Spinal cord

What the sources say

“The Spinal Cord The description of the CNS is concentrated on the structures of the brain, but the spinal cord is another major organ of the system.” Betts et al. 2022, §13.2

“The cervical and lumbar spinal cords have enlargements as a result of larger populations of neurons.” Betts et al. 2022, §13.2

“The posterior columns are composed of axons of ascending tracts.” Betts et al. 2022, §13.2

“The large opening between the vertebral arch and body is the vertebral foramen , which contains the spinal cord.” Betts et al. 2022, §7.3

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• Brain–spine interfaces

  A digital bridge around a spinal cord injury. Implants read movement intentions from the cortex and turn them into stimulation of the lumbar cord, so that a person with paralysis can stand and walk under their own control.

• Central pattern generators

  The spinal circuits that can produce the rhythm of stepping on their own. Graham Brown's half-centre idea, where the circuits sit, and why they matter for walking again after spinal cord injury.

• Corticospinal tract

  The main route for voluntary movement, from the motor cortex down through the brainstem, across the midline and down the cord to the lower motor neurons. Why a cut on one side of the cord weakens the same side below it.

• Grey matter and Rexed laminae

  The H-shaped core of the cord. Its horns sort sensory input, drive muscles and run autonomic outflow, and the dorsal horn is layered into laminae that receive different kinds of sensation.

• Incomplete cord syndromes

  Why damage to one part of the cord's cross-section gives a recognisable pattern. Brown-Séquard, central cord, anterior cord and posterior cord patterns, explained from the tracts and the blood supply.

• Meninges and cerebrospinal fluid

  The three membranes around the brain and cord and the fluid between them. What dura, arachnoid and pia are, where cerebrospinal fluid is made and where it goes, and why a lumbar puncture is done low in the back.

• Spinal cord injury

  What happens when the cord is damaged, how the standard examination classifies the injury by level and completeness, which functions depend on the level, and what research is trying to restore.

• Spinal nerves and roots

  The 31 pairs of mixed nerves that connect the cord to the body. How each forms from a sensory and a motor root, where it leaves the column, and how the nerves regroup into plexuses.

• The action potential and conduction

  How a neuron fires an all-or-none electrical pulse and sends it along its axon, why myelin makes it faster, and the Hodgkin–Huxley equations that describe it.

• The dorsal column–medial lemniscus pathway

  The route for fine touch, vibration and position sense. It climbs the back of the cord on the same side, crosses in the medulla and reaches the sensory cortex through the thalamus.

• The dorsal root ganglion

  The swelling on each dorsal root that holds the cell bodies of the body's sensory neurons. Why those neurons have a single split process, and what surrounds them.

• The spinal cord

  The part of the central nervous system inside the vertebral column. How it is built from grey horns and white columns, why it is shorter than the column, and how its regions are named.

• The spinocerebellar tracts

  The cord's report to the cerebellum about where the body is. The cerebellum compares it with a copy of the motor command and corrects the movement.

• The spinothalamic tract

  The route for pain and temperature. Its fibres synapse as soon as they enter the cord and cross there, so a lesion of one side of the cord affects pain on the other side of the body.

• Vertebral and spinal cord levels

  Why "L1" can mean two different places. The vertebrae and the spinal cord segments have their own numbering, and below the neck they drift apart, because the column grows longer than the cord.