Rexedlaminae

Rexed laminae are a classic cytoarchitectural subdivision of the spinal cord’s dorsal horn, introduced by Bror Rexed in the 1950s. The system labels ten laminae (I–X), defined by cellular organization and staining patterns rather than strict anatomical boundaries. The laminae form a framework for describing where different sensory and reflex pathways terminate within the spinal cord and how they interact with motor outputs.

Laminae I–VI reside in the dorsal horn and are primarily involved in sensory processing. Lamina I (marginal layer) contains neurons that receive nociceptive and thermoreceptive input from A-delta and C fibers and project to higher centers. Lamina II (substantia gelatinosa) modulates nociceptive signaling through interneurons and receptor-rich networks. Laminae III–IV (nucleus proprius) integrate touch and proprioceptive information and relay signals to deeper laminae and ascending pathways. Laminae V–VI further process nociceptive and non-nociceptive input and contribute to the organization of somatotopic and multisensory information.

Lamina VII lies at the border of the dorsal and ventral horns and includes the intermediate zone, Clarke’s column in the thoracic region, and the intermediolateral cell column housing autonomic preganglionic neurons in some segments. Lamina VIII consists of interneurons surrounding the ventral horn and participates in reflex and motor coordination circuits. Lamina IX contains the motor neuron pools that innervate skeletal muscle. Lamina X surrounds the central canal and contains commissural neurons and interneurons linking both sides of the spinal cord.

Rexed laminae remain a foundational reference in neuroanatomy, aiding description of fiber terminations, reflex circuits, and segmental organization. Modern techniques supplement this framework with molecular and functional distinctions, but the laminar map continues to guide interpretation of spinal pathways.