Exam 2 Neuroanatomy & Physiology

What are the Brain Motor Control Centers?

• Primary Motor Cortex (M1)

• Premotor and Supplementary Motor Areas

• Cerebellum

• Basal Ganglia

• Frontal Eye Field

Where is M1 located?

Precentral Gyrus

Where is the origin of the Corticospinal Tracts?

Primary Motor Cortex

What is the Primary Motor Cortex organized by?

Motor Homunculus

What doe M1 initiate?

Voluntary & Conscious Movement

What is the Motor Homunculus?

Map of body’s cortical representation

What are the largest cortical representations of the motor homunculus?

face, mouth, hands

Is the Motor Homunculus static or dynamic?

Dynamic; Not permanent - Use it or Lose it

Are M1 lesions contralateral or ipsilateral?

Loss of voluntary movement in contralateral body (UE/LE/Trunk)

What is Hemiplegia?

Complete, or near complete, paralysis on one side

What is Hemiparesis?

partial muscle weakness on one side of the body

Impaired motor planning is due to what?

A lesion in the Primary Motor Cortex

What are the Occupational Impacts of an M1 lesion?

• Difficulty with basic self-care tasks

• Mobility challenges (rolling in bed, sitting)

• Impaired functional use of affected limbs

Where is the Premotor Area located?

Anterior to M1

What does the Premotor Area do?

• Responsible for motor planning (praxis)

• Cognitive planning of movement

• May compensate for motor association area lesions

What is ideational apraxia?

• Unable to understand task demands

What is ideomotor apraxia?

• inability to execute plan on command

What are the Occupational Impacts of a Premotor Area Lesion?

• Difficulty with cognitive skills needed for motor tasks

• Challenges with sequencing activities

• Awkward movement, poor initiation, and hesitancy of movement

What does the Supplementary Motor Area do?

• Controls bilateral posture and motor planning

• Part of Premotor Area

What are the effects of a lesion in the supplementary motor area?

• Loss of bilateral postural control

• Apraxia

• Decreased standing/sitting balance

• Safety risks during occupational performance

Another name for the Prefrontal Area?

Motor Association Area

Where is the Motor Association Area?

Anterior Frontal Lobe

What does the Motor Association Area demonstrate?

Cognitive planning of movement

What results from lesions to the prefrontal area?

• Loss of motor plan that was present before injury

• Premotor area may compensate

What are the Occupational Performance Implications to the prefrontal area?

Difficulty with cognitive skills needed for motor tasks

What does the frontal eye field control?

Visual Attention and Saccades (quick, simultaneous movements of both eyes that shift your gaze from one focal point to another)

Where is the Frontal Eye Field located?

Anterior to Premotor Area

What are the lesion effects if it occurs in the frontal eye field?

• Impaired visual attention

• Deviation of eyes toward lesion side

What is the Occupational Impact of a lesion in the frontal eye field?

Missing environmental cues, safety issues

What is the “little brain” and the second largest portion of the brain?

Cerebellum

What does the Cerebellum do?

• Contains > 50% of all CNS neurons in 1/10 of the brain’s volume

• Primary function: Smoothing movement

• Primarily receives info from motor cortex

• Sends corrective information to motor cortex

• Receives proprioceptive info from spinal cord

• Compares the intended action with the current muscle state

What is the Cerebellums role in movement?

• Smooths multiple joint, sequential, automatic movements

• Involved in motor learning

What are some examples of cerebellar-dependent activities?

• Distal: buttoning, tying, typing

• Proximal: riding a bike, throwing

• Axial: posture during dynamic activities

Tell me about the signs of a cerebellar lesion?

• No muscle paralysis (unlike UMN/LMN lesions)

• Results in uncoordinated, inaccurate movements

• Three classic signs:
  1. Ataxia (uncoordination)
  2. Dysmetria (inaccuracy in movement)
  3. Intention tremor

If the lesion occurs at the cerebellar midline, what are the results?

