OT Nerves Ch 5

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1

THALAMUS

One thalamic lobe in each hemisphere

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THALAMUS

Considered to be the gateway to the cortex

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THALAMUS

All sensory information, except olfaction, travels through this

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THALAMUS fx

o Sensory Integration

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THALAMUS fx

o Motor Integration

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THALAMUS fx

o Receives sensory information and relays this information to the cerebral cortex.

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THALAMUS fx

o Receives motor information from the cerebral hemispheres, which then transmits this information to other areas of the brain and spinal cord.

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THALAMUS fx

o Links sensation, movement, emotion and memory.

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THALAMUS fx

o Has a role in sleep-wake cycles and levels of consciousness

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THALAMUS fx

o Works with the reticular formation to alert the brain to important sensory information and to calm the body down.

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HYPOTHALAMUS

• Composed of several different areas

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HYPOTHALAMUS

• Located at the base of the brain just anterior and inferior to the thalamus.

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HYPOTHALAMUS

• About the size of a pea

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HYPOTHALAMUS fx

o Organizes homeostatic and social behavior patterns

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HYPOTHALAMUS homeostatic

o Body Temperature – senses changes and makes adjustment

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HYPOTHALAMUS

o Physical aspects of emotions, e.g., heart rate, upset stomach

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HYPOTHALAMUS

 Works with limbic system

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limbic system

Hypothalamus works with _______ to maintain

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HYPOTHALAMUS fx

o Hunger
o Thirst
o Circadian Rhythms
o Heart rate
o Response to pain

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HYPOTHALAMUS fx

o Regulates endocrine activity

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HYPOTHALAMUS fx

 Releases hormones from the pituitary gland, adrenal glands and pineal gland
o

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HYPOTHALAMUS fx

Controls the autonomic nervous system

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LIMBIC SYSTEM

Located on top of the brainstem and under the cortex

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LIMBIC SYSTEM

Forms a ring around the corpus callosum and has many connections to the lobes of the cortex.

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LIMBIC SYSTEM

Phylogenetically the oldest part of the brain.

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LIMBIC SYSTEM

It is also connected to the olfactory apparatus.

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LIMBIC SYSTEM basic fx

Hunger
.

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LIMBIC SYSTEM basic fx

Aggression

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LIMBIC SYSTEM basic fx

Emotions

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LIMBIC SYSTEM basic fx

Endocrine aspects of sexual response.

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LIMBIC SYSTEM basic fx

Central role in memory, learning, and autonomic activities

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LIMBIC SYSTEM structures

the amygdala, hippocampus, thalamus and hypothalamus

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AMYGDALA

Physically located deep in the temporal lobe

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AMYGDALA

Functions:Controls responses related to fear, anger and anxiety

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AMYGDALA

Functions:Center for the identification of danger

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HIPPOCAMPUS

• Physically located within the innermost fold of the temporal lobe.

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HIPPOCAMPUS

• Responsible for creating new memories and spatial memory (knowing how to get from one place to another).

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OPTIC CHIASM

• Cross-shaped connection located between the optic nerves

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OPTIC CHIASM

• Nerves from the right eye that attend to the left temporal visual field (located in the right retina) remain on the right (ipsilateral) side of the brain

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OPTIC CHIASM

• Nerves from the left eye that attend to the right temporal visual field (located in the left retina) remain on the left (ipsilateral) half of the brain.

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left temporal visual field

Nerves from the right eye that attend to the _____________________(located in the right retina) remain on the right (ipsilateral) side of the brain

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right temporal visual field

• Nerves from the left eye that attend to the ______________(located in the left retina) remain on the left (ipsilateral) half of the brain.

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ipsilateral

remain on the same side

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SPINAL CORD

• About 18 inches long and extends from the base of the brain, down the middle of the back, to about the waist.

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SPINAL CORD

• Provides sensory and motor function to the body below the shoulders through the peripheral nerves

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SPINAL CORD

• Extension of the brain

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SPINAL CORD

• The gray matter is a butterfly shape surrounded by white matter.

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SPINAL CORD gray matter

There are dorsal and ventral areas : know as the dorsal and ventral horns.

