Hand Function

Original Editor - Lucinda hampton Top Contributors - Lucinda hampton, Chrysolite Jyothi Kommu and Kim Jackson

Introduction

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The major function of the human hand is to manipulate objects to accomplish a goal.

  • The ability of a human hand to assure a myriad of position and to apply only the precise amount of pressure necessary to hold an object is due to: the mobility and stability supplied by the skeleton: the power of the muscle; the remarkable degree of sensory feedback from the nerves.
  • The sensory feedback is used to asses the shape, size, texture and weight of the object. The feedback used in both grasping and lifting of an object is dependent on the brain interpreting correctly, what is seen on the hand responding appropriately.[1]
  • Hand function has great significance for occupational performance. The greater the difficulties with hand function, the greater the impairment in skills that allow for independence and participation in academic and social activities[2]

Anatomy and Evolution

The features of human hands are easily distinguishable from those of the great apes, and they underpin the refined function and manipulatory abilities of our hands.

  • Hand muscles.png
    The most complex adaptations of the human hand involve the thumb, wherein a unique, fully independent muscle (the flexor pollicis longus) gives this digit remarkable strength in pinch and power grips.
  • The fingertips are broad and equipped with highly sensitive pads of skin.
  • The proportional lengths of the thumb and other fingers give us an opposable thumb with precise, firm contact between its tip and the ends of each of the other fingers.
  • A special saddle joint and associated ligaments at the base of the thumb facilitate refined rotation.
  • Special configurations of joints at the bases of the fifth, fourth, and second fingers facilitate tip-to-tip precision grips with the thumb.
  • Asymmetry of the heads of the second and fifth palm bones allows rotation of the articulated fingers during opposition with the thumb.
  • The small muscles in the hand allow fine control of the thumb and fingers.[3]
  • Hand function does not develop in isolation. Hand function is the result of neurologic development, physiologic maturation, and functional development of learned patterns of movement and motor control. The evolution of the cortical mechanisms in human beings enables the hand to reach its high levels of skill. The ability to perform such fine finger movements depends on the motor and sensory cortices.[4]

Types of Grip

The human hand is a miracle of evolution. Our elongated thumb is able to oppose our fingers, and hence manipulate objects and instruments with a far greater degree of precision than primates and other animals. The function of the hand is to grip, grasp and form precise movements, e.g. writing and sewing.

  • Hammer grip
  • Baseball batter grip
  • Precision grip (tip to tip)
  • Lateral Prehnsion
  • Key grip
  • Hook grip
  • Tripod (pen) grip[5]
The video below (8 minutes) explains the types of grips
[6]

Functional Position of Hand

Functional position of hand
  • It is the position where the hand is immobilized to interact with the surroundings.
  • This position is also used for non functioning hand for splint usage.[7]
  • It helps the non functioning hand to prevent contractures.[8]

Conclusion

Due to the hand's remarkable adaptability to functional requirements, as compared with the specialization in the forelimb of other animals, the hand is largely responsible for the creative manifestations that characterize the human species and that distinguish it from all other known forms of life.

The human arm, supported and controlled by a large number of muscles, together with the elbow and wrist joints, gives freedom to a hand that has become the willing servant of the human intellect. The hands are, as Kant is reported to have said, "man's outer brain."[9]

References

  1. UK Essays The Major Function Of Human Hand Psychology Essay Available from:https://www.ukessays.com/essays/psychology/the-major-function-of-human-hand-psychology-essay.php (last accessed 27.3.2020)
  2. Intervention for Children with Hand Skill Problems Charlotte E. Exner, in Hand Function in the Child (Second Edition), 2006 Available from:https://www.sciencedirect.com/topics/medicine-and-dentistry/hand-function (last accessed 27.3.2020)
  3. ENCYCLOPÆDIA BRITANNICA Human Evolution Available from:https://www.britannica.com/science/human-evolution/The-fossil-evidence (last accessed 27.3.2020)
  4. LYNN BASSINI, MUKUND PATEL, in Fundamentals of Hand Therapy, 2007 Manipulation Skills Available from: https://www.sciencedirect.com/topics/medicine-and-dentistry/hand-function(last accessed 27.3.2020)
  5. Ken hub Anatomy of grip Available from:https://www.kenhub.com/en/library/anatomy/anatomy-of-grip (last ccessed 27.3.2020)
  6. Hand Surgery Functions of the hand Available from:https://www.youtube.com/watch?v=01LyV3zeR2c&app=desktop (last accessed 27.3.2020)
  7. Farlex and Partners.Functional Position of Hand.In The Free Dictionary(2009).Accessed 31 March 2020
  8. Farlex and Partners.Functional hand position.The Free Dictionary(2012).Accessed 31 March 2020.
  9. Alpenfels EJ. The anthropology and social significance of the human hand. Artificial Limbs. 1955 May;2(2):4-21.Available from:http://www.oandplibrary.org/al/1955_02_004.asp (last accessed 27.3.2020)