Parietal Foramen (other)
"Parietal foramen" may refer to: * Pineal foramen, a midline hole in the skull roof which hosts the parietal eye in many vertebrate species * Parietal foramina A parietal foramen is an opening in the skull for the parietal emissary vein, which drains into the superior sagittal sinus. Occasionally, a small branch of the occipital artery can also pass through it. It is located at the back part of the parie ...

Pineal Foramen
A parietal eye, also known as a third eye or pineal eye, is a part of the epithalamus present in some vertebrates. The eye is located at the top of the head, is photoreceptive and is associated with the pineal gland, regulating circadian rhythmicity and hormone production for thermoregulation. The hole in the head which contains the eye is known as a pineal foramen or parietal foramen, since it is often enclosed by the parietal bones. Presence in various animals The parietal eye is found in the tuatara, most lizards, frogs, salamanders, certain bony fish, sharks, and lampreys. It is absent in mammals, but was present in their closest extinct relatives, the therapsids, suggesting it was lost during the course of the mammalian evolution due to it being useless in endothermic animals. It is also absent in the ancestrally endothermic ("warm-blooded") archosaurs such as birds. The parietal eye is also lost in ectothermic ("cold-blooded") archosaurs like crocodilians, and in turtle ...
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