optic chiasm

Scheme

showing central connections of the optic nerves and optic tracts.

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Anatomy of

the base of the human brain - diagram

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The left

optic nerve and the optic tracts.

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{{Information |description = |Other fields 1 = {{Information field|Name={{Ucfirst:{{Plate}}}}|Value=720}} |date = {{Other date|before|1858}} |source = *{{cite book |year=1918 |author=[[:en:Henry Gray|Henry Gray]] |title=Anatomy of the Human Body }} (See "{{Section header|Book}}" section below) *{{Gray"s Anatomy/link|720}} |author = {{Creator:Henry Vandyke Carter}} |other_versions = |permission = }} == {{Section header|Book}} == {{Gray"s Anatomy}} =={{int:license-header}}== {{PD-scan|PD-old-100-1923}} [[Category:Gray"s Anatomy plates|0720]] [[Category:Neuroanatomy]] [[Category:Corpus callosum]] [[Category:Cerebral aqueduct]] [[Category:Pia mater]] [[Category:Anterior commissure]] [[Category:Posterior commissure]] [[Category:Septum pellucidum]] [[Category:Human brain (sagitt

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Hypophyse

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en:Pituitary

gland in MRI (T1 sagittal without contrast enhancement). The arrow points at the posterior pituitary (Neurohypophysis, signalintens), the arrowhead at the anterior pituitary (Adenohypophysis).

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Optic chiasm

• Optic nerve and chiasm (Gray's illustration) - Ganzer Fall bei Radiopaedia

Hacking C, Optic nerve and chiasm (Gray's illustration). Case study, Radiopaedia.org (Accessed on 27 Nov 2022) https://doi.org/10.53347/rID-82179 • CC by-nc-sa 3.0 (modified)

Optic chiasm

• Normal optic nerves and chiasm - Ganzer Fall bei Radiopaedia

Gaillard F, Normal optic nerves and chiasm. Case study, Radiopaedia.org (Accessed on 27 Nov 2022) https://doi.org/10.53347/rID-35818 • CC by-nc-sa 3.0 (modified)

Extraocular

muscles • Eye and extraocular muscles (illustrations) - Ganzer Fall bei Radiopaedia

College, O. Eye and extraocular muscles (illustrations). Case study, Radiopaedia.org. (accessed on 21 Oct 2022) https://doi.org/10.53347/rID-44016 • CC by-nc-sa 3.0 (modified)

Cisterna

magna • Subarachnoid cistern (illustration) - Ganzer Fall bei Radiopaedia

Illustrations, G. Subarachnoid cistern (illustration). Case study, Radiopaedia.org. (accessed on 23 Oct 2022) https://doi.org/10.53347/rID-36291 • CC by-nc-sa 3.0 (modified)

Radiopaedia • CC-by-nc-sa 3.0 • de

The optic chiasm or chiasma is the midline structure where the nasal (medial) fibers of the optic nerves decussate to continue posteriorly as the optic tracts. It lies in the chiasmatic cistern and along with the pituitary stalk, is completely encircled by the circle of Willis.

Gross anatomy

Relations

The circle of Willis encircles the pituitary stalk and optic chiasma.

lateral: anterior perforated substance
anterior: optic nerves
posterior: optic tracts, tuber cinereum, pituitary stalk, mammillary bodies, posterior perforated substance
superior: supraoptic recess of the third ventricle, anterior commissure
superoposterior: hypothalamus
inferior: suprasellar cistern

The anterior-to-posterior location of the chiasm relative to the pituitary fossa is variable :

prefixed: tuberculum sellae (15%)
normal: diaphragma sellae (70%)
postfixed: dorsum sellae (15%)

Blood supply

Small branches of the anterior cerebral artery and the superior hypophyseal artery supply the chiasm and intracranial portion of the optic nerves whereas the optic tracts are supplied by small branches of the anterior choroidal and posterior communicating arteries.