Reflexes
List of reflex types
- Innate (primitieve) and infantile reflexes - Brainstem reflexes - Myotatic reflexes (neuromuscular anatomy, upper motor neuron syndrome, lower motor neuron syndrome). - Superficial reflexes - Urogenital reflexes - Lesion localization (dermatomes and myotomes)
Fast twitch
2b Sprinter - powerful burst followed by fatigue Less vascularization Less mitochondria Glycogen storage and enzymes (glycolytic pathways provide energy) exttensive sarcoplasmic reticulum (Ca++)
Three signs that disappear with age
Moro (startle), Tonic neck reflex, crossed adduction to KJ
Myotatic reflexes
Muscle stretch reflexes, deep tendon reflexes, tendon jerks
clonus
Muscular spasm with repeated contractions.
Signs that appear with age
Neck righting reflex, supporting reaction, Landau (arching back when held prone), parachute, hand grasp
Sensory loss
Pattern of sensory loss Dermatomal vs peripheral nerve distribution vs sensory level.
Ankle
S1
Ankle jerk
S1
Fast vs slow muscle types
Slow - Type 1 Fast - Type 2
Important neurotransmitters
Spinal cord: glutamate excites, glycine inhibits, GABA inhibits.
Reflex
Stimulus - synapse (mono or poly - response
Moro
Sudden loss of support - extension, then flexion, of UEs
Umbilicus
T10
Nipple
T5
Muscle stretch reflex
Tap on the tendon. afferent neuron goes to spinal cord which dorsal horn. Anterior horn sends contraction signal through the efferent neuron
What determines the type of muscle fiber?
The innervation. All the muscle fibers innervated by the same branch will be the same type of muscle fiber. The muscle fiber can change if the innervation changes.
UMN exception
Those with spinal shock will sometimes have hypoactive myotatic response even though the problem is umn.
Rooting reflex
Turning to the nipple.
Hoffman reflex
Upper motor neuron sign
Lower motor neuron syndrome
Weakness Decreased muscle tone - flaccidity Hypoactive myotatic reflexes Loss of cutaneous reflexes Fibrillation and fasciculation
Upper motor neuron syndrome
Weakness Increased muscle tone - spasticity Hyperactie myotatic reflexes Hoffman and Babinski
UMN vs. LMN
asdf
Landou reflex
baby held horizonatl and prone -> extends neck and arches back
Supporting reflex
baby held in standing position is able to support self and step
Tonic neck reflex
fencing posture with neck roation
bulbocavernous reflex
insert gloved finger into anus. Pull on glans penis, should feel anus contract around finger.
Palmomental reflex
pinch of palm causes moth to twitch, open
Anal wink
poke area around anus with a sharp object. Anus wil contract
Parachute reflex
simulated falling -> extension of arms
Crossed adductor reflex
testing knee jerk - adduction of opposite leg
L2-L4 Probably L4
Knee jerk
Knee
L4
Abnormalities
Asymmetry 4+ Some people are normal but lack reflexes
Plantar reflex
Babinski - extension rather than flexion is a uppermotor neuron sign
Objective
Be able to describe and test infantile reflexes that appear and disappear with CNS maturation. Be able to differentiate between dermatomes and myotomes, be able to test sensation in common dermatome and peripheral nerve distribution and know which myotomes are tested during myotatic reflexes. Student will be able to test common superficial and urogenital reflexes Differentiate between the UMN and LMN syndrome. Incorporate findings of sensory loss, weakness and reflex testing in facilitation of lesion localization.
Brachioradialis
C5
Deltoid, biceps absent biceps reflex
C5
Upper arm
C5
Thumb
C6
Wrist
C6
MIDDLE 3 FINGERS
C7
Triceps
C7
Triceps and extensors of wrist and fingers
C7
Pinkie
C8
Innate (primitive) and developmental reflexes
Can be broken down into suppressed by frontal lobes and developmental reflexes.
Urogenital reflexes
Can reveal spinal problems
Brainstem reflexes
Corneal and blink reflexes Afferent limb - CN 5 Efferent limb Bilateral CN 7 pupillary light reflex Gag reflex
Slow
Fatigue resistant Predominant in long distance running. Lots of mitochondira Extensive capillary blood supply
Grasp reflex
Gegenhalten (pull against)
Suppressed by frontal lobes
Glabellar reflex, snout reflex, rooting reflex, palmomental reflex. These are normally repressed. If they reappear, it is in a demented person.
Grading of myotatic reflexes
Graded 0-4 with 0 being no reflex Most people are 2-3
IIa
Intermediate, fast twitch but fatigue resistant
afferents from muscle
Intrafusal fibers Fibers that have muscle spindles coming from them. These spindles inform the CNS of strecht in the muscle
Lesion localization - Weakness
Is it UMN or LMN? Check the muscle tone and myotatic reflexes UMN - spastic with hyperactive response LMN - flaccid with hypoactive response
