1
Q
What two categories can the nervous system be divided into?
A
Structural and Functional
2
Q
The STRUCTURAL organization of the nervous system is broken into the ______ and ______ NS, while the FUNCTIONAL organization is broken into the _____ and _____ NS.
A
Structural: Central and Peripheral
Functional: Sensory and Motor
3
Q
The central NS includes the _____ and _____, while the peripheral NS includes the _______, _______, and ______.
A
- Brain and Spinal Cord
2. Cervical Nerves, Spinal Nerves, and Ganglia
4
Q
The CNS and PNS perform three general
functions:
A
- Collecting information: Receptors detect
changes in the internal and external environment; pass the information on to the CNS - Processing and evaluating information: CNS determines the required response
- Responding to information: CNS initiates nerve impulses to effectors to react to changes in the body’s environment
5
Q
The sensory NS is divided into the _____ and ______, while the motor NS is divided into the ____ and _____.
A
- Somatic Sensory and Visceral Sensory
2. Somatic Motor and Autonomic Motor
6
Q
The sensory NS and motor NS are also called the ______ and _____ respectively.
A
- Afferent NS
2. Efferent NS
7
Q
Describe the two distinct type of cells within the nervous system:
A
- Neurons (nerve cells): Electrically excitable cells that initiate, transmit, and receive nerve impulses
- Glial cells: Nonexcitable cells that support and protect the neurons
8
Q
What is the basic structural unit of the NS?
A
The Neuron
9
Q
What are 3 special characteristics of neurons?
A
– High metabolic rate
– Extreme longevity
– Nonmitotic
10
Q
What are the 3 main structural regions of the neuron?
A
- Cell body
- Dendrites
- Axon
11
Q
______ receive nerve impulses and carry them to the cell body
A
Dendrites
12
Q
Neurons without an axon are called _____
A
Anaxonic
13
Q
What is the axon hillock?
A
The region where the axon connects to the cell body
14
Q
- Axon collaterals:
- Telodendria:
- Synaptic knobs:
A
- Side branches off the main axon
- Fine terminal extensions at the end of the axon and its collaterals
- Expanded regions at the tip of telodendria
15
Q
What 3 ways are neurons classified STRUCTURALLY?
A
- Unipolar: Single, short process that branches like a T
- Bipolar: Two processes, one dendrite and one axon
- Multipolar: Many dendrites and a single axon; most common type of neuron
16
Q
What 3 ways are neurons classified FUNCTIONALLY?
A
- Sensory (afferent): Transmit impulses from sensory receptors to the CNS
- Motor (efferent): Transmit impulses from CNS to muscles or glands
- Interneurons: Facilitate communication between sensory and motor neurons
17
Q
Brain tumors are more likely to be derived
from ______ than neurons, because they are: (2)
A
- Glial cells
2. Mitotic and more numerous
18
Q
What are the 4 types of glial cells found in the CNS?
A
- Astrocytes
- Ependymal cells
- Microglial cells
- Oligodendrocytes
19
Q
The most common and least common types of glial cells are _____ and _____ respectively.
A
- Astrocytes
2. Microglia
20
Q
What are the 6 functions of astrocytes?
A
- Helping form the blood-brain barrier (BBB)
- Regulating tissue fluid composition
- Helping regulate synaptic transmission
- Forming a structural network
- Replacing damaged neurons
- Assisting neuronal development
21
Q
Astrocytes are ______ cells with ________. They are in contact with _______.
A
- Large
- Numerous Processes
- Neurons and Capillaries
22
Q
Ependymal cells are _________ cells that line the ________ and the _____________.
A
- Ciliated cuboidal epithelial
- Ventricles of the brain
- Central canal of the spinal cord
23
Q
Ependymal cells not only ________, but also ______.
A
- Produce the CSF
2. Form the choroid plexus
24
Q
Microglia are _____ cells that _______________, specifically by ____________.
