anatomy of the accommodation reflex
Last reviewed 01/2018
The accommodation reflex has its afferent input from the primary visual pathway, i.e. sequentially: retina - optic nerve - optic chiasm - optic tract - lateral geniculate body - optic radiation - visual cortex, area 17.
The efferent pathway of the reflex starts in visual cortex, area 19. From here, corticocollicular fibres pass to the superior colliculi and corticopretectal fibres pass to the pretectal nuclei. From the superior colliculi, interneuronal links to the oculomotor nucleus in the midbrain permit contraction of the medial recti and thus convergence. From the pretectal nuclei, fibres pass forwards to the parasympathetic nucleus of Edinger Westphal and thence to the orbital cavity within the oculomotor nerve where they synapse with the ciliary ganglion. From the ciliary ganglion, postganglionic fibres innervate the ciliary muscle to broaden the lens, and constrictor pupillae to constrict the iris.