Chapter 2. Prehension

Chapter 5 - Movement Before Contact 193
c
FORCE
PROQ
FPL
FDS
INDl
PROT
b -
I
I
FDP
ECU
b
I - I
1
OPP I - I
ECRL I - I
INTD I
ECRB
ABPB
FPB
&
b -
I
- 4
- I
EPL t
ADP -
SUP t - 4
EPI I - I
FCU 8 -
I
-
LUMB 1 - - I
ABPL I - I
PAL I - 4
FCR
OPT b - I
r I I I I I I I I I I I I
- 600 -400 -200 * 200 400 600 ms
FORCE ONSET
Figure 5.31. EMG activity from muscles in the forearm as fingers
first open and then pinch an object. Some act to preshape the
hand, others to close the fingers (from Smith et al., 1983;
reprinted by permission).
“...stretch the long finger flexors before their
contraction in order to increase prehensile force
and may be somewhat similar to the crouching
that precedes jumping and wide jaw opening
prior to hard biting ...”
Using this as a model then, we can hypothesize what might be occur-
ring. During preshape, the force production muscles are stretched. At