Myodoma

from Wikipedia, the free encyclopedia

The (previously rarely also: the) myodoma (Greek: "muscle house") is an extramural (located outside the meninges), intracranial (located in the skull) paired space of pyramidal shape to accommodate the four straight eye muscles in bony fish (Osteichthyes). For a long time they were considered to be proof of “pointless” formations in living beings, because “why does a fish need such strong, long eye muscles?” But it does need them - against the water that flows past (when moving) that the eyeball moves when it moves easily flutter (especially if something is fixed in front of the mouth with both eyes). Small-eyed, visually impaired fish do not have myodomas. These extend dorsally from the parasphenoid and prooticum from the eye socket ( orbit ) to the rear edge of the basioccipital (e.g. in salmon fish ). Small anterior myodomas (for the two oblique eye muscles; reaching into the nasal capsule) are also often developed.

literature

  • Kurt Fiedler: Textbook of Special Zoology, Volume II, Part 2: Fish. Gustav Fischer Verlag, Jena 1991, ISBN 3-334-00339-6 , p. 49.