A
- Small
- Wander through the CNS and exhibit phagocytic activity
- Removing cellular debris from dead or dying cells
25
Oligodendrocytes are associated with _________. These cells ___________, and they ____________, which is ________.
1. CNS axons ONLY
2. Wrap themselves around axons
3. Produce myelin
4. An electrical insulator
26
Two types of glial cells are found in the PNS:
1. Satellite cells
| 2. Neurolemmocytes
27
Satellite cells are _____ cells, arranged ______________.
1. Flattened
| 2. Around neuronal cell bodies in ganglia
28
Neurolemmocytes, also called _______, are associated with __________. They produce ________, and have the same structure and function as ______.
1. Schwann Cells
2. PNS axons ONLY
3. Myelin
4. Oligodendrocytes
29
What is myelination and what does it do?
The process of wrapping a myelin sheath around an axon, it insulates the axon and allows for better conduction of action potentials
30
Damaged axons can regenerate if ________ and _______.
1. The cell body is intact
| 2. A critical amount of neurilemma remains
31
Axon regeneration depends on the _______ and _____ of the damage.
1. Extent
| 2. Site
32
What are the 5 steps of Wallerian Degeneration?
1. Trauma Severs Axon
2. The proximal portion seals off and swells, while the distal portion and myelin sheath disintegrate but the neurilemma survives.
3. The neurilemma and endoneurium form a regeneration tube
4. The axon regenerates and remyelination occurs
5. Innervation to the effector is restored
33
What is a nerve?
A cable-like bundle of parallel axons
34
Describe the 3 connective tissue wrappings of each nerve?
1. Endoneurium: Around each axon
2. Perineurium: Around individual fascicles
3. Epineurium: Around the entire nerve
35
What are synapses?
Specialized junctions between one axon and another neuron, muscle cell, or gland cell
36
A typical synapse consists of what 3 things?
1. Presynaptic neuron
2. Postsynaptic neuron
3. Synaptic cleft
37
Neurons are grouped into patterns called _________
Neuronal Pools
38
Neuronal pools are defined based on _______, specifically in 4 ways:
```
Defined by FUNCTION:
– Converging
– Diverging
– Reverberating
– Parallel-after-discharge
```
39
Nervous system development begins during ________ and is derived from the _______.
1. Third week of Development
| 2. Ectoderm
40
Thickened ectoderm is called the ________.
Neural Plate
41
Cells of the neural plate are called _____________.
Neuroectoderm
42
What are the 4 major regions of the brain?
1. Cerebrum
2. Diencephalon
3. Brain Stem
4. Cerebellum
43
______ is to Anterior, as ______ is to Posterior
1. Rostral
| 2. Caudal
44
Raised bumps or ridges of the brain are called ______, while the grooves in between them are called ______.
1. Gyri
| 2. Sulci
45
What are the 3 primary brain vesicles by the THIRD week of development?
1. Prosencephalon (forebrain)
2. Mesencephalon (midbrain)
3. Rhombencephalon (hindbrain)
46
By the FIFTH week of development, what are the 5 brain vesicles?
1. Telencephalon (From PROS)
2. Diencephalon (From PROS)
3. Mesencephalon
4. Metencephalon (From RHOM)
5. Myelencephalon (From RHOM)
47
The Telencephalon forms the _________
Cerebrum
48
The Diencephalon forms the ______, _____, and _______.
Thalamus
Hypothalamus
Epithalamus
49
The Metencephalon forms the ______ and _______.
Pons and Cerebellum
50
The Myelencephalon forms the _________.
Medulla Oblongata
51
Gray Matter (3):
- Houses motor neuron and interneuron cell bodies, dendrites, telodendria, unmyelinated axons
- Forms the cortex, which covers the surface of most of the adult brain
- Forms discrete internal clusters called cerebral nuclei
52
White Matter (2):
- Made up of myelinated axons
| - Deep to the gray matter of the cortex
53
What 4 structures protect the brain?
