Download NM Study Guide 2 Lecture #1 10/6/14 I. Normal Upper Extremity

NM Study Guide 2
Lecture #1 10/6/14
I. Normal Upper Extremity Control
Overview of Normal UE control

UE function is essential for performance of activities of daily living as well as mobility tasks such
as walking and crawling

Postural control requires use of UE

Task performance requires understanding of the interaction of 3 factors:
o Constraints of the individual due to impairment resulting from injury
o Requirements of the specific task
o Environmental elements affecting task performance
o Ex: During a reaching task a person with stroke must move the involved UE, constrained
by abnormal tone and the influence of synergies (constraint of the individual). Picking
up a coffee cup requires the individual to adapt their hand to the shape of the cup
(constraints of the task). This is a specific requirement to be successful at the task.
Environmental elements may include the height of the surface that the cup is sitting on or
the floor the patient must stand on during the task. The patient must conform to all of
these task requirements to be successful in lifting the coffee cup from the surface.
Key elements of UE reach, grasp, and manipulation function
1. Locating target, requiring coordination of eye and head movement
2. Reaching, involving transportation of the arm and hand as well as postural support
3. Grasp, including grip formation, grasp and release of the object
4. Hand manipulation of the object
***all 4 must be examined when deficits in UE performance are suspected***
Locating a Target

The object must first be located

Eyes move first to locate object followed by head if necessary

Some tasks require only eye movements while other tasks require turing the head and even rotating the
trunk

Consider postural control that may be needed to accomplish this initial phase of the task

Some patients have difficulty reaching for an object because they are unable to visually locate the target
Reach and Grasp

Reaching is divided into 2 subcomponents: Reach and Grasp.

They are controlled by separate parts of the brain and are dependent upon the characteristic of the task

Sensory system
o provides information about the task such as where the object is located in order to anticipate
the requirements of the task
o Information is also processed during the task to modify and correct the movement.

Visual information
o allows the object to be perceived and recognized. Incoming visual input travels from the visual
cortex to the temporal cortex to identify what the object is.
o Also travels from the visual cortex to the parietal lobe to identify where the object is (position
and orientation). This allows feed-forward control.
o The plan is sent to the Cerebellum and BG to modify and refine the movement.
o Information is then sent to the motor cortex to activate motor pathways to generate movement.
o The cerebellum updates movement using incoming sensory (feedback control) for error
detection and correction

Somatosensory information
o Important for fine regulation of movement during reaching and control of grip forces
o During reaching, joint receptors, muscle spindles, and mechanoreceptors are active in
controlling movement
o Simple non-repetitive movements can be performed without somatosensory information that
way you do not have to feel to perform task, but with repetitive movements, errors develop
and movement pattern drifts. Thus sensory information is useful for correcting the movement.
o During grasping, cutaneous receptors relay information to modify the grip based on
characteristics of the object such as slippery surface, or a delicate, collapsible object
o When reaching for an object, the arm carries the hand toward the object while the hand
simultaneously pre-shapes the fingers to gasp the object. While proprioceptive FB is useful,
visual FB is most critical for final accuracy of attaining the object

Musculoskeletal requirements
o Consider ROM of joint, muscle control, coordination requirements at both ST and GH joints
o Also look at trunk during reaching
Postural Requirement
o Vary according to the reaching task
o Consider differing requirements of reaching while standing vs in seated position
Grasping

2 requirements for successful grip
1. The hand must be adapted to the shape, size, and use of the object
2. Finger movements must be timed so that they close around the object at the
appropriate moment

The shaping of the hand to grasp an object is guided by visual input

Intrinsic properties: objects size, shape, and texture

Extrinsic properties: provide information regarding the objects orientation, distance and location

Object recognition: processed in temporal lobe

Object localization: processed in the parietal lobe

Feed forward control us used to pre-program and sensory information from the limb and visual input
provide FB while the reach is performed (FB control)

Visual FB is useful in the final grasp accuracy

Power (spherical or hook) or precision grips used depending on the goal of the task
Grasp-lift Tasks

Four phases
o Phase one-lift starts with contact between the fingers and the object to be lifted
o Phase two- once contact has been established, the second phase begins with the grip force and
the load force (load on the fingers) increasing
o Phase three—Begins when the load force overcomes the weight of the object and it starts to
move
o Phase four- occurs at the end of the lifting task when there is a decrease in the grip and load
force after the object makes contact with the table

There must be a correct grip to load force ratio to prevent dropping the object of allowing it to slip out of
the grip
Coordination of Reach and Grasp

Task requiring variations in arm transport also result in changes in grasping and tasks with varied grasp
requirements result in deviations in arm transport

Neurologic impairment will likely result in deviations in both arm transport (reach) and grasp

They must be trained separately and together and in varying functional contexts.
Fitts’ Law

Movement time increases linearly with task difficulty. When reaching to a small specific target, it will
take longer than if reaching for a larger target. Movement time is also increased with a longer
movement distance
Bimanual Coordination

It is common to use both UE together, either symmetrically or asymmetrically. B/c there is a tendency
for the limbs to be coupled, limb movement in one extremity may influence movement in another
extremity

Temporal interdependence

Spatial assimilation

Fits law is not upheld in bimanual aiming tasks

Rose and Winstein studied persons with stroke, requiring subjects to bring both hands to a target.
During bimanual movements, the nonparetic limb demonstrated increased movement time (slower
movement) while the paretic limb demonstrated decreased movement time (faster movement) as
compared to unilateral movement of each limb

