I have trouble identifying what this dipness (shaded in blue) is caused by , looked for images I couldn’t find a good reference for it ,is it is caused by the lacrimal bone?
also I am unsure whether the eye lid (eyes corner) sets in front or behind the the lacrimal bone .
thanks in advance .
The reason you are having trouble finding a reference for that furrow is that it is not an “officially named” structure in the anatomical nomenclature. A few of the older anatomy texts named it (e.g. Infrapalpebral furrow, Inferior palpebral sulcus, palpebromalar sulcus, lower palpebral furrow, etc.) Anatomists Quain, Toldt, Wolff, etc. wrote about it, but it has been dropped in most modern texts.
The furrow is the result of a border between the muscles: levator labii alaeque nasi and the orbicularis oculi. Many of the muscles of the face insert into the skin of the face and in this area it is quite tight. This area deepens and often becomes a characteristic of old age or wasting diseases. The area is rich in vasculature, so it can appear dark with “circles under the eyes.”
Incidentally, it corresponds to the deep fold of the upper lid (palpebral sulcus).
For Reference: Wolff’s Anatomy of the Eye and Orbit 6th Ed, edited by RJ Last WB Saunders Company. 1968. has a very nice medical illustrations of the area in Chapter III The Appendages of the Eye, pp 182-240.