Exam 1: Muscle Strength LEs

motor cortex neurons for the cranial nerves descend the ___________ tract to the _________

corticobulbar, brainstem nuclei

motor cortex neurons for the body descend the _________ tract and synapse with their corresponding ________

corticospinal, LMNs

neurological evaluation of muscle integrity is assessed by looking at muscle

volume

tone

strength

the voluntary motor impulses are initiated in the __________ cortex in the _______ lobe on the __________ gyrus

cerebral motor cortex, frontal lobe, precentral gyrus

what are you looking for when inspecting and palpating the LE for the LE motor exam?

observe patient posture (scoliosis, holding extremity unusually, etc.)

observe muscle symmetry/asymmetry, look for swelling, atrophy/hypertrophy

observations can be bilateral or unilateral

define fasciculation and what brings it on

fasciculations = muscle twitching (discrete and palpable)

cxn of muscle fibers brought on by fatigue, cold, caffeine, motor neuron disease (ex: ALS)

fasciculations accompanied by atrophy or weakness are associated with

denervated muscle and pathology

fasciculations unaccompanied by atrophy or weakness

do NOT necessarily indicate the presence of serious disease

when determining muscle volume of the LE, where are the measurements performed?

mid thigh (10-15 cm superior to the superior border of the patella)

midcalf (10 cm below tibial tuberosity)

*compare bilaterally -- difference in thigh by 1.5 cm or in calf by 1 cm is clinically significant

ddx for a patient with asymmetrical LE muscle volume

nerve compression, disuse atrophy, compartment syndrome, DVT, CHF, UMNL, LMNL

neurogenic atrophy results from a lesion involving the:

1. anterior horn (spinal muscular atrophy, poliomyelitis, ALS)

2. nerve root compression

3. peripheral nerve innervating a muscle

atrophy or hypertrophy may be limited to:

1. an individual muscle

2. a muscle (s) supplied by a specific nerve root or peripheral nerve

3. a muscle supplied by certain spinal cord segments

muscle diseases usually only cause ____ to ____ atrophy of the involved muscles. muscular dystrophy can cause _____

mild, moderate, atrophy

disuse atrophy

occurs after immobilization, is usually mild to moderate in severity, and recovers quickly with resumption of use

true muscle hypertrophy

results from an increase in the size of the muscle and is most often physiological hypertrophy from heavy use but can occur in certain neuromuscular disorders

pseudo-hypertrophy

refers to apparent muscle enlargement due to replacement of muscle by fat and fibrous tissue

-ex: large calf muscles in patients with Duchenne Muscular Dystrophy

muscle tone

the tension in the relaxed muscle or the resistance to passive movement when voluntary contraction is absent

resting tone

normal muscles have slight resistance to passive movement even in a relaxed state

where is resting muscle tone the greatest?

in the antigravity muscles that maintain the body in an erect position

factors affecting muscle tone include

pain, fear, swelling, spasm, local shock, fractures, dislocations, adhesions of joints and/or ankylosis of joints, contractures of agonists/antagonists, malingering, catatonic states

diffuse weakness can be found in some myopathies such as

dystrophies, electrolyte disturbances, toxic states, and chronic systemic illness

localized or diffuse weakness may be a manifestation of

myasthenia gravis

3 characteristics of UMNLs

spasticity, hypertonia, hyperreflexia (pathological reflex)

3 characteristics of LMNLs

flaccid, hypotonia, hyporeflexia

test motor strength with peripheral nerve and segmental innervation of each dominate muscle in order to distinguish:

peripheral nerve

plexus lesions

myotome (NR)

the corticospinal tract originates in Broadmann areas ___ and ____, descends via the _____ and _____ tracts, and terminates in the _____ horn on ______ and ______ neurons

4 and 6, anterior and lateral corticospinal tracts, anterior horn on alpha and gamma motor neurons

spasticity

increased muscular resistance that quickly fades away as the joint is opened = "clasped knife"

what is spasticity associated with?

cortical/pyramidal pathway lesions, UMNL

rigidity

involves muscular resistance when moving a resting joint and persists through the entire ROM = "gooseneck" rigidity

-described as bending a microphone holder

what is rigidity associated with?

extrapyramidal path lesions (UMNLs)

what is the most common cause of hypertonia in children?

