Last revised by Daniel J Bell on 12 Aug 2018

The lambda is the midline bony landmark where the lambdoid sutures and sagittal suture meet, between the occipital and two parietal bones. It may be a depression and therefore palpable. Accessory occiptal bones are common near the lambda, usually associated with the lambdoid sutures.

It is the posterior fontanelle in the neonate and closes by the second month after birth 2 (although normal closure can occur up to 6 months after birth).

It is one of the skull landmarks, craniometric points for radiological or anthropological skull measurement.

History and etymology

The lambda is so-called because of the upside-down V shape formed by the two lambdoid sutures meeting at the lambda. The Greek letter lambda 'Λ' is this shape.

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