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What are the 2 major sensory receptors of muscles?
- Muscle spindles
- Golgi tendon organs (GTOs)
What is the function of muscle spindles?
Sense the change in muscle length
What is the function of GTOs?
Sense the change in muscle tension/force
What important function do muscle spindles and GTOs share?
They aid in proprioception
What is another name for muscle spindles?
Intrafusal fibers
How would you describe the location of muscle spindles?
They are parallel with extrafusal muscle fibers in the muscle belly
How would you describe the location of GTOs?
They are in series with extrafusal muscle fibers between the tendon and belly of the muscle (aka in the musculotendinous junction)
What are the different types of extrafusal muscle fibers?
- Slow (S or type I)
- Fast IIa (FF or type IIa)
- Fast IIb (FF or type IIb)
- Intermediates
What are the attachment points of muscle spindles?
A tendon or muscle fiber on each side
How long are muscle spindles?
4-10 mm
What are the two types of intrafusal muscle fibers?
- Nuclear bag (static & dynamic)
- Nuclear chain
Describe a nuclear bag
- Large in diameter
- Clustered, centrally located nuclei
What are the two types of nuclear bags?
- Static nuclear bag
- Dynamic nuclear bag
Describe a nuclear chain
- Smaller in diameter than a nuclear bag
- Nuclei more spread out than a nuclear bag
Are intrafusal muscle fibers contractile?
You betcha
Ia, Ib, & II afferent nerve fibers arise from what kind of muscle fibers?
Intrafusal muscle fibers
What part of intrafusal muscle fibers do Ia afferent nerve fibers attach to?
The area of the muscle belly
What specific kind of intrafusal fiber does Ia phasic nerve fibers attach to?
Dynamic nuclear bag fibers
What specific kind of intrafusal fiber(s) does Ia tonic nerve fibers attach to?
Nuclear chain & static nuclear bag fibers
What are the different kind of Ia afferent nerve fibers?
- Phasic
- Tonic
Where on an intrafusal fiber does II afferent nerve fibers arise from?
Flower spray receptors on polar ends of muscle spindle
What nerve fibers are the primary annulospiral receptors?
Ia phasic & Ia tonic
What do Ia phasic afferent nerve fibers sense?
- Rate/velocity of muscle lengthening
- Changes in muscle length
What do do Ia tonic afferent nerve fibers sense?
- Changes in muscle length
What is the name of the structure getting lengthened and shortened in a GTO?
Collagen fibers
How long are GTOs?
1 mm
What is the diameter of GTOs?
0.1 mm
How many muscle fibers are connected to a single GTO?
15-20
What is the range of minimum force needed to activate a GTO?
2-25 g of force
Are Ia phasic afferents facilitory or inhibitory to an agonist?
Facilitory
Are Ia phasic afferents facilitory or inhibitory to an antagonist?
Inhibitory
Are Ia tonic afferents facilitory or inhibitory to an agonist?
Facilitory
Are Ia tonic afferents facilitory or inhibitory to an antagonist?
Inhibitory
Are GTOs inhibitory or facilitory to an agonist?
Inhibitory
Are GTOs inhibitory or facilitory to an antagonist?
Facilitory
Why does a cross fiber massage at the musculotendinous junction relax a muscle?
The pressure of the massage activities GTOs which inhibits the muscle being massaged
What is the crossed extension reflex?
Contraction of extensor muscles in limb opposite of the one that is withdrawn
What is the basis of crude walking?
The crossed extension reflex
For the crossed extension reflex to occur, what must happen?
II afferents cause flexion of ipsilateral side & extension on the contralateral side
Give an example of a phasic relfex
Deep tendon reflex (DTR)
What reflex do you feel as you elongate a muscle passively?
Tonic reflex
What are the UMN reflexes?
- Clonus
- Babinski
- Hoffman's
What is the purpose of testing DTR?
Checking the integrity of the monosynaptic reflex arc
What are the responses someone could get when checking DTR?
- Hypotonic
- Normal
- Hypertonic
What is the rating scale for DTR?
- 0 (no reflex)
- 1 (somewhat diminished, low normal)
- 2 (average or normal reflex)
- 3 (brisker than average, possibly indicative of disease)
- 4 (very brisk, hyperactive, associated with clonus)
If a patient has no reflex when performing a DTR test, what rating would you give them?
0
If a patient has a diminished reflex when performing a DTR test, what rating would you give them?
1
If a patient has a normal reflex when performing a DTR test, what rating would you give them?
2
If a patient kinda has a hypertonic reflex when performing a DTR test, what rating would you give them?
3
If a patient has a really hypertonic reflex when performing a DTR test, what rating would you give them?
4
What nerve roots are you testing when performing a DTR test at the biceps?
C5 & C6
What nerve roots are you testing when performing a DTR test at the brachioradialis?
C5 & C6
What nerve roots are you testing when performing a DTR test at the triceps?
C6 & C7
When nerve roots are you testing when performing a DTR test at the quads?
L4 & L3
What nerve roots are you testing when performing a DTR test at the ankle?
S1
How do you perform a DTR test at the bicep?
1) Seat patient with arm flexed and supported
2) Place thumb over distal biceps tendon in cubital fossa
3) Strike the thumb with the reflex hammer
4) Observe for a response of the muscle belly or movement of the lower arm
How do you perform a DTR test at the brachioradialis?
1) Seat patient with elbow slightly bent and forearm resting on their lap
2) Strike near origin of brachioradialis
3) Observe the muscle contraction or flexion at the elbow
4) Test bilaterally
How do you perform a DTR test at the triceps?
