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Motor systems of the the Brain
all the parts of the brain and spinal cord that are devoted to the out put of the nervous system
What are the two types of motor output?
- Visceral motor
- Somatic motor
- Smooth muscle, cardiac muscle and glands
- Example: the muscles that move substances in your gut or that control the size of blood vessels(and therefore blood pressure).
Skeletal muscle (voluntary muscle)
Brodmann classification areas, responsible for movement are all in the frontal lobe. They include:
- Area 4: (precentral gyrus):primary Motor cortex, sending axons to the alpha motor neurons of the spinal cord (executing movement)
- Area 6: supplementary motor area (planning or imaging movement)
- Area 8: Frontal eye fields (eye movement)
- Areas 44 and 45: Broca's area. In most people,on the left side, is responsible for the production of speech (movement of the throat and tongue)
Primary Motor Cortex
- region where the signal controlling movement originates
- Anatomically: precentral gyrus
- Brodmann area 4
- Remember that all consciousness is in cortex, so only conscious, planned movement starts here.
True or False
The lateral surface of the brain is supplied by the same set of arteries and arterial branches as the medial surface of the brain.
it is supplied by a different set of arteries and arterial branches
A _______ in the right lateral part of the precentral gyrus would produce paralysis of the _______ ______ of the face.
Stroke, left side
Motor Pathways / Pyramidal system
- Cell bodies in the precentral gyrus
- Send axons down to spinal cord
- Pathway changes names several times but they're still the same axons
- -Internal capsule near the thalamus
- -pyramids in the medulla
- -decussation of the pyramids (pyrimidal decussation)
- -lateral corticospinal tract in the spinal cord
What is the decussation of the pyramids ?
Where the information crosses from the left side of the brain to the right side of the body, and vise versa.
In the ________ _______, the motor pathway is called the lateral corticospinal tract.
The Lateral corticospinal tract
- Motor information from the motor region of the cerebrum (motor cortex) travels in latera corticospinal tract
- When axons reach the "right" level, they enter the anterior horn and make synapses onto motor neurons there.
- Brain cells that control muscle tissue
- The receive input from:
- -the brain and the spinal cord
- -a reflex pathway within the spinal cord
- They generate an electrical impulse(action potential) which travels along a "cable" (axon) to its end (axon terminal)
- Motor neuron action potential arrives
- impulse triggers release of acetylcholine
- ACh diffuses across the muscle cell, triggers muscle cell action potential
- -this eventually causes Ca+ release from stores in muscle
- Acton potential travels along muscle surface
- -ACh removed by the enzyme AchE
Lower Motor Neurons
neurons in the spinal cord that directly innervate skeletal muscle
example: alpha motor neurons with cell bodies in the ventral horn of the spinal cord and an axon that travels as part of a nerve to end in a neuromuscular junction on skeletal muscle
Upper Motor Neurons
All other nerves in the brain and spinal cord that influence movement, but do not make direct contact with a skeletal muscle fiber.
the parts of the nervous system that receive information from the internal or external environment
True or False
The receptors in the homeostasis model are the same as sensory systems in the nervous system.
- Each type of receptor has a relevant stimulus
- this can be photons or chemicals present in the environment around the receptor.
- The process through which environmental energy is transformed into nervous system energy.
- the first step in any sensory system.
True or False
Reflexes operate without us being conscious of them.
The _______ is responsible for deciding which stimuli reach consciousness; accordingly, all ________ _______ (except olfaction) are routed through the thalamus before they reach the _______.
Thalamus, sensory systems, cortex
Sensory System Features
Central Nervous system Pathways
- Information must be sent to the cortex to reach consciousness
- For all but olfaction (smell), sensory info is relayed through the thalamus
- There is a region of cortex that is responsible for perception of each kind of sensation
- If it does not reach the cortex, it is not perceived
- Example: there is a cortical area for skin pressure but not for blood pressure, so you are consciously away of being touched but not of your blood pressure.
- this is the sensory neuron or transductor if it sends its info to the CNS directly.
- if the receptor is lazy the first order neuron carries the info into the CNS where it synapses with a second motor neuron.
The second-order neuron, in turn makes synaptic contact with a third-order neuron
receptors that receive their stimuli form the external environment.
- Examples include the five senses:
- touch, sight, sound, taste, smell, and balance (vestibular sense)
receptors that receive their energy from the internal environment.
- Examples include :
- oxygen levels, glucose level in blood, CO2 level in blood, stretch in stomach and bowel
receptors that integrate information about the states of stretch of skin, muscle and tendons, with info about gravity, to produce a perception of where our joints are in space.
For example: if you close your eyes and someone lifts your leg, you perceive that your leg is extended even though you cant see it