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SPINAL CORD gray matter

is where the connections occur.

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SPINAL CORD

Upper motor neurons end in the gray matter.

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Spinal cord white matter

contains the ascending and descending tracts which take information to and from the brain.

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ascending and descending tracts

take information to and from the brain.

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Spinal cord white matter

Ascending pathways (posterior tracts) carry sensory information from peripheral nerves to brainstem, thalamus and cortex.

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Ascending pathways

also know as (posterior tracts)

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posterior tracts

carry sensory information from peripheral nerves to brainstem, thalamus and cortex.

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Spinal cord white matter

carry sensory information from peripheral nerves to brainstem, thalamus and cortex.
Ascending pathways (posterior tracts)

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Spinal cord white matter

Descending pathways (anterior tracts) carry motor information from cortex to peripheral nerves.

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Descending pathways

(anterior tracts)

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Descending pathways

carry motor information from cortex to peripheral nerves

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spinal cord

31 pairs of spinal nerves are divided into groups (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, coccygeal) and correspond to vertebral segments

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31 pairs

# of spinal nerves in the spinal cord

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groups of spinal nerves

8 cervical, 12 thoracic, 5 lumbar, 5 sacral, coccygeal and correspond to vertebral segments

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cervical group of spinal card

8

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thoracic group

12

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lumbar group

5

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Sacral group

5

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coccygeal

a spinal group

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correspond to vertebral segments

a spinal group

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spinal nerve

divides into a ventral root and a dorsal root near the spinal cord.

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ventral & dorsal root

spinal NERVE divides into these near the spinal cord.

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ventral root

go to voluntary muscles, and to viscera, glands and smooth muscles.

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efferent (motor) fibers

are in the spinal cord

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Dorsal (posterior) root:

come from sensory receptors from skin, joints, and muscles.

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afferent (sensory) fibers

come from sensory receptors from skin, joints, and muscles.

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sensory receptors

fibers that come from _____ from skin, joints, and muscles

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Dorsal (posterior) root:

each possesses a dorsal root ganglion (cell bodies of sensory neurons); there is none for C1

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cell bodies of sensory neurons

each dorsal root possesses

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dorsal root

there is no___________for C1.

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Motor neurons

carrying motor messages from different areas of the nervous system are divided into two categories: upper motor neurons (UMN) and lower motor neurons

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upper motor neurons (UMN) and lower motor neurons

Two categories of motor neurons

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Upper motor neurons

are part of the central nervous system
.

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UMN

Include cranial nerve nuclei (located in the brainstem) and interneurons in the ventral horn

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cranial nerve nuclei

(located in the brainstem

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Lower motor neurons

part of the peripheral nervous system.

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Lower motor neurons

Include cranial nerves, spinal nerves, cauda equine and the ventral horn

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cranial nerves,

included in lower motor neurons

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spinal nerves,

included in lower motor neurons

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cauda equine and

included in lower motor neurons

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the ventral horn

included in lower motor neurons

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REFLEXES

rapid, predictable and involuntary responses to stimuli.”

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REFLEXES

somatic or autonomic

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Somatic reflexes

include all reflexes that stimulate the skeletal muscles.

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Autonomic reflexes

regulate the activity of smooth muscles, the heart and glands.

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Autonomic reflexes

regulate such body functions as digestion, elimination, blood pressure and sweating.

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Reflexes

have a minimum of five elements.

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Reflexes elements

1 stimulus
2 A sensory receptor which reacts to a stimulus;
3 an effector organ – the muscle or gland eventually stimulated;
4 sensory neurons
5 motor neurons to connect the sensory receptor and the effector organ.

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SPINAL REFLEX ARC

• Reflexes are meant to be protective in nature.

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SPINAL REFLEX ARC

Conscious awareness of a reflex is not part of the reflex arc itself.

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consciuos awareness

not part of the reflex arc itself.

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Pathway of the spinal reflex arc

1. sensory stimulus enters the spinal cord via a sensory neuron.
2. sensory neuron either synapses directly with a LMN within the spinal cord, or it synapses with a short interneuron that then synapses with a LMN within the spinal cord.
3. LMN then travels out of the spinal cord to end at the neuromuscular junctions of the fibers of a muscle, where the muscle fibers are directed to contract.

