upper extremity function
- transport hand to desired location
- grasp, dexterity, manipulation
- sensory input from different modalities
-> tactile identification of objects/ properties
-> interaction w/ environment - coordinate visual, tactile information, head and upper extremity movements
- postural adjustments that occur w/ arm movements and bimanual coordination
- maintain balance while functioning in multiple postures
- communication: body language, hand contact
- balance: arm swing, protective arm response, supportive
example of upper extremity impairments
peripheral extremity injuries (e.g. fractures, ligament tears, amputations))
chronic MSK conditions (e.g. rheumatoid, arthritis, osteoarthritis)
neurological conditions (e.g. stroke, parkinson’s, MS)
motor control mechanisms - feed-forward neuromuscular control
- movements are planned based on information from past experiences
- operates on premise of initiating a motor response in anticipation of a load or activity
(e.g. reducing muscle contractions in response to anticipating a heavy load being removed from arm)
motor control mechanisms - feed-back neruromuscular control
- continuously regulates muscle activity through reflexive pathways
- reactive muscle activity
(e.g. reducing muscle contractions in response to a heavy load being removed from arm)
most movements utilise a combination of ____________ and ________________ control
feed-forward; feed-back
there are multiple ways to reach for a target b/c…
three are more than 7 joints involved in upper extremity function w/ multiple degrees of freedom (joint rotations)
general sequence of movement
- initiation and planning (vision, hand-eye coordination)
- trunk adjustment (trunk and spine move first)
- shoulder and scapula movement (position the arm)
- elbow and wrist adjustment (e.g. pronation/supination)
- hand and finger grasp (final stage= precise movement of fingers and thumb to grasp the object)
in reaching…
- elbow and shoulder joint actions cannot be planned independently of each other (you should not see excessive movement of either one)
- single joint assessment may not be relevant
triphasic burst - agonist and antagonist definitions
agonist= a muscle responsible for producing a specific movement through concentric muscle action
antagonist= a muscle responsible for opposing the concentric muscle action of the agonist
triphasic burst
EMG pattern during a fast single-joint movement results in 3 bursts
example-> elbow extension
- agonist: triceps burst
- antagonist: biceps burst with quieting of triceps
- agonist: triceps again to dampen oscillations of moving limb
eye-hand coordination
- eyes direct the movement of the hands to target, relaying the size and shape of object, and this info is used to determine forces required for reach and grasp
- in the dark, eye movements can be aimed toward the hand by just using proprioception
- viewing hand prior to movement improves accuracy
clinical implications: consider interaction of vision and proprioception when sensorimotor impairment
trunk coordination
- exercises w/ trunk restraint may improve arm and hand function after injury (don’t allow compensation w/ trunk, so more focus on true hand/arm skills)
- but… trunk/core exercises may improve arm and hand function b/c:
- trunk control is required for optimal upper extremity function
- ultimately, people do compensate w/ trunk during normal movements
Fitt’s law
increase accuracy, decrease speed
-> valid for tapping, reaching, and grasping movements
-> to reach a smaller target or pick up a smaller cylinder we take more time
what does this mean clinically when restraining reach?
goal-oriented reaching is _______________
smoother and faster
reach and grasp are _____________
coupled
handedness
3 possibilities:
- right
- left (10-25%, usually male)
- ambidextrous (1%)
- in 95% of right handers and 60% of left handers, the left cerebral hemisphere is dominant for language
- handedness assessment plagued w/ ambiguities and inconsistencies (self-report)
- right-handed individuals have stronger right dominant hand (10-12% greater strength)
- left handed individuals have more equal strength b/w hands
- bone mineral density is 3% higher in the dominant right hand; but similar b/w sides in left handed people
dexterity
speed, coordination, fine motor, interaction w/ the environment
a measure of function of the upper extremity