- Bony Cranium
- Blood-brain barrier
- CSF
- Protective connective tissue (meninges)
54
What are the 3 Cranial Meninges (layers of protective tissue)?
1. Pia Mater
2. Arachnoid Mater
3. Dura Mater
55
What are the 4 functions of the cranial meninges?
–Separate soft tissue of the brain from bones of cranium
–Enclose and protect blood vessels that supply the brain
–Contain and circulate cerebrospinal fluid
–Form some of the veins that drain blood from the brain
56
What is the function of the cranial dural septa and what are the names of the 4 of them? (and what do each of them separate)
- They partition parts of the brain to provide stabilization and support
1. Falx Cerebri (Left and Right Cerebral Hemispheres)
2. Tentorium Cerebelli (Cerebrum and Cerebellum)
3. Falx Cerebelli (Left and Right Cerebellar Hemispheres)
4. Diaphragma Celae (Pituitary and Hypothalamus)
57
The dural venous sinuses run within _________. What are the 4 dural sinuses?
- The margins of the dural septa
1. Superior Sagittal sinus (Sup. Falx Cerebri)
2. Inferior Sagittal Sinus (Inf. Falx Cerebri)
3. Transverse Sinuses (Tentorium Cerebelli)
4. Occipital Sinus (Falx Cerebelli)
58
________ are cavities within the brain that contain Cerebral Spinal Fluid.
Ventricles
59
What are the 4 ventricles of the brain?
1. Lateral Ventricles (Right and Left CEREBRUM)
2. Third ventricle (Diencephalon)
3. Fourth Ventricle (Between Pons and Cerebellum)
60
What separates the two lateral ventricles?
The Septum Pellucidum
61
Cerebrospinal fluid (CSF) is a clear, colorless liquid that circulates in the _______ and _________.
1. Ventricles
| 2. Subarachnoid Space
62
What are the 3 main functions of CSF?
1. Buoyancy: Brain floats in CSF
2. Protection: CSF provides liquid cushion
3. Environmental stability: CSF transports nutrients and removes waste from brain
63
Describe the 5 steps in the production and circulation of CSF:
1. CSF is produced in the choroid plexus in the ventricles
2. CSF flows from the 3rd ventricle in to the 4th ventricle via the cerebral aqueduct
3. CSF then flows into the subarachnoid space by passing through the paired lateral apertures or the single median aperture, THEN into the central canal of the spinal cord
4. As CSF flows through the subarachnoid space, it removes waste products and provides buoyancy to support the brain
5. EXCESS CSF flows into arachnoid villi, THEN drains into the dural sinuses. The greater pressure on the CSF in the subarachnoid space ensures that the CSF moves into the sinuses without permitting venous blood to enter the subarachnoid space
64
____________ regulates what substances can enter interstitial fluid of brain
The Blood Brain Barrier
65
The two main structures that contribute to the BBB are ________ and _______.
1. Capillary endothelial cells
| 2. Astrocyte perivascular feet
66
In what 3 locations of the CNS is the BBB missing or reduced?
1. Choroid Plexus
2. Hypothalamus
3. Pineal gland
67
The ________ is the location of conscious thought processes and origin of intellectual functions. For this purpose, it contains ___________ for complex analytical and integrative functions.
1. Cerebrum
| 2. A large number of neurons
68
Describe the 3 regions of the Cerebrum: (From outer to inner)
1. Cortex (Outer Gray Matter)
2. Inner White Matter
3. Cerebral Nuclei (Deep Gray Matter)
69
The surface of the cerebrum is marked by _____, ______, and _______.
1. Sulci
2. Gyri
3. Fissures (Deep Grooves)
70
The paired cerebral hemispheres are divided by __________, which extends along the __________.
1. A longitudinal fissure
| 2. Mid-sagittal plane
71
The hemispheres are separate from one another, except at a few locations where _______________________.
Bundles of axons called tracts form white matter regions that allow for communication between them
72
The __________ is the largest tract and the main tract that connects the two cerebral hemispheres.
