Reflex Vs. Response Flashcards
What makes up reflexes
- Afferent N. (spinal cord segment)
- Efferent N and motor unit
Responses require ________ awareness but do not require ________ input
Responses require Cortical awareness but do not require cerebral input
T/F reflexes imply consciousness and imply perception
false reflexes does not imply consciousness or percerption
what are the two components that make up a reflex arc
- afferent: sensory
- Efferent: motor
what is a monosynaptic spinal reflex arc
it is an arc that consists of one afferent and one efferent nerve
what is a polysynaptic spinal reflex arc
-one afferent and many efferent (some may be stimulatory or inhibitory)
what are 2 unique characteristics associated with polysynaptic reflex arcs
- will have interneuron associated
- Also, the stimulus may travel up the white matter to the cerebral cortex
- this is for perception and memory
- this allows for a reflex to be perceived and can elicit a response to the reflex
what are the target somatic organs
skeletal muscle
what are the target autonomic organs
Smooth/cardiac muscle or glands
What is a “response”
- a voluntary behavior that requires a cortical input
- perception of a stimulus (leads to) responsive movement made
what the difference between the afferent pathway of reflexes and responses
the afferent pathway for responses is the same as reflexes except that the signal continues to the cortex of the brain
what are reflexes
- reflexes are protective mechanisms
- These motions can occur without perception
- the cortex is not necessary for reflexes
what are the questions used by clinicians to determine the presence/location of a spinal cord lesion
- is the reflex intact or absent
- If the reflex is intact is it normal, hyper/hypo-reflexive
- us there an associated response also
What is another name for the Panniculus reflex
cutaneous trunci reflex
The Cutaneous Trunci reflex test the integrity of what
- afferent N
- spinal cord segments
- lateral thoracic nerve
- Cutaneous Trunci M
where are the Afferent fibers contained for the Cutaneous Trunci Reflex
Afferent fibers are contained within the dorsal branches of spinal nerves (C8-L4)
why must we bilaterally test the Cutaneous Trunci Reflex
there could be a unilateral lesion, so we must test bilaterally
what are the afferent n. associated with Cutaneous Trunci Reflex
superficial pain receptors
what spinal segments are associated with Cutaneous Trunci Reflex
From the site of pinch cranially to the cell body of the lateral thoracic nerve located C8-T1
what Efferent n are associated with the Cutaneous Trunci Reflex
lateral thoracic n (cell body originates at C8-T1)
what motor unit is associated with Cutaneous Trunci Reflex
cutaneous trunci mm.
what is the reflex pathway associated with Cutaneous Trunci Reflex
- Afferent n
- travels to the spinal cord segment at the level of “pinch” ascends cranially until C8-T1
- an interneuron activates lateral thoracic nn. bilaterally
- Cutaneous Trunci m contracts
- visible skin twitch
if the Cutaneous Trunci Reflex what are some of the causes
- Damage to afferent nociceptive fiber between C8-L4 spinal cord segments
- Damage to spinal cord
- Damage to the lateral thoracic n
- Damage to the cutaneous trunci m.
where is the site of stimulation for a forelimb withdrawal reflex
pinch a forelimb digit
for the Forelimb withdrawal reflex which afferent pathway is related to the palmar aspect
- median
- ulnar
for the Forelimb withdrawal reflex which afferent pathway is related to the dorsal aspect
Radial n.