When continuous movements are performed the limbs tend to couple and interfere with performance
SEE EXAMPLE PAGE 105

Bimanual timing- limbs also like to time movements together, either in phase or out phase

II. Impairments Affecting UE Use Following Neurologic Injury
Target Location Problems

There are several impairments that can affect ones ability to locate
o Damaged to oculomotor system causing disturbances in eye control
o Damage in the vestibular will disrupt vestibular ocular reflex
o Damage to cerebellum may affect ability to adapt the VOR to the task
o Homonymous hemianopsia will restrict the ability to see half of the visual field and impair
target localization reaching tasks.
o Visual neglect results in decreased ability to detect and locate objects on the involved side
Reach and Grasp Problems

The trajectory (movement path) and duration of the movement used during the transport phase (reach)
varies depending on whether the task goal is to touch the target, grasp the object, or to move the object
in different ways

Motor problems
o Timing-neurologic injuries may demonstrate increased movement times due to lesions
causing delays in movement initiation, slowed movement, or uncoordinated movement
o Inter-joint coordination- Normal movement is synergistic, coordinating multiple muscles
across several joints. Cerebellar damage may result in movement decomposition (moving one
joint at a time) under or overshooting to a target. Movement may become slow to increase
movement accuracy or compensate for poor control
o Spasticity-may constrain UE movements, but extent is unclear. Weakness may be more
limiting of UR function. Fast movements may elicit an inappropriate activation of the stretch
reflex and therefore limit are movement
o Other motor problems-abnormal synergistic movement patterns, weakness and MS
impairments will influence motor control of the UE

Sensory problems
o Vision-FB is used to attainment of final reach accuracy. Visual deficits result in eye-hand
coordination deficits
o Somatosensation-not necessary for movement initiation by for accurate reaching involving
multiple joints
Problems with Grip, Manipulation and Release

Power grips utilize greater force and require less precision while precision grips allow the object to
be manipulated and provide greater fine motor control.

To grip and lift an object forces must be specifically generated for the task and regulated for task
completion

Sensory input from the fingertips is especially important to adjust the amplitude of forces used in
the grip and lift

Motor problems: can affect the activation, coordination and force generation during gripping and
lifting an object
o Damages to the descending corticospinal tracts will lead to weakness and altered muscle
activation
o Persons with PD can modulate their grip force for different objects but they may use a
higher grip force to compensate for their lack of control. They may also have difficulty
quickly releasing an object.
o In hand manipulation requires coordination between the fingers to move the object. This
requires motions that may be difficult due to impairments following neurologic injury

Sensory problems: results in difficulty regulating forces for grasp due to the loss of sensory
feedback. Visual information sent to the parietal lobe is necessary for determining object
orientation.
o Visual information is used concurrently with proprioceptive FB during grasp
o Lesions of the posterior parietal area affect the ability to shape the hand according to the
object size and configuration and integrates visual and motor signals related to object
orientation
o Sensory information is also used prior to grasping and lifting an object (pre-program grip
and lift force)
Examination of UE Reach and Grasp

Performance of function should begin the examination process and specific characteristics of
reaching and grasping will be determined by the parameters of the task and the environment

Performance will be influenced by the individual performer

Key components of UE control (strategy)
o Eye-head coordination-examine eye movement eye and head movement as well as trunk
movement for locating an object
o Postural control- examine tasks with differing postural requirements such as tasks in
sitting and standing. Examine postural control while the task is performed as well as
anticipatory postural adjustments
o Arm and hand transport-examine the ability to lift and move varying objects in
different locations. Look at the movement control, accuracy, and coordination
o
Grasp and release of the object- examine objects places in different locations in varying
orientations. Look at the ability to release objects and place objects at different speeds
with varying degrees of accuracy
o Manipulation of the object- be sure to examine manipulation control and use of an
object to accomplish functional tasks. Manipulated differently based on requirements of
the tasks
o Bimanual control-examine task that utilize symmetric and asymmetric movement
patterns. Examine movement of both limbs and the interaction between the two UEs
III. Common Disorders Affecting Shoulder Function
Normal Osteokinematics

Scapulohumeral humeral rhythm-1:2, during the first phase of scapular movement (0-90) this is
primarily scapular elevation and slight upward rotation of scapula.
o During the second phase (90-120) there is an increase in upward scapular rotation
o Downward dislocation of humerus is prevented by the superior part of the capsule along with
the supraspinatus and to a lesser extent the posterior fibers of the deltoid.
o The slope of the glenoid fossa helps prevent the downward dislocation
o As the head of the humerus is pulled downward, it is forced laterally by the slope of the
glenoid fossa
o The superior part of the joint capsule and the supraspinatus prevent the lateral movement and
therefore downward dislocation (locking mechanism)
o The ordinary effect of gravity on the unloaded arm is counteracted by the superior part of the
capsule and the coracohumeral ligament forms a significant thickening
o The RTC muscles prevent dislocation of the GH joint in this unstable position
o Persons with neurologic injury experience problems with a joint alignment and muscles
activation and are therefore susceptible to shoulder impingement, pain, and subluxation
Shoulder Dysfunction
Altered SHR-when altered there may be a delay in scapular rotation when the arm is lifted.
Structures between the acromion and the head of the humerus are mechanically squeezed
causing trauma
o Impingement occurs when the humerus is flexed or abducted with out the
appropriate SHR. Usually self ROM
o Delayed scapular roation may be due to changes in postural alignment, tone, and
motor control in the muscles which retract and depress the scapula

