The physiological anatomy and physiology of man

Optic nerve axons: life and death before birth

“…He was educated at the Hazelwood School in Birmingham from the age of 10 and, after a period in a country practice, was apprenticed to a locally renowned surgeon, Mr Joseph Hodgson, aged 16 His early scientific work, much of which was published jointly with Robert Bentley Todd (1809-1860) in The Physiological Anatomy and Physiology of Man, 2 accurately showed microscopic anatomy and related structure to function in muscle, kidney, the cochlea, skin, and other organs; he was greatly helped by his inherited drawing skills. Todd and Bowman's views on anatomy and physiology of the optic nerve (ON) were, naturally, coloured by the viewpoints of their teachers: 'Their (the optic nerves) anatomical disposition 'place it beyond all question that they are the proper conductors of visual impressions to the sensorium' and ' from this chiasma, the optic nerves spring, and diverge as they pass forwards into the orbits through the optic foramina'.…”

“…But y the blind spots do not correspond when the eyes are directed to the same object, and hence the blank, which one eye would present, is filled up by the opposite one'. 2 Bowman must have been one of the first to view the ON with an ophthalmoscope after its invention by Helmholtz in 1851, but his apparently expert use of this revolutionary instrument never resulted in publications on the ON, probably because his manual dexterity and the pressures and needs of practice led him to Bowman communicated an early study by the famous anatomist Henry Gray on chick micro-embryology, to the Royal Society in 1850. He was one of the first to recognize that the eye was not just intimately attached to but originated from the brain.…”

“…Other CNS malformations are frequent and may be due to abnormalities of other CNS neuron development. (2) There is a failure of RGC axon initiation and/or guidance, so the axons do not 'sprout' or they fail to reach the optic disc. (Tables 2 and 3).…”

A history of the optic nerve and its diseases

“…But y the blind spots do not correspond when the eyes are directed to the same object, and hence the blank, which one eye would present, is filled up by the opposite one'. 27 Experienced doctors such as the surgeon-anatomist William Cheselden (1688-1752) recognised the potential hazards of a blind spot in an only eye. He related the unfortunate tale of 'a gentleman, who having lost one eye by the smallpox', walked through a hedge in which 'a thorn unseen y struck the other and put it out'.…”

“…They finally opted for the idea of it being 'a power developed in the nervous structure under the influence of appropriate stimuli'. 27 The analogy between animal electricity in a nerve and a current of Voltaic electricity flowing along a conducting wire was commonly made by early investigators but shown to be erroneous in 1850 by Hermann Helmholtz (1821-1894) who measured the speed of nerve conduction and found that it was slower than current electricity. [41][42][43] Ludimar Hermann (1838-1914), a student of du Bois-Reymond, first demonstrated that, unlike current electricity in a wire, the nerve's motive principle was a self-propagating wave of negativity that advanced in segments along it, although he was unable to explain how it was transmitted from segment to segment.…”