[Thoracic vertebral nerve]

Area of Science:

• Comparative anatomy
• Evolutionary biology
• Neuroscience

Background:

• Phylogenetic studies suggest a potential caudal continuation of the vertebral nerve in the thoracic region of Mammalia.
• Understanding the sympathetic trunk's evolution requires investigating all its components.

Purpose of the Study:

• To investigate the existence and anatomical characteristics of the thoracic vertebral nerve in mammals.
• To determine the homology of the vertebral neural trunk in mammals with avian structures.

Main Methods:

• Embryological analysis
• Anatomical dissection
• Comparative studies in humans, cats, and dogs

Main Results:

• The thoracic vertebral nerve was identified in humans, cats, and dogs, alongside the cervical vertebral nerve.
• This nerve forms a plexus on the rudimentary thoracic vertebral artery, originating from multisegmentary gray rami communicantes.
• The thoracic vertebral nerve, combined with the cervical nerve, forms the vertebral neural trunk, homologous to the secondary sympathetic trunk in birds.

Conclusions:

• The thoracic vertebral nerve is an anatomical reality in mammals, contributing to the innervation of somatic and autonomic structures.
• This nerve likely represents a significant pathway in the sympathetic nervous system, potentially influenced by cervical vertebral nerve dysfunction.