The hand extends from the fingertips to the pre & post-central gyri of the parietal lobe. It is an essential tool to interact with the environment. The presence of opposable thumbs has led the human race to build countless tools, from the pre-historic hunter-gatherers to a teenager ‘texting’ around the clock.

1. Mr Vaikunthan Rajaratnam
MBBS(Mal),AM(Mal),FRCS(Ed),FRCS(Glasg),FICS(USA),MBA(USA)
Dip Hand Surgery(Eur), Dip MEd(Dundee),MIDT Dist.(OUM)
FHEA(UK),FFST(Ed),FAcadMEd(UK)
Senior Consultant Hand Surgeon
Hand Biomechanics
and
Basic Functions
www.handsurgerymanual.com
vaikunthan@gmail.com

2. OER for this lecture
http://tinyurl.com/HandAnatomy
From
www.handsurgeryedu.com

3. Understanding Hand Surgery: A guide for junior doctors. (2008).
The hand extends from the fingertips to the
pre & post-central gyri of the parietal lobe. It
is an essential tool to interact with the
environment. The presence of opposable
thumbs has led the human race to build
countless tools, from the pre-historic hunter-
gatherers to a teenager ‘texting’ around the
clock. It enables skilled workers to earn a living
and is an instrument for written speech as
well as non-verbal communication.

4. The signal change in human evolution was due to the upright gait.
When man lifted his hands from the ground they were freed from the purpose of locomotion and were put into the service of
intelligence

6. Brain and Mind
•Cognition•Ego
•Memory•Senses & Motor
TEMPORO
PARIETEAL
LOBE
HIPPOCAMPUS
PREFRONTAL
CORTEX
DORSOLATERAL
PREFRONTAL
CORTEX

7. Drivers for attention of the Brain
•Food
•Fight
•Flight and
•Fornication
http://alieninthecaribbean.blogspot.sg/2011/10/2012-survival-kit-fear-and-fighting.html

8. The seat of learning
• Area 4 the primary motor cortex, and
Area 6 immediately forward of Area 4
• Area 6 the premotor area (PMA) +
signals of sensory components - guide
the movements of the body
• Supplementary motor area (SMA), in the
inner part of Area 6, -planning and
execution of complex movements of
both hands.
• This area together with the lower portion
of the parietal lobe is where the mirror
neuron system

9. Mirror neuron
systems
• active during goal-directed action
and while observing the same
motor act
• meaning of a motor act (action
understanding) is represented in
this “mirror neuron system”
(MNS).
• ability to observe and accurately
imitate
• activated when an action is
executed, observed, anticipated or
imagined
• activated during kinaesthetic
imagery

10. `

11. •
Napier JR (1955) The form and function of the carpo-metacarpal joint of the thumb. J. Anat. 89, 362–369.

12. Prehensile function
• thumb stability
• full abduction or full adduction at CMC joint
• articular surfaces congruent
• Precision thumb fully abducted + stability by opposing another digit
• Power thumb fully adducted

13. Young, R. W. (2003). Evolution of the human hand: the role of throwing and clubbing. Journal of Anatomy, 202(1), 165–174.
https://doi.org/10.1046/j.1469-7580.2003.00144.x
anatomical reconstruction of the hand during human evolution - linked with tool
behaviour

14. Throwing and Clubbing
Grasping a spheroid and precisely controlling its
release, required for accurate throwing, demands a grip
that differs from one that can firmly grasp a cylindrical
club-handle and absorb the reaction force of impact
without release of the weapon
The balance of strength and robusticity has shifted radia
to the thumb, index and middle fingers
The flexor pollicis longus muscle, absent in
chimpanzees, is the most powerful thumb muscle in
humans.
‘precision grip’ is a throwing grip
‘power grip’ is a clubbing grip
Young, R. W. (2003). Evolution of the human hand: the role of throwing and clubbing. Journal of Anatomy, 202(1), 165–174.

15. Adaptations for throwing
•Grip the missile
•Energy transmitted
•Accurate release.

16. Requirements for throwing
• Fingertip grip
• Mobile and long thumb
• Opposable thumb pad to missile
• Other finger pads to opposite side
For accurate release:-
• precise neural control
• absorb the reactive propulsive thrust

17. ‘… there are only two prehensile
actions: these are called the precision grip and the
power grip’ (Napier, 1965).
• fingers rotate towards the central axis to meet the tip of the
thumb
• Metacarpal hamate articulation - supination of the 4th & 5th MC
• heads 2nd & 3rd metacarpals - pronation of the proximal
phalanges.
Stability 3rd metacarpal base –
• dorsal styloid process preventing hyperextension
• Volar ligament - pisiform to the 3rd metacarpal
base

34. OER for this lecture
http://tinyurl.com/HandAnatomy
From
www.handsurgeryedu.com
vaikunthan@gmail.com