About Sir Charles Bell
This segment authored by Jonathan Cole
Bell’s contribution to medicine and what is now termed neuroscience has focussed on the facial nerve and Bell’s palsy for good clinical reason. But he is also remembered for his naming of the long thoracic nerve and the regrettable controversy with Magendie over who first described the dorsal roots as sensory. In this short review, however, I will focus on what I consider to be perhaps his most lasting work contained in his astonishing prescient book on the Hand.1
In this he first described movement and position sense or proprioception (named as such by Sherrington 80 years later), active touch, affective or pleasantness of some sensation, the protective role of sensation in pressure sores, and whether the sense of effort was central from perception of outgoing motor signals or was peripheral originating, something still debated today.
All these ideas were also made in part by deduction since Bell was also kind. For, in the days before anaesthesia, experiments on animals were done while the animal was conscious and without analgesia, conditions similar to those under which surgeons operated on patients. Bell wrote in a letter,
‘I should be writing a third paper on the nerves but I cannot proceed without making some experiments, which are so unpleasant to make that I defer them. You may think me silly, but I cannot perfectly convince myself that I am authorised in nature, or religion, to do these cruelties – for what? – for anything else than a little egotism and self-aggrandisement; and yet, what are my experiments in comparison with those which are daily done? And daily done for nothing.’2
His description of proprioception immediately discusses the way in which this sense of sometimes hidden or implicit and yet at other times becomes very much in mind.
‘When a blind man, or a man with his eyes shut, stands upright… by what means is it that he maintains an erect position? How is it that a man inclines in due degree towards the winds? It is obvious that he has a sense by which he knows the inclination of his body and that he has a ready aptitude to adjust it… It can only be by the adjustment of muscles that the limbs are stiffened. There is no source of knowledge but a sense of the degree of exertion in his muscular frame…
In truth he stands by so fine an exercise of this power, and the muscles are, from habit, directed with so much precision and with an effort so slight, that we do not know how he stand. But if we attempt to walk on a narrow ledge, or stand in a situation where we are in danger of falling we become subject to apprehension; the actions of the muscles are magnified and demonstrative to the degree in which they are excited.
We are sensible of the position of our limbs… although we touch or see nothing. It must be a property internal to the frame… what can it be but a consciousness of the degree of action…’ p197.
‘Great authorities made no account of the knowledge derived from the motions of our own frame. I called this a sixth sense.’ P194.
From an experiment he relates how,
‘muscles [have] two classes of nerves – that on exciting one the muscle contracted; that on exciting the other, no action… a nerve of sensation. Thus it was proved that there is a nervous circle connecting the muscles with the brain… for the regulation of muscular action, there is a muscle of sensibility to convey a sensation of the condition of the muscles to the sensorium, as well as conveying the mandate of the will to the muscles.’
He also described what is today known as active touch, the way in which touch depends on not only sensation on the skin, but a knowledge of the exploratory movements occurring as we manipulate an object in our hand.
‘… in the use of the hand there is a double sense exercised; we must not only feel the contact of the object, but we must be sensible to the muscular effort which is made to reach it, or to grasp it with the fingers. P150.
He also saw how touch unconsciously protects us from pressure sores.
‘everyone changes their position and shifts the weight of his body; were you constrained to retain one position during the whole hour you would rise stiff and lame. The sensibility of the skin is guiding you, which if neglected, would be followed by the death of the part. … A patient with paralysis of the lower part of the body, we must give especial directions to the nurses and attendants that the position of his limbs be changed at short intervals, that pillows be placed under his loins and hams and that they be often shifted. If this is neglected, you know the consequence to be inflammation of the parts that press upon the bed; from which come local irritation, then fever and mortification and death.
Thus you perceive the natural sensibility of the skin, without disturbing your train of thought, to shift the body to permit the free circulation of the blood in the minute vessels... when this is wanting the utmost attention of friends and the watchfulness of the nurse are but a poor substitute.’ P158.
The book is alive with observation and insight.
‘Does an infant feel pain; He is capable of the expression of pain… but the infant during operations makes no effort to repel the instrument of surgeon when being operated on.’ P192.
At the time it was common to cut the nerves from the feet of horses to prevent lameness on the new harder roads, an operation known as foundering.
‘Divide the nerve and the horse, instead of making timid steps, puts out his feet freely and the lameness is cured. But … the foot loses its natural protection, the feeling of the ground, which is necessary to his being perfectly safe as a roadster.’ P185.
He went on to say how this was evident on uneven ground but not on level roads, when peripheral feedback was more important. He realised that the nervous system needs novel stimuli or it would adapt and fatigue,
‘For the nervous system it holds universally that variety of contrast is necessary for sensation, the finest organ of sense losing its property by the continuance of the same impression.’ P160.
In relation to phantom limbs he realised that there was an internal perception, independent of peripheral feedback,
[Phantom limbs] move with change in posture of the body. There is an internal sensibility corresponding with the changing conditions of the body…. P199
He understood that the spring of the foot acts to absorb and then elastic recoil forces during running, which aids propulsion, something shown empirically in the 1980’s. Lastly he realised that, ‘exercise of the muscular frame is the source of some of our chief enjoyments. This activity is followed by weariness and a desire for rest; and although unattended with any describable pleasure of local sensation, there is diffused through every part of the frame a feeling almost voluptuous.
It would appear in modern times that we know comparatively little of the pleasures arising from motion. The Greeks and even the Romans, studied elegance of attitude and of movement… Their dances were not the result of mere exuberance of spirits and activity; they combined harmony in the motion of the body and limbs, with majesty of gait…’
The Hand book is full of observation and theoretical discussion, much of which seems to anticipate neuroscientific ideas by many years.
Reference and Notes.
1. Sir Charles Bell, 1833. The Hand: Its Mechanism and Endowments as Evincing Design. London: Pickering. Reprinted by The Pilgrims Press, Brentwood, Essex, 1979.
2. Sir Gordon Gordon-Taylor and EW Walks, Sir Charles Bell: His Life and Times, 1958. They comment, ‘The particular period of his surgical activity before the advent of anaesthesia prevented one of his gentle humanity from equalling the exploits of surgical competitors who were cast in a tougher mould.’
3. He also catalogued the way in which animals were created (by God he thought) successively and in a manner appropriate for different environments. ‘any other hypothesis that that of a new creation of animals suited to the successive changes in the inorganic material of the globe – the condition of the water, atmosphere and temperature – brings with it only an accumulation of difficulties.’ P149. Darwin was not impressed that Bell was a religious creationist.