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The archosaurian shift from larynx to syrinx must have conferred a selective advantage for crown birds, but the causes for this shift remain unknown. [10] To complicate matters, the syrinx falls into an unusual category of functional evolution: arising from ancestors with a larynx-based sound source, the syrinx contains significant functional overlap with the structure it replaced.
Lateral dominance of the hypoglossal nerve conveying messages from the brain to the syrinx was first observed in the 1970s. [3] [4] This lateral dominance was determined in a breed of canary, the waterschlager canary, bred for its long and complex song, by lesioning the ipsilateral tracheosyringeal branch of the hypoglossal nerve, disabling either the left or right syrinx.
The avian vocal organ is called the syrinx; [12] it is a bony structure at the bottom of the trachea (unlike the larynx at the top of the mammalian trachea). The syrinx and sometimes a surrounding air sac resonate to sound waves that are made by membranes past which the bird forces air.
Adult neurogenesis in the avian brain occurs in many different pallial regions, including the song nuclei, the hippocampus, and the olfactory regions. [6] Even though adult neurogenesis is widespread across the telencephalon, all the regions where it is especially high are associated with the learning of new information, suggesting a possible function of adult neurogenesis to be offering an ...
A fluid-filled lesion forms, known as a syrinx. [1] This can vary in size significantly between patients. [1] Nerve fibres may be compressed where they cross the midline, or in other parts of the spinal cord. [1] Cranial nerves may be affected. [3] Syringobulbia may be associated with syringomyelia, a syrinx limited to the spinal cord. [4]
The vocal tract is the cavity in human bodies and in animals where the sound produced at the sound source (larynx in mammals; syrinx in birds) is filtered.. In birds, it consists of the trachea, the syrinx, the oral cavity, the upper part of the esophagus, and the beak.
Diagram showing the general layout of air sacs in a bird. Birds have a system of air sacs in their ventilation system. [2] The air sacs work to produce a unidirectional flow where air enters and exits the lung at the same rate, contrasting the lungs of other tetrapods such as mammals where air enters and exits the lung in a tidal ventilation.
Cerebrospinal fluid fills the syrinx. Pressure differences along the spine cause the fluid to move within the cyst. Physicians believe that it is this continual movement of fluid that results in cyst growth and further damage to the spinal cord. In the case of syringomyelia, the syrinx can expand and elongate over time, destroying the spinal ...