1) Seat patient with arm supported at shoulder height
2) Strike the triceps tendon proximal to the elbow
3) Look for elbow extension or triceps contraction
4) Test bilaterally
How do perform a DTR test at the quad?
1) Seat patient with knee flexed and foot unsupported
2) Hit patellar tendon
3) Look for knee extension
4) Test bilaterally
How do you perform a DTR test at the ankle?
1) Seat patient with knee flexed and foot in slight dorsiflexion
2) Strike tendon just above insertion at calcaneous
3) Look for plantarflexion
4) Test bilaterally
What is the jendrassick maneuver? Why would it be performed?
When an individual clenches their teeth and hook their fingers together and pulls apart. This would be done when looking at a patient's DTR and this would help make the DTR more prevalent
Define tonic reflexes
Resistance to passive stretch
What is the purpose of performing a modified ashworth scale (MAS)?
"feel" a patient's tone and assess their tonic reflexes. The goal is to see if the patient has hypertonia
How long does it take to do a MAS?
Less than 5 minutes
What equipment is required to perform a MAS?
Mat table
What populations would you perform a MAS with?
- Adults & children with lesions of CNS
- Cerebral palsy
- MS
- Pediatric hyper- & hypotonia
- Spinal cord injuries
- Stroke
- Traumatic brain injury
At what speed do you perform the MAS?
Start slow & gradually get faster
What is the scoring for the MAS?
- 0 = no increase in muscle tone
- 1 = slight increase in muscle tone with a catch and release or minimal resistance at end of ROM
- 1+ = slight increase in muscle tone with a catch followed by minimal resistance throughout remainder (less than half) of the ROM
- 2 = more marked increase in muscle tone through most of the ROM but affected part(s) easily move
- 3 = considerable increase in muscle tone, passive movement difficult
- 4 = affected part(s) rigid
You are doing the MAS with a patient and score them a 0. What does that mean?
They had no increase in muscle tone during the test
You are doing the MAS with a patient and score them a 1. What does that mean?
They had a slight increase in muscle tone with a catch and release or minimal resistance at the end of ROM
You are doing the MAS with a patient and score them a 1+. What does that mean?
They had a slight increase in muscle tone with a catch followed by minimal resistance throughout the remainder (less than half) of the ROM
You are doing a MAS with a patient and score them a 2. What does that mean?
More marked increase in muscle tone through most of the ROM but affected part(s) easily moved
You are doing a MAS with a patient and score them a 3. What does that mean?
They have a considerable increase in muscle tone and passive movement is difficult
You are doing a MAS with a patient and score them a 4. What does that mean?
Their affected part(s) are rigid
What are some UMN test for tone?
- Clonus
- Hoffman's
- Babinski
What is the purpose of a clonus test?
Test for over-activity of phasic reflexes or monosynaptic reflex are in the plantar flexors
When would you perform a clonus test?
When the patient has hyperactive reflexes
How do you perform a clonus test?
1) Support the knee in a partly flexed position (roughly 20 degrees)
2) Quickly dorsiflex the foot and observe for rhythmic clonic movements
3) Repeat with knee fully extended
What is the rating scale for the clonus test?
- 0 = absent
- 1 = unsustained
- 2 = sustained
- 3 = spontaneous/light touched provoked
What rating on the clonus test is considered normal?
0
You are performing a clonus test on a patient and rate them a 0. What does that mean?
There was no monosynaptic reflex response (aka normal)
You are performing a clonus test on a patient and rate them a 1. What does that mean?
They had a monosynaptic reflex response but it went away on its own
You are performing a clonus test on a patient and rate them a 2. What does that mean?
They had a monosynaptic reflex response that would not go away unless acted upon by an outside force
You are performing a clonus test on a patient and rate them a 3. What does that mean?
They had a monosynaptic reflex that was either spontaneous or triggered very easily
How do you perform a babinski test?
Move a blunt object along the lateral edge of the foot on the plantar surface (starting at the heel) and then cut across medially to the big toe at the ball of the foot
What would be a positive babinski test?
Big toe dorsiflexes and the other 4 abduct
How do you perform Hoffman's test?
1) Have patient's hand pronated
2) Flick the DIP of their middle finger into extension
What is a positive Hoffman's test?
When index finger and thumb come together after flicking the DIP of the middle finger
Hypertonicity is always a result of what kind of lesion(s)?
UMN
Hypotonicity is always a result of what kind of lesion(s)?
UMN or LMN
When performing a proprioception test for a patient, what must you have them do with their eyes?
Close them or blindfold them
What can the mirroring proprioception exam test for?
- Motion sense
- Position sense
What is motion sense?
The ability to detect joint motion but not what direction the joint is moving
What is position sense?
When an individual can reproduce the exact position of "involved" joint via the uninvolved joint.
They can detect joint motion, direction, and speed.
What are the two ways to test motion sense?
- Mirroring
- Passively moving involved joint and asking patient to state what direction the joint is moving in
When performing a mirroring test, are you, the therapist, testing the involved or uninvolved side?
Involved
What side is a patient moving during a mirroring test?
The uninvolved side
What things must you do when performing a mirroring test?
- Test 4-6 positions per joint
- Start at the most proximal joint and work your way distally
- Start with large movements and end with small movements
- Move the joint in a variety of directions
- Move the joint at a variety of speeds
What do you do for a stereognosis test?
Put different objects in a patient's hand with their eyes close with increasing similarities to test their higher cortical control and combined sensations of touch, pressure, and proprioception
What sensations are tested during a stereognosis test?
- Touch
- Pressure
- Proprioception