Shoulder Subluxation
o Intrinsic causes
trunk/joint malalignment

imbalance of the muscle activation

weakness

abnormalities of tone

soft tissue extensibility
o Extrinsic causes

positioning

handling

assistive devices
o Effects of shoulder subluxation

not painful

vulnerable and can easilty be traumatized

total paralysis patients is common (60-70%)

usually develops first three weeks after injury, but patient will have full
ROM

patient will experience dragging

3 types of subluxations

Inferiorly (most common)-causes include loss of scapular
stability on the ribcage. A loss of trunk control, scapular muscle
weakness, flaccid paralysis of the UE. Joint could also be
hypermobile due to the stretched anterior and superior
structures.

anteriorly

posteriorly

Painful shoulder
o Develops in a typical pattern although is can occur as a result of a specific traumatic
incident.
o
The patient may initially complain of sharp pain at the EROM when the arm is
movement passively
o If causative factors are not eliminated the patient will increase
Examination and Interventions for Shoulder Dysfunction

Examination should be a task oriented approach

Specifically note:
o Trunk posture statically and dynamically
o Scapular and humeral position/mobility
o SHR
o MS impairments limiting normal movement

Subluxation is palpated and described in terms of how many finger widths are present
Prevention and treatment of Shoulder impingement, subluxation, and pain

Early intervention is important for maintaining a healthy shoulder

Early goals are directed at maintaining alignment and preventing the development of soft tissue
restrictions and other secondary impairments. Patient and caregiver education are extremely
important for helping prevent injury and maintaining appropriate positioning and alignment

Slings do not reduce subluxation

During all activities consideration must be given as to the position of the UE
Lecture #2 10/13/14

all tasks require postural control

posture has an orientation and stability component

orientation: ability to maintain an appropriate relationship between body segments and between body
segments and environment during tasks. For most of ADLs, we maintain out body in a vertical alignment
(sitting, standing tasks)

Stability: ability to maintain ones center of mass (COM) w/in the limits of their BOS
o Referred as balance by clinicians and equilibrium coordination in text

Both orientation and stability very depending on the task and the environment

Maintaining postural control requires interaction of 3 systems:
1. Sensory system: somatosensation, vestibular, visual input
2. Neuromuscular: CNS integration of information
3. Musculoskeletal: executes postural adjustment
Stance Postural Control

Postural sway: during quiet stance the body sways back and forth and side to side in small amounts

Base of support: (during quiet stance) the outer rim of the feet in contact with the ground

The COM must be kept within the BOS to maintain stability

Stability limits: the boundaries within which an individual can move of sway and maintain stability without
changing their BOS
o Determined by their strength, jt ROM, the task that they are performing and the environment in
which is carried out. FOF may reduce and individual’s LOS and they will take a step in response to
a small displacement of their COM

Postural tone: maintained by muscles throughout the body. Postural muscle stay tonically active during
quiet stance to maintain the body in an upright narrowly confined position
o Muscles that are tonically active during quiet stance: gastroc-soleus complex, tibialis anterior,
TFL, iliopsoas, abdominals, erector spinae

Optimal alignment: achieved when the postural muscles expend the least amount of energy possible. As
postural sway increases and the COM moves outside this narrow range of optimal alignment, more muscle
effort is required to maintain stability and compensatory postural strategies are activated to prevent loss of
balance.
Postural Control and Compensatory Postural Strategies During Stance

A postural strategy is a type of normal muscle synergy whereby a group of postural muscles are constrained
to work together as a unit. These strategies can be used in either a feedback or feed forward mode

Cordo and Nashner: demonstrated that the posterior postural muscles of the legs and trunk were activated
before the biceps muscles when subjects were asked to pull on a handle. The anterior postural muscles were
activated before the triceps muscles when subjects were asked to push on a handle

Adaptive postural control: occurs in response to a destabilizing external force
o Adaptive utilizes feedback mechanisms-the CNS responds to information received during or after a
movement and attempts to restore stability
o Most patients adaptive postural control and not anticipatory. PT should address this during
intervention by pushing patient or throwing/catching a ball

Anticipatory (proactive) Postural control: occurs in preparation of self-initiated voluntary movements that
have the potential to destabilize the body.
o
Utilizes a feed forward mechanism- the CNS sends signals to postural muscles in advance of self
initiated movement to ready the system and prevent loss of stability
o
Anticipatory postural control relies on past experiences.
Three types of compensatory postural strategies used to maintain AP stability and stance

ankle, hip, and stepping strategies have been described as separate entities however most individuals use
various combinations of these strategies

in response to larger or faster perturbation, the ankle strategy will begin first and the involved muscles will
increase their force output as the hip strategy kicks in.

In addition the stepping strategy should not be viewed as a strategy of last resort; research has shown it is
initiated will before COM moves beyond limits of stability
1. Ankle Strategy

Occurs in response to a small perturbation on a firm support surface.

