Fig. 1
From: Vocal tract anatomy of king penguins: morphological traits of two-voiced sound production
Syrinx anatomy of the king penguin. a: Image of a male king penguin’ syrinx at the bifurcation of the trachea in the two primary bronchi (dorsal view). Internal illumination of the left bronchus reveals the pronounced vasculature of the medial labium (ML) and the medial tympaniform membrane (MTM). b: μCT 3D visualization of the right bronchus showing osseous tracheal rings and osseous (dark blue) and cartilaginous (light blue) bronchial rings surrounding the vibratory membranes. B1-B5 are completely ossified bronchial full rings, while B6 is a C-shaped half rings. B7-B22 are C-shaped cartilaginous half rings. B5-B11-B22: C-shaped cartilaginous rings of the main bronchus. c: μCT 3D visualization of a parasagittal section through the left side of the syrinx showing the lateral labium (LL), the ML, the MTM, bronchial cartilaginous rings (turquoise) and ossified bronchial rings superior to the vibratory tissue (dark blue)