Extra Neuro Flashcards
Where are muscle spindles found?
Fibres within hidden within the contractile fibres (intrafusal)
What are muscle spindles innervated by?
Gamma motor neurons
What is a muscle spindle?
Stretch receptors that are wrapped round intrafusal muscle fibres (within the muscle)
Withdrawal reflex: what does reciprocal innervation of antagonistic muscles explain?
It explains why the contraction of one muscle induces the relaxation of the other; this permits the execution of smooth movements.
What do golgi tendon organs measure?
Mechanoreceptors that measure changes in tension of a muscle.
What nerve fibres innervate golgi tendon organs?
Afferent type 1b sensory nerve fibres (inhibitory).
What is the response of golgi tendon organs if they detect a change in tension?
They inhibit alpha motor neurones to prevent muscle contraction if the force gets too great.
What is a LMN?
A neurone that carries signals to effectors. The cell body is located in the brain stem or spinal cord.
What is an UMN?
A neurone that is located entirely in the CNS. Its cell body is located in the primary motor cortex.
What are the signs of UMN weakness?
- Increased muscle tone.
- Hyper-reflexia.
- Spasticity.
- Minimal muscle atrophy.
What are the signs of LMN weakness?
- Decreased muscle tone.
- Hypo-reflexia.
- Flaccid.
- Muscle atrophy.
- Fasciculations.
Define a Motor pool
All the lower motor neurones that innervate a single muscle
* The motor pool contains both the alpha and gamma motor neurons (see later) * Motor pools are often arranged in a rod like shape within the ventral horn of the spinal column
What do medial alpha neurones (near the spinal chord supply)
Proximal muscles
What do lateral alpha neurones supply
distal muscles
Define motor unit
an alpha neurone and all the extrafusal skeletal muscle fibres it innervates
What does it mean if a motor unit has a small amount of muscle fibres?
Where would you see this?
it allows for greater movement resolution, as there is a greater variation of movement
In the finger tips or tongue
Where do first order neurones for the olfactory nerve synapse?
in the olfactory bulb
Where is the degree of pain judged?
in the insula
Where is the emotional response to pain generated?
The cingulate gyrus
What is a collection of cell bodies called in the
a CNS?
b PNS
a Nucleus
b Ganglion
What is a collection of axons called in the
a CNS?
b PNS
a Tract
b Nerve
What neuroens are mylinated?
A and B fibres
What the differnece between A and B fibres? (they are both mylinated)
A is THICK
B is THIN
A transmission speed is 100m/sec
B transmission speed is 10m/sec
What kind of fibres are unmylinated?
C fibres, they are very thin
Their transmission speed is 1m/sec
what makes up myelin in the
a CNS
b PNS
CNS - Oligodendrocytes
PNS - Schwann Cells
In the spinal chord, what is conveyed in the
a VENTRAL ROOT/RAMUS
b DORSAL ROOT/RAMUS
Ventral root - Motor, efferent
Dorsal Root - Sensory, afferent
What can the motor branches either be?
Autonomic (can be sensory or motor)
or Somatic