W4

Question 1

what are the 4 essential components of reach to grasp?

Answer 1

1. object location and identification
   using eye movement; head movement as well as visual information to pre-program the required forces and scaling of the grasp
2. postural control
   postural adjustments made first so that subsequent arm movements don’t destabilise the body
3. transport
   acceleration and deceleration - precise spatial positioning of the thumb with a straight path to the object
4. manipulation
   3 major movement types:
   - translation - moving objects from palm to fingertips and vice versa
   - shift- linear movement along an object such as a pencil
   - rotation

Question 2

what are the kinematics of reach to grasp depending on how far away the object is?

Answer 2

within arms length -> involves shoulder, elbow and wrist

beyond arm length - add hip and trunk

degrees of freedom:
- shoulder -3
- elbow - 1
- forearm - 1
- wrist - 2
- scapulohumeral complex - multiple

Question 3

what are the contributions of the hand during reach to grasp?

Answer 3

shaping hand for grasp - palmar arch, finger joint movement
intent to grasp - est early by these movements
during transport phase the thenar contributes more then the hypothenar eminence to modulating the hand shape
the hypothenar eminence is more involved in the hand pre-shaping phase

Question 4

how does the reach to grasp relate to the systems model of motor control?

Answer 4

• reach to grasp tasks is influence by object size, fragility, texture, weight
• also influence by the location of the object in relation to the individual
• these affect visual and motor processing times - ipsilateral reaches are faster
• the goal of the task has an effect - the need for more accuracy will show the movement.

Question 5

what are common reach and grasp deficits after stroke and what causes the deficits?

Answer 5

• difficulty with object location -> assoicated with visual loss or dysfunction
• variable transport phase -> impaired timing and larger movement errors. greater variability.
• compensatory use of the trunk -> impaire strength and or coordination of the shoulder
• poor apertre formation and hand orientation - more severly affect use trunk movements to orient the hand
• poor finger position for grasp -> inaccurate hand shaping to open and close the grasp
• somatosensory dysfunction - poor grip force control leading to crushing fragile objects or dropping an object
• poor manipulation -> inaccurate finger force magnitude and direction

Question 6

how can you assess arm function after CNS damage (e.g. stroke)?

Answer 6

MMAS
- item 6 upper arm section
- item 7 hand section
- item 8 advanced hand section

purdue pegboard test

box and block test

MTAHS

Question 7

what are the common main impairments in arm function following CNS damage?

Answer 7

muscle weakness:
- impaired motor unit recruitment and muscle activation and loss of coordination
- distal joints tend to be most affected with stroke

muscle stiffness:
- secondary adaptations such as length associated changes in muscles and connective tissues
- risk -> muscles become stiffer and shorter and can form contractures
- risk -> GHJ risk of sublucation
- spasticity may develop
- learned non use

Question 8

intervention for arm dysfunction following CNS damage:

Answer 8

• always include a target/ object
• vary objects with patients attenstion directed to differences in what they need to pick up
• focus on strength training relevant to the task
• encouarge somatoesnroy/ visual infomation
  -use internal and external feedback
• modify task to maximise what the patient can do
• bimanual training
• forcused use of arm

Question 9

what supplemental methods could be used for arm dysfunction training?

Answer 9

E-stims
mental practice
robotic training devices
computerised training
virtual environments