The Human Brain : From Neurone to Nervous System

SPINAL CORD :Anatomy


  1. The spinal cord is a segmented structure which gives rise to spinal nerves that emerge from the vertebral column below the corresponding vertebra. In humans there are 8 cervical, 12 thoracic, 5 lumbar and 5 sacral segments

  2. The spinal cord is arranged as a series of segments, each of which has a similar structure. The cord is attached to the brainstem and ends at the second lumbar vertebral segment (L2). In humans there are 8 cervical, 12 thoracic, 5 lumbar and 5 sacral segments and the spinal nerves from each segment of the cord emerge from the vertebral column below the corresponding vertebra.

  3. The sacral and coccygeal nerves arise from the cord above vertbral segment L2, but travel within the meninges before they emerge from the vertebral column in the sacrum: these nerves are called the ‘cauda equina’, because of their resemblance to a horse’s tail.

  4. Each spinal nerve is joined to the cord in two roots, the dorsal and ventral roots. The dorsal roots contain sensory fibres and have cell bodies in the dorsal root ganglion; the ventral roots contain motor axons whose cell bodies are within the grey matter of the spinal cord.

  5. Sensory neurones have cell bodies in the dorsal root ganglia and axons that enter the cord via the dorsal roots. The peripheral terminations of the sensory neurones end in the tissues of the body.

  6. Key Words: Spinal segments, spinal nerves, dorsal and ventral roots, dorsal root ganglia, white and grey matter, cauda equina.









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