Sense organs (eye and ear)
Retina
Retina
- Origin
- Innermost neurosensory layer of the globe, from the optic disc to the ora serrata
- Insertion
- Lies against the retinal pigment epithelium and the choroid; the axons gather into the optic nerve
- Function
- Converts light into nerve impulses: rods for dim light, cones for colour and acuity in the macula lutea and fovea centralis
- Innervation
- Forms the beginning of the optic pathway itself (cranial nerve II); supplied by the central retinal artery and the choroid
- Movement & chain
- Follows the globe; saccades keep the fovea aimed at the point of fixation
- Palpation
- Fundoscopy of disc, vessels, macula and periphery; visual acuity and visual field testing
- Clinical
- Retinal detachment (flashes, floaters, a curtain), diabetic retinopathy, age-related macular degeneration, central retinal artery occlusion
- Segmental innervation
- Cranial nerve II; visual pathway to the occipital lobe
- In clinical practice
- Acute painless visual loss is an emergency; annual fundus screening in diabetes
- Region in the model
- Sense organs (eye and ear)