Neurological Motor Exam

What is muscle tone?

Resistance to passive motion

What contributes to normal muscle tone?

Inertia, mechanical properties of the joint, and most importantly, output from alpha and gamma motor neurons

What can hypertonicity indicate?

UMN lesion

What causes spastic tone?

Corticospinal tract disease

How is spastic tone described?

Clasp-knife

What is the key characteristic of spasticity?

Varies with the speed of movement

What causes rigid tone?

A lesion involving the basal ganglia and/or their connections

Does rigidity vary with movement speed?

No

What is cogwheel rigidity?

A jerky form of rigidity where the limb appears to "give way" in small steps, like a cogwheel or ratchet

What can hypotonicity indicate?

LMN

Peripheral nerve

Neuromuscular junction

Muscle

What direction should tone testing proceed?

Proximal → distal

What can cause decreased muscle strength?

Either a UMN or LMN lesion

How can increased vs decreased tone help distinguish UMN vs LMN weakness?

Weakness + increased tone → UMN

Weakness + decreased tone → LMN

What findings strongly suggest an LMN lesion?

Atrophy

Fasciculations

Decreased tone

What direction should strength testing proceed?

Proximal → distal

Deltoid—myotome and action?

C5 — shoulder abduction

How do you test deltoid strength?

Patient abducts arms to horizontal while examiner pushes downward; patient resists maximally

Biceps—myotome and action?

C5, C6 — elbow flexion

How do you position the patient to test biceps?

Elbow at 90°, palm up/supinated

Triceps—myotome and action?

C7 — elbow extension

Wrist extensors—myotomes and action?

C6-C7 — wrist extension

Wrist flexors—myotomes and action?

C6-T1 — wrist flexion

Grip—myotomes and action?

C7-C8 — finger flexion

Finger extension—myotomes?

C7-C8

Finger abduction—myotomes?

C8-T1

Finger flexion—myotomes?

C8-T1

Hip flexion—myotomes?

L1-L2

Knee extension—myotomes?

L3-L4

Knee flexion—myotomes?

L3-L4

Ankle dorsiflexion—myotomes?

L4-L5

Ankle plantarflexion—myotome?

S1

What do DTRs assess?

Integrity of the monosynaptic reflex arc at the level of a single nerve root

What happens first after a tendon is tapped?

Sudden lengthening of the muscle spindle

What happens next?

Muscle spindle primary afferents send impulses into the spinal cord

What happens in the spinal cord?

The afferent synapses directly onto alpha motor neurons

What is the final response?

Reflex contraction of the muscle, observed as a limb jerk

What conditions commonly accompany clonus?

Spasticity and hyperreflexic DTRs associated with corticospinal tract disease

Biceps reflex

C5

Brachioradialis reflex

C6

Quadriceps/patellar reflex

L4

Achilles reflex

S1

What is the proper general order for DTR testing?

Upper extremity → lower extremity, with testing proceeding proximal → distal

What does a positive Babinski sign indicate?

Corticospinal tract lesion

What path does the stimulus follow?

Heel → lateral foot → ball of foot → curve medially → great toe

What is the normal response to plantar stimulation?

Flexion/curling of all toes

What is a positive Babinski response?

Extension of the great toe + fanning of toes 2-5

What structures are required for fine motor control?

Corticospinal tracts

Cerebellum

Intact proprioceptive pathways

What happens with a unilateral cerebellar hemisphere lesion?

Ipsilateral arm and leg abnormalities

What happens with a midline cerebellar vermis lesion?

Problems with midline balance, such as standing with feet together or tandem walking

What is pronator drift used to detect?

Very mild corticospinal tract (CST) deficits

Which muscles are minimally weak with a mild CST lesion?

Extensors

Supinators

Abductors

Which stronger muscles overcome the weak CST muscles?

Pronators

Biceps

Internal shoulder rotators

What happens during pronator drift?

The hand pronates, elbow flexes, and arm drifts downward

How is pronator drift performed?

Patient closes eyes and holds both arms out in front with palms up

How long should you observe for pronator drift?

At least 10 sec

What is a positive pronator drift?

One arm pronates and drifts/drops below the other

What does the Romberg test assess?

Used to isolate dorsal column proprioceptive disturbance

What is the key finding in a positive Romberg?

The patient is stable with eyes open but sways or falls when the eyes are closed