cerebral palsy

LMNL

Lesion of the anterior horn cells out to the myoneural junction (motor neuron to end plate)

UMNL

Lesion of the brain & Spinal cord not including anterior horn cells (brain to motor neurons, not including motor neurons)

-lesions of the extrapyramidal and corticospinal complexes whether cerebral in origin or due to interruption of the descending motor pathways

-produce loss of strength and power but is generally involved with the whole extremity/gross movements

define true muscle weakness

smooth weakened resistance throughout that muscle's entire ROM

which is stronger: antigravity muscles vs their antagonists? quadriceps vs hamstrings? gastroc/soleus vs tibialis anterior?

stronger = antigravity muscles, quads, and gastroc/soleus

power is classified as

kinetic and static

kinetic power

the force exerted on a changing position

ex: performing a bench press and getting the bar off the support rack

static power

the force exerted in resisting a movement

ex: performing a bench press and lowering the bar to your chest

T/F: most pathologies both kinetic and static are affected equally

true

extrapyramidal syndromes (increase/decrease) kinetic power while static remains normal

decrease

muscle tone is characterized by

1. normal tone (WNL)

2. increased tone -- UMNL (spastic tone)

3. decreased tone -- LMNL (flaccid tone)

functional neurological disorder (FND) previously known as hysteria causes

real physical symptoms triggered by psychological stress

-this unconscious process can lead to fabrication of illness leading to malingering

in the malingering patient, muscle contractions are ________ sustained and may give away _______ rather than _______

poorly sustained, abruptly, gradually

how can you discern if pt is malingering?

there may be absence of follow-through when the examiner withdraws pressure

there may be an increase rather than a decrease in strength with repeated testing

malingering aka

give away weakness

muscle grading scale

5/5 - normal: complete ROM against gravity with full resistance

4/5 - good: complete ROM against gravity with some resistance

3/5 - fair: complete ROM against gravity, no resistance

2/5 - poor: complete ROM gravity eliminated (turn pt on side to eliminate gravity)

1/5 - trace: evidence of slight cxn but no joint motion

0/5 - complete paralysis: no evidence of cxn

hip flexion NR and peripheral nerve

L1-L4

femoral n (psoas major)

hip extension NR and peripheral nerve

L5-S2

inferior gluteal n (glute max), superior gluteal n (glute med and min)

hip abduction NR and peripheral nerve

L4-S1

superior gluteal n (glute med and min)

hip adduction NR and peripheral nerve

L2-L4

obturator n (adductors)

knee flexion NR and peripheral nerve

L5-S2

tibial n and common fibular n (for short head of biceps femoris)

knee extension NR and peripheral nerve

L2-L4

femoral n

ankle plantarflexion NR and peripheral nerve

S1**-S2

tibial n

ankle dorsiflexion NR and peripheral nerve

L4-L5**

deep fibular n

ankle inversion NR and peripheral nerve

L5-S1

tibial n

ankle eversion NR and peripheral nerve

L4-S1

superficial fibular n

toe flexion NR and peripheral nerve

L5-S2

tibial n

toe extension NR and peripheral nerve

L4-S1

deep fibular n

where should doctor's hands be placed for a hip abduction muscle strength exam (aka motor test)

proximal to knee and on hip to stabilize

2 additional tests for hip abduction muscle strength exam (aka motor test)

hip extension (inf gluteal n)

plantarflexion (S1-S2)

what muscles is a hip abduction motor exam testing?

gluteus medius, gluteus minimus, piriformis, sartorius, and TFL

2 additional tests for hip adduction motor exam

hip flexion (L1-L4) and knee extension (L2-L4)

what muscles is a hip adduction motor exam testing?

adductor brevis, adductor longus, adductor magnus, pectineus, gracilis, quadrator femoris, obturator externus, and hamstrings

how to distinguish L4 NR radiculopathy vs femoral n compression

L4 NR radiculopathy typically includes the medial foot and femoral n does not

meralgia paraesthetica

Caused by compression of lateral cutaneous nerve of thigh (L1-L3), localized SENSORY symptoms

-wearing tight clothing, heavy belts, weight gain, trauma to hip

*sensory findings on lateral upper thigh with NO motor findings

what makes meralgia paresthetica worse? better?