• Affects axial muscles

• Disorders of stance and gait

• Positive Romberg’s test

• Bilateral symptoms

What occurs when Vestibular Function is impaired?

• Postural sway and arms drift toward affected side

• Falls toward affected side

What is the Romberg Test used for?

To asses disequilibrium

How would you conduct a Romberg Test?

Stand feet together

shoulders flexed to 90 degrees

eyes closed (monitor client & be prepared for loss of balance)

If the cerebellar hemisphere has a lesion, what are the results?

• Affects distal muscles

• Dyssynergia and dysdiadochokinesis

• Pastpointing and intention tremors

• Ipsilateral symptoms

What happens in the Basal Ganglia?

• Facilitates motor activity

• Filters inappropriate muscle activity

• Influences mental activities, emotions, and memories

What are the Basal Ganglia Inputs?

• Receives information from all cortical lobes

• No input from spinal cord

What are the Basal Ganglia Outputs (via Thalamus)?

• Area 6 (motor planning)

• Prefrontal association cortex (higher mental functions)

• Orbitofrontal cortex (emotions and motivation)

What connects to the Prefrontal Association Cortex?

Basal Ganglia

Are mental deficits possible with damage for the Cerebellum or Basal Ganglia?

Basal Ganglia

What are the general features for a Basal Ganglia Disorder?

• Disturbances in muscle tone (hypotonia to rigidity)

• Akinesia (difficulty initiating movement)

• Involuntary movements:

  • Athetosis (slow, writhing movements)

  • Resting tremor

  • Chorea (rapid, jerky movements)

  • Dystonia (twisting movements)

  • Dyskinesia (rhythmic, repetitive movements)

What is Parkinson’s Disease?

progressive neurodegenerative disorder

What are the symptoms of Parkinson’s Disease?

• Akinesia and bradykinesia

• Cogwheel rigidity

• Characteristic resting tremor

• Stooped posture and shuffling gait

• Loss of reciprocal arm swing

• "Mask-like" facial expression

• Impaired postural reflexes

• Micrographia

• Mental deterioration
  
  

What might you observe in the gait pattern of someone who has Parkinson’s Disease?

• Shuffling steps

• Reduced arm swing

• Forward-leaning posture

What treatments are used for Parkinson’s disease?

• L-DOPA

  • helps symptoms temporarily

  • does not prevent neurodegeneration

• Deep Brain Stimulation

  • targets specific basal ganglia regions

  • may help control some symptoms

What is Huntington’s Disease?

• Hereditary neurodegenerative disorder

• Adult onset

• Progressive and chronic

• Features:

  • Chorea ("fidgets") - rapid, jerky movements

  • Mental deficits

  • Eventually fatal

What is the result of Hemiballism?

• Violent, flinging movements (usually unilateral)

• Associated with subthalamic nucleus lesion

What is Tardive Dyskinisia?

• Related to chronic use of dopamine antagonists

• Affects face, mouth, jaw, tongue

• Persists after medication discontinuation

What are some of the Occupational Performance Implications to consider of a Basal Ganglia Disorder?

• Self-care activities

• Productivity/work tasks

• Leisure activities

• Social participation

What are the functions of the Vestibular System?

• Maintain equilibrium

• Maintain balance

• Maintain head in an upright vertical position

• Helps coordination of head and eye movements through the vestibulo-ocular reflex (VOR)

• Influences muscle tone through motor neurons and the medial and lateral vestibulospinal tracts

What are the functions of the Vestibulospinal Tract?

• Unconscious motor control – regulates muscle tone

• Facilitates antigravity (extensor) muscles

• Facilitates muscles responsible for posture and stance

What are the pathways of the Vestibulospinal Tract?

• vestibular nuclei (medulla)

• ipsilateral

• Innervates extensor muscle groups in the PNS

• Extrapyramidal tract – does not travel through the pyramids

What happens when there is damage in any brainstem tract?

