Dissected : the incredible human hand.

In the first of two programmes, biologist Dr George McGavin is joined by leading anatomy experts to dissect one of the most amazing structures in the natural world: the human hand. In a purpose-built lab, the team dissect a real hand, taking it apart layer by layer to reveal what makes it unique. The human hand’s unrivalled combination of power and precision has enabled us to shape the world around us. In the anatomy lab of Glasgow University, a tissue specimen is prepared by anatomist Dr Quentin Fogg according to medical and ethical protocols. With assistance from leading hand surgeon Donald Sammutt, the team begin at the forearm. The fat is removed to reveal the muscle; the source of power for the fingers. Each muscle connects to a tendon which actuates the movement. Sammut discusses different types of grip – the scoop, power and key grip – which give our hands versatility. With the assistance of Dr Nigel Callender, McGavin tests his finger strength against rock climber Ned Feehally, who can exert a quarter more force. Callender explains how both tendons and pulleys (soft tissues that hold the tendons against the finger bone) become thicker in climbers. The human hand is also a precision instrument. Magician Kevin McMahon discusses sleight of hand techniques. Crucial to all card tricks is the thumb – the most versatile and important of our digits. The team start dissecting the hand itself, revealing the size of the muscles dedicated to the thumb. Moving on to the skeleton, Sammutt demonstrates how the thumb joints allow for opposability. McGavin meets Dr Tracy Kivell to learn more about the differences between our hands and those of our closest animal cousins, chimpanzees. While all apes and monkeys have opposable thumbs, theirs are far shorter and weaker. The evolution of the human hand is likely to have been driven by stone tool use, Kivell explains. Surprisingly, it is far better to lose an index than a little finger, which is the most mobile after the thumb. Using the action of unscrewing a bottle top, Sammutt demonstrates the precision grip – the three jaw chuck. Fogg isolates the lumbrical muscles, revealing how they subtly alter finger movements. Finally, McGavin explores the sensitivity of the nerves in our fingertips and their interactions with our brain, allowing us to perceive and understand our environment. The fat pads of the finger tips are one of the most densely concentrated areas of nerve endings in the body. Sensitivity specialist Dr Frances McMahon discusses their various microbiological structures. At Exeter University, McGavin meets Dr Ian Summers, who is developing technology to simulate touch remotely. The machine works by making small pins vibrate to simulate the surface of fabrics.