what spinal cord segment is responsible for the forelimb withdrawal reflex
spinal cord segment C6-T2
what are the efferent nerves that are associated with the forelimb reflex
- Musculocutaneous n
- Median and ulnar
what motor units are associated with the Musculocutaneous n of the forelimb withdrawal reflex
- Biceps brachii
- brachialis
what motor units are associated with the Median and ulnar n of the forelimb withdrawal reflex
Flexors of the carpus and the digits
what is the nerve pathway of the pelvic limb withdrawal reflex for plantar surface of pes stimulation (efferent)
stimulation is carried via tibial n to the sciatic n to lumbosacral intumescence (L4-S2)
what are the afferent motor units associated with the pelvic limb withdrawal reflex with the femoral nerve
- Flexors of the hip
- iliospoas
- sartorius
- rectus femoris
what are the afferent motor units associated with the pelvic limb withdrawal reflex with the Sciatic nerve
- flexors of the stifle
- Biceps femoris
- semimembranosus
- semitendinosus
what are the afferent motor units associated with the pelvic limb withdrawal reflex with the common peroneal nerve
- (AKA fibular n)
- Flexors of the tarsus
- cranial tibial
- peroneus
- longus mm
which nerve inhibits the extension of the stifle with the pelvic limb withdrawal reflex
Femoral n will inhibit tone to the remaining 3 heads of the quadriceps
can different branches of the same nerve (femoral) be stimulated and inhibited at the same time
yes
Can the same nerve that was used as an afferent n be used as an efferent nerve
- yes
- tibial to sciatic
- sciatic n to stimulate flexion of the stifle
- tibial to sciatic
what is crossed extensor reflex
Extension of the limb opposite of the withdrawal stimulus
when can the crossed extensor reflex be seen
only in the normal standing patients
what is the purpose of the crossed extensor reflex
to keep us standing despite the need for withdrawal reflex
when is a cross-extensor reflex seen in recumbent animals
with spinal cord damage cranial to the limb that shows the reflex
I.E.: a lesion at L2 spinal cord segment. This animal will have intact crossed extensor reflex of the hind limb while in lateral recumbency
what suppresses the crossed extensor reflex when we are laying down
proprioception would suppress this reflex as soon as we lay down
what is a Perineal reflex
- when a light touch/pinch to the skin of the anus/perineum to activate touch pressure receptors/nociceptors
- this will result in the tightening of the anal sphincter m.
what is the afferent and efferent nerve of the perineal reflex
Pudendal nerve
What spinal cord segment does the perineal reflex test
S1-S3 and the pudendal n.
when is the perineal reflex absent
with damage to the spinal cord segment S1-S3, or along the pudendal n pathway
what are the other names for the Myotatic reflex
- Muscle spindle reflex
- tendon tap reflex
- stretch reflex
what is an example of a myotatic reflex and what does it protect
- Patellar reflex
- Prevents damage from overstretching a ligament
what is the result in the muscles of the myotatic reflex
to increase tone to the muscle being stretched
what are the two pathways a myotatic reflex can take place
- Tonic stretch reflex
- Phasic stretch reflex
what is the Tonic stretch reflex of the myotatic reflex
Manipulate limbs to determine resistance to manual manipulation
what is the phasic stretch reflex of the myotatic reflex
Use reflex hammer to strike tendon and rapidly stretch muscle
what are the afferent nerves used in the myotatic reflex
Afferents from muscle spindle receptors sensing muscle/tendon stretch
What is a Clonus reflex
- a cloned reflex
- after the first reflex, the upper motor neuron should moderate the reflex (inhibit the reflex)
- if the patient has UMN disease (a lesion cranial to the reflex arc) they will often present with hyper-reflexive and or clonus
what are the parts of the normal pain response circuit
- nociceptive afferent fibers
- spinal segment
- afferent neuron to the brain
- normal parietal lobe (for conscious cortical involvement)
how hard should you pinch to test pain response
pinch increasingly harder until you see a behavioral response from the animal
Do you test deep pain if superficial pain is intact
No because compressive lesions of the spinal cord result in predictable loss of nervous function
what is the order of loss of nervous function from a compressive lesion from first to last
- Proprioception is lost 1st
- motor function is lost next
- Pain is lost last
- superficial pain is lost first
- deep pain will be lost last
Is it possible to have an absent withdrawal reflex along with a normal pain response
Yes: efferent peripheral motor neuron could have a lesion
Complete spinal cord lesions result in muscle tone and reflexes which are:
Absent At the site of the lesion and will show increased tone and hyper-reflexive caudal to the lesion
