ANATOMY QUESTION. Spinal nerves.

[elto]

Please explain: "Dorsal root ganglion contains the SOMATA of the afferent neurons"....Does it mean the "body" of th neurons? I understand there is only one afferent neuron needed on the PNS (no synapsis).....Help, I am soooooo confused!!!! I don't even know if my question makes sense

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[plunger]

Please explain: "Dorsal root ganglion contains the SOMATA of the afferent neurons"....Does it mean the "body" of th neurons? I understand there is only one afferent neuron needed on the PNS (no synapsis).....Help, I am soooooo confused!!!! I don't even know if my question makes sense

The preganglionic outflow of the parasympathetic nervous system arises from the cell bodies of the motor nuclei of the cranial nerves III, VII, IX and X in the brain stem and from the second, third and fourth sacral segments of the spinal cord. It is therefore also known as the cranio-sacral outflow.

Preganglionic fibres run almost to the organ which is innervated, and synapse in ganglia close to or within that organ, giving rise to postganglionic fibres which then innervate the relevant tissue. The ganglion cells may be either well organised (e.g. myenteric plexus of the intestine) or diffuse (e.g. bladder, blood vessels).

The cell bodies of the sympathetic preganglionic fibres are in the lateral horns of the spinal segments T1-L2, the so called thoraco-lumbar outflow. The preganglionic fibres travel a short distance in the mixed spinal nerve, and then branch off as white rami (myelinated) to enter the sympathetic ganglia. These are mainly arranged in two paravertebral chains which lie anterolateral to the vertebral bodies and extend from the cervical to the sacral region. They are called the sympathetic ganglionic chains. The short preganglionic fibres which enter the chain make a synapse with a postsynaptic fibre either at the same dermatomal level, or at a higher or lower level, and then the longer postganglionic fibres usually return to the adjacent spinal nerve via grey rami (unmyelinated) and are conveyed to the effector organ

 

[elto]

Thanks a lot for your explanation!!!