Corpus Callosum
73
The two hemispheres of the cerebrum appear as anatomic mirror images, but they display some functional differences, termed ___________.
Hemispheric Lateralization
74
Each hemisphere of the cerebrum is divided into 5 distinct lobes:
1. Frontal
2. Parietal
3. Temporal
4. Occipital
5. Insula
75
The Frontal Lobe is involved with: (6)
```
Concentration
Voluntary Motor Function
Verbal communication
Decision making
Planning
Personality
```
76
The Parietal Lobe is involved with __________.
General Sensory Functions
77
The Temporal Lobe is involved with __________.
Hearing and Smell
78
The Occipital Lobe is involved with __________.
Processing visual information and storing visual memories
79
The Insula is involved with ____________, and it also contains the _________.
1. Memory and interpretation of taste
| 2. Primary Gustatory Cortex
80
What are the 3 different categories/types of functional areas within the cerebrum?
1. Motor areas: Control voluntary motor functions
2. Sensory areas: Provide conscious awareness of sensation
3. Association areas: Integrate and store information
81
The primary motor cortex controls _____. It is located within the ________, and its axons project ___________.
1. Voluntary skeletal muscle activity
2. Pre-central Gyrus
3. Contra-laterally to the brain stem and spinal cord
82
Broca's area is also known as the _______, as it controls ___________. It is located within the ____________.
1. Motor Speech Area
2. Muscular movements necessary for vocalization
3. Infero-lateral portion of the left frontal lobe
83
The Primary somatosensory cortex receives general somatic sensory information from ______, ______, ______, and ______ receptors. It is located within the ______.
1. Touch, Pressure, Pain, and Temperature
| 2. Post-central Gyrus
84
The primary visual cortex is located within the ______.
Occipital Lobe
85
The primary auditory cortex is located within the _______.
Temporal Lobe
86
The primary olfactory cortex is located within the _____.
Temporal Lobe
87
The primary gustatory cortex is located within the ______.
Insula
88
Most myelinated axons in the central white matter are organized into ______, which are classified in what 3 categories:
- TRACTS
1. Association tracts
2. Commissural tracts
3. Projection tracts
89
An example of a commissural tract is _________.
The Corpus Collosum
90
The 2 kinds of association tracts are:
Arcuate Fibers
| Longitudinal Fasciculi
91
______ are paired masses of gray matter found deep within the central white matter
Cerebral Nuclei
92
What are 4 specific types of Cerebral Nuclei?
1. Caudate Nuclei
2. Amygdaloid body
3. Lentiform Nuclei
4. Claustrum
93
The Lentiform Nuclei are composed of what two structures?
The Putamen and Globus Pallidus
94
The diencephalon is composed of what 3 things?
Epithalamus
Thalamus
Hypothalamus
95
What are the 2 components of the Epithalamus?
1. Pineal Gland
| 2. Habenular Nucleus
96
The Thalamus is the ________ for sensory information that will be ___________.
1. Principal and final relay point
| 2. Processed and projected to somatosensory cortex
97
The brainstem connects the ____ and ____ to the _____.
1. Prosencephalon and Cerebellum
| 2. Spinal cord
98
The brainstem houses many __________.
Nuclei of the cranial nerves
99
The 3 regions of the brainstem are:
1. Midbrain
2. Pons
3. Medulla Oblongata
100
The cerebral aqueduct extends through the ______ and connects the ______ and the _______.
1. Midbrain
| 2. Third and Fourth Ventricles
101
The cerebral aqueduct is surrounded by ___________.
Periaqueductal gray matter
102
The nuclei of which two cervical nerves are housed in the midbrain?
Oculomotor (3)
| Trochlear (4)
103
Axons from the Primary Motor Cortex descend through the ______ to the _______.
1. Cerebral Peduncles
| 2. Spinal Cord
104
The _______ connect the CEREBELLUM to the midbrain.
