Dissected : the incredible human foot.

In the second of two programmes, biologist Dr George McGavin is joined by leading anatomy experts to dissect the human foot, taking it apart layer by layer to reveal what makes it unique in the animal kingdom, enabling us to stand and walk upright for long periods. In the anatomy lab of Glasgow University, a tissue specimen is prepared by anatomist Dr Quentin Fogg according to medical and ethical protocols. Fogg, overseen by leading foot surgeon Kartik Hariharan, pulls back the skin from the sole, which acts as a shock absorbing pad. Hariharan uses McGavin’s feet to demonstrate the distribution of sensation across the sole. In Dundee, McGavin meets biomechanics expert Professor Rami Abboud, who is researching the effects of walking and running. Running in training shoes exerts forces equivalent to three times our body weight through the heel. This level of impact places immense pressure on the knees and hips; Abboud’s findings show that barefoot running significantly reduces stress to the joints by shifting the strike to the ball of the foot. Next, the dissection team reveal the plantar fascia, an important tissue layer which connects the toes to the heel, giving mechanical strength to the foot. Moving on to the calf muscles, the team illustrate how, together with the Achilles tendon, they provide the power we need for movement. But our feet are also capable of precise movements; artist Tom Yendell was born without arms and uses his feet to paint and draw. Under the planta fascia are many smaller tendons allowing for flexibility. At Chester Zoo, McGavin meets Professor Robin Crompton, who studies modern primates to better understand how we walk. Orang-utans use their feet in a similar way to our hands. This flexibility comes from the mid-tarsal joint, long thought to be defunct in humans. Crompton’s research has shown that, in fact, our mid-tarsal joint can bend when we walk – our foot’s apparent rigidity is due to soft tissues, which allow our feet to be both rigid and flexible. Ligaments help to stabilise the joints without using energy. Eve Mutso, soloist with Scottish Ballet, demonstrates pointe work – an example of the foot’s immense power and flexibility. Finally, the team dissect the big toe. McGavin concludes by investigating balance. At Manchester Metropolitan University, he meets Professor Ian Loram who specialises in how our bodies control movement. According to Loram, there are three elements to balance: vision, vestibular apparatus and proprioception. The latter (a sense of where the body is in space) is possible because the muscles are continually sending information to the brain, communicating their precise location. It relies on contact between the muscles in our legs and feet and a stable ground surface. Loram demonstrates a machine that reduces proprioception by removing this stability. A second experiment requires McGavin to walk along a narrow plank on the floor, and again on the same plank raised high off the ground. When in the air, McGavin’s muscles tense, distorting his sense of proprioception and reducing his balance, making the process far more difficult. The experiment demonstrates how a psychological effect can impair a physical function.