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An experimental study concerning the accessory nerve in the chicken and turkey
Anatomischer Anzeiger
|January 1, 1975
Summary
Accessory nerve transection in chickens and turkeys reveals its origin exclusively from the ipsilateral dorso-central motor column. This finding clarifies avian neuroanatomy, showing homology with the mammalian external ramus but an absence of the internal ramus.
Area of Science:
- Neuroscience
- Comparative Anatomy
- Avian Biology
Background:
- The precise origin of the accessory nerve in birds has been a subject of anatomical inquiry.
- Understanding cranial nerve origins is crucial for avian neurobiology and comparative studies.
Purpose of the Study:
- To definitively identify the origin of the accessory nerve in chickens and turkeys.
- To establish the homologies between the avian accessory nerve and its mammalian counterpart.
Main Methods:
- Surgical transection of the accessory nerve in avian subjects (chicken and turkey).
- Histological examination to observe retrograde degeneration patterns.
- Tracing neural pathways to identify the nerve's origin nucleus.
Main Results:
- Retrograde degeneration confirmed the accessory nerve originates exclusively from the ipsilateral dorso-central motor column.
- This nucleus extends through cervical neuromeres and connects to the hypoglossal nucleus.
- The avian accessory nerve is homologous to the mammalian external ramus; an internal ramus is absent in birds.
Conclusions:
- The study precisely localizes the accessory nerve's origin in birds.
- It provides critical insights into the comparative neuroanatomy of cranial nerves between birds and mammals.