• Decerebrate rigidity

  • Vestibulospinal tract fires without modification from the brainstem and cortex

  • Spasticity of muscles of the upper and lower extremities

  • Much poorer prognosis than decortitate rigidity

How do Visual, Vestibular, and Proprioception relate to each other?

• Work together to maintain an understanding of the body’s position in space

• If one system becomes compromised, the others are used to compensate

Why is it that disorders in the vestibular system sometimes go unnoticed?

• person grows increasingly reliant upon the visual and proprioceptive systems

• Patients will experience difficulty, however, when visual and proprioceptive cues cannot be accurately used

What are the functions of the Vestibulo-Ocular Reflexes?

• integrates information from the inner ear via CN 8 Vestibulocochlear
  (sensory)

• communicates with CNs 3, 4, and 6 (motor – eye movement) to
  stabilize an image on the retina while the head is moving

When the head moves in one direction, what direction will the eyes reflexively follow?

Opposite direction

What does an impaired VOR lead to?

• blurred vision

• difficulty reading during movement

Where is and what is the reticular activating system?

• located in the brainstem

• responsible for excitatory and inhibitory functions

• screens sensory information to alert the brain to attend to important incoming sensory data

How does the reticular activating system relate to the vestibular system?

• integrates information from the vestibular system

• responds to vestibular stimulation by arousing or calming the brain and body

  • Inhibitory vestibular input, such as slow rocking, are integrated by this system to calm the individual.

  • Excitatory vestibular input, such as fast dancing, spinning (rotary acceleration), and riding roller coasters (linear acceleration), are integrated by this system and arouse the brain/body.

Why do children seek vestibular input?

• to facilitate the development and organization of their nervous systems

• The need for intense vestibular stimulation decreases as humans age and can be aversive for adult

What is the relationship between the Autonomic Nervous System and the Vestibular System?

• Mediates CN 10

• conduct signals to and from the gastrointestinal tract

• These connections may explain why over excitation of the vestibular system can induce nausea and vomiting

What are the Signs and Symptoms of Vestibular Impairment?

• PNS and CNS dysfunction of this type present the following:

  • Nystagmus

  • Tinnitus

  • Vertigo

  • Hearing loss

  • Loss of balance and possible falls

  • Broad-based stance (to accommodate for imbalance)

  • Sweating, nausea, and vomiting (due to ANS involvement)

Motion sickness is a disorder of which system?

Vestibular

What is motion sickness caused by & what are the symptoms?

• Caused by repeated rhythmic stimulation (eg, car, plane, or boat travel).

• Vertigo, nausea, vomiting, lowered blood pressure, tachycardia, and sweating

• Can sometimes be alleviated by obtaining a match between visual and
  motion signals reaching the vestibular system

• Usually decreases in severity with repeated exposure

Anti–motion sickness drugs suppress the activity of which system?

Vestibular

What are the Occupational Performance Implications of a disorder in the Vestibular System?

• loss of functions is compensated through increased use of proprioceptive and visual sensory input.

• When walking on sand or in dim lighting a person may experience increased challenge maintaining their balance.

• Without the VOR, unable to read while moving
  
  

What are the names of the Incomplete Syndromes regarding Spinal Cord Injury & Disease?

• Anterior Cord

• Central Cord

• Posterior Cord

• Brown Sequard

• Cauda Equina

What symptoms occur with damage to the anterior portion of the spinal cord?

Loss/Decrease:

• pain

• temperature below injury level

• touch

• vibration

• proprioception relatively spared

What symptoms occur with damage to the central portion of the spinal cord?

• Loss of arm function

• Some leg function may be preserved—as well as bowel/bladder

What symptoms occur with damage to the posterior portion of the spinal cord?

• Decreased muscle coordination

• Good muscle power as well as pain and temperature sensations in tact

What symptoms occur with damage to the spinal cord regarding Brown-Sequard Syndrome?

