Optic chiasm
Updates to Article Attributes
Body
was changed:
The optic chiasm or chiasma is the midline structure where the nasal (medial) fibres 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: infundibular recess of the third ventricle
Blood supply
Small branches of the ACA 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 PCom arteries.
Related pathology
Lesions compressing the chiasm classically produce the visual field defect of bitemporal hemianopia, where thethere is loss of the temporal fields.
-</ul><h4>Blood supply</h4><p>Small branches of the <a href="/articles/anterior-cerebral-artery">ACA</a> and the <a href="/articles/superior-hypophyseal-artery">superior hypophyseal artery</a> supply the chiasm and intracranial portion of the optic nerves whereas the optic tracts are supplied by small branches of the <a href="/articles/anterior-choroidal-artery">anterior choroidal</a> and <a href="/articles/posterior-communicating-artery">PCom arteries</a>.</p><h4>Related pathology</h4><p>Lesions compressing the chiasm classically produce the visual field defect of bitemporal hemianopia, where the is loss of the temporal fields.</p>- +</ul><h4>Blood supply</h4><p>Small branches of the <a href="/articles/anterior-cerebral-artery">ACA</a> and the <a href="/articles/superior-hypophyseal-artery">superior hypophyseal artery</a> supply the chiasm and intracranial portion of the optic nerves whereas the optic tracts are supplied by small branches of the <a href="/articles/anterior-choroidal-artery">anterior choroidal</a> and <a href="/articles/posterior-communicating-artery">PCom arteries</a>.</p><h4>Related pathology</h4><p>Lesions compressing the chiasm classically produce the visual field defect of bitemporal hemianopia, where there is loss of the temporal fields.</p>
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