Taxonomy of Finfish (1+2)

2.1.5.10 Median groove

Median longitudinal groove or fontanel are two longitudinal-externally visible long depressions on the head and covered by skin in catfishes. They may be single or double and are in the center of the head extending from near the snout to the base of the occipital process. When single (Fig.21 A) it is a continuous depression without a break. When double it is interrupted (Fig. 21 B) in the middle by a short bone. These represent the passage for the cranial nerves in the skull. When covered with thick skin its extent can be found by inserting a needle and dragging (Fig. 21 C).

Fig. 21 Median groove. A. Continuous. B. Interrupted as two fontanels. C. Extent and identification of fontanel.