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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

Freidrichs ataxia is from what tract

Spinocerebellar