L11 - Prehension and Work Flashcards
What is prehension?
Prehension is the ability of the fingers and thumb to grasp and pick up objects.
What are the elements of prehension?
- Area of contact with hand
- Number of involved fingers
- Finger position
- Thumb position
- Wrist position
What are the 2 types of prehension?
- Grip
- Pinch
Name the types of grip prehension. (5)
- Power grip
- Precision grip
- Hook grip
- Cylindrical grip
- Lumbrical Grip
Name the types of pinch grip. (3)
- Key pinch
- Tip pinch
- 3-point (palmar) pinch
Grip Prehension
Describe the components of the power grip.
- wrist
- fingers
- thumb
What is the use of the power grip? + ex
- Wrist extension and ulnar deviation
- MP , PIP and DIP in flexion
- Thumb in abduction (around object)
Use: stability and large force
–> ex: holding a bat
See NDC p.9 for illustration
Grip Prehension
Describe the components of the precision grip.
- thumb
- fingers
- force
What is the use of the precision grip? + ex
- Thumb partially abducted
- Fingers partially flexed
* Force variable
Use: delicate control
–> ex: holding ball or egg with finger/thumb tips
(Grip modified depending on object in hand)
See NDC p.10 for illustration
Grip Prehension
Describe the components of the hook grip.
- thumb
- fingers
What is the use of the hook grip? + ex
- Flexion of PIP and DIP joints
- Thumb does not contribute to grip
–> only the fingers solicited
Use: finger grasp
–> ex: holding a briefcase or purse, rock climbing
See NDC p.11 for illustration
Grip Prehension
Describe the components of the cylindrical grip.
- thumb (2)
- fingers
What is the use of the cylindrical grip? + ex
- Thumb does not touch fingers.
- Thumb abduction and opposition
- Finger flexion around object
Use: grasp large cylinder
–> ex: holding a glass or a water bottle
See NDC p.12 for illustration
Grip Prehension
Describe the components of the lumbrical grip. (3)
What is the use of the lumbrical grip? + ex
- Flexion of MPs
- PIP and DIP joint in extension
- Flexion of thumb MP with IP in extension
Use: stabilization
–> ex: holding paper
See NDC p.13 for illustration
Pinch Prehension
Describe the components of the tip pinch. (3)
What is the use of the tip pinch? + ex
- Opposition to fingertip
- Thumb MP and IP in slight flexion
- Finger flexed
Use: holding something small in finger tips
–> ex: holding a needle
See NDC p.14 for illustration
Pinch Prehension
Describe the components of the lateral pinch. (2) (key pinch)
What is the use of the lateral pinch?
What happens if the thumb adductor is weak?
- Thumb adducted
- Index finger flexed
Use: holding a key
In the case of a weak adductor, compensation with flexion of thumb IP joint
See NDC p.15 for illustration
Pinch Prehension
Describe the components of the palmar pinch. (2)
What is the use of the palmar pinch?
(pads fo fingers-thumb)
- Thumb in opposition with IP in extension
- Finger DIP in extension
Use: pads of finger and thumbs
–> writing, zipper buttons
See NDC p.16 for illustration
Measurement of Prehension
How can measure power grip?
Dynamometer
–> gives amount of grip strength in lbs or kg
See NDC p.17 for illustration
Measurement of Prehension
How can measure latera, palmar or tip pinch?
Pinch meter
See NDC p.17 for illustration
Out of the 3 pinch prehensions, what is the most commonly used?
Palmar pinch is the most frequently used for picking up and holding an object.
See NDC p.18 for table
What is the relative importance of prehension patterns with respect to hand function and autonomy?
- Palmar pinch (both hands)
- Lumbrical grasp (left hand, non-dominant)
- Cylindrical grasp (right hand, dominant)
What are the changes in the hand in ulnar nerve palsy?
Also known as claw hand.
- Intrinsic minus position of fingers
- MP hyperextension
- PIP and DIP flexion
Innervation to intrinsic hand muscles which flex MP and extends IPs
–> so without = opposite
See NDC p.20-21 for illustration
What is the consequence of median nerve palsy?
What is the compensation?
Median nerve innervates opponens pollicis.
Wrist level median nerve injury results in inability to
oppose thumb.
Compensatory movement with thumb adductor.
See NDC p.22 for illustration –> red cirlce