Superior CEREBELLAR Peduncles
105
The ______ is between the substantia nigra and the periaqueductal gray matter and is responsible for ___________.
1. Tegmentum
| 2. Relaying information between cerebrum and cerebellum
106
The substantia nigra houses clusters of neurons that produce _________, which affects brain processes that control movement, emotional response, and the ability to experience pleasure and pain.
The neurotransmitter dopamine
107
Degeneration of cells in the substantia nigra can lead to ___________.
Parkinson's disease
108
Superior and inferior colliculi are ______ and ______ centers, respectively
1. Visual Reflex
| 2. Auditory Reflex
109
The middle cerebellar peduncles are _______ that connect the _____ to the ______.
1. Transverse fibers
2. Pons
3. Cerebellum
110
The Pons contains autonomic nuclei in the _______, which helps _______.
1. Pontine respiratory center
| 2. Regulate breathing
111
The Pons houses cranial motor and sensory nuclei for the _____, _____ and _____ nerves.
1. Trigeminal (5)
2. Abducens (6)
3. Facial (7)
112
The ________ nuclei receive auditory input and help localize sound
Superior olivary complex
113
The pyramids are located in the ______, and are composed of _________ called the _________.
1. Medulla Oblongata
2. Projection tracts
3. Corticospinal tracts
114
Paired _________ connect medulla oblongata to cerebellum
Inferior cerebellar peduncles
115
What are the 4 main groups of autonomic nuclei in the medulla oblongata organized into?
1. CARDIAC center: Heart rate/strength of contraction
2. VASOMOTOR center: Controls blood pressure by regulating contraction/relaxation of sm. musc. arterioles
3. MEDULLARY RESPIRATORY center: Respiratory rate
4. OTHER nuclei involved in coughing, sneezing, salivation, swallowing, gagging, and vomiting
116
What are the 2 longitudinal depressions on the external surface of the spinal cord?
1. Posterior Median Sulcus
| 2. Anterior Median Fissure
117
What are the 5 parts of the spinal cord?
1. Cervical
2. Thoracic
3. Lumbar
4. Sacral
5. Coccygeal
118
The spinal cord is shorter than the _______, which houses it.
Vertebral Canal
119
The tapering inferior end of the spinal cord is called the ________.
Conus Medullaris
120
Inferior to the conus medullaris, groups of axons called the _________ project from the spinal cord.
Cauda Equina
121
Within the cauda equina is the ________, which is a thin strand of ______ that helps anchor the _______ to the _______.
1. Filum Terminale
2. Pia Mater
3. Conus Medullaris
4. Coccyx
122
The ________ is located in the inferior cervical part of the spinal cord and innervates the upper limbs.
Cervical Enlargement
123
The _________ extends through the lumbar and sacral parts of the spinal cord and innervates the lower limbs.
Lumbosacral Enlargement
124
```
The spinal cord is associated with _____ pairs of spinal nerves:
____ cervical nerves
____ thoracic nerves
____ lumbar nerves
____ sacral nerves
____ coccygeal nerves
```
```
---->31 Pairs:
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
```
125
The spinal cord is protected and encapsulated by _______, which are continuous with the ________.
1. Spinal cord meninges
| 2. Cranial meninges
126
The ______ lies between the dura mater and the periosteum of the spinal cord.
Epidural space
127
The subarachnoid space of the spinal cord is significant because it is _______.
Filled with CSF
128
The Pia mater has paired, lateral triangular extensions called ________, which _____________.
1. Denticulate ligaments
| 2. Suspend and anchor the spinal cord laterally to the dura mater
129
Describe the inner and outer region of the spinal cord:
Outer: Gray Matter, contains dendrites and cell bodies of neurons, un-myelinated axons, and glial cells
Inner: White Matter, contains myelinated axons
130
What are the 4 sections that the inner gray matter of the spinal cord is divided into?
1. Anterior Horns
2. Lateral Horns
3. Posterior Horns
4. Gray Commissure
131
What are the 4 sections that the outer white matter of the spinal cord is divided into?
