Human Anatomy Part 2 - K. A. Dyubenko, A. K. Kolomiytsev, Yu. B. Chaykovsky 2008

Special Part
Sense Organs, organa sensuum
Organ of Vision - Pathway of the Visual Analyzer

Light rays pass through the cornea, the anterior and posterior Chambers of the eye, the lens, the vitreous body, and the retina. The outer layer of the neural retina contains photoreceptors—rod and cone neurosensory Cells. Under METABOLISM/18.html">The Influence of light, the rhodopsin in these cells decomposes, generating an impulse that is transmitted to bipolar neurocytes (the 1st neuron of the visual pathway). Next, the impulse is transmitted to ganglion neurocytes (the 2nd neuron), whose axons form the Optic nerve (n. opticus) in the posterior pole region of the eye. After a partial decussation, these same axons form the optic tracts (tr. optici). Each tract includes the medial half of the fibers from the contralateral optic nerve and the lateral half of the fibers from the ipsilateral nerve. The nerve fibers of the optic tracts terminate in the thalamus, the lateral geniculate bodies, and the superior colliculi of the Midbrain. Nerve Cells of the latter establish connections with the nuclei of Cranial Nerves III, IV, and VI (regulation of Eyeball movements and pupil diameter changes) and with the anterior horns of the Spinal Cord (tr. tectospinalis).

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Fig. 219. Diagram of the visual pathway (according to I. Ye. Kefeli)

Axons of the Neurons of the thalamus and lateral geniculate bodies (the 3rd neuron) pass through the posterior limb of the internal capsule to the region of the sulcus calcarinus (area 17), where the cortical center of the visual analyzer is located.



Last update: 08/08/2026

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