Spinal Cord And Somatic Reflexes Flashcards
Sectional anatomy of the nervous system.
Gray matter: neural cell bodies
White matter: axons, tracts
Outside world sensors
Somatic
Inside world sensors
Visceral
Sight, hearing, taste, smell, and equilibrium
Special senses!
Peripheral nervous system
Sensory information to the brain via afferent nerves.
Sensory information goes to?
The CNS, the control center! Where integration takes place!
Peripheral nervous that exit the brain
Motor neurons! Efferent nerves.
Somatic nervous system
PNS that control skeletal muscle
Autonomic nervous system
Sympathetic and parasympathetic. Effectors: smooth muscle, glands, adipose tissue.
Sympathetic
Flight are flight. Sweating.
Parasympathetic
Resting and digesting.
Central nervous system organization
Tracts (white matter)and centers (gray matter) and tracts (white matter).
Centers, integrate information
Decussation
?
Nerves are mostly?
Axons!
Spinal cord function
Conduction of information between sensors, CNS and effectors.
Integration or reflexes
Meninges
- Dura mater
- Arachnoid mater
- Pita mater
Sectional anatomy of the spinal cord.
Gray matter: neural cell bodies.
White matter: tracts (axons)
“Elevator”
Ascending tracts
Sensory! Up!
Neural pathways: first, second and third order neurons.
First order neuron
Afferent
Second order neurons
Interneuron
Third order neuron
Thalamus
Gracile fasciculus
Carries sensation of trunk and movement, deep touch, visceral pain and vibration.
Below T6.
To the thalamus
Cuneate fasciculus
Caries sensation of movement, deep touch, visceral pain, and vibration.
Above T6
To thalamus
Spinothalamic
Carries sensations of light touch, itch, temperatures, pain and pressure.
To thalamus
Spinoreticular
Carries sensations of pain and injury.
Spinocerebellar
Carries information on muscle position. (Proprioception)
Goes to cerebellum
Descending tract organization
Upper neuron: originates in the brain
Lower motor neuron: innervated muscle as part of NMJ
Synapse at grey horns.
Corticospinal
Fine control of limbs.
Tectospinal
Reflexive head movement
Reticulospinal
Balance and posture, regulation of awareness of pain.
Vestibulospinal
Lateral: valence and posture.
Medial: control of head position.
Spinal nerves
Carry sensory input and motor output. PNS!
Location!
Dermatomes
Region of skin innervated by spinal nerves.
Can be used to locate spinal damage.
Reflex arc
Stimulus Sensory neuron activation Integration by interneuron Motor neuron activation Effector response
Reflex properties
Require stimulation
Rapid
Involuntary
Non-variable
Muscle spindles
Proprioceptors:
Give information on muscle position.
Intrafusal fibers
Afferent neurons monitor rate of change (primary) and the length (secondary).
Muscle spinal activity: motor neurons
Alpha: extrafusal fibers
Gamma: intrafusal fibers
Somatic reflexes
Affecting muscles
Stretch reflex
As a muscle is stretched: can involve many neurons or as little as two.
Tone increases
Maintains posture
Stabilizes movement
Monosynaptic reflexes
Patellar reflex
No interneurons!
Sensor directly stimulants motor neuron.
Primary
Polysynaptic reflexes
One or more interneurons connect afferent (sensory) and efferent (motor) signals.
Withdrawal reflexes
Stimulated by painful stimuli.
Reciprocal inhibition
1. Contraction of the agonists.
2. Relaxation of antagonists
Crossed extensor reflex
Painful stimulus to foot while walking
One side contraction of agonist, relaxation of antagonists.
Reversed on the other side.
Tendon reflex
A stretch reflex, when the stretch is created by a blow upon a muscle tendon.
Decussation
In anatomy the term chiasma or chiasm means nearly the same as decussation.
Contralateral
relating to or denoting the side of the body opposite to that on which a particular structure or condition occurs.
Ipsilateral
belonging to or occurring on the same side of the body.
Proprioceptor
a sensory receptor that receives stimuli from within the body, especially one that responds to position and movement.
Extrafusal fibers
Extrafusal muscle fibers are the skeletal standard muscle fibers that are innervated by alpha motor neurons and generate tension by contracting, thereby allowing for skeletal movement. They make up large mass of skeletal (striated) muscle and are attached to bone by fibrous tissue extensions (tendons).