1. Anterior Funiculus
2. Lateral Funiculus
3. Posterior Funiculus
4. White Commisure
132
The anterior horns contain _________, so the nuclei housed here are _________ nuclei.
1. Cell bodies of SOMATIC motor neurons
| 2. Somatic Motor Nuclei
133
The lateral horns contain __________, so the nuclei housed here are _________ nuclei.
1. Cell bodies of AUTONOMIC motor neurons
| 2. Autonomic Motor Nuclei
134
The lateral horns are only found in the ______ parts of the
| spinal cord.
T1–L2
135
The posterior horns contain ________________, so the nuclei housed here are ________ and ______ nuclei.
1. Axons of sensory neurons and cell bodies of interneurons
| 2. Somatic sensory and Visceral Sensory Nuclei
136
The gray commissure contains ______________. Also it houses the ___________.
1. Unmyelinated axons and serves as a communication route between the right and left side
2. Central Canal
137
The axons within each funiculus of the spinal cord white matter are organized into ________.
Tracts
138
What are the 3 connective tissue wrappings of the spinal nerves?
1. Endoneurium
2. Perineurium
3. Epineurium
139
_________ are rapid, automatic, involuntary reactions of muscles or glands to a stimulus
Reflexes
140
A rapid response requires that _______ and ________.
1. Few neurons be involved
| 2. Synaptic delay be minimal
141
A _______ is the neural wiring of a single reflex. It ALWAYS begins at ___________.
1. Reflex Arc
| 2. A receptor in the PNS
142
What are the 5 basic components of a reflex arc?
1. Reception of stimulus at PNS receptor
2. Nerve impulse travels through sensory neurons to the spinal cord
3. Nerve impulse is processed in the integration center by interneurons
4. Motor neuron transmits nerve impulse to effector
5. Effector responds to nerve impulse from motor neuron
143
A reflex arc may be: (2)
– Ipsilateral: Both the receptor and effector organs are on the same side
– Contralateral: The sensory impulses from a receptor organ cross over through the spinal cord to activate effector organs on the opposite limb
144
The reflex itself may also be: (2)
– Monosynaptic: Sensory axons synapse directly on motor neurons, whose axons project to the effector
– Polysynaptic: More complex pathways that exhibit a number of synapses involving interneurons within the reflex arc
145
The _________ is an example of a polysynaptic
| reflex arc, and it has 3 components:
Withdrawal Reflex:
– Painful stimulus causes transmission of sensory information to the spinal cord
– Interneurons receive the sensory information and stimulate the motor neurons to direct flexor muscles to contract in response
– Simultaneously, antagonistic extensor muscles are inhibited so that the traumatized body part may be quickly withdrawn from the harmful stimulation
146
The _______ is an example of a monosynaptic reflex arc, and it has 2 components:
Stretch Reflex:
– Stretch in a muscle is monitored by a stretch receptor called the muscle spindle
– When a stimulus results in the stretching of a muscle, the muscle reflexively contracts
147
The ________ is another example of a polysynaptic reflex arc. A brief description of this reflex is ________.
Golgi Tendon Reflex:
-Stretch on the tendon where it meets the muscle signals interneurons to inhibit motor neurons from causing muscle contraction
148
Each nervous system pathway consists of a ______ and a _______.
1. Tract
| 2. Nucleus
149
A _______ is a collection of neuron cell bodies located in the CNS.
Nucleus
150
Ascending pathways are _______ because they carry _______ information from the ______ to the _______.
1. Sensory
2. Sensory
3. Body
4. Brain
151
Descending pathways are ________ because they carry _____ information from the ____ to the ______.
1. Motor
2. Motor
3. Brain
4. Muscles or glands
152
If a pathway decussates, it is considered to be _______.
Contralateral
153
Somatotopy:
A point-to-point correspondence exhibited by most neural pathways
(i.e. Specific parts of the body match up at specific points in the primary somatosensory cortex in the post central gyrus)
154
Sensory pathways have _____, _____, and _____ neurons while Motor pathways have _____ and _____ neurons.
