Reach, Grasp, and Manipulation Flashcards
(41 cards)
What are the key components of UE control
- Locate the object
- transportation of arm in space
- grasp/release
- in hand manipulation
Hand movements are more accurate if:
eye movements are involved
during smooth pursuits there is an increase in gain if:
the hand also follows the target
Kinematic studies of locating a target show
eyes reach object before head movement occurs
EMG studies of locating a target show
neck muscles are activated first
Control of movement: pointing
all segments of the arm are controlled as a unit
Control of movement: reach and grasp
- arm carries out transport phase
- hand carries out grasp phase
each appears to be controlled by separate brain areas.
grasping patterns vary depending on
- location
- size
- shape of object
- power vs precision
what is the power grip
the finger and thumb pads are directed toward the palm and transmit force to the object
when would you use a hook grasp
grabbing the handle of a suitcase
when would you use a spherical grasp
holding a softball
when would you use a cylindrical grasp
holding a bottle
Precision grip
the forces are directed between the thumb and fingers
allows movement of the object relative to the hand and within the hand.
Requirements for successful grasp
- the hand must be adapted to the shape, size, and use of the object
- the finger movements must be timed appropriately in relation to transport so that they close on the object just at the appropriate moment
Shaping of the hand for grasp occurs during which phase?
transportation phase
Shaping of the hand is affected by
- the intrinsic properties of the object (size, shape, texture)
- the extrinsic properties (orientation, distance from body, location)
- size of max grip opening is proportional to size of object
What are the 4 phases of grasp at lift tasks
- contact between fingers and object
- grip force and load force (load on fingers) increase
- load force overcome weight of object (movement starts)
- end of task
what marks the end of grasp and lift tasks
decrease in grip and load force shortly after object makes contact with table
role of cerebellum in grasp and lift tasks
predictive control of grip forces
cerebellar lesion effect on grasp and lift tasks
poor predictive control of grip forces
cortical lesion effect on grasp and lift tasks
normal timing of predictive grip forces but reduced amplitudes
T/F: with a patient with coordiation dysfunction with reach and grasp, you need to train separately and together
True
Changes in reach/grasp:
Hierarchical theory
reflexes provide physiological substrate for reaching.
The transition from reflex to voluntary behaviors is a gradual process
development of reaching:
4-5 months
more accurate reaching and grasp components
