Neurology #3 Flashcards
What is a dermatone?
An area of the skin that is a combination of the receptive field of the sensory axons originating from a single nerve
How are dermatone’s named?
they are named according to the spinal nerve which supplies them.
Where does C5 supply nerves?
Lateral shoulder and arm
Where does C6 supply nerves?
Thumb, index finger, radial border of the hand
Where does C7 supply nerves?
Middle finger
Where does C8 supply nerves?
Digiti minimi (i.e ulnar border of hand)
Where does T1 supply nerves?
Medial Elbow (i.e heart attack)
What are the thoracic dermatomes land marks of T2-T12?
intercostal nerves form segmental strips on thorax
What are the thoracic dermatomes land marks of T10?
Goes across the umbilicus
What are the thoracic dermatomes land marks of T12?
Subcostal nerve which goes across upper edge of pubic bone
What are cutaneous receptors?
Sensory receptors found in the dermis or epidermis
Where are meissner corpuscles & merkel cells found?
found in the uppermost part of the dermis
Where are meissner corpuscles & merkel cells especially found?
Superficial layers of glabrous skin hairless skin (fingertips, lips)
What do meissner corpuscles & merkel cells detect?
Fine discriminative touch
Where are Ruffini corpuscle found?
They are found in the glabrous skin
What are Ruffini corpuscle sensitive to?
Skin stretch
Slippage of objects along the skin allowing modulation of grip on an object
Where are the Pacinian corpuscles found?
Deeper skin and subcutaneous tissue
What do Pacinian corpuscles detect?
Pressure or deep touch
What are Bulbs of Krause?
Multi layered capsules with many branched nerve endings.
What are bulbs of Krause suppose to help us feel?
Extreme cold
What are two classifications of the morphology of a receptor?
Naked free nerve endings that are unmyelinated Example Nociceptors
Encapsulated sensory receptors often referred to as sense organs
Example: Pacinian Corpuscle
What do photoreceptors respond to?
Photoreceptors respond to light
What do chemoreceptors respond to?
Respond to chemical stimuli e.g smell taste
What do thermoreceptors respond to?
Respond to temperature, heat, cold.
What do mechanoreceptors respond to?
Respond to mechanical stress and depolarize when their membranes are physically stretched.
Damage to the nervous system due to disease or trauma, may cause what kind of pain?
Neurogenic pain
What are two major types of nociceptors?
A-Delta
C aka C-PMN (polymodal)
Which nociceptor is myelinated?
A-Delta
What kind of stimulus does A-Delta nociceptors pick up?
Thermal
Mechanical Pressure that can potentially damage tissue
What kind of stimulus does C nociceptors pick up?
Thermal
Mechanical Pressure
Chemical
Which nociceptors carries faster A-Delta or C?
A-Delta carries faster
Which noncicpetors responds to deeper part of the skin and in every other tissue except nervous tissue?
C aka C-PMN
Which nociceptor are able to pick up the sharpest sensations?
A-Delta
Sharp, stinging, cutting, stabbing sensation is usually associated with which type of nocicpetor?
A-Delta
Dull, burning aching throbbing, itch is usually associated with which type of nocicpetor?
C
What is the pain response of A-Delta?
Withdraw response
What is the pain response of C-PMN?
immobilization
What is proprioception?
It is the ability to know where your body is in space without the use of vision.
What do muscle spindles detect?
Rate of change in muscle length
Static length of the muscles
Where are muscle spindles found most abundantly?
delicate fine contractile activity, they are especially abundant in the small muscles of the hand and foot.
What is a 1A Fibre?
Unipolar neuron coming from a muscle spindle
What are muscle spindles?
Sensory receptors located within muscles and consist of intrafusal muscle fibers and peripheral axons of 1A unipolar sensory neurons.
What is the most abundant type of lower motor neuron?
Alpha motor neuron
Which motor neuron are actually used in the force for muscle contraction?
Alpha Motor Neuron
What does alpha motor neurons innervate?
Extrafusal muscle fibers (aka skeletal muscle cells) outside of the spindle. Goes to the muscle fibre.
What lower motor neuron innervates intrafusal fibres?
Gamma motor neuron
Is there more gamma motor neurons or alpha motor neurons?
Alpha Motor Neurons
What horn of the Spinal column are gamma motor neurons located?
Anterior horn
What Lower Motor Neuron adjust the sensitivity of the muscle spindles?
Gamma motor neuron
How does the stretch reflex work as a protective reflex?
Muscle lengthens too quickly –> Muscle spindle is stretched –> 1a activity increases –> increases alpha motor neuron activity –> Extrafusal fibers contract and resist the stretching another set of neurons causes the antagonist of the action to relax.
How cant you tell whether some posses a high gamma gain?
If it is more difficult to bend a patients arm at the elbow back and forth, then they have higher gamma gain as opposed to someone whose arm moves easily has lower gamma gain
What is a unipolar neuron coming from a Golgi tendon organ referred to as?
1b Fibre
What is the function of the Golgi tendon?
Monitor muscle tension
Where are Golgi tendons located?
near the transition between muscle and tendon, the musculotendinous junction
Does Golgi tendon organ respond to both to passive and stretch? and which one is it most sensitive to?
Yes most sensitive to stretch.
What is autogenic inhibition mean?
When muscle contraction exceeds a certain threshold the muscles relaxes due to the influence of Golgo tendon organs
