Motor Fxn I: Part One Flashcards
Stretch reflex Characteristics
- Stretch stretches Group Ia Afferent
- Ia synapse on AMN of SAME Muscle
- Muscle Contracts to decrease tension on Spindle
Types of intrafusal fibers
- Nuclear BAG
- Nuclear CHAIN
Golgi tendon organ
- Group Ib Afferents
- Arranges in SERIES w/ EF fiber
- Detect Tension
Lower motor neurons are classified into what categories?
- Alpha
- Beta
- Gamma
Nuclear bag fibers
- Detection
- Innervation
- Nuclei
- Detect Change in LENGTH
- Ia and dynamic Gamma efferent
- Mult. Located in the Bag
Gamma motor neurons do what?
Keep Muscle SPINDLE Taught
Characteristics of Interneurons
- Bipolar shape
- Capable of Spontaneous activity
- Responsible for most of SPINAL cord integrative fxn
Motor Nerve Cells deal with what kind of movement?
Voluntary movement
Fxn of Renshaw cells
- Receive branches from AMN
- Transmit Inhibitory signals to surrounding MN
(Lateral Inhibition) - Enhance FLUIDITY of limb movement
The Afferent neurons are ____.
Sensory
Muscle Spindle Fxn
- Dynamic Stretch Reflex
- Static Reflex
- Damping (Prevents Jerking)
Bran Areas that control Gamma Fibers
- Bulboreticular Region of Brain Stem
- Cerebellum
- Basal Nuclei
- Cerebral cortex
Excitatory Interneurons
- Spinal Reflex
(Step on a Tack) - Ipsilateral and Contralateral signals
- Can cut the head off of a chicken and it can still move*
Result of Stretch reflex
Synergistic Muscles are Activated and Antagonistic muscles are inhibited
Nuclear Chain fibers
- Detection
- Innervation
- Nuclei
- STATIC Change
- Group II and static gamma
- More numerous than NBF
- Nuclei located in a chain
Efferent Neurons are _____.
Motor
What NT do RENSHAW cells use?
Glycine
NT for Alpha and Gamma MN
Both use ACh
Golgi tendon Organ
- Orientation to EFF
- Stimulation
- Detection
- Overall fxn
- Arranges in Series w/ EF Fibers
- Stimulated by Contraction or Stretch
- Detects Tension
- Deals with RELAXATION of muscles to heavy load
The Babinski reflex is seen in ____.
Infants
1 AMN can innervate how many muscle fibers?
3000+
What are the types of Motor Neurons in the Spinal Cord?
- Alpha
- Gamma
Lesion effects on REFLEXES: UMN vs LMN
UMN:
- Increased
LMN:
- Absent
Major Volitional Movement go through what Tract in the Spinal Cord?
Cortico-Spinal Tract
- UMN
Pacinian Corpuscles
- Group II
- Detect VIBRATIONS
Lower Motor neurons go from ______ to ______.
- Spinal cord
- Effector (Sk. Muscle)
T/F: INTERNEURONS are 30x more Numerous as Ant. Motor Neurons
True
Motor Neuron pool
AMN that innervate a MUSCLE
Does the muscle spindle fxn as a motor or sensory receptor?
Sensory
Excitatory IN use _____ and Inhibitory IN use ______.
- GABA
- Glutamate
Ib Inhibitory Neurons
- AUTOGENIC Inhibition reflex
- GOLGI tendon activated with Stretch
- Responsible for smooth muscle contraction
- Protects from tears
Free Nerve Endings
- Group III and IV Afferent
- Detect Noxious stimuli
What is the NT of the UMN to the LMN?
Glutamate
Ia Inhibitory Neurons
- Inhibits ANTAGONISTIC muscle
- Avoids Spasticity
LMN terminate at Effector and use what NT
ACh
Large Motor neurons
- Muscle innervation
- Threshold
- Firing time
- Force
- Many
- High
- Fire LAST
- LARGE
Small Motor neurons
- Muscle innervation
- Threshold
- Firing time
- Force
- Innervate Few muscle fibers
- LOW threshold
- Fire FIRST
- Small force
Golgi Tendon Reflex is _____ to Stretch Reflex
Opposite
Motor Unit Consists of what?
- A SINGLE Motor Neuron
- The muscle FIBERS it Innervates
Where are the cell bodies of Motor neurons located?
3 places:
- Motor Cortex
- Brain Stem
- Spinal Cord
What are the INTERNEURONS in the Spinal Cord called?
RENSHAW Cells
Muscle Spindle
- Group Ia and II Afferents
- Arranges in PARALLEL w/ EF fiber
- Direct both Dynamic and STATIC changes is muscle length
Ia Inhibitory Neurons receive signals from what?
Muscle SPINDLE
Lesion effects on Muscle Tone: UMN vs LMN
UMN:
- Spastic
LMN:
- Flaccid
In the Spinal Cord, the Sensory fibers are ____ and the Motor Neurons are ____.
- Lateral
- Medial
Are Cranial Nerve UMN or LMN?
LMN
