1.4- Anatomy of Cerebellum, Brain Stem, & SC Flashcards
What controls balance, posture maintenance, and complex muscular movements?
Cerebellum
What is responsible for integration, coordination, and execution of multijoint movements?
Cerebellum
What is located between cerebrum and SC?
Brain stem
What is the function of the brainstem?
To relay
Where is the brain stem located?
Between cerebrum and SC
What is the midbrain?
A relay station between cerebrum and SC
What is important in reflex including righting of the head and auditory reflexes?
Midbrain
What is made of fibers running between cerebellum and rest of CNS?
Pons
What is important for balance, equilibrium, coordinating movement?
Pons
Why is the Pons important?
for balance, equilibrium, coordinating movement
Why is the Medulla Oblongata important?
It is the control center for heart and breathing rate.
Where does the decussation (crossing) of motor and sensory neurons occur?
Medulla Oblongata
What contains the Reticular Activating System?
Medulla Oblongata
What is the Reticular Activating System?
adjusts level of arousal and sleep-wake cycles
What is the Foramen Magnum?
large opening at the base of the skull that serves as a boundary between brainstem and SC
What is the Spinal Column?
bony structure that protects SC
How far down does the spinal cord extend?
the first lumbar vertebrae
Nerve roots from the SC at the thoracic and lumbar level must descend _____ before exiting.
2 levels
How many enlargements in the spinal cord?
2- first enlargement (cervical enlargement) and second enlargement (lumbar enlargement)
Where is the first enlargement located?
third cervical vertebrae through second thoracic segment
Why is the first enlargement wider?
because of the many sensory and motor neurons coming from the UE’s
Where is the narrow area of the spinal cord?
thoracic area
Why is the thoracic area of the spinal cord narrow?
because relatively few motor and sensory neurons from this area
Where is the second enlargement of the spinal cord located?
first lumbar through third sacral
Why is the lumbar area of the spinal cord enlarged?
because of number of sensory and motor connections from LE’s
Generally the SC is _____ at top than bottom because nerves join the SC as it ______
larger at top
ascends
At approx. L1 the SC becomes a cone shaped structure called the _____________
Conus Medullaris
Where does the SC become the Conus Medullaris?
L1
What makes the Conus Medullaris?
sacral spinal segments
Below the Conus Medullaris the SC ends in a mass of spinal nerve roots called the _____________
Cauda Equina
What is the Cauda Equina?
a mass of spinal nerve roots after the Conus Medullaris
In the brain, the Dura has 2 layers. It the SC, the dura has 1 layer. The layer is ____________.
Visceral layer (no periosteal layer in the SC)
Dura does not adhere to bone- it forms a ____.
sac
Why does the Dura not adhere to bone and instead form a sac?
because the spinal column is flexible and it would tear with movement if attached
True or False: The Arachnoid is the same in the SC as it is in the brain.
True. I is pushed against Dura due to SCF pressure but not physically attached.
The Pia is connected to ____________.
the SC itself
What term describes the flaps in the pia that attach through the arachnoid to the Dura, anchors the SC?
Denticulate ligaments
What are Denticulate Ligaments?
flaps in the pia that attach through the arachnoid to the dura, anchors the SC
Pia continues around the cauda equine down to the coccyx where it forms a strand and attaches to anchor the SC- called the ____________
Filum Terminale
Where does the dural sac eventually join the filum terminale and attach to the coccyx?
External Filum Terminale or the Coccygeal Ligament
In the SC, white matter is ______ while the gray matter is __________.
white matter is outside while the gray matter is inside
In the SC, gray matter is divided into __________.
3 horns: dorsal (posterior) horn, lateral horn, and ventral (anterior) horn
Dorsal horn is ___________.
Lateral horn is ___________.
Ventral horn is _________.
Dorsal horn- sensory
Lateral horn- motor
Ventral horn- motor
Cell bodies of neurons that carry sensory info up to the brain.
Dorsal (posterior) horn
Contains cell bodies of preganglionic sympathetic neurons
Lateral horn
Processes autonomic info
Lateral horn
Found only between T1-L2
Lateral horn
Lateral horn contains cell bodies of ____________ neurons.
preganglionic sympathetic
Lateral horn processes ___________ and is found only between __________.
processes autonomic info
found only between T1-L2
Ventral horn is cell bodies of _______ neurons that drive ________.
Alpha motor neurons
drive voluntary muscle
Cell bodies of Alpha motor neurons that drive voluntary muscle
Ventral (anterior) horn
White matter is divided into ____________.
3 columns: Dorsal (posterior) column, lateral column, ventral (anterior) column
Dorsal column is ________.
Lateral column is _________.
Ventral column is __________.
Dorsal column is sensory fibers running up to the brain.
Lateral column is both motor and sensory fibers.
Ventral column is mostly motor fibers.