worse: walking, standing, extension of the hip

better: sitting, flexion of the hip

ddx of meralgia paresthetica

L2-L4 NR compression, spine or pelvic tumors

2 additional tests for hip flexion motor exam

knee extension (femoral n)

hip adduction (L2-L4)

muscles tested in hip flexion motor exam

psoas major (L1-L4)

psoas minor (if present) (L1-L2)

iliacus

iliopsoas (L2-L4)

2 additional tests for hip extension motor exam

knee flexion (L5-S2)

hip abduction (L4-S1)

muscles being tested in a hip extension motor exam

gluteus maximus, hamstring (biceps femoris, semitendinosus, semimembranosus), adductor magnus

2 additional tests for knee extension motor exam

hip adduction (L2-L4)

hip flexion (femoral n)

muscles tested in knee extension motor exam

quadriceps (rectus femoris, vastus medialis, vastus intermedius, vastus lateralis)

2 additional tests for knee flexion motor exam

plantarflexion (S1-S2)

foot inversion (tibial n)

muscles tested in knee flexion motor exam

hamstrings (biceps femoris, semitendinosus, semimembranosus)

2 additional tests for ankle dorsiflexion motor exam

hip flexion (L1-L4)

hip extension (L5-S2)

muscles tested in ankle dorsiflexion motor exam

tibialis anterior, extensor digitorum longus, extensor hallucis longus

2 additional tests for ankle plantarflexion

foot inversion (L5-S1 and tibial n)

knee flexion (tibial n)

muscles tested in ankle plantarflexion motor exam

gastrocnemius, soleus, flexor digitorum longus, flexor hallucis longus

2 additional tests for ankle inversion motor exam

knee flexion (tibial n)

plantarflexion (tibial n)

muscles tested in ankle inversion motor exam

tibialis posterior muscle, (assisted by tibialis anterior, gastroc, soleus, flexor digitorum longus, flexor hallucis longus)

2 additional tests for ankle eversion motor exam

hip abduction (L4-S1)

toe extension (L4-S1)

muscles tested in ankle eversion motor exam

fibularis longus and brevis

ankle INVERSION sprains typically affect which ligaments?

anterior talofibular ligament (MC), calcaneofibular ligament (common), posterior talofibular ligament (severe)

ankle EVERSION sprains typically affect which ligaments?

deltoid ligament (3 specific parts not a TQ)

foot drop is a weakness of ankle _______ that may produce a _________

dorsiflexion, steppage gait

steppage gait

characterized by excessive hip and knee flexion during swing phase to allow toes to clear the ground (picking up leg higher because foot is plantarflexed and dragging)

weakness of ankle dorsiflexion

MC with foot drop

deep fibular n, predominantly L5 NR

weakness of ankle eversion

superficial fibular n, predominantly L4-S1 NR

weakness of ankle inversion

tibial n, predominantly L5-S1 NR

ddx for ankle: L5 radiculopathy

weakness may involve ankle dorsiflexion, toe extension, ankle eversion, and ankle inversion because the L5 NR contributes to muscles supplied by both the fibular and tibial nerves

ddx for ankle: common fibular neuropathy

weakness typically involves ankle dorsiflexion and eversion

-ankle inversion and plantarflexion is spared because the tibialis posterior is innervated by the tibial n and does not travel through the common fibular n

2 additional tests for toe extension motor exam

dorsiflexion (deep fibular n)

hip abduction (L4-S1)

muscles being tested in toe extension motor exam

extensor hallucis longus, extensor digitorum longus, extensor digitorum brevis

2 additional tests for toe flexion motor exam

knee flexion (L5-S2)

foot inversion (tibial n)

muscles being tested in toe flexion motor exam

flexor hallucis longus, flexor hallucis brevis, flexor digitorum longus, flexor digitorum brevis, flexor digiti minimi, abductor hallucis, abductor digiti minimi, lumbricals

supraspinatus motion, NR, and peripheral n

shoulder abduction (first 15 degs), external rotation of arm

C5**-C6

suprascapular n

deltoid motion, NR, and peripheral n

shoulder abduction, flexion, and extension

C5**-C6

axillary n

biceps brachii motion, NR, and peripheral n

forearm flexion

C5**-C6

musculocutaneous n

brachioradialis motion, NR, and peripheral n

forearm flexion

C5**-C6

radial n