This anatomical structure, called the lacrimal opening, is a channel located inside the tissue protrusion called the lacrimal papilla in the eye and is connected to a channel called the lacrimal duct. “Lacrimal” meaning “related to tears” does indeed have a meaning-related function.
Although it is generally thought to have the purpose of “secreting tears”, the structure that performs this function is actually a “tear fountain” and its location is located in the inner part of the eye, which is closer to the nose.
The task of these holes is to ensure that the secreted tears are reabsorbed.
These channels open into a structure called the lacrimal sac. The walls of these two structures consist of elastic tissue and are surrounded by fibers that form the lacrimal parts of the orbicularis muscles, also known as Horner’s muscles.
The length of the first part of the channels is 2 millimeters. Then comes a slightly wider part called the ampulla, this part is located at the bottom of the lacrimal canals.
The canals then continue for 8 millimeters horizontally, and the canals of the lower and upper eyelids merge into a single canal. Consisting of the junction of two channels, this channel pierces the periorbital structure surrounding the lacrimal sac and enters from the lateral part of the sac. The angle of entry of this channel into the pouch acts as a physiological valve cover and prevents the backflow of tears.
The main reason your nose runs when you cry is related to these holes and channels.
The lacrimal opening flexes or contracts depending on the action of the orbicularis muscles. Tears are transferred to this opening with the effect of gravity. Thus, tears are sent to the nasal cavity through the Hasner valve. These holes and ducts are thought to provide an evolutionary advantage, as excess tears will restrict vision.
Bonus: İlker Yılmaz, who used this channel and hole to squirt milk from his eye, was included in the Guinness Book of Records.
References: 1, 2
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