RexedLamina

Rexed laminae, or Rexed’s laminae, are a standardized cytoarchitectural subdivision of the spinal cord gray matter into ten layers (I through X). Described by Harald Rexed in 1952, the scheme provides a consistent framework for labeling neuronal populations and their connections across species. The laminae are arranged from the dorsal to the ventral horn and central region, with distinctive cellular composition and presumed functions.

Lamina I – marginal layer; receives and processes nociceptive and thermoreceptive input from primary afferents. Lamina II – substantia gelatinosa; site of extensive modulation of pain and temperature signals. Laminae III–V – nucleus proprius; integrative processing of cutaneous and proprioceptive information. Lamina VI – base of dorsal horn; receives proprioceptive input and participates in sensorimotor integration (in humans this boundary is less clearly defined). Lamina VII – dorsal nucleus (including Clarke’s column in the thoracic and upper lumbar regions) and the intermediolateral cell column; autonomic and proprioceptive integration occur there. Lamina VIII – interneurons coordinating spinal reflexes and motor output. Lamina IX – motor neuron columns (anterior horn) giving rise to alpha and gamma motor neurons. Lamina X – around the central canal; contains interneurons and neurons linking left-right reflex circuits.

Clinical and research use: The mapping allows localization of deficits after spinal cord injury or disease; for example, pain-related dysfunction is often associated with laminae I–II, while motor weakness relates to lamina IX. Clarke’s column in lamina VII contributes to proprioceptive signaling. The Rexed scheme remains a foundational reference in neuroanatomy, though exact borders vary by species and developmental stage. See also Clarke’s column, dorsal horn, Lissauer’s tract, spinothalamic tract.