers
stimulation is a treatment for parkinsons disease
515
pretectum
receives binocular input
pupillary light reflex- produces change in pupil size in response to light input
516
internal capsule
route through which thalamic fibers pass to and from cortex
517
posterior limb of the internal capsule
corticospinal tract fibers
sensory fibers (including medial lemniscus and anterolateral system) from the body
518
Internal capsule- genu contains
corticobulbar fibers which run between the cortex and the brainstem
519
anterior limb of the internal capsule contains
1) fibers from frontal cortex to pons
2) fibers connecting the medial and anterior nuclei of the thalamus to frontal lobes (these are severed during a prefrontal lobotomy)
520
retrolenticular part of internal capsule contains
- fibers from the optic system, coming from the lateral geniculate nucleus of thalamus
- more posteriorly, this becomes optic radiation
- some fibers from the medial geniculate nucleus (which carry auditory information) also pass in this capsule
521
internal capsule impairment
-occlusion/ hemorrhage to arteries supplying internal capsule is common
522
small lesions of internal capsule
- prevents messages from corticospinal, corticobulbar, corticopontine, corticoreticular, and thalamocortical fibers from reaching destination.
- causes contralateral decrease in voluntary movement
- contralateral decrease in automatic movement control
- contralateral loss of conscious somatosensation
a lesion further posterior would result in contralateral visual field loss due to loss of optic radiation fibers
523
vascular supply of internal capsule
MCA
524
association fibers
interconnect cortical structures within the same cerebral hemisphere
-arcuate fasciculus (language)
- inferior fasciculus (occipital to temporal lobe, contributes to visual recognition)
525
commissural fibers
fibers that run from one hemisphere to the other
corpus callosum
anterior commissure
526
3 anatomic structures of brain stem
medulla
pons
midbrain
527
vertical tracts in brain stem
brain stem acts as a conduit for afferent and efferent information between the spinal cord and the brain
some tracts are modified as they pass through the brain stem
528
4 ascending tracts through brain stem
spinothalamic
Dorsal column
Spinocerebellar
Trigeminal lemiscus
529
spinothalamic and brain stem
not modified
530
dorsal column and brainstem
axons synapse in nucleus gracilis or cuneatus (medulla); neurons cross midline to form medial lemniscus
531
spinocerebellar and brainstem
axons leave brainstem via inferior and superior cerebellar peduncles to enter cerebellum
532
trigeminal lemniscus and brain stem
neuron cell bodies located in main sensory nucleus and spinal nucleus of trigeminal nerve and cross the midline
533
Autonomic tracts and brain stem
-sympathetic- not modified
-parasympathetic- axons synapse with BS. parasympathetic nuclei or continue through brainstem and cord to the sacral level of SC
534
Descending tracts and brain stem (4)
corticospinal- not modified
corticobulbar- axons synapse with cranial nerve nuclei in brainstem
corticopontine- axons synapse with nuclei in pons
coricoreticular- axons synapse with reticular formation
535
inferior medulla
-continuous structurally with spinal cord )central canal)
-85% of corticospinal tract axons cross at pyramids
-spinothalamic tracts maintain an anterolateral position similar to that in the SC
- dorsal column fibers synapse with cuneatus and gracilis cross at medial meniscus and ascend posteriorly
-Cranial nerve V synapse here
536
Upper medulla
central canal widens to form the fourth ventricle
Cranial nerve nuclei
nucleus ambiguus
cochlear and vestibular nuclei
inferior olive nucleus
537
crania nerve nuclei of upper medulla
clustered dorsally (medial to lateral)
XII
X- motor/sensory, vagus
VII
IX
VIII
538
nucleus ambiguus of upper medulla
motor supply to Ix, X
bilateral corticobulbar tracts provide input
539
cochlear and vestibular nuclei and upper medulla
receive auditory and vestibular information via VIII
540
inferior olive nucleus of upper medulla
receives input from motor areas of brain and spinal cord
communicates with cerebellum via olicocerebellar tract
signals cerebellum when actual movement differs from planned movement(comparator)
541
Upper medulla fibers project to cerebellum via cerebellar peduncle
spinocerebellar
olivocerebellar
vestibulocerebellar
reticulocerebellar
542
upper medulla fibers received from cerebellum
vcerebellovestibular tract
543
medulla function
cardiovascular control
breathing
head movement
swallowing
functions executed by VII, VIII, IX, X, XII (all have nuclei in medulla)
neuronal networks of medulla are influenced by cerebral activity
544
Pons
located between midbrain and medulla
545
most vertical tracts pass through the pons unchanged
only corticopontine (pontine nucleus) and corticobulbar tracts (trigeminal motor nucleus and facial nucleus) synapse in the pons
546
anterior pons section carries descending tracts
corticospinal
corticobulbar
corticopontine
547
pons- tegmentum
posterior section of pons
contains sensory tracts, reticular formation, autonomic pathways, medial longitudinal fasciculus
nuclei CN V-VII
548
nuclei CN V