Stability is restored by moving the body around the ankle joint like an inverted pendulum

Use of the ankle strategy required full ROM and strength in the ankle joints

Muscles fire distal to proximal

Muscle synergy induced by forward sway: gastroc-soleus, hamstrings, paraspinals

Muscle synergy induced by backward sway: anterior tib, quads, abdominals
2. Hip Strategy

Occurs in response to larger, faster perturbations or when the support surface is
compliant or narrow

Restored by producing a large and rapid flexion or extension motion at the hip joints

Muscles fire proximal to distal

Muscle synergy induced by forward sway: abdominals, quads

Muscle synergy induced by backward sway: Paraspinals, hamstrings
3. Stepping strategy

Occurs in response to large and fast perturbations or when the ankle or trunk
musculature is weak and ineffective.

Stability is restored by stepping or hopping in the same direction as the destabilizing
perturbation.

UE movements assist in re-establishing stability and serve a protective function by
absorbing impact ad protecting the head in the event of a fall
Mediolateral Stability

Less known but research has demonstrated that most movement occurs at the hip joint

The hip abductor and adductor muscles control the loading and unloading of the LE causing lateral
movement of the pelvis via relative hip abduction of one LE and hip adduction of the other

Larger perturbations will result in side or cross over step
Sensory Mechanism Related to Postural Control

The CNS must know where the body is in space and whether or not the body is in motion or stationary

This is accomplished by organizing and interpreting information from the visual, somatosensory, and
vestibular inputs.

The cerebellum interprets information and corrects postural control

Postural problems occur when 2 out of the 3 inputs have deficits

If vision and somatosensory inputs are compromised, the vestibular system becomes dominant

There is a redundancy of the postural control system and normal postural control requires an individual to
adapt the senses to the task at hand

Visual Inputs-provides the brain with information on the position and motion of the head. Infants rely
heavily on visual inputs to elicit postural responses and restore stability

Somatosensory Inputs-provides the brain with information about the position and motion of the body with
respect to the support surface as well as the position of body parts relative to one another
o Provides the greatest and most reliable information
o When it is compromised, visual input assumes a greater role

Vestibular Inputs-provides the brain with info about the position and movement of the head with respect to
gravity and inertial forces. The semicircular canals sense angular acceleration and the otoliths sense vertical
and horizontal acceleration of the head
Adapting Senses for Postural Control- depending on the task and environment in which it is carried out, the
CNS must adapt how it uses somatosensory, visual and vestibular inputs to maintain stability. Example: running at
the beach requires a lot of visual input and riding a rollercoaster at dusk requires more vestibular input
Outcome Measure: Sensory Organization Test (SOT) or the Clinical Test of Sensory Interaction in Balance
(CTSIB)


The CNS’s ability to adapt how it uses sensory information is critical for maintaining stability in a constantly
changing environment.
SOT/CTSIB is used to assess three adaptation and to assist in determining whether or not one of the three
senses is impaired or absent. The test uses a tilting platform (altering somatosensory), a blindfold (eliminate
visual input), and moving visual surround which movements with body sway (to provide inaccurate visual
info) ***See page #78 in Notepack***
Sensory
condition
Accurate
Sensory
information
Inaccurate
Sensory
information

1
2
3
4
5
6
Vest, vision,
SS
Vest, SS
Vest, SS
Vest, Vision
Vest
Vest
None
None
Vision
SS
SS
Vision and
SS
Foam and Dome Test: simplified version of the SOT/CTSIB and can be used in clinic or home setting,
Medium density foam is used to reduce SS input, and a dome is place of the patients head to alter visual
input. They have to remain standing for 30 seconds for each of the six conditions. The amount of sway or
number of falls can be assessed and will normally increase from left to right.
Abnormal Postural Control

Impaired postural control and instability are common to a wide variety of nuerological disorders (stroke, TBI,
Parkinsons, MS, CP)

Balance is a composite impairment and can result when damage occurs to NM, MS, or sensory systems

Impaired balance will result if the integration centers of the brain (cerebellum) are damaged

Neuromuscular Balance impairments
o Muscle sequencing problems during activation of postural strategies- occurs when postural
synergy are activated in the wrong order. Individuals with this impairment may activate
abdominals before the tibialis anterior during a small posterior perturbation (ankle strategy)
o Co-activation of antagonist muscles- occurs when both the anterior and posterior postural synergy
muscles fire, regardless of the direction or the perturbation

Communing in PD in the posterior direction
o Delayed activation of postural synergies- when postural synergies are delayed the individual will
appear unsteady and easily loose stability
o Difficulty scaling the amplitude of postural synergy-can lead to either a reduced ability to
increase the amplitude of response to increasing levels of perturbations (a weak muscles synergy
response will occur regardless of the strength of the perturbation) or alternatively, an excessive
muscles synergy response will occur in response to a small perturbation

Hypermetria-causes excessive compensatory sway in the direction opposite the initial
direction of instability. For example is you push and individual in an anterior direction,
possibly falling forward (they overcorrect or overshoot). Usually due to cerebellar
problem
o Motor adaptation problems- individuals with UMN lesions may become fixed in stereotypical
patterns of movement and e unable to adapt to the postural synergy to the environment or size of
perturbation.
o Muscles paresis-weakness will render the postural strategies ineffective
o Loss of anticipatory control- loss of anticipatory control may cause instability and loss of balance
during self-initiated movement such as lifting, reaching, and carrying. This is difficult to treat

