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The nictitating membrane of a masked lapwing as it closes over the left eye, originating from the medial canthus. The nictitating membrane (from Latin nictare, to blink) is a transparent or translucent third eyelid present in some animals that can be drawn across the eye from the medial canthus to protect and moisten it while maintaining vision.
Ileum, caecum and colon of rabbit, showing Appendix vermiformis on fully functional caecum The human vermiform appendix on the vestigial caecum. The appendix was once believed to be a vestige of a redundant organ that in ancestral species had digestive functions, much as it still does in extant species in which intestinal flora hydrolyze cellulose and similar indigestible plant materials. [10]
punching out holes in bones or other tissues •Henckle's punch forceps: punching out holes in bones or other tissues Eustachian (tube) catheter: on certain procedures of the eustachian tube or the middle ear like patency test; inflate middle ear and clear eustachian tube blockade; removal of foreign body of the nose; as a suction cannula. Mirrors
The membrane works to protect and moisten the eyelid while maintaining visibility. It also contributes to the aqueous portion of the tear film and possibly immunoglobulins. [ 14 ] Humans and some primates have a much smaller nictitating membrane; this may be because they do not capture prey or root vegetation with their teeth, so that there is ...
Treatment consists in proper eye hygiene and avoiding the allergens that trigger the condition. In rare cases, topical creams may be used but only under a doctor's supervision. Ptosis (drooping eyelid) is when the upper eyelid droops or sags due to weakness or paralysis of the levator muscle (responsible for raising the eyelid), or due to ...
Surgery involves gland replacement, not excision, by anchoring the membrane to the orbital rim or using a pocket technique. [3] In severely infected cases, preoperative antibiotics may be necessary by means of antibiotic eye ointment. [3] Removal of the gland was once an acceptable treatment, and made the eye appear completely normal. [5]
In simpler terms, a palatal obturator covers any fistulas (or "holes") in the roof of the mouth that lead to the nasal cavity, providing the wearer with a plastic/acrylic, removable roof of the mouth, which aids in speech, eating, and proper air flow. Palatal obturators are not to be confused with palatal lifts or other prosthetic devices. A ...
When the animal completely submerges, the nictitating membranes cover its eyes. Glands on the nictitating membrane secrete a salty lubricant that keeps the eye clean. When a crocodilian leaves the water and dries off, this substance is visible as "tears". [40] While eyesight in air is fairly good, it is significantly weakened underwater. [65]