Unit 9 MSK pt. 2 Patho Flashcards
Neural reflex pathways can be classified in different ways: Describe the efferent division the controls the effector. (1st) (What do somatic motor neurons control and Autonomic neurons control)
A) somatic motor neurons control skeletal muscles
B) Autonomic neurons control smooth and cardiac muscle, glands, and adipose tissue
Neural reflex pathways can be classified in different ways: Describe the integrating region within the CNS. (2nd) (Spinal and cranial reflex)
A) Spinal reflexes do not require input from the brain
B) Cranial reflexes are integrated within the brain
Neural reflex pathways can be classified in different ways: Describe the time at which the reflex develops. (3rd)
A) Innate (inborn) reflexes that are genetically determined
B) Learned (condition) reflexes are acquired through experience
Neural reflex pathways can be classified in different ways:Describe the number of neurons in the reflex pathway. (4th) (Monosynaptic and Polysynaptic)
A) Monosynaptic reflexes only have two neurons: one afferent and one efferent
{Only somatic motor can be monosynaptic} (Patellar tendon reflex)
B) Polysynaptic reflexes include one or more interneurons between the afferent and efferent neurons.
{Autonomic reflexes are polysynaptic} (Arm being pulled away from noxious stimulate, like a hot stove)
In polysynaptic reflex, compare divergence and convergence.
Divergence of pathways allows a single stimulus to affect multiple targets
Convergence integrates the input from multiple sources to modify the response
What are autonomic reflexes?
Known as visceral reflexes, often involve internal organs of the body. Some visceral reflexes such as urination and defecation are spinal reflexes that take place without input of brain, through excitatory or inhibitory signals
Where are autonomic reflexes integrated in the brain? What are the functions?
Primarily in the hypothalamus, thalamus and brain stem
They coordinate body functions needed to maintain homeostasis, such as HR, BP breathing, eating, water balance and maintaining body temp.
Brain stem also contains integrating centers for autonomic reflexes such as vomiting, salivating, sneezing, swallowing, and gagging
What is the limbic system in charge of?
The site of primitive drives such as sex, fear, rage, aggression, and hunger- has been call the “visceral brain” because it’s in charge of emotional driven reflexes
(Gut-feeling, and “butterfly’s in stomach”)
What are the three proprioceptors found in the body?
Joint Receptors
Golgi Tendon organ
Muscle spindles
Describe joint receptors (one of the proprioceptors)
Found in the capsules and ligaments around joints in the body. Sensory information is integrated primarily in the cerebellum. They are stimulated by mechanical distortion and changes in relative positioning of bones linked by flexible joints
Describe Golgi Tendon Organ (GTO) (One of the proprioceptors)
Found at the junction of tendons and muscles fibers. GTOs respond primarily to muscle tension created during the isometric phase of contraction and are relatively insensitive to muscle stretch.
Muscle contraction pulls on collagen fibers within the GTO, pinching sensory endings of the afferent neurons and causing them to fire
Describe muscle spindles. (One of the proprioceptors)
Stretch receptors the send information to the spinal cord and brain about muscle length and changes in muscle length. They are small, elongated structures scattered among and arranged parallel to the contractile extrafusal muscle fibers.
Each spindle consist of a connective tissue capsule that encloses the infrafusal fibers. The reflex pathway in which muscle stretch initiated a contraction response is known as a stretch reflex
What are extrafusal fibers?
Fibers that build up, generate force and execute movement. Innervated by alpha motor neuron
What are infrafusal fibers?
Fibers that are part of the muscle spindles- sensory receptors for muscle control and movements. Innervated by gamma motor neurons
What is Alpha gamma coactivation?
Gamma motor neurons keep muscle spindles active no matter what the muscle length is. When alpha motor neurons fire, muscle shortens which releases tension on muscle spindle capsule. Gamma motor neurons then come in to active and shorten the spindle. This excitation of both gamma and alpha motor neurons at the same time is known as alpha gamma coactivation.
How are stretch reflex and alpha gamma coactivation activated during plyometric exercise?
The stretch reflex will lead to strong contraction and the alpha-gamma activation helps the muscle spindles detect the stretch reflex otherwise, the muscle spindle intrafusal muscle would not detect the quick stretch without being taut or contracted as well as gamma neurons.
How will a PNF quick stretch technique facilitate a muscle contraction?
Because it helps induce the alpha gamma coactivation that leads to extrafusal and intrafusal fibers to reinforce contraction and possibly make it stronger.
Explain patellar tendon reflex.
It’s a monosynaptic reflex, a rubber hammer is hit below the knee cap, tendon pulls on bone of patella and contracts quad muscle attached to patella.
This contraction of quads while hamstrings relaxes causes the leg to kick out. When the knee goes back to flexion, it requires the hamstrings to contract and for the quads to relax
Explain the cross extensor reflex.
(Stepping on a Lego) Divergence
A flexion reflex causes extension of the opposite limb, this contraction of reflexes with postural adjustments is essential for maintaining balance.
Flexors contract moving foot away from painful experience
Extensors contract as weight shifts to other leg