prehension.pptx

Gghu

1. PREHE NSION

2. Prehension activities involves grasping or taking hold of an object between any 2 surfaces of hand. Thumb paticipate in most but not all the prehension activities. Prehension Power grip (full hand prehension) Precision handling (finger thumb prehension)

3. POWER GRIP PRECISION Forceful act resulting in flexion of all finger joints. The thumb acts as a stabilizer to the object held in fingers or palm. Skillful placement of an object between fingers or between finger & thumb. No involvement of palm. Phases Opening of hand Positioning the fingers Bringing the fingers to the object Maintaining the static phase Opening of hand Positioning the fingers Bringing the fingers to the object Object is grasped to move through space by some proximal joints Fingers & thumb grasps the object to manipulate it within the hand Thumb is generally adducted. Thumb is generally abducted.

4. POWER GRIP Fingers function to clamp on or hold an object into the palm. Fingers sustain flexion position that varies in degree with size, shape & weight of the object; palmar arches around it. Thumb – serves as additional surface to finger palm by adducting against the object. Different power grips – Cylindrical grip Spherical grip Hook grip Lateral prehension

5. Involves use of all finger flexors FDP works predominantly I n t e r o s s e i m u s cl e s – p r im a r y M C P flexors, abductors/adductors Thumb usually comes arround the object F P L & t hena r m u s cl e s - f l e xi o n & adduction of thumb. l / CYLINDRICAL GRIP

6. Abductor digiti minimi -Flex and abduct 5 th mcp joint Opponent digiti minimi and flexor digiti minimi -opposition and flexion of 5 th mcp joint Cylindrical grasp is typically performed with the wrist in neutral flexion/extension and slight ulnar deviation Eg:turning a door knob,Holding a glass,etc

7. Most respect to cylindrical grip but greater spread of fingers to encompass the object. More activity of interosseus for e.g. holding a ball. SPHERICAL GRIP

8. Specialised form of prehension- function primarily of fingers. Major activity of FDP &FDS. Load – more distally FDP, proximally (FDS) Thu m b - m ode r a t e t o f u l l extension. E.g. - carrying a briefcase. HOOK GRIP

9. Contact between two fingers. MCP & IP joint- in extension as contigious MCP joint simultaneously abduct & adduct Extensor musculature pre dominates. E.g. holding a paper LATERAL PREHENSION

10. PRECISION HANDLING Require much finer motor control & more dependent on intact sensation. In “two – jaw chuck”,one jaw is thumb( abducted & rotated) & 2 nd jaw is by distal tip, the pad or the side of finger. 3 varieties of prcesion are – Pad to pad prehension Tip to tip prehension Pad to side prehension.

11. Involves opposition of pad or pulp of thumb to pad or pulp of finger. The pad has greatest concentration of tactile corpuscles. MCP & proximal IP joint of the finger – partially flexed Distal IP joint- extended or slightly flexed. Thumb- CMC flexion, abduction & rotation; MCP & IP joint partially flexed or extended. E.g. holding a foreceps PAD TO PAD P REHENSION

12. Muscle activity almost same to pad to pad prehension with some key differences like IP joint of the fingers & the thumb have range & force to create full flexion. MCP joint of opposing finger deviates ulnarly . E.g. holding a pen. TIP TO TIP PREHENSION

13. Key grip or lateral pinch. Between thumb & side of index finger Thumb-more adducted & less rotated least precise form of precesion handling . Eg.holding a key SIDE TO SIDE PREHENSION

14. FUNCTIONAL POSITION OF WRIST & HAND The functional position is – Wrist complex in slight extension (20°) & slight ulnar deviation (10°) Fingers moderately flexed at MCP joint (45°) & proximal ip joint (30°) & slightly flexed at distal IP joint It is the position in which all wrist muscles are under equal tension.