Ventral columns are made of several distinct bundles called _______.
tracts
a tract is a group of nerve fibers similar in ______, ___________, and ____________.
origin, destination, and function
- large with slightly flattened shape
- more white matter with large ventral horn
cervical
- ventral horn is narrow (few muscles in the area)
- small dorsal horn- little sensation coming from the area
thoracic
- broadens with large dorsal and ventral horns due to lots of motor and sensory activity from the area
lumbar
- lots of gray matter with very little white matter (tracts mostly entre or leave the SC at levels about this region)
sacral
SC has ____ segments with a pair of ________ coming from each segment
31
spinal nerves
All segments have _______ and _______ components except C1 which only has _______.
sensory and motor
motor
What part of the SC does not have both motor and sensory components.
C1- sensory info carried thru cranial nerves
Each spinal nerve is made of what 2 roots?
dorsal root and ventral root
The dorsal root is made of _________ fibers.
afferent (sensory)
The ventral root is made of __________ fibers.
efferent (motor)
Enlargement of the dorsal root that contains the cell bodies of sensory neurons (cell bodies are outside the SC itself)
Dorsal Root Ganglion
What is the Dorsal Root Ganglion?
enlargement of the dorsal root that contains the cell bodies of sensory neurons
Union of the dorsal and ventral roots forms the _________.
spinal nerves
Tracts (white matter)- columns consist of several tracts- bundles of ____________ that run up and down the cord.
myelinated fibers
Lateral Corticospinal Tract does what?
voluntary motor system
Starts in area 4 of the cortex (Brodmann’s cortical numbering system) and eventually innervates muscle
Lateral Corticospinal Tract
Corresponds with the Homunculus in the primary motor cortex
Lateral Corticospinal Tract
The Lateral Corticospinal Tract corresponds with the ___________ in the primary motor cortex.
Homunculus
Motor tracts are a 2 neuron system- _______ and _______ _______ neuron
upper and lower motor neuron
The Upper Motor Neuron begins in the ________, runs through the ________ to the _________.
Begins in the cortex, runs through the internal capsule to the medulla oblongata
In the medulla, 85% of the fibers cross and descend through the SC as the ___________.
Lateral Corticospinal Tract
The 15% that don’t immediately cross ___________.
do so eventually
The axon exits the SC through the _______ where it synapses onto an ______ or directly onto the ___________.
through the Ventral horn where it synapses onto an interneuron or directly onto the Lower Motor Neuron
The lower motor neuron is generally an __________.
Alpha Motor Neuron
The lower motor neuron then travels through the _________ to ___________.
Ventral root to innervate muscles
If the upper motor neuron is destroyed:
1.
2.
3.
- effects seen on opposite side
- paralysis, hypertonic, hyperreflexia- Spastic Paralysis
- Minimal atrophy
If lower motor neuron is destroyed: 1. 2. 3. 4.
- effects on the same side
- paralysis, flaccid, atonia, no reflexes- Flaccid paralysis
- significant atrophy
- may see fasciculations of the muscle fibers
If both upper and lower motor neurons destroyed:
1.
- characteristics of lower motor neuron lesion- no reflexes, flaccid paralysis
Destroyed upper or lower motor neuron:
- effects on the same side?
- minimal atrophy?
- Flaccid paralysis?
- fasciculations of the muscle fibers?
- lower motor neuron
- upper motor neuron
- lower motor neuron
- lower motor neuron
Dorsal Column System can’t be called a tract because it ______________.
originates outside the CNS
What carries vibration and light touch?
Dorsal Column System
What has large myelinated fibers (fast)?
Dorsal Column System
What carries pain, temp, some touch?
Lateral Spinothalamic Tract
What has very small unmyelinated fibers- slow conduction?
Lateral Spinothalamic tract
What are the differences between the dorsal column system and the lateral spinothalamic tract?
- myelination
- where it synapses
- where it crosses
Dorsal Column System~ #1 neuron enters thru the \_\_\_\_\_ into the SC on the \_\_\_\_\_; travels up the SC on the \_\_\_\_\_ into the \_\_\_\_\_ where it synapses with neuron #2; #2 neuron crosses to the \_\_\_\_\_\_\_ as it goes through the \_\_\_\_\_ & into the \_\_\_\_\_\_; #2 neuron synapses with the #3 neuron in the \_\_\_\_\_ and goes to area \_\_\_\_\_\_\_\_\_\_\_\_
dorsal root same side same side medulla oblongata opposite side brainstem & into the thalamus thalamus and goes to area 3, 2, 1, of sensory cortex
Where does the dorsal column system cross to the opposite side?
as it goes through the brainstem and into the thalamus
Lateral Spinothalamic tract~ #1 neuron enters through the \_\_\_\_\_ into the \_\_\_\_ and synapses immediately; #2 neuron crosses in the \_\_\_\_\_ of the SC to the \_\_\_\_\_\_ before it ascends up the SC; #2 neuron end and synapses with #3 neuron in the \_\_\_\_\_\_; #3 neuron runs up to \_\_\_\_\_\_\_\_\_\_\_\_\_\_
dorsal root into the dorsal horn
lateral column of the SC to the opposite side
thalamus
3, 1, 2, in sensory cortex
Where does the lateral spinothalamic tract cross to the opposite side?
crosses in the lateral column of the SC to the opposite side before it ascends up the SC
