hand closing
DESCRIPTION
TRANSCRIPT
Hand 1
Human hand is a complex structure of bones, arteries, nerves, ligaments, and tendons which
performs many functions. The primary function of the hand is prehension. For closing of hand it
requires coordinated movements of the joints in flexion. The forearm muscle is primary group
acted during most of the hand function. They are connected to the fingers by tendons which pass
through different channels.
Muscles involved in closing of hand
Extrinsic Muscles
Flexor digitorum profundus (FDP)
Flexor digitorum superficialis (FDS)
Flexor digiti minimi brevis.
Flexor pollicis longus
Extensor digitorum
Intrinsic Muscles
Lumbricals
Interossei
Adductor pollicis
Kinesiology and Kinetics of the hand
A powerful closing of the hand requires flexion of MP, PIP, and DIP joints, and
activation of FDP, FDP, and Interossei muscles. In contrast with finger flexors, wrist extensors
Hand 2
will work as a synergistic. The primary function of the extensor carpi radials brevis, extensor
digitorum help in maintains a powerful prehension. Placing the wrist in slight extension and
ulnar deviation increases the finger flexion strength, whereas wrist in flexion and radial deviation
decreases the wrist strength.
Mechanism of gripping
Torque
Grip
Shear Force
T = torque, S = total frictional or shear force, and D = handle diameter
T= S.D
Torque is dependent on handle diameter, large torque required for larger diameter.
Hand and Finger functions
A firm grip requires maximum output of extrinsic muscle torque. Whereas fine grip requires
more of the intrinsic muscles of the torque for fine-tune of the movements. There are different
types of handling.
Prehension handling:
Handle Diameter
Hand 3
Power grip
Precision handling
Cylindrical grip
Hook grip
Precision handling:
Pad-to-Pad prehension
Tip-to-Tip prehension (Precision pinch)
Pad-to-Side prehension (Power pinch)
Hand 4
Powerful grip (full hand prehension)
For powerful grip it requires fist position with flexion at all three joints of MP, PIP, and DIP
Example: holding the hammer, holding the bat.
Precision grip (finger-thumb prehension)
Hand 5
For fine precision there will flexion at PIP and DIP joints with one or two fingers
Example: Holding a ball, keeping the buttons.
Cylindrical grip
Hand 6
Finger tips towards the thumb
Example: holding a glass
Power Pinch (key pinch)
Hand 7
Stabilizing an object between the thumb and lateral border of index finger
The power pinch is formed by the activation of first dorsal Interossei and adductor pollicis.
Precision Pinch (tip-to-tip or pulp-to-pulp)
Hand 8
Object is hold between the thumb and index finger
Example: Holding a pen,
Hook grip
Hand 9
Holding the hook by partially flexing of PIP and DIP
Example: carrying luggage
References
Levangie, P.K., Norkin, C. C. (2001). Joint structure and function (3rd ed.). New Delhi: India.
Neumann, D.A. (2002). Kinesiology of the musculoskeletal system. Missouri: St. Louis.
Pennsylvania State University: Pennsylvania [Images]. Retrieved from: www.bsu.edu/.../hand
finger/ overview/overview.htm