Optic chiasm at a glance
- What it is
- The optic chiasm is the X-shaped junction where fibres from the two optic nerves partly cross.
- Location
- It lies above the diaphragma sellae and pituitary gland, at the base of the brain in front of the infundibulum and below the hypothalamus.
- Function
- Fibres from the nasal half of each retina cross to the opposite optic tract, so that each tract carries information from the opposite visual field.
- Body system
- Nervous · single, midline structure
- FMA ID
- FMA62045 (Foundational Model of Anatomy)
Key facts
- Crossing fibres carry information from the temporal visual fields.
- Uncrossed fibres from each temporal retina pass along its lateral edges into the ipsilateral optic tract.
- It lies in front of the infundibulum and is bathed by the chiasmatic cistern; the internal carotid arteries lie beside it.
Clinical relevance
Pituitary tumours that compress the chiasm typically cause bitemporal hemianopia.
Structures next to the optic chiasm
The nearest named structures in the 3D model, measured from the centre of each part:
- Hypothalamus · nervous
- Lamina terminalis · nervous
- Anterior communicating artery · cardiovascular
- Pituitary gland · endocrine
- Mammillary body · nervous
- Posterior communicating artery · cardiovascular
- Precommunicating part of posterior cerebral artery · cardiovascular
- Anterior cerebral artery · cardiovascular
- Anterior commissure · nervous
- Peduncle of midbrain · nervous
References
- Foundational Model of Anatomy: Optic chiasm (FMA62045). EMBL-EBI Ontology Lookup Service.
- OpenStax. Anatomy and Physiology 2e, §12.1 Basic Structure and Function of the Nervous System. Rice University, 2022.
- Mitsuhashi N. et al. (2009). BodyParts3D: 3D structure database for anatomical concepts. Nucleic Acids Research 37, D782–D785. Data © The Database Center for Life Science, CC BY 4.0.
Related anatomy
Explore the whole body in the interactive 3D human anatomy model, or browse the A–Z list of human structures.