1. Primary, Secondary, and SOMETIMES Tertiary
| 2. Upper and Lower Motor
155
The 2 types of sensory pathways are _______ and _______.
Somatosensory
| Viscerosensory
156
The three types of somatosensory pathways include:
1. Posterior funiculus–medial lemniscus pathway (PF-ML)
2. Anterolateral pathway
3. Spinocerebellar pathway
157
The posterior funiculus–medial lemniscal pathway projects through the ______, ______, and _______ before terminating within the _______.
1. Spinal Cord, Brain Stem, and Diencephalon
| 2. Cerebral cortex
158
The PF-ML pathway conducts SENSORY stimuli concerned with information about ______, _____, _____, and ______.
1. Limb position
2. Discriminative touch
3. Pressure
4. Vibration
159
The two tracts of the PF-ML pathway are the ________, which houses axons of sensory neurons in the ____________. And the _________, which houses axons of sensory neurons in the _____________. In the spinal cord, these tracts are collectively called the _______, while in the brain stem they are collectively called the _______.
1. Funiculus Cuneatus: Upper limbs, superior trunk, neck, and posterior region of the head
2. Funiculus Gracilis: Lower Limbs and Inferior trunk
3. Posterior Funiculus
4. Medial Lemniscus
160
Descending Projection Tracts are ______ pathways that originate from the ____ and _______.
1. Motor
2. Cerebral Cortex
3. Brain Stem
161
The Upper Motor Neuron is housed either within the _______ or ________.
1. Cerebral Cortex
| 2. A Nucleus within the Brain Stem
162
The Lower Motor Neuron is housed either within the _______ or ________.
1. Anterior horn of the spinal cord
| 2. Within a Brain Stem Cranial Nerve Nucleus
163
The Upper Motor Neuron either ________ or _______, whereas the Lower Motor Neuron is ALWAYS _______ because its axon ________.
1. Excites or Inhibits the Lower Motor Neuron
2. Excitatory
3. Connects directly to skeletal muscle fibers
164
Motor neuron axons form two types of somatic motor pathways:
1. Direct pathway: Conscious control of skeletal muscle activity
2. Indirect pathway: Unconscious control of skeletal muscle activity
165
The direct pathway is also called the __________, because it originates in the _____________. Its axons descend through the _________, enter the _________, and ultimately form ______ descending motor tracts.
1. Pyramidal pathway
2. Pyramid cells of the Primary Motor Cortex
3. Internal Capsule
4. Cerebral Peduncles
5. THREE
166
The three descending motor tracts of the DIRECT pathway include:
1. Corticobulbar tract
2. Lateral corticospinal tract
3. Anterior corticospinal tract
167
The corticospinal tracts descend from the _______ and form a pair of thick anterior bulges in the _______ called the _______. Then the axons of upper motor neurons synapse on lower motor neurons in the _______.
1. Cerebral cortex
2. Medulla oblongata
3. Pyramids
4. Anterior Horn of the Spinal Cord
168
Axons of the lower motor neurons in the LATERAL and ANTERIOR Corticospinal tracts innervate ________ and _______ respectively.
1. Skeletal Muscles in the LIMBS that control skilled movements
2. Skeletal Muscles in the Axial skeleton
169
The Upper motor neurons of the LATERAL and ANTERIOR Corticospinal tracts decussate in the _____ and _____ respectively before synapsing with Lower motor neurons in the ______ and ______ of the spinal cord respectively.
1. Pyramids of the Medulla Oblongata
2. White Commissure of the Spinal Cord
- ---------------------
3. Lateral Funiculi
4. Anterior Funiculi
170
If an upper motor neuron is damaged, the result will be ________, whereas if a lower motor neuron is damaged, the result will be _____________.
1. Spastic Paralysis
| 2. Flaccid Paralysis
Anatomy 165
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