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sensory stimulus

enters the spinal cord via a sensory neuron.

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sensory neuron

synapses directly with a LMN within the spinal cord, or
it synapses with a short interneuron that then synapses with a LMN within the spinal cord.

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sensory neuron

it synapses with a short interneuron that then synapses with a LMN within the spinal cord.
OR
synapses directly with a LMN within the spinal cord,

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LMN

travels out of the spinal cord to end at the neuromuscular junctions of the fibers of a muscle, where the muscle fibers are directed to contract.

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neuromuscular junctions

LMN travels out of the spinal cord to end at the ________________of the fibers of a muscle, where the muscle fibers are directed to contract.

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muscle fibers

where the ________are directed to contract after the LMN then travels out of the spinal cord to end at the neuromuscular junctions of the fibers of a muscle.

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reflex arc.

the pathway of a reflex is often called a

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pathway of a reflex

Because of the shape of the sensory neuron INTO the spinal cord and the motor neuron OUT of the spinal cord

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SPINAL CORD REFLEXES

• Involuntary responses to stimuli; basic, specific and predictable; dependent upon intact neural pathway
.

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Spinal cord reflexes

• Provide basis for unconscious motor function and basic defense mechanisms

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reflex action

consists of a specific, stereotyped response to an adequate stimulus.

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Stretch reflex

• Stimulus: muscle stretch.

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Stretch reflex fx

Maintain muscle tone
Support agonist muscle contraction
Provide feedback about muscle length.
Prevents excessive stretching that might tear the muscle

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Stretch reflex fx

Support agonist muscle contraction

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Stretch reflex fx

Provide feedback about muscle length.

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Stretch reflex fx

Prevents excessive stretching that might tear the muscle

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Stretch reflex fx

Maintain muscle tone

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Stretch reflex

o Increasing muscle length activates muscle spindle receptor which synapses with a motor neuron causing the muscle to contract
o Example: Patellar reflex

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Patellar reflex

Example of stretch reflex

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Increase muscle length

Stretch reflex

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Activates muscle spindle receptor

stretch reflex

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contractiton

Synapses with motor neuron causing ______________

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Withdrawal reflex

• Stimulus: cutaneous sensory stimuli, usually pain.

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Withdrawl reflex fx

o Protective, withdrawal mechanism to remove body part from harmful stimuli.

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Withdrawl reflex

the flexor muscles contract, the extensor muscles on the same side of the body relax to allow the flexor movement.

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Withdrawl reflex Example:

When a person touches something hot the elbow flexes to withdraw the limb from the stimulus.

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Reciprocal inhibition

• Happens to allow the withdrawal to happen

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Reciprocal inhibition

The antagonist to a joint action relaxes when the agonist of that joint action contracts

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The antagonist

__________to a joint action relaxes when the agonist of that joint action contracts

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action contracts

The antagonist to a joint action relaxes when the agonist of that joint _____________

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Example: reciprocal inhibition

when the biceps contracts a signal is sent to the triceps to relax to allow the movement of the biceps.

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Reciprocal inhibition

• Muscles that are on the opposite sides of a joint have opposite actions at that joint
(i.e., their actions are antagonistic to each other).

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Reciprocal inhibition

• The muscle that moves the joint is called the agonist.

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...

• The muscle on the opposite side is termed the antagonist.

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actions are antagonistic

• Muscles that are on the opposite sides of a joint have opposite actions at that joint (in reciprocal inhibition)

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Crossed extension reflex

• Works with the withdrawal reflex.

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Crossed extension reflex stimulus

Pain and withdrawal on the opposite side.

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Crossed extension reflex fx

Creates a balanced posture of the body when one side flexes and withdraws

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Crossed extension reflex fx

Keeps the body from falling when it happens in the lower extremity.

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Crossed extension reflex

If a limb is in flexor withdrawal the opposite limb extends

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Crossed extension reflex Example:

Foot withdraws from stepping on something sharp, opposite knee extends.