Two fibromuscular transverse ligaments related to the levator palpebrae superioris: Whitnall's ligament and an intermuscular transverse ligament.

BACKGROUND

This study was performed to reinvestigate the detailed anatomy of the connective tissues related to the levator palpebrae superioris (LPS).

MATERIALS AND METHODS

One hundred and twenty human orbits were prepared macroscopically or with the help of an operational microscope. Connective tissues related to the LPS were measured, removed, and prepared for histology. Different staining procedures including immunohistochemistry for alpha-smooth muscle actin were applied to analyze the quality of these tissues.

RESULTS

Preparation consistently revealed two definite fibromuscular transverse ligaments related to the LPS, i.e., Whitnall's ligament (WL) and a definite intermuscular transverse ligament (ITL) underlying the LPS. The ITL exhibited a greater anterio-posterior extension than WL. In sagittal section, the ITL was observed slightly more posterior in the orbit than WL. Histologically, both ligaments consisted of collagenous fibers, elastic fibers, and smooth muscle fibers. WL was connected with the LPS by sagittal fibroelastic connecting strands.

CONCLUSIONS

Two transverse ligaments of fibromuscular tissue, WL and the ITL, form a sleeve superior and inferior to the LPS. This sling is supposed to assist the LPS in its action and should be preserved at ptosis surgery.