Musculoskeletal impairments (indirect) and constraints
o Disuse atrophy
o Muscles stiffness and loss of ROM-due to pain?
o Abnormal postural alignment- kyphosis, fwd head
o Use of AFO

Sensory impairments and problems with sensory adaptations
o Available sensory info varies depending on environment and an individual must be able to adapt
the senses to maintain stability.
o If UMN lesion has a loss of 1 out of 3 senses, they must rely on other 2 senses. If deficits in 2
senses, instability and falls will ensure

Impaired cognitive function and postural control-UMN demonstrate often cognitive impairments and
research shows a relationship between cognitive impairment and postural instability.
o
Individuals with dementia and impaired postural control are at increased risk for falls. The
mechanisms behind the relationship between cognitive impairment and postural instability remain
unknown and are currently under research investigation.

Impaired postural control under dual task conditions- when individuals with UMN lesions are engaged in
a balance task along with either a secondary motor task or cognitive task, their postural sway increases more
than a neurologically healthy individual
Clinical Assessment of Balance

Occurs in seated and standing position and involves static and dynamic components as well as anticipatory
and adaptive postural control

Static balance can be challenged to assess anticipatory postural control and adaptive control. The ability to
adapt between the senses can be tested by asking pt to close their eyes or stand to sit on foam while
continuing to maintain the static standing or seated position.

Dynamic balance refers to the individuals ability to maintain their COM over their BOS or independently
recover stability when their COM approaches their limits of stability

Dynamic balance can all be challenged to assess anticipatory postural control and adaptive control. The
ability to adapt between senses can be tested by altering vision or the support surface
Outcome measure for the assessment of postural control

Rhomberg

Sharpened Romberg

Function reach

Multidirectional reach

Berg balance

Timed up and go

Times up and go “dual task”

Walkie talkie test
Lecture #3 10/20/14
I. Control for Normal Gait

Can be thought of as a dynamic balance activity, whereby it is a series of losses and recoveries of balance

Anterior sway causes the bodies COM to move forward and beyond the foot’s location on the ground (BOS)

In order to prevent fall, forward step is taken and balance is desired

3 essential Requirements for gait
o Progression: Rhythmic patterns of muscles activation advance the body in the desired diraction
o Stability: Maintaining upright posture against gravity and against perturbation (expected and
unexpected)
o Adaptation: Altering the gait pattern to meet the demands of the environment (negotiating
obstacles, uneven terrain, and altering speed and direction)

components of the gait cycle
o stance phase (support phase): The period of time when the foot is on the ground. (60%)

Subphases-Rancho (Traditional)

Initial contact (heel strike)

Loading response (Foot flat)

Midstance (Midstance)

Terminal Stanct (heel off)

Preswing (toe off)
o swing phase: the period of time when the foot is off the ground (40%)

Subphases-Rancho (traditional)

Initial swing (acceleration)

Midswing (midswing)

Terminal Swing (deceleration)
o Double support:Takes place during the first and last 10% of stance phase
o Single support: occurs when the opposite limb is in swing

Distance and temporal factors
o Step length- The distance from initial contact of one foot to initial contact of the other foot (30
inches)
o Stride length- the distance covered from initial contact of one foot to the following initial contact
by the same foot
o Step width-horizontal distance between the middle heel of one foot and the middle heel of the
opposite foot
o Cadence (step rate)- the number of steps per unit of time (112.5 per minute or 1.9 steps/second)
o
Gait velocity/speed: the average horizontal speed of the body reported in meters/second (1.46m/s)



A person’s preferred walking speed is at his/her point of minimal energy expenditure
with swing phase requiring very little energy
Determinants of normal gait
o Vertical displacement- viewed from the side, the head bobs up and down 5cm. The COM
movement followings 2 sinusoidal wave patterns per gait cycle. Max height occurs during
midstance, and minimum height occurs during each DLS
o Medial-Lateral displacement of COM-viewed from behind, the head moves side to side 4cm.
The COM movement follows 1 sinusoidal wave pattern per gait cycle

Maximum displacement to the left occurs during left LE midstance and max
displacement to the right occurs during right LE midstance.

If you can see this displacement, it is too much
Strategies to minimize energy expenditure- to optimize energy efficiency the body uses the combine action
of several kinematic strategies to minimize the displacement of the COM
o Medial-lateral displacement is minimized by

Lateral pelvic/hip motion- Reducing step width minimizes the medial and
lateral displacement of the COM
o Impaired individuals: an increase in step width will increase
stability while concurrently reducing energy efficiency
o Vertical displacement is minimized by

Horizontal pelvic rotation- as the swing leg advances, the pelvis rotate
forward 5 degrees in the horizontal plane to increase the relative leg length.
This strategy minimizes downward displacement of the COM

Lateral pelvic tilt- At midstance the contralateral pelvis drops in the frontal
plane to lower the body and thus minimizes upward displacement of the
COM

Knee flexion during stance and swing phase- occurs during stance phase
limits the maximum vertical excursion of the COM. Knee flexion during
swing shortens the length of the leg allowing the foot to clear the ground this
minimizing upward displacement of the COM.

