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The cellular laminae, also called Rexed laminae, are ten recognisable layers of grey matter in the spinal cord. They are arranged from the back, or dorsal side, towards the front, or ventral side. Each layer contains groups of nerve cells and connections that handle particular kinds of sensory, motor, or autonomic information.
Brief anatomy of the cellular laminae
The name Rexed laminae refers to the work of Bror Rexed, who described layers of spinal grey matter according to their cellular structure and function rather than location alone. This gives learners another way to understand the spinal cord alongside named nuclei and pathways.
Primary sensory neurons enter through the dorsal roots. Their cell bodies are located in dorsal root ganglia, which sit outside the central nervous system. Their incoming processes carry information from receptors in the skin, muscles, joints, and internal organs.
Different signals tend to terminate in different laminae. Pain and temperature information is strongly associated with the superficial dorsal horn, while touch, position sense, and muscle-related information reach deeper layers. Interneurons connect local groups of cells and can also link several spinal segments, helping shape reflexes and communication with the brain.
Functions of the cellular laminae
Together, the laminae form the grey-matter “butterfly” seen in a cross-section of the spinal cord. Their arrangement changes slightly at different levels of the cord, reflecting the different sensory and motor demands of the neck, trunk, and limbs.
Laminae I–VI: the dorsal horn
Receives mainly pain and temperature signals and contributes to pathways that carry these messages towards the brain.
Helps process sensory input and modulate pain. It is associated with the substantia gelatinosa.
Participates in light touch and position-related information and connects with deeper dorsal-horn layers.
Processes largely non-painful sensory information and forms part of the region associated with the nucleus proprius.
Integrates sensory signals, including potentially painful input, and receives influences from descending motor pathways.
Most evident in cervical and lumbosacral enlargements, it receives information from muscle spindles and supports reflex processing.
The first six laminae make up the dorsal horn. Sensory fibres entering the spinal cord synapse with interneurons here, allowing information to be sorted and relayed through ascending pathways such as the spinothalamic and spinocerebellar systems.
Lamina VII: an intermediate region
Lamina VII lies between the dorsal and ventral horns and changes in appearance according to the spinal level. It receives information from several dorsal-horn layers as well as from internal organs. It includes regions associated with autonomic control and with Clarke’s nucleus, which contributes to pathways carrying unconscious proprioceptive information towards the cerebellum.
Laminae VIII–IX: motor control
Laminae VIII and IX are prominent in the ventral horn, where motor output to skeletal muscle begins. Lamina VIII helps organise and modulate motor activity. Lamina IX contains clusters of larger motor neurons: alpha motor neurons supply skeletal muscle fibres, while gamma motor neurons regulate the sensitivity of muscle spindles.
The exact shape and distribution of these layers varies between cervical, thoracic, lumbar, and sacral levels. This variation reflects the changing number and type of muscles and sensory receptors served by each part of the spinal cord.
Lamina X: around the central canal
Lamina X surrounds the central canal in the middle of the spinal cord. It is sometimes described as the grey commissure. Connections crossing the midline in this region help coordinate activity between the two sides of the cord, while nearby cells contribute to the handling of visceral and other internal signals.
References and image source
This overview is intended as an accessible introduction. For detailed study, consult a current anatomy or neuroscience textbook and compare terminology across reliable educational references.
- Rexed, B. Research describing the cytoarchitectonic organisation of the spinal cord.
- Standard neuroanatomy references covering the spinal cord, grey matter, sensory tracts, and motor neurons.
- Image source: Unsplash photographs used for illustrative layout only.