• Ipsilateral to the injury: muscle weakness

• Contralateral to injury: loss of pain and temp

What symptoms occur with damage to the cauda equina?

Below Level of Injury: partial to complete loss of movement & sensation

This client presents as sensory incomplete. They tend to progress a little quicker with therapy goals because proprioception and light touch are intact.

What SCI/D Syndrome do they present with?

Anterior Cord Syndrome

This client has significantly more impairment in the UEs than the LEs. The degree of impairment varies. Spasticity is often an issue. Many of these clients do better with lower body ADLs than upper body ADLs because they have the balance to lean forward and reach down, but UE weakness limits upward reaching. Bladder function is often impaired but has the potential for recovery.

What SCI/D Syndrome do they present with?

Central Cord Syndrome

Functional performance for all ADLs can be impacted due to poor motor control.

What SCI/D Syndrome do they present with?

Posterior Cord Syndrome

In many ways this client appears to have hemiplegia, but sensory awareness on each side of the body is different. Level of injury is going to affect specific impairments. Safety education is critical since the side with active movement most likely has minimal pain/temperature awareness.

What SCI/D Syndrome do they present with?

Brown-Sequard Syndrome

This client will typically progress quickly with seated-level ADLs, but will have difficulty with dynamic standing balance, standing-level ADLs, and IADLs.

What SCI/D Syndrome do they present with?

Cauda Equina Syndrome

What is Tetraplegia?

• Impairs all 4 limbs, trunk, and pelvic organ function

• Occurs in C1-T4 region

• Lesions above C4 prevent independent breathing (need ventilator)

What is Paraplegia?

• Lesion of cord below cervical level

• Usually at T12 SC level or below

What is the outcome of a Complete SCI/D?

Absence of sensory & motor functions below the level of the lesion

What is the outcome of a Incomplete SCI/D?

• Partial preservation of sensory & motor functions below the level of the lesion

• Prognosis is better than a complete injury (preserved axon function)

• Occur more frequently than the other option

What does ASIA stand for?

American Spinal Injury Association

What did the American Spinal Injury Association standardize?

Assessment for evaluating neurologic level in SCI/D

How does ASIA assess the neurological level in SCI/D?

• Key muscles are tested

• Key sensory points tested with safety pin to determine the ability to distinguish sharp from dull

• light touches with cotton to determine ability to localize light touch

Where and when does Spinal Shock occur?

• Loss of all spinal reflexes below the lesion level

• Occurs immediately after SCI/D

How long does Spinal Shock happen for?

Can last for hours, days or weeks

During Spinal Shock, are sensory or motor pathways lost?

How does that loss present itself?

Motor pathways are lost

• Flaccid paralysis

• Loss of tendon reflexes

• Loss of autonomic function

When Spinal Shock is resolved, how is the spinal reflex activity affected?

Returned function

Does a higher or lower level of injury result in increased severity of spinal shock?

Higher level of injury

What is Autonomic Dysreflexia?

• involves an acute episode of exaggerated sympathetic reflex responses in SCI/D

• occurs because higher center reflex regulation is lost

Autonomic Dysreflexia is a medical emergency can affect people with SCI/D above which nerve?

T6

What is the immediate life-threatening concern when someone experiences Autonomic Dysreflexia?

Stroke

The following occurs when an unperceived noxious stimulus below the level of injury elicits uncoordinated autonomic control responses…

Can be one symptom or a combination

• Elevated BP

• Pallor below the lesion

• Sweating and flushing above the lesion

• Pounding headache

• Reduced heart rate

What are some common causes of Autonomic Dysreflexia?

• Full bladder or rectum (check catheter)

• Stimulation of pain receptors (i.e. pressure ulcers)

• Ingrown toenails

• Dressing changes (to wound)

• Visceral contractions (sexual organs [orgasm], bladder spasms)

What is another name for Postural Hypotension?

Orthostatic Hypotension