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One of my textbook says this: "A double chain of ganglia on each side of the nerve cord belongs to the spinal cord."

But the diagrams I saw on internet depict only one dorsal root ganglion.

I am unclear which is wrong my textbook or the diagram.

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There are only single dorsal root ganglia on each side of the spinal cord, within the dorsal (sensory) root of the spinal nerves. If it is specifically referring to dorsal root spinal ganglia, the textbook is presumably describing the bilateral anatomy as a 'double chain'.

In addition, the dorsal root ganglia develop in the embryo from neural crest cells, as opposed to neural tube cells. Thus, the spinal ganglia can be considered grey matter of the spinal cord that is translocated to the periphery: that is, they 'belong to the spinal cord'.

Alternatively, the textbook may be referring to the Sympathetic Chain of Ganglia, a 'double chain' whose two components lie either side of the vertebral column and spinal cord, and consist of nerve fibres emanating from its ventral roots. Any decent textbook of Anatomy should be pretty clear about this.

For your interest, 'Wikipedia' describes the latter in part as follows:

Sympathetic Chain Ganglia.

The bilaterally symmetric sympathetic chain ganglia, also called the paravertebral ganglia, are located just ventral and lateral to the spinal cord. The chain extends from the upper neck down to the coccyx, forming the unpaired coccygeal ganglion. Each ganglion within this chain is either cervical, thoracic, lumbar, or sacral. Preganglionic nerves from the spinal cord synapse at one of the chain ganglia, and the postganglionic fiber extends to an effector, a visceral organ in the thoracic cavity, abdominal cavity, or pelvic cavity.

There are usually 22–23 pairs of these ganglia (which is interesting number in view of chromosomal numbers): 3 in the cervical region (cervical ganglia), 11 in the thoracic region (including the stellate cervicothoracic ganglia), 4 in the lumbar region and 4–5 in the sacral region, collectively known as the 'Sympathetic Trunk'.


I hope this helps to clarify things in an area which is clearly problematic to describe without a precise anatomical diagram.

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  • $\begingroup$ Can someone please explain the down-vote: is the answer incorrect or incomplete? And voting like that without explanation is akin to assaulting someone on a public street for no apparent reason. Very cowardly. State your case sir. $\endgroup$
    – jeremiah
    Commented Mar 22 at 15:56

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