Gamma motor neuron
is a type of lower motor neuron that takes part in the process of muscle contraction, and represents about 30% of fibers going to the muscle.
Primary afferent fiber
A spinal reflex in which a painful (pressure) stimulus applied to a toe, coronary band or heel bulb, results in a flexion, or withdrawal, of the leg. A test of the integrity of the reflex arc and sensory pathways. Called also withdrawal reflex.
Spinal cord function
Conduction of information between sensors , control centers (CNS) and effectors.
Integration of reflexes.
What is a somatic reflex?
Somatic reflexes involve the stimulation of skeletal muscles by the somatic division of the nervous system.
Ex Patellar reflex. Achielles, Corneal,
The over all structure of the nervous system.
- CNS, brain and spinal cord.
2. PNS, everything outside of the brain and spinal cord.
Reflex
Requires stimulation
Very rapid! Ex. Removing your hand from a hot stove.
Involuntary
Non-variable
Reflex arc
- Stimulus
- Sensory neuron activation. Opening MGC. Depolarization!
- Integration by interneurons. In the spinal cord.
- Motor neuron activation.
- Effector response
Homeostatic feedback loop
Muscle spindles: Proprioceptors
Give information on muscle position
Intrafusal fibers
Afferent neurons monitor rate of change(primary) and length(secondary). Rate is more important.
Alpha neurons
Extrafusal fibers (NMJ)
Gamma neurons: efferent
Go to Intrafusal fibers
CNS organization
Tracts and centers and tracts
Spinal cord function
- Conduction of information between sensors, Control centers and effectors.
- Integration of reflexes.
Peripheral Organization
Nerves and ganglia.
Ascending tracts
The pathway by which sensory information from the PNS is sent to the CNS
Neural pathways: first-second-third order neurons.
Gracile fasciculus
Carries sensations of trunk position and movement, deep touch, visceral pain, and vibration below T6
Cuneate fasciculus
Carries sensations of movement, deep touch, visceral pain, and vibration above T6
Spinothalamic
Carries sensation of light touch, itch, temperature, pain, and pressure
Spinoreticular
Carrie sensation of pain from injury
Spinocerebellar
Carries information on muscle position (proprioception)
Desending tracts
Pathways where motor information is sent from the brain to lower motor neurons.
Upper motor neuron
Originates in the brain
Lower motor neurons
Innervated muscle as part of the NMJ.
Corticospinal
Fine control of limbs
Tectospinal
Reflexive head movement
Reticulospinal
Balance and posture, regulation of awareness of pain.
Vestibulospinal
Lateral: balance and posture
Medial: control of head position
Spinal nerves
Carrie sensory input and motor output
Location location location!
Dermatomes
Region of skin innervated by spinal nerves. Can be used to locate spinal damage.
Reflex overview
Require stimulation
Rapid
Involuntary
Nonvariable
Reflex arc
Stimulus Sensory neuron activation Integration by inter-neurons Motor neuron activation Effector response
Muscle spindles
Proprioceptors
Give information about muscle position
Intrafusal fibers
A Ferent neurons monitor rate of change Open parentheses primary) and link (secondary)
Muscle spindle activity
Alpha motor neurons
Extrafusal fibers, generate tension by contracting there by allowing skeletal muscle movement.
Gamma motor neurons
Intrafusal fibers, detect the amount and rate of change in length of muscle
Stretch reflex
As a muscles is stretched, tone increases
Maintains posture and balance and stabilize his movements
Can involve multiple neurons, or as little as two
Monosynaptic reflexes
Only involves two to neurons. What is sensory and one motor. No Interneurons!
EX. Patellar reflex
Polysynaptic reflexes
One or more Interneurons connect Afferent (sensory) and Efferent (motor) signals.
Withdrawal or flexor reflex (Polysynaptic)
Stimulated by painful stimuli
Reciprocal inhibition
Contraction of agonists
Relaxation of antagonists
Crossed extensor reflex
Painful stimulus to foot while walking
One side contraction of agonist, relaxation of antagonist
Reversed on the other side
Tendon reflex
Caused by a blow upon a muscle tendon and example would be the patellar reflex
Decussation
An example would be the optic chiasma
Contralateral
Relating to the side of the body opposite to that on which a particular structure or condition occurs.
Ipsilateral
Referring to occurring on the same side of the body
Primary afferent fiber
Constantly monitors how fast a muscle stretch changes
Secondary afferent fiber
Constantly monitoring how fast a muscle stretch changes