Ankle rotation (dorsiflexion/plantarflexion)- at heel contact the protruding
calcaneus makes contact with the ground and functionally elongates the leg
length. In addition, during terminal stance, the LE is elongated via ankle
plantarflexion (heel rise). Thus at both ends of stance phase downward
displacement of the COM is minimized.
II. Muscle activation Patterns During Normal Gait

Hip Extensors (gluteus maximus)
o Terminal swing: eccentrically to decelerate in preparation for IC
o Initial Contact to midstance: concentric
o Late Stance: concentric to propel body forward

Hip flexors
o Terminal Stance: eccentric
o Pre-swing to initial swing: concentric
o Hip flexion during the second half of swing phase is generated by the forward momentum of the
leg. This hip flexion motion is controlled by the eccentric activation of the hip extensors in
preparation for initial contact

Hip abductors (gluteus medius and minimus)
o During SLS- ipsilateral eccentrically

Knee Extensors (quadriceps)
o Loading response: eccentric
o Midstance: concentric
o Preswing: eccentric

Knee Flexors (hamstrings)
o Terminal Swing: eccentric

Ankle Plantarflexors (gastrocnemius and soleus)
o Loading response (foot flat) to midstance: eccentric
o Terminal stance to pre-swing (toe-off): concentric

Ankle dorsiflexion (tibialis anterior)
o Initial contact to loading response: eccentric
o Swing phase: concentric
III. Control mechanism for gait

Central pattern Generators
o Animal Research
o
During the late 1800’s Charles Sherrington and his colleagues discovered that spinalized cats (a
spinal preparation cuts the spinal cord at the level of the thoracic spine to isolate the hind limb
musculature from any descending input from the brain) were still able to produce rhythmic
walking movements of the hind limbs.
o
Later, experiments by Graham Brown (1911) demonstrated that the deafferented lumbosacral
spinal cord (i.e. the dorsal horns are cut) of cats also produced rhythmic walking movements.
o
These two experiments demonstrated that the spinal cord was capable of generating a basic
locomotor pattern in the absence of supraspinal (descending brain input) and sensory input.
o
basic walking patterns were generated solely by the spinal cord without any sensory input or
control from the brain! However, it is important to note that the gait pattern generated by the
spinal cord was clumsy and not fully able to adapt to environmental demands (i.e. obstacles).
o
The central pattern generator (CPG) was therefore discovered and is described as a neuronal
network located in the lumbosacral spinal cord.
o
When stimulated, it generates an oscillating efferent output to stimulate flexor and extensor
muscle.
o
CPG is thought to be made up of a flexion spinal circuit and an extension spinal circuit, otherwise
known as flexor and extensor half centers.
o
These two spinal cord half centers are neurally connected such that when the flexion half center
activates flexor muscles of one extremity, the extension half center is concurrently inhibited in the
same extremity to allow for swing phase and vice versa for stance phase.
o Human Research

Humans with complete SC injuries are not able to produce spontaneous stepping
movements; however, when trained with a treadmill and harness system and using
specific externally provided sensory cues, they can produce LE muscle activity consistent
with walking

CPG’s also exist in humans but due to the balance demands of bipedal gait, humans are
much more dependent on supraspinal brain input than cats and may explain why
complete SC injuries do not produce spontaneous stepping movements.

Supraspinal Input- descending is critical for functional control of walking
o the mesencephalic locomotor region of the BS initiates walking and controls speed
o the reticulospinal pathway connects the mesencephalic region to the CPG;s of the SC
o the cerebellum fine tunes walking via error detection.
o Lesion to the cerebellum will produce ataxic gait pattern
o Hippocampus, parietal cortex, and frontal cortex, and the BG also have a role in modulating and
planning locomotor movements

Sensory feedback-sensory info from all of our sense are necessary to regulate and adapt gait to
environmental demands
o Adaptive strategies for modifying gait
o Anticipatory strategies for modifying gait
o Muscle Spindle-MS in the hip flexor contribute to initiation of swing in the ipsilateral leg. As leg
approaches terminal stance, the Ia afferents are stretched and the hip flexors are reflexively
activated by the stretch reflex while the extensor muscles are inhibited.
o GTO- GTO receptors in the LE assist in supporting the leg during stance phase of the ipsilateral
leg. AS the leg makes initial contact with the ground, the Ib afferents are stimulated causing
ipsilateral activation of the extensors (knee and ankle extensors)

Non neural contributions to locomotion- The force of gravity and momentum assist in the forward
progression of the limbs during the gait cycle
IV. Abnormal Gait

Motor Impairments- Motor, sensory, perceptual and cognitive impairments contribute to abnormal gait.
Individuals will attempt to maintain functional gait with the use of compensatory strategies.
o Abnormal Tone- Both spasticity and increased muscle stiffness are common following an upper
motor neuron lesion and lead to abnormal gait patterns during portions of stance and swing when
the affected muscle is lengthened.