processes sensation of face, motor of chewing
549
nuclei CN VI
controls lateral eye movement
550
nuclei CN VII
controls facial muscles
551
Midbrain
uppermost part of brainstem
connects diencephalon and pons
552
3 regions of midbrain
basis pedunculi
tectum
tegmentum
553
Midbrain- basis
most ventral portion
corticospinal and corticobulbar tracts lie here
554
midbrain- tectum
"roof" in latin
areas posterior to ventricular space
only prominent in midbrain; superior and inferior colliculi (tectal plate)
555
midbrain- tegmentum
means covering
lies ventral to cerebral aqueduct in midbrain
ventral to 4th ventricle in pons and medulla
bulk of brainstem nuclei and reticular formation
556
4 main pathways
1)corticospinal- descending motor
2)spinothalamic- ascending pain/temperature
3)dorsal column/ medial lemniscus- ascending somatosensory and conscious proprioception
4) spinocerebellar- ascending unconscious proprioception
557
Brain stem nuclei
major neurotransmitter nuclei
reticular formation (not really a nucleus but acts like a group of nuclei)
associated with cranial nerves
558
ventral tegmental area
produces dopamine
provides dopamine to cerebral areas responsible for motivation and decision making- frontal cortex, limbic areas
559
pedunculopontine nucleus
caudal midbrain
560
ascending axons of pedunculopontine nucleus project to
frontal cerebral cortex
intralaminar thalamus
561
pedunculopontine nucleus influences movement via connections with
GP/ subthalamic nuclei
vestibular nuclei
reticular area
562
raphe nuclei
ridge of cells along the midline in the center of the midbrain
multiple nuclei
major serotonin nuclei
technically part of reticular formation
563
caudal raphe nuclei
projections to the spinal cord and other parts of the brainstem
564
rostral raphe nuclei
projections to multiple cortical areas
565
raphe nuclei ascending pathways involved in many neurobehavioral phenomena
mood
sleep
feeding
satiety
566
raphe nuclei descending pathways modulate spinal cord function
pain
567
Locus ceruleus
major norepinephrine
dorsal wall of rostral pons
568
locus ceruleus projects to
spinal cord
brain stem
cortex
569
function of locus ceruleus
arousal
modulation of stress responses
accounts for some of the psychiatric systems in parkinsons disease
570
locus ceruleus linked to
depression
anxiety
PTSD
571
brain stem reticular formation
reticular=netlike
loosely defined nuclei and tracts
extends through central part of medulla, pons, midbrain
input and output to virtually all parts of the CNS
572
brain stem reticular formation intimately associated with
ascending/ descending pathways
cranial nerves/ nuclei
573
3 longitudinal zones of brain stem reticular formation
midline- raphe nuclei
medial zone- long ascending and descending projections
lateral zone- cranial nerve reflexes and visceral functions
574
reticular formation 3 functional zones
lateral
medial
midline
575
lateral reticular formation zone
integrates sensory and cortical input, generalized arousal
576
medial reticular formation zone
vital functions, somatic motor activity, attention
577
midline reticular formation zone
transmissions of pain information, somatic motor activity, consciousness levels
578
reticular activating systems
regulation of consciousness
sleep, alertness, attention
axons from RAS project to basal forebrain, thalamus, cortex
579
connectivity of brain stem reticular formation
-extremely complex
-many different types of neurons
-innervate multiple levels of spinal cord
-numerous ascending and descending collaterals
-some have bifurcating collaterals that do both
-many have large dendritic fields that traverse multiple levels of the brain stem
580
reticular formation functions
I. participates in control of movement through connections with both the spinal cord and cerebellum
II. modulates transmission of information in Pain Pathways
III. autonomic reflex circuitry
IV. involved in control of arousal and consciousness
581
Anteromedial lesions in brainstem and Medulla
corticospinal tract-fractionated movement
medial lemniscus- discriminative touch, coscious proprioception
hypoglossal nerve- tongue movement
582
anteromedial lesions in brainstem and pons
medial longitudinal fasciculus- adduction of eye past midline during lateral gaze.
583
lateral lesions in brain stem and medulla/pons
spinothalamic tract- pain and temp sensation from body
spinal tract and CN V nucleus- pain and temp sensation from face
Vestibular nuclei- control of posture, head position, eye movement
584
lateral lesions in brain stem and medulla
inferior cerebellar peduncle- smoothness of movement
vagus nerve- digestion
585
lateral lesion in brainstem and pons
middle cerebellar peduncle- smoothness of movement
main sensory nucleus of CN V- discriminative touch from face
Motor nucleus trigeminal nerve- motor to muscles of mastication
facial nerve- control of facial expression
586
anterior lesions in brain stem to brain stem
coricospinal-control fractionated movement
corticobulbar- weakness or paralysis of muscles supplied by CNs below lesion
Oculomotor Nerve- medial, downward and upward eye movement, drooping under eyelid, dilated pupil.
587
Olivary nucleus
Staging area for sensory and motor information from cerebellum
588