Plantar flexion hypertonia- Excessive activity and or stiffness of the PF may prevent
heel strike at initial contact

Result: flat foot (entire foot hits ground) or forefoot contact (unstable contact)

Compensation: Knee hyperextension, forward trunk, short step

o
During swing phase, PF hypertonia leads to toe drag
o Compensation: Vaulting on contralateral limb, contralateral trunk
lean, ipsilateral hip hiking, ipsilateral circumduction

Excessive PF and posterior tibialis activity leads to equanovarus foot position
and initial contact is made with the lateral border of the foot

Excessive PF and peroneus brevis activity leads to equanovalgus foot position
and initial contact is made with the medial border of the foot

Quadriceps Hypertonia-knee flexion during loading response can trigger excessive
quadriceps activity leading to knee hyperextension

Compensation-Knee hyper extension, fwd trunk lean, short step

Hamstring Hypertonia-Excessive HS activity and or stiffness results in knee flexion at
initial contact

excessive HS activity and or stiffness throughout the stance phase increases the
demand on the quadriceps to control the knee and therefore may result in
buckling of the knee

Compensation-Short step, decrease stance time of that limb

Crouched gait- results from excessive bilateral HS activity during stance and swing
phase and is common in certain types of CP

Adductor Hypertonia-Excessive adductor activity and or stiffness during stance phase
causes the contralateral pelvis to drop

Excessive adductor activity and or stiffness during the swing phase causes
medial displacement of the leg which reduces the BOS and compromises
stability

Scissoring gait results from excessive B adductor activity and is common in CP

Hip flexor stiffness- results in a reduction of hip extension during mid and terminal
stance and forces the trunk to flex forward. Forward trunk flexion compromises stability
and increases the demand on the hip extensors to prevent trunk collapse

Compensation- knee flexion in order to bring pelvis under alignment under
body- works to keep COM over BOS
Weakness/Paresis-Weakness is often a primary impairment following un UMN lesion and unlike
abnormal tone, it leads to abnormal gait patterns during portions of stance and swing when the
affected muscles is both lengthened and shortened

Plantarflexion Weakness- During stance , PF weakness causes excessive knee flexion
due to an inability to eccentrically control forward translation of the tibia

During terminal stance, PF weakness leads to a decrease in heel rise and a
decrease in the propulsive forces

Dorsiflexion Weakness- during initial contact DF weakness leads to foot flat or forefoot
contact.

Alternatively heel strike may occur but is followed by a rapid foot drop of the
foot (foot slap) and is due to the inability to eccentrically lower the foot to the
ground

During swing, DF weakness will lead to toe drag or decreased foot clearance

Compensation- Ipsilateral circumduction, ips. Hip hike, ips. Trunk lean, cont.
vaulting

Quadriceps Weakness-during the loading response weak quadriceps (3+ to 4 grade)
will lead to poor knee control and possibly cause the knee to buckle. During midstance
excessive weakness (0-3 grade) will destabilize the knee

Compensation- knee hyper extension with fwd trunk lean

Hip Flexor Weakness- normal gait requires a 2+ strength grade. Excessive weakness
(<2+ grade) will lead to problems with limb advancement during swing phase. A loss of
hip flexion momentum indirectly causes a decreased knee flexion which makes foot
clearance more difficult and shortens the step length.

Compensation- ipsilateral post trunk lean, ipsilateral circumduction,
contralateral trunk lean, contralateral vaulting

Hip Extensor Weakness-during the stance phase, hip extensor weakness causes a fwd
trunk lean (Extensors are unable to control the anterior trunk movement that occurs with
fwd gait progression) which compromises stability

Compensation- post. Trunk lean, little extension activity is needed.

Hip Abductor Weakness- during the stance phase of gait weak hip abductors (g.
medius) leads to an excessive and uncontrolled contralateral pelvic drop (i.e. the


ipsilateral abductors are unable to eccentrically control the contralateral pelvic lowering)
Trendelenburg

Compensation-trunk lean ipsilateral over stance limb
o Abnormal Synergies- due to corticospinal lesions and results from an abnormal mass pattern of
movement during gait they are manifested as either total extension (stance or swing phase) or total
flexion (swing phase)
Sensory Impairments
o Somatosensory

Result: sensory ataxia (wide stance)

Compensation- increase reliance on vision
o Visual-vision is used for anticipatory control to maintain balance in response to obstacle
negotiation. Vision loss results in decreased stability and a decreased ability to adapt gait to meet
the demands of the environment

Compensation-gait is slow and increase reliance on auditory cues
o Vestibular-loss of vestibular input results in ataxic gait and difficulty stabilizing the head and eyes
(impaired gaze stabilization)

Compensation-gait is slow
Perceptual and Cognitive Impairments
o Neglect –left sides neglect may cause a right sided trunk lean and a decrease ability to avoid
obstacles in the left side of the environment

Need to teach patients to slow down and scan
o Impaired Memory and Attention- impaired memory and attention cause problems with gait
initiation, gait adaptability, and obstacle avoidance. Individuals with memory deficits are more
likely to fall than those without.
Gait Cycle: Normal Joint Motion Review
STANCE
Weight Acceptance Single Limb Support
Rancho
Initial Loading
Mid
Terminal
Pre
Los Amigos
Contact Response Stance Stance
Swing
Terms
Traditional Heel
Mid
Foot Flat
Heel Off
Toe Off
Terms
Strike
Stance
Pelvis
Hip
5
5 Forward
Forward
0
Rotation
Rotation
30
30 Flexion 30-0
Flexion
Knee
0
0-15
15-0
Ankle
0
0-15 PF
15PF 10DF
Heel
Strike
Controlled
knee and
ankle
motion
Ankle
rocker to
pull the
body up
and over
Toes
NOTES/
Critical
Elements
5
5 Backward
Bkwd
Rotation
Rot
10 Ext
0-10
Extension
to 0
0-35
0
Flex
010 DF – 0
20PF
0-30
Extension
SWING
Limb Advancement
Initial
Swing
Mid
Swing
Terminal
Swing
Acceleration
Mid
Swing
Deceleration
5 Backward
0
Rotation
0-20
Flexion
35-60
Flexion
20-10 PF
20-30
Flexion
60-30
Flexion
10PF 0
5 Forward
Rotation
30 Flexion
30 -0
0
Hip
Locked
flexion,
ankle with Passive
Knee and hip ankle DF, Knee
heel rise and knee
flexion
and
extension
hip in
flexion
vertical
extension
tibia
Lab #6 10/22/14 pg 318
Postural control and Strategies in sitting

Backward sway elicits a response primarily from the hip flexor muscles (abdominals, neck flexors may also
be elicited

Forward sway elicits a response primarily from the extensor muscles of the hip (along with the extensors of
the trunk, and neck)

If the feet are in contact with the ground during forward reaching, the tibialis anterior assists to stabilize the
body and the plantar flexors assist in returning the body to an upright neutral position
Station #1 Clinical Assessment of Balance- should be examined in both a seated and standing position. Static and
Dynamic components of balance should be assessed

Unchallenged static balance-refers to the individuals ability to independently maintain their COM within
their BOS with minimal sway (sitting or standing)

Challenged static balanceo Ask patient to self initiate arm or head movement while maintain a seated or standing position
(anticipatory)
o Nudge patient in multiple directions (adaptive/reactive) while they sit or stand
o Ask them to close their eyes and sit or stand on foam while continuing to maintain the seated or
standing position (adapting between senses)

Unchallenged dynamic Balance- refers to the individuals ability to move their COM within their BOS and
both independently and efficiently recover stability when they reach the edge of their limits of stability (ex.
Sitting or standing and weight shifting)

Challenged dynamic Balanceo Ask patient to reach outside their BOS for weighted object (anticipatory)
o Nudge patient in multiple directions while they are reaching (anticipatory and adaptive)
o Ask patient to close their eyes and sit or stand on foam while they reach outside their BOS (adapt
between senses)
**Assessing balance under these conditions will assist the therapist in determining if the balance strategies are

Present and normal

Present and delayed

Present but inappropriate for the situation

Abnormal

Absent
Station #2 Foam and Dome Test (SOT/CTSIB)-assesses the adaptation and to assists in determining whether or not
one of the three senses is impaired or absent.

Measures body sway under six different sensory conditions.

Maintain standing position with minimal sway for 30 seconds.

Three trails are given and the average time in balance is recorded

Time in balance and increased sway or LOB is documented and c/o dizziness and the postural strategies
used.
Interpretations from Foam and Dome

Increased sway on 2,3,5,6- indicates that the patient is dependent on VISION for postural control

Increased sway on 4,5,6-indicates that the patient is dependent on SOMATOSENSATION

Increased sway on 5,6-indicted that the patient demonstrates vestibular loss

LOB on 3,4,5,6- the patient may have sensory selection problem or be unable to adapt sensory information
for postural control
Station #3

Romberg Test- The patient is going to stand with their ankles touching and the hands crossed across the
chest (eyes on and closed). Test is 30 seconds.
o Criteria to stop- if patient moves feet changes arm position or opens eyes. <79 y.o. should be able
to make it for 30 seconds
o If the person is able to maintain balance with the eyes open but no closed=positive Romberg
indicative of proprio or ss loss.

They are relying on vision to compensate for SS loss.

Patients with vestibular problems may do well on test due to the fact that they us the SS
input to compensate for the loss of vision.

Patients with cerebellar dysfunction will not maintain stability with eyes open or closed.

Graded no sway, minimal, moderate, severe/fall

Sharpened Rhomberg Test-patient is just tandem but exactly like traditional romberg

Functional Reach Test- used to evaluate patients limit of stability in the forward direction (dynamic,
unchallenged, anticipatory)
o 2 practice trials and 3 actual trials
o has to move 6 inches. Make sure consistent with measures
o arm at 90

Multidirectional Reach –same as functional reach but in multiple directions
o 2 trials recorded for each and take the average score
o Fwd-9 inches; bwd-4.5-5 inches; SR 6-7 inches

Berg Balance Scale-a 14 item tasks and scoring the lowest response for each item
o <45 score=fall risk
o 6.5=significant difference of scores
Station #4

Timed up and Go (TUG)- measured in seconds the time taken by an individual to stand up from a standard
arm chair (46cm) walk a distance of 3 meters (10 feet) turn around and walk back and sit down again.
o Dynamic anticipatory!!!
o In the frail elderly

<10 seconds= freely independent

> 30 seconds= dependent in most activities, not a community ambulatory, FALL RISK!

Timed up and Go “Dual Task”-same as TUG, but while carrying water
o Difference between TUG and TUBDual= >4.5 seconds is a greater fall risk over the next 6 months
o TUG Manual- >14.5 sec is at risk for falls
o TUG, Cognitive-TUG while subtracting by 3 from a random number 20-100 or reciting 7 item
grocery list
o TUG>15 seconds-discriminates fallers from non-fallers

Walkie-Talkie Test-The therapist walks alongside a patient while walking and begins a conversation. (yes
or no questions). The patient will stop to answer and that is a positive test and reveals important information
about cognitive function and attentional demands of postural control.

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